Spine



10.1055/b-0037-144946

Spine

























Table 1.1 Congenital and developmental abnormalities of the spinal cord or vertebrae


Table 1.2 Abnormalities involving the craniovertebral junction


Table 1.3 Intradural intramedullary lesions (spinal cord lesions)


Table 1.4 Dural and intradural extramedullary lesions


Table 1.5 Extradural lesions


Table 1.6 Solitary osseous lesions involving the spine


Table 1.7 Multifocal lesions and/or poorly defined signal abnormalities involving the spine


Table 1.8 Traumatic lesions involving the spine


Table 1.9 Lesions involving the sacrum



Introduction



Spine and Spinal Cord


Imaging techniques commonly used to evaluate for spinal abnormalities include MRI, MRA, CT, CT myelography, CTA, conventional angiography, and radiographs. MRI is a powerful imaging modality for evaluating normal spinal anatomy and pathologic conditions involving the spine and sacrum. Because of the high soft tissue contrast resolution of MRI and multiplanar imaging capabilities; pathologic disorders of bone marrow (such as neoplasm, inflammatory diseases, etc.), epidural soft tissues, disks, thecal sac, spinal cord, intradural and extradural nerves, ligaments, facet joints, and paravertebral structures are readily discerned to a much greater degree than with CT.


The normal spine is comprised of seven cervical, twelve thoracic, and five lumbar vertebrae ( Fig. 1.1 ). The upper two cervical vertebrae have different configurations than the other vertebrae. The atlas (C1) has a horizontal ringlike configuration with lateral masses that articulate with the occipital condyles superiorly and superior facets of C2 inferiorly ( Fig. 1.2 ). The dorsal margin of the upper dens is secured in position in relation to the anterior arch of C1 by the transverse ligament. Ligaments at the craniovertebral junction include the alar, transverse, and apical ligaments (see Fig. 1.50 and Fig. 1.51 ). The alar ligaments connect the lateral margins of the odontoid process with the lateral masses of C1 and medial margins of the foramen magnum. The alar ligaments limit atlantoaxial rotation. The transverse ligament extends medially from the tubercles at the inner aspects of the lateral articulating masses of C1 behind the dens, stabilizing the dens with the anterior arch of C1. The transverse ligament is the horizontal portion of the cruciform ligament, which also has fibers that extend from the transverse ligament superiorly to the clivus, and inferiorly to the posterior surface of the dens. The apical ligament (middle odontoid ligament) extends from the upper margin of the dens to the anterior clival portion of the foramen magnum. The tectorial membrane is an upward extension from the posterior longitudinal ligament that connects with the body of C2 and the occipital bone (jugular tubercle and cranial base). Other ligaments involved with stabilization of the mid and lower cervical spine include the anterior and posterior longitudinal ligaments, ligamenta flava, and nuchal ligament ( Fig. 1.3 ). Various anomalies occur in this region, such as atlanto-occipital assimilation, segmentation (block vertebrae, etc.), basiocciput hypoplasia, condylus tertius, os odontoideum, etc. The lower five cervical vertebral bodies have more rectangular shapes, with progressive enlargement inferiorly. Superior projections from the cervical vertebral bodies laterally form the uncovertebral joints. The transverse processes are located anterolateral to the vertebral bodies and contain the foramina transversaria, which contain vertebral arteries and veins. The posterior elements consist of paired pedicles, articular pillars, laminae, and spinous processes. The cervical spine has a normal lordosis.

Lateral view of the normal osseous anatomy and alignment of the spine. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.
Lateral view of the normal osseous anatomy and alignment of the cervical vertebrae. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.

The twelve thoracic vertebral bodies and five lumbar vertebral bodies progressively increase in size caudally ( Fig. 1.1, Fig. 1.2, Fig. 1.4 , and Fig. 1.5 ).

Lateral view of the normal osseous and ligamentous anatomy of the cervical spine. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.
Lateral view of the normal osseous anatomy and alignment of the thoracic vertebrae. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.

The posterior elements include the pedicles, transverse processes, laminae, and spinous processes. The transverse processes of the thoracic vertebrae also have articulation sites for ribs. The thoracic spine has a normal kyphosis and the lumbar spine a normal lordosis. Anterior and posterior longitudinal ligaments connect the vertebrae, and interspinous ligaments and ligamentum flavum provide stability for the posterior elements ( Fig. 1.6 ).


The cortical margins of the vertebral bodies have dense compact bone structure that results in low signal on T1-and T2-weighted images. The medullary compartments of the vertebrae are comprised of bone marrow and trabecular bone. The signal intensity of the medullary compartment is primarily due to the proportion of red versus yellow marrow. The proportion of yellow to red marrow progressively increases with age, resulting in increased marrow signal on T1-weighted images. Similar changes are pronounced in patients who have received spinal irradiation. Pathologic processes (such as tumor, inflammation, or infection) cause increased T1 and T2 relaxation coefficients, which result in decreased signal on T1-weighted images and increased signal on T2-weighted images. MRI with fat-signal suppression techniques (short time to inversion recovery [STIR] sequence, and fat-frequency-saturated T1- and T2-weighted sequences) provide optimal contrast between normal and pathologic marrow. Corresponding abnormal gadolinium enhancement is also usually seen at the pathologic sites, which can also be optimized using fat-frequency-saturated T1-weighted sequences. Because it allows direct visualization of these pathologic processes in the marrow, MRI can often detect the abnormalities sooner than CT, which relies on later indirect signs of trabecular destruction for confirmation of disease.

Lateral view of the normal osseous anatomy and alignment of the lumbar vertebrae. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.

The intervertebral disks enable flexibility of the spine. The two major components (nucleus pulposus and annulus fibrosus) of normal disks are usually seen well with MRI. The outer annulus fibrosus is made of dense fibrocartilage and has low signal on T1- and T2-weighted images. The central nucleus pulposus is made of gelatinous material and usually has high signal on T2-weighted images. The combination of various factors, such as decreased turgor of the nucleus pulposus, and loss of elasticity of the annulus, with or without tears, results in degenerative changes in the disks. MRI features of disk degeneration include decreased disk height, decreased signal of nucleus pulposus on T2-weighted images, disk bulging, and associated posterior vertebral body osteophytes. Tears of the annulus fibrosus often have high signal on T2-weighted images at the site of injury. Annular tears can be transverse, which are oriented parallel to the outer annular fibers, and are sometimes referred to as annular fissures. Annual tears can also be radial, extending from the central portion of the disk to the periphery. Radial tears are often clinically significant, and are associated with disk herniations. The term disk herniation usually refers to extension of the nucleus pulposus through an annular tear beyond the margins of the adjacent vertebral body end plates. Disk herniations can be further subdivided into protrusions (when the head of the herniation equals the neck in size), extrusions (when the head of the herniation is larger than the neck), or extruded fragments (when there is separation of the herniated disk fragment from the disk of origin). Disk herniations can occur in any portion of the disk. Posterior and posterolateral herniations can cause compression of the thecal sac and contents, as well as compression of epidural nerve roots in the lateral recesses or within the intervertebral foramina. Lateral and anterior disk herniations are less common but can cause hematomas in adjacent structures. Disk herniations that occur superiorly or inferiorly result in focal depressions of the end plates, i.e., Schmorl′s nodes. Recurrent disk herniations can be delineated from scar or granulation tissue because herniated disks do not typically enhance after gadolinium contrast administration, whereas scar/granulation tissue typically enhances.

Lateral view of the normal ligamentous and osseous anatomy at the thoracolumbar junction. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.

The thecal sac is a meningeal covered compartment that contains cerebrospinal fluid (CSF), which is contiguous with the basal subarachnoid cisterns. The thecal sac extends from the upper cervical level to the level of the sacrum, and it contains the spinal cord and exiting nerve roots. The distal end of the conus medullaris is normally located at the T12–L1 level in adults. Lesions within the thecal sac are categorized as intradural and intra- or extramedullary. Intramedullary lesions directly involve the spinal cord, whereas extramedullary lesions do not primarily involve the spinal cord. Extradural or epidural lesions refer to spinal lesions outside of the thecal sac.


The high soft tissue contrast resolution of MRI enables evaluation of various intradural pathologic conditions, such as congenital malformations, neoplasms, benign mass lesions (dermoid, arachnoid cyst, etc.), inflammatory/infectious processes, traumatic injuries (spinal cord, contusions, hematomas), vascular malformations, and spinal cord ischemia/infarction, as well as the adjacent CSF and nerve roots. With the intravenous administration of gadolinium contrast agents, MRI is useful for evaluating lesions within the spinal cord as well as neoplastic or inflammatory diseases within the thecal sac.


The normal blood supply to the spinal cord consists of seven or eight arteries that enter the spinal canal through the intervertebral foramina, which divide into anterior and posterior segmental medullary arteries to supply the three main vascular territories of the spinal cord (cervicothoracic—cervical and upper three thoracic levels; mid thoracic—T4 level to T7 level; and thoracolumbar—T8 level to lumbosacral plexus) ( Fig. 1.7 and Fig. 1.8 ). The cervicothoracic vascular distribution is supplied by radicular branches arising from the vertebral arteries and costocervical trunk. The midthoracic territory is often supplied by a radicular branch at the T7 level. The thoracolumbar territory is supplied by a single artery arising from the ninth, tenth, eleventh, or twelfth intercostal arteries (75%); the fifth, sixth, seventh, or eighth intercostal arteries (15%); or the first or second lumbar arteries (10%). The artery is referred to as the artery of Adamkiewicz. The anterior segmental medullary arteries supply the longitudinally oriented anterior spinal artery, which is located in the midline anteriorly adjacent to the spinal cord and supplies the gray matter and central white matter of the spinal cord. The posterior segmental medullary arteries also supply the two major longitudinally oriented posterior spinal arteries, which course along the posterolateral sulci of the spinal cord and supply one-third to one-half of the outer rim of the spinal cord via a peripheral anastomotic plexus. Ischemia or infarcts involving the spinal cord are rare disorders associated with atherosclerosis, diabetes, hypertension, abdominal aortic aneurysms, and abdominal aortic surgery. Venous blood from the spinal cord drains into the anterior and posterior venous plexuses, which connect to the azygos and hemiazygos veins via the intervertebral foramina ( Fig. 1.9 ). Vascular malformations can be seen within the thecal sac, with or without involvement of the spinal cord.


Epidural structures of clinical importance include the lateral recesses (anterolateral portions of the spinal canal located between the thecal sac and pedicles and that contain nerve roots, vessels, and fat), the dorsal epidural fat pad, the posterior elements and facet joints, and the posterior longitudinal ligament and ligamentum flavum. The intervertebral foramina are bony channels between the pedicles through which the nerves traverse.


Narrowing of the thecal sac, lateral recesses, and intervertebral foramina can result in clinical signs and symptoms. Narrowing can be caused by disk herniations, posterior vertebral body osteophytes, hypertrophy of the ligamentum flavum and facet joints, synovial cysts, excessive epidural fat, epidural neoplasms, abscesses, hematomas, spinal fractures, and spondylolisthesis or spondylolysis. MRI is useful for evaluating these disorders and for categorizing the degree of narrowing of the thecal sac, as well as compression of nerve roots in the lateral recesses and intervertebral foramina.

Axial view of the arterial supply to the vertebrae and spinal canal. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.
The arterial supply to the spinal cord. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.
The venous drainage from the vertebral column. From THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System, © Thieme 2005, Illustration by Karl Wesker.


Spinal Development


During the second week of gestation, the developing embryo consists of a layer of cells adjacent to the yolk sac referred to as the hypoblast, and a layer of cells adjacent to the amnion referred to as the epiblast. Cells in the midline of the embryo form the primitive knot (Hensen′s node) and adjacent primitive streak posteriorly. At the beginning of the third week, cells from the rostral portion of the primitive streak (Hensen′s node) extend between the epiblast and hypoblast to eventually form the notochord. The gastrulation stage of development of the spine begins during the third week of gestation, when the bilaminar embryonic disk differentiates into a trilaminar disk consisting of endoderm, mesoderm, and ectoderm ( Fig. 1.10 ). During the third week of gestation, the notochord induces the overlying ectoderm to form the neural plate, which thickens and folds to form the neural tube (this process is referred to as primary neurulation) ( Fig. 1.10 ) . After 5 weeks, the embryonic caudal cell mass forms the secondary neural tube, which will form the tip of the conus medullaris and filum terminale in a process referred to as secondary neurulation.


Between the fourth and fifth weeks of gestation, the notochord also induces adjacent paraxial mesoderm (derived from the primitive streak) to form bilateral somites, which form the myotomes that will eventually develop into the paraspinal muscles and skin and the sclerotomes that will develop into the bones, cartilage, and ligaments of the spinal column ( Fig. 1.10 and Fig. 1.11 ). At 5 weeks, each sclerotome separates into superior and inferior halves, which fuse with corresponding halves of the adjacent sclerotomes to form the vertebral bodies (this process is referred to as resegmentation). Portions of the notochord between the newly formed vertebral bodies evolve into the nucleus pulposus of each disk. Chondrification of the vertebrae occurs after 6 weeks, followed by ossification after 9 weeks. Except for C1 and C2, each vertebra has two ossification centers in the vertebral body that merge, and single ossification centers in each side of the vertebral arch ( Fig. 1.12 ). In C1, a single ossification center or two or more ossification centers can occur in the anterior arch. Six ossification centers and four synchondroses typically occur in C2 ( Fig. 1.13 ).


Disruption of any of these developmental processes can lead to the various anomalies of the spinal cord or vertebrae.

Early embryologic development of the spinal cord, myotomes, sclerotomes, and dermatomes in the first month of gestation.
Early embryologic development of the vertebrae between 4 and 5 weeks’ gestation.
Locations of ossification centers in the vertebrae and sacrum.
Multiple ossification centers in C1 and C2 at birth.


Table 1.1 Congenital and developmental abnormalities of the spinal cord or vertebrae



  • Congenital and Developmental Abnormalities Involving Neural Tissue and Meninges




    • Chiari I malformation



    • Chiari II malformation (Arnold-Chiari malformation)



    • Chiari III malformation



    • Myelomeningocele/Myelocele



    • Myelocystocele



    • Lipomyelocele/Lipomyelomeningocele



    • Intradural lipoma



    • Dorsal dermal sinus



    • Tethered spinal cord, thickened filum terminale



    • Fibrolipoma of the filum terminale



    • Meningocele



    • Diastematomyelia (split-cord malformation)



    • Ventriculus terminalis of the conus medullaris



    • Neurenteric cyst



    • Epidermoid



    • Dermoid



  • Congenital and Developmental Abnormalities Involving Vertebrae




    • Atlanto-occipital assimilation/Nonsegmentation



    • Atlas anomalies



    • Os odontoideum



    • Klippel-Feil anomaly



    • Sprengel deformity



    • Hemivertebrae



    • Butterfly vertebra



    • Tripediculate vertebra



    • Spina bifida occulta



    • Spina bifida aperta (Spina bifida cystica)



    • Syndrome of caudal regression



    • Short pedicles—Congenital/developmental spinal stenosis



  • Genetic Developmental Abnormalities of the Spine




    • Achondroplasia



    • Neurofibromatosis type 1



    • Marfan syndrome



    • Mucopolysaccharidosis (MPS)



    • Spondylometaphyseal dysplasia (SMD)























































































































































Congenital and developmental abnormalities of the spinal cord or vertebrae

Abnormalities

Imaging Findings

Comments

Congenital and Developmental Abnormalities Involving Neural Tissue and Meninges


Chiari I malformation ( Fig. 1.14 )

Cerebellar tonsils extend more than 5 mm below the foramen magnum in adults, or 6 mm in children < 10 years old. Syringohydromyelia occurs in 20 to 40% of cases, hydrocephalus in 25%, and basilar impression in 25%. Less common associations are Klippel-Feil anomaly and atlanto-occipital assimilation.

Cerebellar tonsillar ectopia. Most common anomaly of CNS. Not associated with myelomeningocele.


Chiari II malformation (Arnold-Chiari malformation) ( Fig. 1.15 )

Small posterior cranial fossa with gaping foramen magnum, through which there is an inferiorly positioned vermis associated with a cervicomedullary kink. Beaked dorsal margin of the tectal plate. Myeloceles or myelomeningoceles in nearly all patients. Hydrocephalus and syringohydromyelia common. Dilated lateral ventricles posteriorly (colpocephaly).

Complex anomaly involving the cerebrum, cerebellum, brainstem, spinal cord, ventricles, skull, and dura. Failure of fetal neural folds to develop properly results in altered development affecting multiple sites of the CNS.


Chiari III malformation

Features of Chiari II plus lower occipital or high cervical encephalocele.

Rare anomaly associated with high mortality.


Myelomeningocele/Myelocele ( Fig. 1.15 )

MRI is often performed after surgical repair of myelocele or myelomeningocele. Preoperative MRI shows posterior protrusion of spinal contents and unfolded neural tube (neural placode) through defects in the bony dorsal elements of the involved vertebrae or sacral elements. The neural placode is usually located at the lower lumbosacral region, with resultant tethering of the spinal cord. If the neural placode is flush with the adjacent skin surface, the anomaly is referred to as a myelocele. If the neural placode extends above the adjacent skin surface, the anomaly is referred to as a myelomeningocele. ± syringohydromyelia.

Failure of developmental closure of the caudal neural tube results in an unfolded neural tube (neural placode) exposed to the dorsal surface in the midline without overlying skin. Other features associated with myelomeningocele and myelocele include dorsal bony dysraphism, deficient dura posteriorly at the site of the neural placode, and Chiari II malformation. By definition, the spinal cord is tethered. These abnormalities are usually repaired surgically soon after birth.


Myelocystocele ( Fig. 1.16 and Fig. 1.17 )

A terminal myelocystocele is a herniation of a tethered lower spinal cord (containing a localized cystic dilatation of the central canal of the spinal cord) into a posterior meningocele. The posterior meningocele extends through a spina bifida and is located deep to the dorsal subcutaneous fat. Because myelocystoceles are covered by skin, they are considerd a form of occult spinal dysraphism.


A nonterminal myelocystocele is a dorsal herniation of a dilated central canal through a spina bifida. Nonterminal myelocystoceles are covered by skin and subcutaneous tissue.

Terminal myelocystoceles represent 1–5% of skincovered masses at the dorsal lumbosacral region. There is anomalous development of the lower spinal cord, vertebral column, sacrum, and meninges, ± association with genitourinary tract anomalies (epispadias, caudal regression syndrome, anomalies of the genitourinary system and hindgut). Nonterminal myelocystoceles occur most commonly in the cervical and thoracic regions.


Lipomyelocele/Lipomyelomeningocele ( Fig. 1.18 and Fig. 1.19 )

Unfolded caudal neural tube (neural placode) covered by a lipoma that is continuous with the dorsal subcutaneous fat through defects (spina bifida) involving the bony dorsal vertebral elements. The neural placode is usually located at the lower lumbosacral region, with resultant tethering of the spinal cord, ± syringohydromyelia. With lipomyelomeningocele, the dorsal lipoma, which extends into the spinal canal, is asymmetric, resulting in rotation of the placode and meningocele.

Failure of developmental closure of the caudal neural tube results in an unfolded neural tube (neural placode) connected to a lipoma that is continuous with the subcutaneous fat. The overlying skin is intact, although the subcutaneous lipoma usually protrudes dorsally. The nerve roots arise from the placode. Features associated with lipomyelomeningoceles and lipomyeloceles include tethered spinal cords, dorsal bony dysraphism, and deficient dura posteriorly at the site of the neural placode. Not associated with Chiari II malformations. Diagnosis occurs more often in children, occasionally in adults.


Intradural lipoma ( Fig. 1.20, Fig. 1.21 , and Fig. 1.22 )

Focal dorsal dysraphic spinal cord attached to a lipoma, which has high signal on T1-weighted imaging. The lipoma often extends from the central canal of the spinal cord to the dorsal pial surface, + intact dorsal dural margins, and posterior vertebral elements.

Intradural lipomas usually occur in the cervical or thoracic region. Can result in fixation of the upper and mid portions of the spinal cord, or tethering of the lower spinal cord.


Dorsal dermal sinus ( Fig. 1.23 )

Thin tubular structure extending internally from a dimple in the dorsal skin of the lower back, with or without extension into the spinal canal through the median raphe or spina bifida, ± associated dermoid or epidermoid in spinal canal (50%).

Epithelium-lined fistula that extends from a dimple in the dorsal skin surface (± hairy nevus, hyperpigmented patch, or hemangioma at ostium of dimple) toward and/or into the spinal canal. Results from lack of normal developmental separation of superficial ectoderm from neural ectoderm. Location: Lumbar > thoracic > occipital regions. Potential source of infection involving spine and spinal canal.


Tethered spinal cord, thickened filum terminale ( Fig. 1.24 and Fig. 1.25 )

The distal end of the conus medullaris is located below the L2–L3 level, in association with a thickened filum terminale that can be fibrous or composed of fibrous and adipose tissue.

Abnormal thickening of the filum terminale can limit the normal developmental ascent of the conus medullaris, resulting in a tethered spinal cord. Presenting symptoms include leg weakness, back and/or leg pain, scoliosis, gait problems, and bowel and/or bladder symptoms. Occurs in 0.1% of young children. Traction on the spinal cord results in decreased blood flow, causing abnormal metabolic changes and neurologic dysfunction. For symptomatic patients, transection of the filum can lead to resolution of symptoms.


Fibrolipoma of the filum terminale ( Fig. 1.26 )

Thin linear zone of high signal on T1-weighted imaging along the filum terminale, usually < 3 mm in diameter, with normal position of conus medullaris (typically not associated with tethering of spinal cord).

Asymptomatic incidental finding that occurs in ~ 5% of patients. The distal end of the conus is normally positioned.


Meningocele ( Fig. 1.27 )

Protrusion of dura, CSF, and meninges laterally from the thecal sac or through a dorsal vertebral defect, caused by either surgical laminectomies or congenital osseous anomaly. Sacral meningoceles can alternatively extend anteriorly through a defect in the sacrum and can be associated with neurofibromatosis type 1.

Acquired meningoceles are more common than meningoceles resulting from congenital dorsal bony dysraphism or localized weakening of the dura. Anterior sacral meningoceles can result from trauma or be associated with mesenchymal dysplasias (neurofibromatosis type 1, Marfan syndrome, or syndrome of caudal regression). Multiple lateral meningoceles involving the spine can be seen with a rare hereditary connective tissue disorder (lateral meningocele syndrome), which is often associated with facial dysmorphism, hypotonia, muscle weakness, scoliosis, abdominal hernias, and cryptorchidism.


Diastematomyelia (split-cord malformation) ( Fig. 1.28 and Fig. 1.29 )

Division of spinal cord into two hemicords, usually from T9 to S1, ± fibrous or bony septum that partially or completely separates the two hemicords. Hemicords located within two separate dural tubes separated by a fibrous or bony septum over multiple vertebral levels are referred to as type I split-cord malformations and account for up to 70% of cases. Hemicords located within one dural tube are referred to as type II split-cord malformations. ± Syringohydromyelia at, above, or below the zone of diastematomyelia. Often associated with tethering of the conus medullaris, osseous anomalies (butterfly vertebrae, hemivertebrae, block vertebrae). Diastematomyelia is seen in 15% of patients with Chiari II malformations.

Developmental anomalies related to abnormal splitting of the embryonic notochord, with abnormal adhesions between the ectoderm and endoderm. Can present in children with clubfeet, or adults and children with neurogenic bladder, lower extremity weakness, and chronic pain, ± association with nevi or lipomas.


Ventriculus terminalis of the conus medullaris ( Fig. 1.30 )

Well-defined, longitudinally oriented, intramedullary zone with low signal on T1-weighted imaging and high signal on T2-weighted imaging (equivalent to CSF) located in conus medullaris. This intramedullary cystic zone usually measures 25–40 mm craniocaudad × 17–25 mm in the axial plane and is surrounded by a thin rim of spinal cord 2 mm thick or less. There is no gadolinium contrast enhancement, and usually no syrinx above the level of the intramedullary cystic zone in the conus medullaris.

Ventriculus terminalis is a congenital anomaly that consists of a persistent, ependymal-lined, dilated lumen containing CSF located in the conus medullaris. The lumen forms during embryonic development of the spinal cord during the stage of secondary neurulation (~ 5 weeks of gestation).


Neurenteric cyst ( Fig. 1.31 )

MRI: Well-circumscribed, spheroid, intradural extra-axial or extramedullary lesions, with low, intermediate, or high signal on T1-weighted imaging (related to protein concentration) and on T2-weighted imaging, and usually no gadolinium contrast enhancement.


CT: Circumscribed, intradural extra-axial or extramedullary structures with low-intermediate attenuation and usually no contrast enhancement.

Neurenteric cysts are malformations in which there is a persistent communication between the ventrally located endoderm and the dorsally located ectoderm secondary to developmental failure of separation of the notochord and foregut. Obliteration of portions of a dorsal enteric sinus can result in cysts lined by endothelium, fibrous cords, or sinuses. Observed in patients < 40 years old. Location: Thoracic > cervical > posterior cranial fossa > craniovertebral junction > lumbar. Usually midline in position and often ventral to the spinal cord or brainstem. Associated with anomalies of the adjacent vertebrae and clivus.


Epidermoid

MRI: Well-circumscribed spheroid or multilobulated intradural ectodermal-inclusion cystic lesions with low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging, mixed low, intermediate, or high signal on FLAIR images, and no gadolinium contrast enhancement. Can be associated with dorsal dermal sinus.


CT: Well-circumscribed spheroid or multilobulated extramedullary ectodermal-inclusion cystic lesions with low-intermediate attenuation.

Nonneoplastic congenital or acquired extra-axial or extramedullary lesions filled with desquamated cells and keratinaceous debris, usually with mild mass effect on adjacent spinal cord and/or nerve roots, ± related clinical symptoms. Occur in adults and in males and females equally.


Dermoid ( Fig. 1.32 )

MRI: Well-circumscribed spheroid or multilobulated intradural lesions, usually with high signal on T1-weighted images and variable low, intermediate, and/or high signal on T2-weighted imaging. There is no gadolinium contrast enhancement, ± fluid–fluid or fluid–debris levels.


CT: Well-circumscribed spheroid or multilobulated extramedullary lesions, usually with low attenuation, ± fat–fluid or fluid–debris levels. Can be associated with dorsal dermal sinus.

Nonneoplastic congenital or acquired ectodermal-inclusion cystic lesions filled with lipid material, cholesterol, desquamated cells, and keratinaceous debris, usually with mild mass effect on adjacent brain, ± related clinical symptoms. Occur in adults and in males slightly more often than in females. Can cause chemical meningitis if dermoid cyst ruptures into the subarachnoid space.


Congenital and Developmental Abnormalities Involving Vertebrae


Atlanto-occipital assimilation/Nonsegmentation (See Fig. 1.56 )

Often seen as fusion of the occipital condyle with the anterior arch, posterior arch, or one or both lateral masses of C1, or combinations of the above. In 20% of cases, there are associated congenital anomalies, such as external ear deformities, cleft palate, C2–C3 nonsegmentation, and/or cervical ribs.

Most common congenital anomaly of the craniovertebral junction. Failure of segmentation of the occipital condyles (fourth occipital sclerotome) and the C1 vertebra (first cervical sclerotome). Can be associated with C1–C2 instability.


Atlas anomalies (See Fig. 1.57 and Fig. 1.58 )

Unilateral or bilateral hypoplasia/aplasia of the posterior arch of C1. Clefts can also be seen in C1, most commonly at the posterior arch in the midline.

The first spinal sclerotome forms the atlas vertebra, while caudal portions of the proatlas form the lateral masses and upper portions of the posterior arch. Anomalies include aplasia of C1 or partial aplasia/hypoplasia of the posterior arch, ± atlanto-axial subluxation. Another, more common type of anomaly involving C1 is clefts in the atlas arches (rachischisis) from developmentally defective cartilage formation. Clefts most commonly occur in the posterior arch in the midline (> 90%), followed by lateral clefts and anterior clefts.


Os odontoideum (See Fig. 1.59 and Fig. 1.60 )

Separate, corticated, bony structure positioned below the basion and superior to the C2 body at the normally expected site of the dens, often associated with enlargement of the anterior arch of C1 (which may sometimes be larger than the adjacent os odontoideum). Instability can result when the gap between the os and the body of C2 is above the plane of the superior articular facets and below the transverse ligament.

Independent bony structure positioned superior to the C2 body and lower dens at the normally expected site of the mid to upper dens, often associated with hypertrophy of the anterior arch of C1, ± cruciate ligament incompetence/instability (± zone of high signal on T2-weighted imaging in spinal cord). Os odontoideum can be associated with Klippel-Feil anomaly, spondyloepiphyseal dysplasia, Down syndrome, and Morquio syndrome. Possibly a normal variant or due to childhood injury (between 1 and 4 years), with fracture/separation of the cartilaginous plate between the dens and body of axis.


Klippel-Feil anomaly ( Fig. 1.33 )

Segmentation anomaly involving adjacent vertebral bodies, which have narrow, tall configurations with decreased AP dimensions, absent or small intervening disks, ± fusion of posterior elements, ± occipitalization of atlas, ± congenital scoliosis, ± kyphosis, ± Sprengel deformity.

Represents congenital partial or complete fusion of two or more adjacent vertebrae resulting from failure of segmentation of somites (third to eighth weeks of gestation). Occurs in 1/40,000 births. Can be asymptomatic or result in limitations in range of neck motion. Can be associated with Chiari I malformation, syringohydromyelia, diastematomyelia, anterior meningocele, or neurenteric cyst.


Sprengel deformity ( Fig. 1.34 )

The scapula is malformed and in an abnormally high, adducted position. The scapula often has a convex medial margin, concave lateral margin, decreased height to width ratio, and associated hypoplasia of the scapular muscle. In up to 50% of patients, omovertebral bone or a fibrocartilaginous structure is present between the medial border of the scapula and cervical vertebrae. Can be associated with vertebral anomalies, such as butterfly vertebra, Klippel-Feil anomaly, diastematomyelia, and spina bifida occulta.

Dysmorphic high-positioned scapula at birth that results from lack of normal caudal migration of the scapula during embryogenesis. During the fifth week of gestation, the scapula develops as a mesenchymal structure adjacent to the C4 or C5 vertebra. From the fifth to twelfth weeks of gestation, the fetal scapula normally migrates inferiorly to its normal position, where the inferior angle is located at the T6–T8 levels. In up to 50% of cases, a fibrous, cartilaginous, and/or osseous (omovertebral bone) structure is present between the cervical vertebrae and scapula. Surgical resection of the interposed structure between the scapula and spine can be beneficial. Sprengel deformity can occur in association with Klippel-Feil anomaly, hemivertebrae, diastematomyelia, spina bifida occulta, and morphologic rib and clavicular abnormalities.


Hemivertebrae ( Fig. 1.35 )

Wedge-shaped vertebral body, ± molding of adjacent vertebral bodies toward the shortened side of hemivertebra.

Disordered embryogenesis in which the paramedian centers of chondrification fail to merge, resulting in failure of formation of the ossification center on one side of the vertebral body. May be associated with scoliosis.


Butterfly vertebra ( Fig. 1.36 )

Paired hemivertebrae with constriction of height in the midsagittal portion of the vertebral body, ± molding of adjacent vertebral bodies toward midsagittal constriction.

Disordered embryogenesis in which there is persistence of separate ossification centers in each side of the vertebral body (failure of fusion).


Tripediculate vertebra ( Fig. 1.37 )

Wedge-shaped vertebral body containing two pedicles on enlarged side and one pedicle on the shortened side. There may be multiple levels of involvement, ± adjacent hemivertebrae, ± molding of adjacent vertebral bodies toward shortened side of involved segments, + scoliosis.

Disordered embryogenesis at more than one level, with asymmetric malsegmentation, + scoliosis.


Spina bifida occulta ( Fig. 1.38 )

Minimal defect near midline where lamina do not fuse, with no extension of spinal contents through defect. Most commonly seen at the S1 level; other sites include C1, C7, T1, and L5.

Mild anomaly with failure of fusion of dorsal vertebral arches (lamina) in midline. Usually a benign normal variation.


Spina bifida aperta (Spina bifida cystica) ( Fig. 1.39 )

Wide defect where lamina are unfused, and through which spinal contents extend dorsally (myelocele, myelomeningocele, meningocele, lipomyelocele, lipomyelomeningocele, and myelocystocele).

Usually associated with significant clinical findings related to the severity and type of neural tube defect.


Syndrome of caudal regression ( Fig. 1.40, Fig. 1.41 , and Fig. 1.42 )

Partial or complete agenesis of sacrum/coccyx, ± involvement of lower thoracolumbar spine. Symmetric sacral agenesis > lumbar agenesis > lumbar agenesis with fused ilia > unilateral sacral agenesis. Prominent narrowing of thecal sac and spinal canal below lowest normal vertebral level, ± myelomeningocele, diastematomyelia, tethered spinal cord, thickened filum, and lipoma.

Congenital anomalies related to failure of canalization and retrogressive differentiation, resulting in partial sacral agenesis and/or distal thoracolumbar agenesis, ± association with other anomalies, such as imperforate anus, anorectal atresia/stenosis, malformed genitalia, and renal dysplasia, ± distal muscle weakness, paralysis, hypoplasia of lower extremities, sensory deficits, lax sphincters, and neurogenic bladder. Mild forms may not have clinical correlates.


Short pedicles—Congenital/developmental spinal stenosis ( Fig. 1.43 )

Narrowing of the anteroposterior dimension of the thecal sac to less than 10 mm, resulting predominantly from developmentally short pedicles. May occur at one or multiple levels.

Developmental variation with potential predisposition to spinal cord injury from traumatic injuries or disk herniations, as well as early symptomatic spinal stenosis from degenerative changes.


Genetic Developmental Abnormalities of the Spine


Achondroplasia ( Fig. 1.44 )

Vertebral anomalies include shortening and flattening of vertebral bodies, ± anterior wedging of one or multiple vertebral bodies, and shortened pedicles with spinal stenosis.


Anomalies at the craniovertebral junction include small foramen magnum, basioccipital hypoplasia, odontoid hypoplasia, basilar invagination, hypertrophy of posterior arch of C1, platybasia, and atlanto-occipital dislocation.

Autosomal dominant rhizomelic dwarfism with abnormally reduced endochondral bone formation. Most common nonlethal bone dysplasia and shortlimbed dwarfism, with an incidence of 1/15,000 live births. More than 80–90% of cases are caused by spontaneous mutations involving the gene that encodes the fibroblast growth factor receptor 3 (FGFR3) on chromosome 4p16.3. Mutations typically occur on the paternal chromosome and are associated with increased paternal age. The mutated gene impairs endochondral bone formation and longitudinal lengthening of long bones.


Neurofibromatosis type 1 ( Fig. 1.45 )

CT: Neurofibromas are ovoid or fusiform lesions with low-intermediate attenuation. Lesions can show contrast enhancement. Often erode adjacent bone. Dural dysplasia/ectasia, often with scalloping of the dorsal aspects of vertebral bodies, dilatation of intervertebral and sacral foraminal nerve sheaths, and lateral meningoceles.


MRI: Neurofibromas are circumscribed or lobulated extra-, intra-, or both intra- and extradural lesions, with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging (T2WI), + prominent gadolinium (Gd) contrast enhancement. High signal on T2WI and Gd contrast enhancement can be heterogeneous in large lesions. Findings with dural dysplasia include erosions of adjacent vertebral bone by dilated dura containing CSF, ± lateral meningoceles.

Autosomal dominant disorder (1/2,500 births) caused by mutations of the neurofibromin gene on chromosome 17q11.2. Represents the most common type of neurocutaneous syndrome, and is associated with neoplasms of the central and peripheral nervous systems (optic gliomas, astrocytomas, plexiform and solitary neurofibromas) and skin lesions (caféau-lait spots, axillary and inguinal freckling). Also associated with meningeal and skull dysplasias, as well as hamartomas of the iris (Lisch nodules). Dural dysplasia/ectasia can involve multiple spinal levels and can also occur with Marfan syndrome.


Marfan syndrome ( Fig. 1.46 )

CT: Dural ectasia, often with scalloping of the dorsal aspects of vertebral bodies, dilatation of intervertebral and sacral foraminal nerve sheaths, and lateral meningoceles.


MRI: Findings with dural ectasia include erosions of adjacent vertebral bone by dilated dura containing CSF, ± anterior or lateral meningoceles.

Autosomal dominant disorder caused by missense mutations of the fibrillin-1 gene on chromosome 15, resulting in abnormal connective tissue. Prevalence of 1/10,000. Clinical findings include aortic root dilatation, aortic dissection or rupture, ocular lens dislocations, and dural ectasia. Dural ectasia is defined as expansion of the dural sac, often in association with herniation of nerve root sleeves through foramina. In addition to occurring in neurofibromatosis type 1 and Marfan syndrome, dural ectasia can occur in Ehlers-Danlos syndrome, in ankylosing spondylitis, in scoliosis, and with trauma.


Mucopolysaccharidosis (MPS) ( Fig. 1.47 and Fig. 1.48 )

MRI: Hypoplastic/dysplastic dens (decreased height, broad base with flattened tip) and soft tissue thickening adjacent to the dens at the C1–C2 level that has low-intermediate signal on T1- and T2-weighted imaging. Most commonly occurs with Morquio syndrome (MPS type IV) and Hurler syndrome (MPS type I). Can result in spinal canal stenosis. Wedge-shaped vertebral bodies with anterior beaks (central = Morquio; anteroinferior = Hurler/Hunter), decreased height of vertebral bodies, widened disks, spinal canal stenosis, thick clavicles, paddle-shaped ribs, widened symphysis pubis, flared iliac bones, widening of the femoral necks, ± absent femoral heads, coxa valga, shortened metacarpal bones, Madelung′s deformity, and diaphyseal widening of long bones. Marrow MRI signal may be within normal limits, or slightly decreased on T1-weighted imaging, and/or slightly increased on T2-weighted imaging.

Inherited disorders of glycosaminoglycan (GAG) catabolism from defects in specific lysosomal enzymes. MPS I (Hurler-Scheie syndromes) = deficiency of α-L-iduronidase; MPS II (Hunter syndrome) = X-linked deficiency of iduronate-2-sulfatase; MPS III (Sanfilippo A, B, C, D) = autosomal recessive deficiency of enzymes that break down heparan sulfate; MPS IV (Morquio syndrome) = autosomal recessive deficiency of galactose 6-sulfate sulfatase (type A Morquio syndrome) or β-galactosidase (type B Morquio syndrome); MPS VI (Maroteaux-Lamy syndrome) = autosomal recessive deficiency of N- acetylgalactosamine-4-sulfatase ; MPS VII (Sly syndrome) = autosomal recessive deficiency of β-glucuronidase ; MPS IX = hyaluronidase deficiency. These disorders are characterized by accumulation of GAGs in lysosomes, extracellular matrix, joint fluid, and connective tissue, which results in axonal loss and demyelination. Treatments include enzyme replacement and bone marrow transplantation.


Spondylometaphyseal dysplasia (SMD) ( Fig. 1.49 )

Spine: Kyphoscoliosis, atlanto-axial instability, platyspondyly with rounded anterior margins of the vertebral bodies, vertebral bodies wider than pedicles (“overfaced pedicles”), narrowing of the interpedicular distances at the lower lumbar spine, ± amorphous ossifications in posterior portions of vertebral bodies. Tubular bones: Metaphyseal dysplasia observed in children more than 5 years old, usually involving proximal femurs, variable in other bones. Femoral necks are short and there are irregularities and sclerosis of metaphyses, as well as coxa vara, ± irregular femoral epiphyses, ± radiolucent bands at metadiaphyseal junction.


Flat bones: Short, squared iliac bones, and acetabula have a horizontal configuration.

SMD is a heterogeneous group of bone dysplasias involving vertebrae and metaphyses of appendicular bones. Most common type is the Kozlowski type, SMD-K, which usually has an autosomal dominant inheritance pattern involving mutations of the TRPV4 gene. The TRPV4 gene normally encodes a calcium-permeable cation channel in osteoblasts and osteoclasts. Other mutations involving the TRPV4 gene are associated with other skeletal dysplasias, such as brachyolmia and metatropic dysplasia, as well as parastremmatic dysplasia, SMD Maroteaux type, and familial digital arthropathy. SMD-K has a prevalence of 1/100,000. Results in dwarfism (adult height < 140 cm). Patients appear normal at birth, but present with a waddling gait at 1 to 4 years. Clinical findings include short stature, short trunk, bowlegs, and a short and broad thorax.

Sagittal T1-weighted imaging of a 12-year-old male shows a Chiari I malformation with the cerebellar tonsils extending below the foramen magnum to the level of the posterior arch of C1. A large syrinx is seen in the spinal cord (arrow).
(a) Sagittal and (b) axial T2-weighted images of a neonate with a Chiari II malformation show an unfolded neural tube (neural placode) not covered by skin protruding through the dysraphic lower spinal canal, representing a myelomeningocele (arrows). The nerve roots from the placode are seen extending anteriorly into the spinal canal.
(a) Sagittal T2-weighted imaging of a 4-day-old female shows nonterminal myelocystocele that is a herniation of a tethered thoracic spinal cord containing a localized cystic dilatation of the central canal of the spinal cord into a posterior meningocele (arrow). (b) As seen on this photograph, the meningocele is covered by skin (arrow).
(a) Sagittal T1-weighted imaging and (b) sagittal and (c) axial T2-weighted images of a neonate show a terminal myelocystocele that is a tethered spinal cord containing a localized cystic dilatation of the central canal of the tethered lower spinal cord that extends through a spina bifida into a posterior meningocele that is covered by skin and subcutaneous fat (arrows).
Sagittal T1-weighted imaging of a 3-year-old female shows a lipomyelocele (arrows) that is an unfolded caudal neural tube (neural placode) covered by a lipoma, which is contiguous with the dorsal subcutaneous fat through defects (spina bifida) involving the bony dorsal vertebral elements. There is resultant tethering of the spinal cord with syringohydromyelia.
(a) Axial T1-weighted imaging and (b) sagittal fat-suppressed T2-weighted imaging of a 37-year-old woman with a lipomyelocele show a tethered lower spinal cord from a lipoma attached to the dorsal margin of an unfolded lower neural tube that is contiguous with subcutaneous fat (arrows) through a spina bifida aperta in the lumbosacral region.
(a) Sagittal T1-weighted imaging and (b) T2-weighted imaging show an intradural lipoma (arrows) attached to the focal dorsal dysraphic margin of the lower cervical and upper thoracic spinal cord. The dural margins and posterior vertebral elements are intact.
(a) Sagittal T1-weighted imaging and (b) fat-suppressed T2-weighted imaging of a 35-year-old woman show an intradural lipoma (arrows) attached to the focal dorsal dysraphic margin of the lower thoracic spinal cord. The dural margins and posterior vertebral elements are intact. (c) Axial T2-weighted imaging shows clockwise rotation of the spinal cord from the dorsally attached lipoma (arrows).
Sagittal T1-weighted imaging of a 2-year-old male shows an intradural lipoma (arrow) associated with tethering of the spinal cord.
Sagittal T2-weighted imaging shows a dorsal dermal sinus (lower arrow) that extends into the spinal canal through dysraphic posterior elements at the L4–L5 level. There is tethering of the spinal cord, which is attached to a dorsal lipoma (upper arrow).
Sagittal T2-weighted imaging of a 2-year-old male with a tethered low-lying spinal cord from a thickened filum terminale (arrow) in association with caudal regression and formation of only three sacral segments.
(a,b) Sagittal T2-weighted imaging of a 76-year-old man shows a tethered spinal cord with the conus medullaris at the L4 level (arrow in a) attached to a thickened filum terminale (arrow in b).
(a) Sagittal and (b) axial T1-weighted imaging, and (c) sagittal T2-weighted imaging show a fibrolipoma of the filum terminale (arrows) that has signal that is isointense to fat. The conus medullaris is in normal position.
Coronal T2-weighted imaging shows a lateral meningocele on the left (arrows).
(a,b) Coronal T2-weighted imaging shows multiple segmentation anomalies involving the lower cervical and upper thoracic vertebrae associated with a split-cord malformation (diastematomyelia). (c) Axial T2-weighted imaging shows a bony septum separating two dural sacs, each containing a hemicord.
(a) Sagittal and (b) axial T2-weighted images of a 15-year-old male show a split-cord malformation at the L3 level, with a bony septum separating two dural sacs containing hemicords.
(a) Sagittal T1-weighted imaging and (b) sagittal T2-weighted imaging of a 2-year-old female show a well-defined, longitudinally oriented intramedullary zone with CSF signal located in the conus medullaris (arrows) representing a ventriculus terminalis of the conus medullaris.
(a) Lateral radiograph of a 7-year-old female shows multiple segmentation anomalies of the cervical vertebrae. (b) Sagittal T1-weighted imaging shows a circumscribed, intradural extramedullary lesion with high signal anterior to the spinal cord (arrows) representing a neurenteric cyst. (c) Sagittal fat-suppressed T1-weighted imaging shows persistent high signal related to the elevated protein content within the lesion (arrows). (d) The lesion (arrow) has low signal on sagittal fat-suppressed T2-weighted imaging.
(a) Sagittal T1-weighted imaging of a 27-year-old woman shows a circumscribed, intradural dermoid at the L2 level that has intermediate and high signal (arrow), and (b) persistent high signal on sagittal fat-suppressed T1-weighted imaging (arrow). (c) The lesion (arrow) has low signal on sagittal fat-suppressed T2-weighted imaging.
(a) Sagittal T2-weighted imaging and (b) sagittal CT of a 16-year-old female show a Klippel-Feil anomaly involving the C5 and C6 vertebral bodies (arrows), which have narrowed AP dimensions separated by a small rudimentary disk (arrows). (c) Sagittal CT also shows fusion of the posterior elements (arrow).
Klippel-Feil anomaly and Sprengel deformity in a 13-year-old female. (a) AP radiograph shows a malformed scaplula, which is in an abnormally high adducted position (arrow). (b) Sagittal and (c) axial T2-weighted images show Klippel-Feil segmentation anomalies involving the C4 to C7 vertebral bodies as well as an omovertebral bone (arrows) between the medial border of the scapula and spinous process of the C6 vertebra. (d) The omovertebral bone (arrows) has a triangular shape on oblique sagittal volume-rendered CT.
Coronal volume-rendered CT of an 11-year-old female shows a right hemivertebra (arrow) associated with rotatory scoliosis.
(a) Coronal CT and (b) coronal T2-weighted imaging in two different patients show paired hemivertebrae with constriction of height in midsagittal portions of the vertebral bodies associated with molding of adjacent vertebral bodies toward midsagittal constrictions (arrows)—butterfly vertebra.
(a) Sagittal and (b) coronal CT show a patient with scoliosis related to a tripediculate vertebra, which is seen as a wedge-shaped vertebral body containing two pedicles on the enlarged left side (arrows) and one pedicle on the shortened side, with associated molding of adjacent vertebral bodies toward the shortened side.
Axial CT shows spina bifida occulta with a midline defect where the lamina do not fuse (arrow).
Axial CT in a patient with a surgically repaired myelocele shows spina bifida aperta with a wide defect where lamina are unfused (arrow).
Sagittal T2-weighted imaging of a neonate shows severe caudal regression with agenesis of the lumbar spine, sacrum, and coccyx (arrow). Prominent narrowing of the thecal sac and spinal canal is seen below the lowest normal vertebral level.
Sagittal T1-weighted imaging of a neonate with caudal regression syndrome shows agenesis of the lower sacral segments and coccyx, and tethering of the spinal cord containing a distal syrinx from a thickened lipomatous filum terminale (arrows).
Sagittal fat-suppressed T2-weighted imaging shows caudal regression with agenesis of the lower three sacral segments and coccyx (arrow). The lower spinal cord is not tethered in this patient.
(a) Sagittal and (b) axial T1-weighted imaging of a 25-year-old man show developmentally short pedicles at the L3 and L4 vertebrae, resulting in spinal canal narrowing at these levels (arrows).
(a) Sagittal fat-suppressed T2-weighted imaging and (b) sagittal and (c) axial images of a 41-year-old man with achondroplasia show shortening and flattening of vertebral bodies and shortened pedicles, resulting in severe multilevel spinal canal stenosis.
(a) Sagittal fat-suppressed T2-weighted imaging and (b) axial T2-weighted imaging of a 28-year-old woman with neurofibromatosis type 1 show dural dysplasia/ectasia with scalloping of the dorsal aspects of the vertebral bodies, as well as lateral meningoceles.
Sagittal T2-weighted imaging of a 67-year-old woman with Marfan syndrome shows an anterior sacral meningoecele (arrow) as well as mild scalloping of the dorsal aspects of the lumbar vertebral bodies.
(a) Lateral radiograph and (b) sagittal T2-weighted imaging of a 9-year-old male with Morquio syndrome show wedge-shaped vertebral bodies with anterior central beaks, decreased height of vertebral bodies, and widened disks.
Sagittal CT of a 10-year-old male with Hurler-Scheie syndrome shows wedge-shaped vertebral bodies with anterior beaks, decreased height of vertebral bodies, and widened disks.
(a) Sagittal and (b) coronal CT and (c) sagittal T2-weighted imaging of a 1-year-old female with spondylometaphyseal dysplasia show kyphoscoliosis and platyspondyly. The disks are thick relative to the vertebral body heights. (d) AP radiograph of the patient 4 years later shows metaphyseal dysplasia in both proximal femurs (observed in children more than 5 years old), shortened femoral necks, irregularities and sclerosis of metaphyses, coxa vara, and irregular epiphyses.


Abnormalities Involving the Craniovertebral Junction


The craniovertebral junction consists of the occipital bone, C1 and C2 vertebrae, and connecting ligaments. The articulations of the occipital-atlanto (C0–C1) and atlanto-axial (C1–C2) joints are different from the lower cervical levels. With the occipital-atlanto articulation, the occipital condyles rest along the superior facets of the lateral masses of C1. This configuration allows for 20 degrees of flexion and extension while limiting axial rotation and lateral flexion. With the C1–C2 articulation, a small rounded facet (fovea dentis) at the dorsal aspect of the anterior arch of C1 articulates with the anterior margin of the dens. This configuration enables the skull and atlas to rotate laterally as a unit around the vertical axis of the dens. Ligaments at the craniovertebral junction include the alar, transverse, and apical ligaments ( Fig. 1.50 and Fig. 1.51 ). The alar ligaments connect the lateral margins of the odontoid process with the lateral masses of C1 and medial margins of the foramen magnum. The alar ligaments limit atlanto-axial rotation. The transverse ligament extends medially from the tubercles at the inner aspects of the lateral articulating masses of C1 behind the dens, stabilizing the dens to the anterior arch of C1. The transverse ligament is the horizontal portion of the cruciform ligament, which also has fibers that extend from the transverse ligament superiorly to the clivus and inferiorly to the posterior surface of the dens. The apical ligament (middle odontoid ligament) extends from the upper margin of the dens to the anterior clival portion of the foramen magnum. The tectorial membrane is an upward extension from the posterior longitudinal ligament that connects with the body of C2 and the occipital bone (jugular tubercle and cranial base). Above the C2 level, the tectorial membrane merges with dura mater. The anterior and posterior atlanto-occipital membranes are superior extensions of the flaval ligament.

Sagittal view diagram of the ligaments stabilizing the craniovertebral junction.
Posterior view diagram of the dorsal aspects of the cruciform ligament, alar ligaments, and tectorial membrane.


Table 1.2 Abnormalities involving the craniovertebral junction




  • Congenital and Developmental




    • Basiocciput hypoplasia



    • Chiari I malformation



    • Chiari II malformation



    • Chiari III malformation



    • Condylus tertius



    • Atlanto-occipital assimilation/nonsegmentation



    • Atlas anomalies



    • Os odontoideum



    • Achondroplasia



    • Down syndrome (Trisomy 21)



    • Ehlers-Danlos syndrome



    • Mucopolysaccharidosis (MPS)



    • Osteogenesis imperfecta (OI)



    • Neurenteric cyst



    • Ecchordosis physaliphora



  • Osteomalacia




    • Renal osteodystrophy/secondary hyperparathyroidism



    • Paget disease



    • Fibrous dysplasia



    • Hematopoietic disorders



  • Traumatic Lesions




    • Fracture of skull base



    • Atlanto-occipital dislocation



    • Jefferson fracture (C1)



    • Hangman′s fracture (C2)



    • Odontoid fracture (C2)



  • Inflammation




    • Osteomyelitis/epidural abscess



    • Langerhans’ cell histiocytosis



    • Rheumatoid arthritis



    • Calcium pyrophosphate dihydrate (CPPD) deposition



  • Malignant Neoplasms




    • Metastatic disease



    • Myeloma



    • Chordoma



    • Chondrosarcoma



    • Squamous cell carcinoma



    • Nasopharyngeal carcinoma



    • Adenoid cystic carcinoma



    • Invasive pituitary tumor



  • Benign Neoplasms




    • Meningioma



    • Schwannoma



    • Neurofibroma



  • Tumorlike Lesions




    • Epidermoid



    • Arachnoid cyst



    • Mega cisterna magna



































































































































































































Abnormalities involving the craniovertebral junction

Lesions

Imaging Findings

Comments

Congenital and Developmental


Basiocciput hypoplasia ( Fig. 1.52 )

Hypoplasia of the lower clivus results in primary basilar invagination. Results in elevation of the dens more than 5 mm above Chamberlain′s line (line between the hard palate and opisthion, the posterior margin of the foramen magnum on sagittal MRI). Can also result in abnormally decreased clival-canal angle below the normal range of 150 to 180 degrees, ± syrinx formation in the spinal cord.

The lower clivus is a portion of the occipital bone (basiocciput), which is composed of four fused sclerotomes. Failure of formation of one or more of the sclerotomes results in a shortened clivus and primary basilar invagination (dens extending > 5 mm above Chamberlain′s line). Can be associated with hypoplasia of the occipital condyles. The occipital condyles develop from the ventral segment of the proatlas derived from the fourth occipital sclerotome.


Chiari I malformation ( Fig. 1.53 )

Cerebellar tonsils extend more than 5 mm below the foramen magnum in adults, 6 mm in children < 10 years old. Syringohydromyelia occurs in 20 to 40% of cases. Hydrocephalus in 25%. Basilar impression in 25%. Less common associations are Klippel-Feil anomaly and atlanto-occipital assimilation.

Cerebellar tonsillar ectopia. Most common anomaly of CNS. Not associated with myelomeningocele.


Chiari II malformation ( Fig. 1.54 )

Large foramen magnum through which there is an inferiorly positioned vermis associated with a cervicomedullary kink. Myelomeningoceles occur in nearly all patients, usually in the lumbosacral region. Hydrocephalus and syringomyelia are common. Dilated lateral ventricles posteriorly (colpocephaly). Multifocal scalloping at the inner table of the skull (Luckenschadel) can be seen, but it often regresses after 6 months.

Complex anomaly involving the cerebrum, cerebellum, brainstem, spinal cord, ventricles, skull, and dura. Failure of fetal neural folds to develop properly results in altered development affecting multiple sites of the CNS. Dysplasia of membranous skull/calvarium in Chiari II (referred to as Luckenschadel, lacunar skull, or craniolacunae) can occur, with multifocal thinning of the inner table due to nonossified fibrous bone caused by abnormal collagen development and ossification.


Chiari III malformation

Features of Chiari II plus lower occipital or high cervical encephalocele.

Rare anomaly associated with high mortality.


Condylus tertius ( Fig. 1.55 )

Ossicle seen between the lower portion of a shortened basiocciput and the dens/atlas.

Condylus tertius, or third occipital condyle, results from lack of fusion of the lowermost fourth sclerotome (proatlas) with the adjacent portions of the clivus. The third occipital condyle can form a pseudojoint with the anterior arch of C1 and/or dens and can be associated with decreased range of movement.


Atlanto-occipital assimilation/nonsegmentation ( Fig. 1.56 )

Often seen as fusion of the occipital condyle with the anterior arch, posterior arch, one or both lateral masses of C1, or combinations of the above, ± associated congenital anomalies, which occur in 20% of cases, such as external ear deformities, cleft palate, C2–C3 nonsegmentation, and/or cervical ribs.

Most common congenital osseous anomaly involving the craniovertebral junction. Failure of segmentation of the occipital condyles (fourth occipital sclerotome) and the C1 vertebra (first cervical sclerotome). Can be associated with C1–C2 instability.


Atlas anomalies ( Fig. 1.57 and Fig. 1.58 )

Unilateral or bilateral hypoplasia/aplasia of the posterior arch of C1. Clefts can also be seen in C1, most commonly at the posterior arch in the midline.

The first spinal sclerotome forms the atlas, while caudal portions of the proatlas form the lateral masses and upper portions of the posterior arch. Anomalies include aplasia of C1, or partial aplasia/hypoplasia of the posterior arch, ± atlanto-axial subluxation. Another more common anomaly involving C1 is rachischisis, clefts in the altas arches caused by developmentally defective cartilage formation. Clefts most commonly occur in the posterior arch in the midline (> 90%), followed by lateral clefts, and anterior clefts.


Os odontoideum ( Fig. 1.59 and Fig. 1.60 )

Separate corticated bony structure positioned below the basion and superior to the C2 body at site of normally expected dens, often associated with enlargement of the anterior arch of C1 (which may sometimes be larger than the adjacent os odontoideum). Instability can result when the gap between the os and the body of C2 is above the plane of the superior articular facets and below the transverse ligament.

Independent bony structure positioned superior to the C2 body and lower dens at site of normally expected mid to upper dens, often associated with hypertrophy of the anterior arch of C1, ± cruciate ligament incompetence/instability (± zone of high signal on T2-weighted imaging in spinal cord). Os odontoideum can be associated with Klippel-Feil anomaly, spondyloepiphyseal dysplasia, Down syndrome, and Morquio syndrome. Os odontoideum is considered to be a normal variant or arising from a childhood injury (between 1 and 4 years), with fracture/separation of the cartilaginous plate between the dens and body of axis.


Achondroplasia ( Fig. 1.61 )

The calvarium/skull vault is enlarged in association with a small skull base and narrow foramen magnum. Cervicomedullary myelopathy and/or hydrocephalus can result from a narrowed foramen magnum. The posterior cranial fossa is shallow, and basal foramina are hypoplastic. Small jugular foramina can restrict venous outflow from the head. Other findings include short wide ribs, square iliac bones, champagne-glass-shaped pelvic inlet, and short pedicles involving multiple vertebrae/congenital spinal canal stenosis.

Autosomal dominant rhizomelic dwarfism that results in abnormal reduced endochondral bone formation. Most common nonlethal bone dysplasia and shortlimbed dwarfism, with an incidence of 1/15,000 live births. More than 80–90% are spontaneous mutations involving the gene that encodes the fibroblast growth factor receptor 3 (FGFR3) on chromosome 4p16.3. The mutations typically occur on the paternal chromosome and are associated with increased paternal age. The mutated gene impairs endochondral bone formation and longitudinal lengthening of long bones.


Down syndrome (Trisomy 21) ( Fig. 1.62 )

Separation between the anterior arch of C1 and the anterior margin of the upper dens by more than 5 mm and narrowing of the spinal canal, ± indentation on the spinal cord.

Common genetic disorder, with an incidence of 1 in 733 live births. Can be associated with atlanto-occipital instability (up to 60%) or atlanto-axial instability (up to 30%). Can result from ligamentous laxity, ± associated persistent synchondroses, posterior C1 rachischisis, and os odontoideum (6%).


Ehlers-Danlos syndrome

Separation between the anterior arch of C1 and the anterior margin of the upper dens by more than 5 mm and narrowing of the spinal canal, ± indentation on the spinal cord.

Mutation involving genes involved with the formation or processing of collagen, which results in ligamentous laxity at the atlanto-axial joint.


Mucopolysaccharidosis (MPS) ( Fig. 1.63 )

MRI: Hypoplastic/dysplastic dens (deceased height, broad base with flattened tip) and soft tissue thickening adjacent to the dens at the C1–C2 level that has low-intermediate signal on T1- and T2-weighted imaging. Most commonly occurs with Morquio syndrome (type IV) and Hurler syndrome (type I). Can result in spinal canal stenosis. Findings include wedge-shaped vertebral bodies with anterior beaks (central, Morquio; anteroinferiorly, Hurler/Hunter), decreased heights of vertebral bodies, widened discs, spinal canal stenosis, thick clavicles, paddle-shaped ribs, widened symphysis pubis, flared iliac bones, widening of the femoral necks, ± absent femoral heads, coxa valga, shortened metacarpal bones, Madelung′s deformity, and diaphyseal widening of long bones. Marrow MRI signal may be within normal limits or slightly decreased on T1-weighted imaging and/or slightly increased on T2-weighted imaging.

Inherited disorders of glycosaminoglycan (GAG) catabolism caused by defects in specific lysosomal enzymes. MPS I (Hurler, Scheie syndromes) is a deficiency of α-L-iduronidase; MPS II (Hunter syndrome) is an X-linked deficiency of iduronate-2-sulfatase; MPS III (Sanfilippo A, B, C, D syndrome) is an autosomal recessive deficiency of enzymes that break down heparin sulfate; MPS IV (Morquio syndrome), is an autosomal recessive deficiency of N- acetylgalactosamine-6-sulfatase; MPS VI (Maroteaux-Lamy syndrome) is an autosomal deficiency of N- acetylgalatosamine-4-sulfatase ; MPS VII (Sly syndrome) is an autosomal recessive deficiency of β-glucuronidase;and MPS IX is a hyaluronidase deficiency. Disorders are characterized by accumulation of GAGs in lysosomes, extracellular matrix, joint fluid, and connective tissue, resulting in axonal loss and demyelination. Treatments include enzyme replacement and bone marrow transplantation.


Osteogenesis imperfecta (OI) ( Fig. 1.64 )

Diffuse osteopenia, decreased ossification of skull base with microfractures, infolding of the occipital condyles, elevation of the posterior cranial fossa and posterior cranial fossa, and upward migration of the dens into the foramen magnum, resulting in basilar impression (secondary basilar invagination).

Also known as brittle bone disease, OI has four to seven types. OI is a hereditary disorder with abnormal type I fibrillar collagen production and osteoporosis resulting from mutations involving the COL1A1 gene on chromosome 17q21.31-q22.05 and the COL1A2 gene on chromosome 7q22.1. OI results in fragile bone prone to repetitive microfractures and remodeling. Type IV is most commonly associated with abnormalities at the craniovertebral junction.


Neurenteric cyst ( Fig. 1.65 )

MRI: Well-circumscribed, spheroid, intradural, extra-axial lesions, with low, intermediate, or high signal on T1- and T2-weighted imaging and FLAIR and usually no gadolinium contrast enhancement.


CT: Circumscribed, intradural, extra-axial structures with low-intermediate attenuation. Usually no contrast enhancement.

Neurenteric cysts are malformations in which there is a persistent communication between the ventrally located endoderm and the dorsally located ectoderm secondary to developmental failure of separation of the notochord and foregut. Obliteration of portions of a dorsal enteric sinus can result in cysts lined by endothelium, fibrous cords, or sinuses. Observed in patients < 40 years old. Location: thoracic > cervical > posterior cranial fossa > craniovertebral junction > lumbar. Usually midline in position and often ventral to the spinal cord or brainstem. Associated with anomalies of the adjacent vertebrae and clivus.


Ecchordosis physaliphora

MRI: Circumscribed lesion ranging in size from 1 to 3 cm, with low signal on T1-weighted imaging, intermediate signal on FLAIR, and high signal on T2-weighted imaging. Typically shows no gadolinium contrast enhancement.


CT: Lesions typically have low attenuation, ± remodeling/erosion of adjacent bone, ± small calcified bone stalk.

Congenital benign hamartoma composed of gelatinous tissue with physaliphorous cell nests derived from ectopic vestigial notochord. Incidence at autopsy ranges from 0.5 to 5%. Usually located intradurally, dorsal to the clivus and dorsum sella within the prepontine cistern, and rarely dorsal to the upper cervical spine or sacrum. Rarely occurs as an extradural lesion. Derived from an ectopic notochordal remnant or from extension of extradural notochord at the dorsal wall of the clivus through the adjacent dura into the subarachnoid space. Typically is asymptomatic and is observed as an incidental finding in patients between the ages of 20 and 60 years.


Osteomalacia


Renal osteodystrophy/secondary hyperparathyroidism (See Fig. 1.268 )

CT: Trabecular bone resorption with a salt-and-pepper appearance from mixed osteolysis and osteosclerosis, osteiitis fibrosa cystica, cortical thinning, coarsened trabecular pattern, and osteolytic lesions/brown tumors. Another pattern is ground-glass appearance with indistinct corticomedullary borders.


MRI: Zones of low signal on T1- and T2-weighted imaging corresponding to regions of bone sclerosis. Circumscribed zones with high signal on T2-weighted imaging can be due to osteolytic lesions or brown tumors.

Secondary hyperparathyroidism related to renal failure/end-stage kidney disease is more common than primary hyperparathyroidism. Osteoblastic and osteoclastic changes occur in bone as a result of secondary hyperparathyroidism (hyperplasia of parathyroid glands secondary to hypocalcemia in end-stage renal disease related to abnormal vitamin D metabolism) and primary hyperparathyroidism (hypersecretion of PTH from parathyroid adenoma or hyperplasia). Can result in pathologic fractures due to osteomalacia. Unlike secondary hyperparathyroidism, primary hyperparathyroidism infrequently has diffuse or patchy bony sclerosis. Brown tumors are more common in primary than in secondary hyperparathyroidism.


Paget disease ( Fig. 1.66 )

Expansile sclerotic/lytic process involving the skull.


CT: Lesions often have mixed intermediate and high attenuation. Irregular/indistinct borders between marrow and inner margins of the outer and inner tables of the skull.


MRI: MRI features vary based on the phases of the disease. Most cases involving the skull and vertebrae are the late or inactive phases. Findings include osseous expansion and cortical thickening with low signal on T1- and T2-weighted imaging. The inner margins of the thickened cortex can be irregular and indistinct. Zones of low signal on T1- and T2-weighted imaging can be seen in the diploic marrow secondary to thickened bony trabeculae. Marrow in late or inactive phases of Paget disease can have signal similar to normal marrow, contain focal areas of fat signal, have low signal on T1- and T2-weighted imaging secondary to regions of sclerosis, have areas of high signal on fat-suppressed T2-weighted imaging caused by edema or persistent fibrovascular tissue, or have various combinations of the aforementioned.

Paget disease is a chronic skeletal disease in which there is disordered bone resorption and woven bone formation, resulting in osseous deformity. A paramyxovirus may be the etiologic agent. Paget disease is polyostotic in up to 66% of patients. Paget disease is associated with a risk of < 1% for developing secondary sarcomatous changes. Occurs in 2.5 to 5% of Caucasians more than 55 years old, and in 10% of those more than 85 years old. Can result in narrowing of neuroforamina, with cranial nerve compression and basilar impression, ± compression of brainstem.


Fibrous dysplasia ( Fig. 1.67 )

CT: Lesions involving the skull are often associated with bone expansion. Lesions have variable density and attenuation on radiographs and CT, respectively, depending on the degree of mineralization and number of the bony spicules in the lesions. Attenuation coefficients can range from 70 to 400 Hounsfield units. Lesions can have a ground-glass radiographic appearance secondary to the mineralized spicules of immature woven bone in fibrous dysplasia. Sclerotic borders of varying thickness can be seen surrounding parts or all of the lesions.


MRI: Features depend on the proportions of bony spicules, collagen, fibroblastic spindle cells, and hemorrhagic and/or cystic changes. Lesions are usually well circumscribed and have low or low-intermediate signal on T1-weighted imaging. On T2-weighted imaging, lesions have variable mixtures of low, intermediate, and/or high signal, often surrounded by a low-signal rim of variable thickness. Internal septations and cystic changes are seen in a minority of lesions. Bone expansion is commonly seen. All or portions of the lesions can show gadolinium contrast enhancement in a heterogeneous, diffuse, or peripheral pattern.

Benign medullary fibro-osseous lesion of bone, most often sporadic. Fibrous dysplasia involving a single site is referred to as monostotic (80–85%) and that involving multiple locations is known as polyostotic fibrous dysplasia. Results from developmental failure in the normal process of remodeling primitive bone to mature lamellar bone, with resultant zone or zones of immature trabeculae within dysplastic fibrous tissue. The lesions do not mineralize normally and can result in cranial neuropathies caused by neuroforaminal narrowing, facial deformities, sinonasal drainage disorders, and sinusitis. Age at presentation is < 1 year to 76 years; 75% of cases occur before the age of 30 years. Median age for monostotic fibrous dysplasia = 21 years; mean and median ages for polyostotic fibrous dysplasia are between 8 and 17 years. Most cases are diagnosed in patients between the ages of 3 and 20 years.


Hematopoietic disorders

Enlargement of the diploic space, with red marrow hyperplasia and thinning of the inner and outer tables. Involved marrow has slightly to moderately decreased signal relative to fat on T1-weighted imaging and T2-weighted imaging, isointense to slightly hyperintense signal relative to muscle and increased signal relative to fat on fat-suppressed T2-weighted imaging.

Thickening of diploic space related to erythroid hyperplasia caused by inherited anemias, such as sickle-cell disease, thalassemia major, and hereditary spherocytosis. Sickle-cell disease is the most common hemoglobinopathy, in which abnormal hemoglobin S is combined with itself, or other hemoglobin types such as C, D, E, or thalassemia. Hemoglobin SS, SC, and S-thalassemia have the most sickling of erythrocytes. In addition to marrow hyperplasia seen in sickle-cell disease, bone infarcts and extramedullary hematopoeisis can also occur. Beta-thalassemia is a disorder in which there is deficient synthesis of β chains of hemoglobin, resulting in excess α chains in erythrocytes, causing dysfunctional hematopoiesis and hemolysis. The decrease in β chains can be severe in the major type (homozygous), moderate in the intermediate type (heterozygous), or mild in the minor type (heterozygous).


Traumatic Lesions


Fracture of skull base ( Fig. 1.68 )

CT: Fracture line, ± displaced fragments, epidural or subdural hematoma.


MRI: Abnormal low signal on T1-weighted imaging and high signal on T2-weighted imaging in marrow at the site of fracture, ± abnormal high signal on T2-weighted imaging involving the brainstem and/or spinal cord, ± subgaleal hematoma, ± epidural hematoma, ± subdural hematoma, ± subarachnoid hemorrhage.

Traumatic fractures of the skull (calvarium and/or skull base), occipital condyles, C1, and/or C2 can be associated with traumatic injury of brainstem and upper spinal cord, epidural hematoma, subdural hematoma, subarachnoid hemorrhage, and CSF leakage (rhinorrhea, otorrhea).


Atlanto-occipital dislocation ( Fig. 1.69 )

CT: Abnormal increased distance from the basion of the clivus to the tip of the odontoid, as measured by the basion–axial interval (BAI) and/or basion–dental interval (BDI). The BAI is the distance from the basion to a line drawn along the dorsal surface of the C2 body (normal range of BAI for adults is -4 to 12 mm, for children, 0–12 mm). The BDI is used only in patients more than 13 years old and is the distance from the basion to the tip of the dens (normal range is 2–12 mm).


MRI: Disruption/tears of alar ligaments and tectorial membrane with associated abnormal high T2 signal and capsular edema.

Unstable traumatic injury with disruption of the alar ligaments and tectorial membrane between the occiput and C1, with or without injury to the brainstem and/or upper spinal cord. Most commonly occurs in children.


Jefferson fracture (C1) ( Fig. 1.70 )

CT: Rough-edged fractures of the arch of C1, often with multiple fracture sites.

Compression burst fracture of the arch of C1, often stable, but can be unstable when there is disruption of transverse ligament or comminution of anterior arch. Often associated with fractures of other cervical vertebrae.


Hangman′s fracture (C2) ( Fig. 1.71 )

Disrupted ring of C2 caused by bilateral pedicle fractures separating the C2 body from the posterior arch of C2. Skull, C1, and C2 body are displaced anterior with respect to C3.

Unstable injury due to traumatic bilateral pedicle fractures caused by hyperextension and distraction mechanisms, with separation of the C2 body from the posterior arch of C2. Fractures can extend into the C2 body and/or through the foramen transversarium, with injury/occlusion of the vertebral artery. Often associated with spinal cord injury.


Odontoid fracture (C2) ( Fig. 1.72 and Fig. 1.73 )

Type I: Fracture at the upper portion of the dens above the transverse ligament (unstable) due to avulsion at the alar ligament.


Type II: Transverse fracture through the lower portion of the dens (may be unstable).


Type III: Oblique fracture involving the dens and body of C2 (usually stable).

Traumatic fracture involving the upper, mid, and/or lower portions of the dens.


Inflammation


Osteomyelitis/epidural abscess ( Fig. 1.74 )

CT: Zones of abnormal decreased attenuation, focal sites of bone destruction, ± complications, including subgaleal empyema, epidural empyema, subdural empyema, meningitis, cerebritis, intra-axial abscess, and venous sinus thrombosis.


MRI: Zones with low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging and fat-suppressed T2-weighted imaging, ± high signal on diffusion-weighted imaging and low signal on ADC. Usually there is heterogeneous gadolinium (Gd) contrast enhancement, ± adjacent intracranial dural and/or leptomeningeal Gd contrast enhancement, ± abnormal high T2 signal and contrast enhancement of brain tissue/abscess formation.

Osteomyelitis (bone infection) of the skull base and upper cervical vertebrae can result from surgery, trauma, hematogenous dissemination from another source of infection, or direct extension of infection from an adjacent site, such as the sphenoid sinus, nasopharynx, oropharynx, petrous apex air cells, and/or mastoid air cells.


Langerhans’ cell histiocytosis ( Fig. 1.75 )

Single or multiple circumscribed soft tissue lesions in the marrow of the skull and/or vertebrae associated with focal bony destruction/erosion and with extension extra- or intracranially and/or spinal canal.


CT: Lesions usually have low-intermediate attenuation, + contrast enhancement, ± enhancement of the adjacent dura.


MRI: Lesions typically have low-intermediate signal on T1-weighted imaging and heterogeneous slightly high to high signal on T2-weighted imaging (T2WI) and fat-suppressed (FS) T2WI. Poorly defined zones of high signal on T2WI and FS T2WI are usually seen in the marrow and soft tissues peripheral to the lesions secondary to inflammatory changes. Lesions typically show prominent gadolinium contrast enhancement in marrow and extraosseous soft tissue portions.

Disorder of reticuloendothelial system in which bone marrow–derived dendritic Langerhans’ cells infiltrate various organs as focal lesions or in diffuse patterns. Langerhans’ cells have eccentrically located ovoid or convoluted nuclei within pale to eosinophilic cytoplasm. Lesions often consist of Langerhans’ cells, macrophages, plasma cells, and eosinophils. Lesions are immunoreactive to S-100, CD1a, CD-207, HLA-DR, and β2-microglobulin. Prevalence of 2 per 100,000 children < 15 years old; only a third of lesions occur in adults. Localized lesions (eosinophilic granuloma) can be single or multiple in the skull, usually at the skull base. Single lesions are commonly seen in males more than in females, and in patients < 20 years old. Proliferation of histiocytes in medullary bone results in localized destruction of cortical bone with extension into adjacent soft tissues. Multiple lesions are associated with Letterer-Siwe disease (lymphadenopathy hepatosplenomegaly) in children < 2 years old, and Hand-Schüller-Christian disease (lymphadenopathy, exophthalmos, diabetes insipidus) in children 5–10 years old.


Rheumatoid arthritis ( Fig. 1.76 and Fig. 1.77 )

MRI: Hypertrophied synovium (pannus) can be diffuse, nodular, and/or villous, and usually has low to intermediate or intermediate signal on T1-weighted imaging. On T2-weighted imaging, pannus can have low to intermediate, intermediate, and/or slightly high to high signal. Signal heterogeneity of hypertrophied synovium on T2-weighted imaging can result from variable amounts of fibrin, hemosiderin, and fibrosis. Chronic fibrotic nonvascular synovium usually has low signal on T1- and T2-weighted imaging. Hypertrophied synovium can show prominent homogeneous or variable heterogeneous gadolinium contrast enhancement. Erosion of the dens and destruction of the transverse ligament can occur, as well as basilar impression.


CT: Zones of erosion and/or destruction of the dens and atlas, ± basilar impression/invagination.

Chronic multisystem disease of unknown etiology with persistent inflammatory synovitis involving appendicular and axial skeletal synovial joints in a symmetric distribution. Hypertrophy and hyperplasia of synovial cells occurs in association with neovascularization, thrombosis, and edema, with collections of B-cells, antibody-producing plasma cells (rheumatoid factor and polyclonal immunoglobulins), and perivascular mononuclear T-cells (CD4+, CD8+). T-cells produce interleukins 1, 6, 7, and 10, as well as interferon gamma, G-CSF, and tumor necrosis factor alpha. These cytokines and chemokines are responsible for the inflammatory synovial pathology associated with rheumatoid arthritis. Can result in progressive destruction of cartilage and bone, leading to joint dysfunction. Affects ~ 1% of the world′s population. Eighty percent of adult patients present between the ages of 35 and 50 years. Most common type of inflammatory synovitis causing destructive/erosive changes of cartilage, ligaments, and bone. Inflammatory spondylarthritis and sacroiliitis occur in 17% and 2% of patients with rheumatoid arthritis, respectively.


Calcium pyrophosphate dihydrate (CPPD) deposition ( Fig. 1.78 )

CT: Thickened synovium at C1–C2 containing multiple calcifications.


MRI: At the C1–odontoid articulation, hypertophy of synovium can be seen, with low-intermediate signal on T1- and T2-weighted imaging. Small zones of low signal may correspond to calcifications seen with CT. Minimal or no gadolinium contrast enhancement.

CPPD disease is a common disorder, usually in older adults, in which there is deposition of CPPD crystals, resulting in calcifications of hyaline and fibrocartilage, and is associated with cartilage degeneration, subchondral cysts, and osteophyte formation. Symptomatic CPPD disease is referred to as pseudogout because of overlapping clinical features with gout. Usually occurs in the knee, hip, shoulder, elbow, and wrist, and occasionally at the odontoid–C1 articulation.


Malignant Neoplasms


Metastatic disease ( Fig. 1.79 )

Single or multiple well-circumscribed or poorly defined lesions involving the skull base and/or vertebrae.


CT: Lesions are usually radiolucent and may also be sclerotic, ± bone destruction with extraosseous tumor extension, usually + contrast enhancement, ± compression of neural tissue or vessels.


MRI: Single or multiple well-circumscribed or poorly defined lesions involving the skull base and/or vertebrae, with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, and usually gadolinium contrast enhancement, ± bone destruction, ± compression of neural tissue or vessels.

Metastatic lesions represent proliferating neoplastic cells that are located in sites or organs separated or distant from their origins. Metastatic carcinoma is the most frequent malignant tumor involving bone. In adults, metastatic lesions to bone occur most frequently from carcinomas of the lung, breast, prostate, kidney, and thyroid, as well as from sarcomas. Primary malignancies of the lung, breast, and prostate account for 80% of bone metastases. Metastatic tumor may cause variable destructive or infiltrative changes in single or multiple sites.


Myeloma

Plasmacytoma (solitary myeloma) or multiple myeloma are well-circumscribed or poorly defined lesions involving the skull and dura.


CT: Lesions have low-intermediate attenuation, usually + contrast enhancement, + bone destruction.


MRI: Well-circumscribed or poorly defined lesions involving the skull and dura, with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, and usually gadolinium contrast enhancement, + bone destruction.

Multiple myeloma are malignant tumors composed of proliferating antibody-secreting plasma cells derived from single clones. Multiple myeloma primarily involves bone marrow. A solitary myeloma or plasmacytoma is an infrequent variant in which a neoplastic mass of plasma cells occurs at a single site of bone or soft tissues. In the United States, 14,600 new cases occur each year. Multiple myeloma is the most common primary neoplasm of bone in adults. Median age at presentation = 60 years. Most patients are more than 40 years old. Tumors occur in the vertebrae > ribs > femur > iliac bone > humerus > craniofacial bones > sacrum > clavicle > sternum > pubic bone > tibia.


Chordoma ( Fig. 1.80 )

Well-circumscribed lobulated lesions along the dorsal surface of the clivus, vertebral bodies, or sacrum, + localized bone destruction.


CT: Lesions have low-intermediate attenuation, ± calcifications from destroyed bone carried away by tumor, + contrast enhancement.


MRI: Lesions have low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging, + gadolinium contrast enhancement (usually heterogeneous). Chordomas are locally invasive and associated with bone erosion/destruction, encasement of vessels (usually without luminal narrowing) and nerves. Skull base-clivus is a common location, usually in the midline for conventional chordomas, which account for 80% of skull base chordomas. Chondroid chordomas tend to be located off midline near skull base synchondroses.

Chordomas are rare, locally aggressive, slow-growing, low to intermediate grade malignant tumors derived from ectopic notochordal remnants along the axial skeleton. Chondroid chondromas (5–15% of all chordomas) have both chordomatous and chondromatous differentiation. Chordomas that contain sarcomatous components are referred to as dedifferentiated chordomas or sarcomatoid chordomas (5% of all chordomas). Chordomas account for 2–4% of primary malignant bone tumors, 1–3% of all primary bone tumors, and < 1% of intracranial tumors. The annual incidence has been reported to be 0.18 to 0.3 per million. Dedifferentiated chordomas or sarcomatoid chordomas account for less than 5% of all chordomas. For cranial chordomas, patients’ mean age = 37 to 40 years.


Chondrosarcoma

Lobulated lesions with bone destruction at synchondroses.


CT: Lesions have low-intermediate attenuation associated with localized bone destruction, ± chondroid matrix calcifications, + contrast enhancement.


MRI: Lesions have low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging, ± matrix mineralization-low signal on T2-weighted images, + gadolinium contrast enhancement (usually heterogeneous), locally-invasive associated with bone erosion/destruction, encasement of vessels and nerves, skull base petro-occipital synchondrosis common location, usually off midline.

Chondrosarcomas are malignant tumors containing cartilage formed within sarcomatous stroma. Chondrosarcomas can contain areas of calcification/mineralization, myxoid material. and/or ossification. Chondrosarcomas rarely arise within synovium. Chondrosarcomas represent 12–21% of malignant bone lesions, 21–26% of primary sarcomas of bone, 9–14% of all bone tumors, 6% of skull base tumors, and 0.15% of all intracranial tumors.


Squamous cell carcinoma

MRI: Destructive lesions in the nasal cavity, paranasal sinuses, and nasopharynx, ± intracranial extension via bone destruction or perineural spread. Intermediate signal on T1-weighted imaging, intermediate-slightly high signal on T2-weighted imaging, and mild gadolinium contrast enhancement. Can be large lesions (± necrosis and/or hemorrhage).


CT: Tumors have intermediate attenuation and mild contrast enhancement. Can be large lesions (± necrosis and/or hemorrhage).

Malignant epithelial tumors originating from the mucosal epithelium of the paranasal sinuses (maxillary sinus, 60%; ethmoid sinus, 14%; sphenoid and frontal sinuses, 1%) and nasal cavity (25%). Includes both keratinizing and nonkeratinizing types. Accounts for 3% of malignant tumors of the head and neck. Occurs in adults, usually > 55 years old, and in males more than in females. Associated with occupational or other exposure to tobacco smoke, nickel, chlorophenols, chromium, mustard gas, radium, and material in the manufacture of wood products.


Nasopharyngeal carcinoma

CT: Tumors have intermediate attenuation and mild contrast enhancement. Can be large lesions (± necrosis and/or hemorrhage).


MRI: Invasive lesions in the nasopharynx (lateral wall/fossa of Rosenmüller, and posterior upper wall), ± intracranial extension via bone destruction or perineural spread. Lesions have intermediate signal on T1-weighted imaging, intermediate-slightly high signal on T2-weighted imaging, and often gadolinium contrast enhancement. Can be large lesions (± necrosis and/or hemorrhage).

Carcinomas arising from the nasopharyngeal mucosa with varying degrees of squamous differentiation. Subtypes include squamous cell carcinoma, nonkeratinizing carcinoma (differentiated and undifferentiated), and basaloid squamous cell carcinoma. Occur at higher frequency in Southern Asia and Africa than in Europe and the Americas. Peak ages: 40–60 years. Nasopharyngeal carcinoma occurs two to three times more frequently in men than in women. Associated with Epstein-Barr virus, diets containing nitrosamines, and chronic exposure to tobacco smoke, formaldehyde, chemical fumes, and dust.


Adenoid cystic carcinoma

MRI: Destructive lesions with intracranial extension via bone destruction or perineural spread, with intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, and variable mild, moderate, or prominent gadolinium contrast enhancement.


CT: Tumors have intermediate attenuation and variable mild, moderate, or prominent contrast enhancement.

Basaloid tumor comprised of neoplastic epithelial and myoepithelial cells. Morphologic tumor patterns include tubular, cribriform, and solid. Accounts for 10% of epithelial salivary neoplasms. Most commonly involves the parotid, submandibular, and minor salivary glands (palate, tongue, buccal mucosa, and floor of the mouth, as well as other locations). Perineural tumor spread is common, ± facial nerve paralysis. Usually occurs in adults > 30 years old. Solid type has the worst prognosis. Up to 90% of patients die within 10–15 years of diagnosis.


Invasive pituitary tumor

MRI: Tumors often have intermediate signal on T1- and T2-weighted imaging, often similar to gray matter, ± necrosis, ± cyst, ± hemorrhage, and usually show prominent gadolinium contrast enhancement. Tumor can extend into the suprasellar cistern with waist at diaphragma sella, ± extension into cavernous sinus, and occasionally invades skull base.


CT: Tumors often have intermediate attenuation, ± necrosis, ± cyst, ± hemorrhage, and usually show contrast enhancement. Tumor can extend into the suprasellar cistern with waist at diaphragma sella, ± extension into cavernous sinus, and can invade the skull base.

Histologically benign pituitary macroadenomas or pituitary carcinomas can occasionally have an invasive growth pattern, with extension into the sphenoid bone, clivus, ethmoid sinus, orbits, and/or interpeduncular cistern.


Benign Neoplasms


Meningioma ( Fig. 1.81 )

Extra-axial dura-based lesions, well circumscribed, supra- > infratentorial. Some meningiomas can invade bone or occur predominantly within bone.


MRI: Tumors often have intermediate signal on T1-weighted imaging and intermediate-slightly high signal on T2-weighted imaging, and typically show prominent gadolinium contrast enhancement, ± calcifications, ± hyperostosis and/or invasion of adjacent skull. Some meningiomas have high signal on diffusion-weighted imaging.


CT: Tumors have intermediate attenuation, usually prominent contrast enhancement, ± calcifications, ± hyperostosis of adjacent bone.

Benign slow-growing tumors involving cranial and/or spinal dura that are composed of neoplastic meningothelial (arachnoidal or arachnoid cap) cells. Usually solitary and sporadic but can also occur as multiple lesions in patients with neurofibromatosis type 2. Most are benign, although ~ 5% have atypical histologic features. Anaplastic meningiomas are rare and account for less than 3% of meningiomas. Meningiomas account for up to 26% of primary intracranial tumors. Annual incidence is 6 per 100,000. Typically occur in adults (> 40 years old), and in women more than in men. Can result in compression of adjacent brain parenchyma, encasement of arteries, and compression of dural venous sinuses.


Schwannoma

MRI: Circumscribed spheroid or ovoid lesions with low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging (T2WI) and fat-suppressed T2WI, and usually prominent gadolinium (Gd) contrast enhancement. High signal on T2WI and Gd contrast enhancement can be heterogeneous in large lesions due to cystic degeneration and/or hemorrhage.


CT: Circumscribed spheroid or ovoid lesions with intermediate attenuation, + contrast enhancement. Large lesions can have cystic degeneration and/or hemorrhage, ± erosion of adjacent bone.

Schwannomas are benign encapsulated tumors that contain differentiated neoplastic Schwann cells. Multiple schwannomas are often associated with neurofibromatosis type 2 (NF2), which is an autosomal dominant disease involving a gene mutation at chromosome 22q12. In addition to schwannomas, patients with NF2 can also have multiple meningiomas and ependymomas.


Schwannomas represent 8% of primary intracranial tumors and 29% or primary spinal tumors. The incidence of NF2 is 1/37,000 to 1/50,000 newborns. Age at presentation is 22 to 72 years (mean age = 46 years). Peak incidence is in the fourth to sixth decades. Many patients with NF2 present in the third decade with bilateral vestibular schwannomas.


Neurofibroma ( Fig. 1.82 )

MRI: Solitary neurofibromas: Circumscribed spheroid or ovoid extra-axial lesions with low-intermediate signal on T1-weighted imaging (T1WI), intermediate-high signal on T2-weighted imaging (T2WI), + prominent gadolinium (Gd) contrast enhancement. High signal on T2WI and Gd contrast enhancement can be heterogeneous in large lesions.


Plexiform neurofibromas: Appear as curvilinear and multinodular lesions involving multiple nerve branches and have low to intermediate signal on T1WI and intermediate, slightly high to high signal on T2WI and fat-suppressed T2WI, with or without bands or strands of low signal. Lesions usually show gadolinium contrast enhancement.


CT: Ovoid, spheroid, or fusiform lesions with low-intermediate attenuation. Lesions can show contrast enhancement. Often erode adjacent bone.

Benign nerve sheath tumors that contain mixtures of Schwann cells, perineural-like cells, and interlacing fascicles of fibroblasts associated with abundant collagen. Unlike schwannomas, neurofibromas lack Antoni A and B regions and cannot be separated pathologically from the underlying nerve. Most frequently occur as sporadic, localized, solitary lesions, less frequently as diffuse or plexiform lesions. Multiple neurofibromas are typically seen with neurofibromatosis type 1, which is an autosomal dominant disorder (1/2,500 births) caused by mutations of the neurofibromin gene on chromosome 17q11.2.


Tumorlike Lesions


Epidermoid ( Fig. 1.83 )

MRI: Well-circumscribed lesion with low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging and diffusion-weighted imaging, and mixed low, intermediate, and/or high signal on FLAIR. No gadolinium contrast enhancement.


CT: Circumscribed radiolucent lesion within the skull, ± bone expansion or erosion. Extra-axial lesions often have low attenuation.

Epidermoid cysts are ectoderm-lined inclusion cysts that contain only squamous epithelium, desquamated skin epithelial cells, and keratin. Result from persistence of ectodermal elements at sites of neural tube closure and suture closure. Can occur within bone or as an extra-axial lesion.


Arachnoid cyst ( Fig. 1.84 )

MRI: Well-circumscribed extra-axial lesion with low signal on T1-weighted imaging, FLAIR, and diffusion-weighted imaging and high signal on T2-weighted imaging similar to CSF. No gadolinium contrast enhancement. Common locations: anterior middle cranial fossa > suprasellar/quadrigeminal > frontal convexities > posterior cranial fossa.


CT: Well-circumscribed extra-axial lesions with low attenuation and no contrast enhancement.

Nonneoplastic congenital, developmental, or acquired extra-axial lesions filled with CSF, usually with mild mass effect on adjacent brain, ± related clinical symptoms. Locations: supratentorial > infratentorial. Occur in males more than in females.


Mega cisterna magna ( Fig. 1.85 )

MR and CT: Variably enlarged posterior cranial fossa with prominent cisterna magna. The fourth ventricle and vermis are often within normal limits in size and configuration. The cerebellar tonsils are typically normal in position relative to the foramen magnum.

Developmental variant with slightly enlarged posterior cranial fossa associated with a large cisterna magna. Some cases may represent a mild form of the Dandy-Walker spectrum when there is associated mild hypoplasia of the inferior vermis.

Sagittal T1-weighted imaging shows basiocciput hypoplasia, with the dens extending intracranially above Chamberlain′s line by more than 5 mm.
Sagittal T1-weighted imaging in a 19-year-old woman shows a Chiari I malformation, with the cerebellar tonsils (arrow) extending below the foramen magnum to the level of the posterior arch of the C1 vertebra. The fourth ventricle has a normal appearance.
Sagittal T1-weighted imaging of a patient with a Chiari II malformation shows a small posterior cranial fossa and a large foramen magnum through which the cerebellum extends inferiorly. There is absence of the normal shape of the fourth ventricle. Hypoplasia of the posterior portion of the corpus callosum is also seen.
Condylus tertius. (a) Sagittal CT and (b) sagittal T2-weighted imaging of a 16-year-old male show an ossicle (condylus tertius) between the lower portion of a shortened basiocciput and dens/atlas (arrows).
(a) Coronal and (b) and sagittal CT show unilateral nonsegmentation (assimilation) involving the right occipital condyle and right lateral articulating mass of the C1 vertebra (arrows). Also seen is nonsegmentation involving the C2 and C3 vertebrae (Klippel-Feil anomaly).
(a) Axial and (b) sagittal CT images of a 58-year-old woman show absence of the posterior arch of C1 (arrow in b). Also seen is an anterior cleft in C1 (arrow in a).
Atlas anomalies. (a) Axial CT of a 13-year-old female shows clefts involving both the posterior and anterior arches of C1. (b) Axial CT of a 30-year-old woman shows a posterior cleft in C1.
A 38-year-old woman with an os odontoideum. (a) Sagittal CT and (b) and sagittal T1-weighted imaging show a corticated bony structure (arrows) positioned below the basion and superior to the C2 body and lower dens. Os odontoideum is often associated with enlargement of the anterior arch of C1 (which may sometimes be larger than the adjacent os odontoideum).
A 16-year-old male with an os odontoideum. (a) Sagittal CT, (b) sagittal T1-weighted imaging, and (c) T2-weighted imaging show a corticated bony structure (arrows in a and c) positioned below the basion and superior to the C2 body. Enlargement of the anterior arch of C1 is seen that is larger than the adjacent os odontoideum. An abnormally decreased clivis canal angle is present.
An 8-week-old female with achondroplasia. Sagittal T1-weighted imaging shows a severely narrowed foramen magnum indenting the upper cervical spinal cord (arrows). The posterior cranial fossa is shallow.
A 46-year-old woman with Down syndrome. (a) Lateral radiograph and (b) sagittal T1-weighted imaging show separation (arrow) between the anterior arch of C1 and the anterior margin of the upper dens by more than 5 mm, resulting in narrowing of the spinal canal and ventral indentation on the spinal cord.
A 9-year-old male with Morquio type of mucopolysaccharidosis. (a) Lateral radiograph shows wedge-shaped vertebral bodies with anterior beaks. (b) Sagittal T2-weighted imaging shows soft tissue thickening adjacent to the dens at the C1–C2 level that has low-intermediate signal.
A 15-year-old female with osteogenesis imperfecta. (a) Lateral radiograph shows diffuse osteopenia and basilar invagination. (b) Sagittal T2-weighted imaging shows upward intracranial extension of the dens, which indents the pontomedullary junction.
An intradural neurenteric cyst is seen anteriorly within the thecal sac on the left at the C1–C2 level. The cyst has high signal on (a) sagittal T1-weighted imaging (arrow) and (b) axial fat-suppressed T1-weighted imaging (arrow), and high signal on (c) axial FLAIR (arrow). The high signal of the lesion on fat-suppressed T1-weighted imaging is related to elevated protein content within the fluid of the cystic lesion.
An 84-year-old woman with Paget disease involving the skull. (a) Axial CT shows diffuse expansion of bone containing mixed intermediate and high attenuation, with irregular/indistinct borders between marrow and inner margins of the outer and inner tables of the skull. (b) Sagittal T2-weighted imaging shows osseous expansion, cortical thickening with low signal, and marrow with heterogeneous low and intermediate signal. There is a flattening deformity of the skull base (platybasia) secondary to the effects of gravity on the softened pagetoid bone.
Sagittal CT shows diffuse sclerosis of the clivus caused by fibrous dysplasia (arrows).
(a) Sagittal and (b) coronal CT images show a displaced fracture (arrows) of the left occipital condyle in a 20-year-old woman.
A 5-year-old male with atlanto-occipital dislocation. Sagittal T2-weighted imaging shows disruption of the alar ligaments and tectorial membrane (arrow), with adjacent abnormal high-signal fluid, as well as abnormal high signal in the spinal cord and cerebellum representing severe injuries.
Axial CT of a 45-year-old woman with a Jefferson fracture with three fracture sites (arrows) involving the C1.
(a) Axial and (b) sagittal CT show a hangman′s fracture with bilateral pedicle fractures separating the C2 body from the posterior arch of C2 (arrow).
Type II odontoid fracture. Coronal CT shows a transverse fracture through the lower portion of the dens (arrow).
Type III odontoid fracture. Coronal CT shows an oblique fracture (arrow) involving the dens and body of C2.
A 59-year-old man with pyogenic osteomyelitis and epidural abscess at the craniovertebral junction. (a) Sagittal fat-suppressed T2-weighted imaging shows abnormal high signal in the marrow of the C1 and C2 vertebrae and lower clivus, with (b) corresponding abnormal gadolinium contrast enhancement on fat-suppressed T1-weighted imaging. A peripherally enhancing fluid collection (epidural abscess) is seen indenting the ventral margin of the spinal cord at the C1–C2 level. Abnormal gadolinium contrast enhancement is also seen in the prevertebral soft tissues, representing a phlegmon.
A 23-year-old man with an eosinophilic granuloma involving the left occipital condyle. (a) Axial CT shows an osteolytic lesion (arrows). (b) Axial and (c) sagittal fat-suppressed T1-weighted MRI images show the lesion (arrows) to have prominent intraosseous gadolinium contrast enhancement, with ill-defined margins that extend into, and involve the adjacent soft tissues.
A 72-year-old woman with rheumatoid arthritis. (a) Sagittal fat-suppressed T1-weighted imaging shows gadolinium-enhancing pannus (arrow) at the C1-dens joint eroding the cortical margins and extending into the marrow. (b) Axial CT shows erosive changes involving the dens (arrow) caused by the pannus.
A 60-year-old woman with rheumatoid arthritis that eroded the transverse ligament, resulting in upward intracranial displacement of the dens that compresses the ventral margin of the medulla on sagittal T2-weighted imaging.
An 80-year-old man with calcium pyrophosphate dihydrate (CPPD) deposition at the C1–odontoid articulation. (a) Sagittal CT shows thickened synovium containing multiple calcifications (arrow). (b) The hypertrophied synovium (arrow) has intermediate signal on sagittal T1-weighted imaging and (c) low-intermediate signal on sagittal T2-weighted imaging.
A 76-year-old woman with metastatic breast carcinoma involving the marrow of the dens that has intermediate signal on (a) sagittal T1-weighted imaging and shows gadolinium contrast enhancement on (b) sagittal T1-weighted imaging. The tumor destroys cortical bone and extends into the prevertebral and epidural spaces causing spinal canal compression.
A 44-year-old woman with a chordoma destroying the lower clivus that shows gadolinium contrast enhancement on (a) sagittal T1-weighted imaging and has heterogeneous mostly high signal on (b) axial T2-weighted imaging (arrow). The tumor extends into the ventral portion of the craniovertebral junction and upper ventral portion of the spinal canal.
(a) Sagittal T1-weighted imaging shows a gadolinium-enhancing meningioma (transitional cell type) along the endocranial surface of the clivus that displaces posteriorly the brainstem and cerebellum. (b) The meningioma has mixed intermediate and slightly high signal on axial T2-weighted imaging.
A 22-year-old woman with neurofibromatosis type 1 who has multiple neurofibromas that have high signal on (a) axial T2-weighted imaging and show gadolinium contrast enhancement on (b) axial fat-suppressed T1-weighted imaging, including two bilateral epidural neurofibromas (arrows) that compress and deform the thecal sac and spinal cord.
Epidermoid in the inferior portion of the fourth ventricle, foramen of Magendie, and foramen magnum that has heterogeneous mostly low signal on (a) sagittal T1-weighted imaging (arrow), mixed low, intermediate, and slightly high signal on (b) axial FLAIR (arrow), and (c) restricted diffusion on axial diffusion-weighted imaging.
Sagittal T1-weighted imaging shows a large arachnoid cyst with CSF signal in the posterior cranial fossa associated with anterior displacement of the vermis and erosion of the inner table of the occipital bone.
Sagittal T2-weighted imaging shows a slightly enlarged posterior cranial fossa with prominent cisterna magna filled with CSF located below the cerebellum and cerebellar tonsils.


Table 1.3 Intradural intramedullary lesions (spinal cord lesions)




  • Neoplasms




    • Astrocytoma



    • Ependymoma



    • Ganglioglioma



    • Hemangioblastoma



    • Glioneuronal tumor



    • Oligodendroglioma



    • Primitive neuroectodermal tumor (PNET)



    • Atypical teratoid/rhabdoid tumor



    • Metastatic tumor



  • Demyelinating Disease




    • Multiple sclerosis (MS)



    • Neuromyelitis optica



    • Acute disseminated encephalomyelitis (ADEM)



    • Transverse myelitis



  • Other Noninfectious Inflammatory Disease Involving the Spinal Cord




    • Sarcoidosis



    • Sjögren syndrome



  • Infectious Diseases of Spinal Cord




    • Viral infection



    • Abscess/nonviral infectious myelitis



    • Parasitic infection



  • Vascular Lesions




    • Intramedullary hemorrhage



    • Posthemorrhagic lesions



    • Arteriovenous malformation (AVM)



    • Cavernous malformation



    • Venous angioma (Developmental venous anomaly)



    • Spinal cord infarct/ischemia of arterial etiology



    • Ischemia—Venous infarction/congestion



  • Traumatic Lesions




    • Spinal cord contusion



    • Spinal cord transection



    • Chronic injury



  • Degenerative Abnormalities




    • Myelomalacia



    • Wallerian degeneration



    • Amyotrophic lateral sclerosis



    • Poliomyelitis



    • Radiation myelopathy



  • Other Lesions




    • Syringohydromyelia



    • Vitamin B12 deficiency (Subacute combined degeneration)



    • Superficial siderosis













































































































































































Intradural intramedullary lesions (spinal cord lesions)

Lesions

Imaging Findings

Comments

Neoplasms


Astrocytoma ( Fig. 1.86, Fig. 1.87, Fig. 1.88 , and Fig. 1.89 )

MRI: Intramedullary, expansile, eccentric lesions with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging (T2WI) ± ill-defined margins, ± tumoral cysts (high signal on T2WI), ± syringohydromyelia, ± irregular gadolinium contrast enhancement, ± peripheral high signal on T2WI (edema). Lesions often extend approximately four vertebral segments. Low-grade tumors can have defined margins, whereas high-grade tumors often have irregular margins. Locations: cervical spinal cord > upper thoracic spinal cord > conus medullaris.

Neoplasms that arise from astrocytic glial cells, astrocytomas account for up to 60% of spinal cord tumors in children. Most common subtypes are grade I pilocytic astrocytomas (which displace adjacent tissue, often contain Rosenthal fibers, and typically lack mitotic activity), and grade II infiltrative fibrillary astrocytomas. Fibrillary astrocytomas with increased infiltrative cellularity, mitotic figures, and nuclear atypia represent uncommon grade III anaplastic astrocytomas. Glioblastomas (grade IV) account for less than 2% of spinal cord astrocytomas. Treatment is with surgery. Five-year survival for grades I and II tumors is up to 95%, whereas survival is lower for grades III and IV tumors.


Ependymoma ( Fig. 1.90, Fig. 1.91 , and Fig. 1.92 )

MRI: Intramedullary, circumscribed or ill-defined, expansile lesions with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging (T2WI), ± peripheral rim of low signal (hemosiderin) on T2WI, ± tumoral cysts (high signal on T2WI), ± syringohydromyelia, ± gadolinium contrast enhancement (84%), ± peripheral high signal (edema) on T2WI. Often midline/central location in spinal cord. Intramedullary locations: cervical spinal cord 44%, both cervical and upper thoracic spinal cord 23%, thoracic spinal cord 26%. Lesions often extend ~ 3.6 vertebral segments, ± scoliosis, chronic bone erosion.

Neoplasms that arise from ependymal cells lining the central canal of the spinal cord. Most common intramedullary tumor in adults (60% of glial neoplasms), and second most common spinal cord tumor in children, accounting for up to 30%. Intramedullary ependymomas involving the upper spinal cord often are cellular or mixed histologic types, whereas ependymomas at the conus medullaris or cauda equina usually are myxopapillary. Slight male predominance. Usually are slow-growing neoplasms associated with long-duration neck or back pain, sensory deficits, motor weakness, and bladder and bowel dysfunction. Prognosis depends on tumor grade and presence of tumor dissemination into the CSF. Multiple ependymomas can occur in patients with neurofibromatosis type 2 (NF2), which is an autosomal dominant disease involving a gene mutation at chromosome 22q12. In addition to ependymomas, patients with NF2 can also have multiple schwannomas and meningiomas. The incidence of NF2 is 1/37,000 to 1/50,000 newborns. Age at presentation is 22 to 72 years (mean age = 46 years). Peak incidence is in the fourth to sixth decades.


Ganglioglioma ( Fig. 1.93 and Fig. 1.94 )

MRI: Intramedullary tumor with variable mixed low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging (T2WI) ± ill-defined margins, ± cysts, ± gadolinium contrast enhancement (85%), usually minimal or no surrounding edema (high signal on T2WI). Association with scoliosis (44%) and bone erosion (93%).


CT: ± calcifications.

Uncommon tumors involving the spinal cord (1–15% of spinal cord neoplasms). Tumors contain neoplastic ganglion and glial cells. Tumors are commonly slow-growing and low grade (I or II). May extend inferiorly from lesion in cerebellum: ganglioglioma (contains glial and neuronal elements) or ganglioneuroma (contains only ganglion cells). An uncommon slow-growing tumor in patients < 30 years old = gangliocytoma (contains only neuronal elements).


Hemangioblastoma ( Fig. 1.95 and Fig. 1.96 )

MRI: Tumors usually located in the superficial portion of the spinal cord; small gadolinium-enhancing nodule, ± cyst, or larger lesion with prominent heterogeneous enhancement ± flow voids within lesion or at the periphery; intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging with ill-defined margins, occasionally lesions have evidence of recent or remote hemorrhage, usually associated with syrinx. Locations: thoracic spinal cord (50–60%), cervical spinal cord (40–50%).

Benign, grade I, slow-growing, capillary tumors that can occur as sporadic lesions or as multiple lesions in von Hippel-Lindau disease (50%). Represent ~ 5% of spinal cord neoplasms. Usually occur as intramedullary lesions (75%), but occasionally extend into the intradural space or in extramedullary locations in association with nerve roots. Tumors occur as sporadic mutations of the VHL gene or as an autosomal dominant germline mutation of the VHL gene on chromosome 3p25–26, resulting in von Hippel-Lindau disease (VHL disease). In VHL disease, multiple hemangioblastomas involving the central nervous system occur, as well as clear-cell renal carcinoma, pheochromocytoma, endolymphatic sac tumor, neuroendocrine tumor, adenoma of the pancreas, and epididymal cystadenoma. Occurs in adolescents and young and middle-aged adults. Treatment is surgical resection without or with preoperative embolization.


Glioneuronal tumor ( Fig. 1.97 and Fig. 1.98 )

MRI: Tumors often have heterogeneous low and intermediate signal on T1-weighted imaging, heterogeneous intermediate-high signal on T2-weighted imaging, and heterogeneous gadolinium contrast enhancement.

Rare infiltrating astrocytic tumor (WHO grade II or III) composed of pseudostratified layers of small cuboidal glial cells with round nuclei, hyalinized blood vessels, and collections of neurocytes and ganglion cells. Immunoreactive to glial fibrillary acidic protein, NeuN, synaptophysin, neuron-specific enolase, and class III β-tubulin. Usually occur in the brain and rarely in the spinal cord. Patients range from 4 to 75 years old (mean age = 27 years). Long-term survival is typical after surgical resection.


Oligodendroglioma ( Fig. 1.99 )

MRI: Intramedullary expansile lesions with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, ± tumoral cysts (high signal on T2WI), ± syringohydromyelia, ± irregular gadolinium contrast enhancement, ± peripheral high signal on T2WI (edema). Low-grade tumors can have defined margins, whereas high-grade tumors often have irregular margins.

Rare primary tumors that account for 2% of spinal cord tumors. Composed of neoplastic monomorphic cells with round nuclei resembling oligodendrocytes. Associated with translocation involving chromosomes 1 and 19, [t (1,19) (q10;p10)] with deletions of chromosome arms 1p and19q. Low-grade lesions have 75% 5-year survival; higher-grade lesions have a worse prognosis.


Primitive neuroectodermal tumor (PNET)

MRI: Circumscribed or invasive lesions with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, ± cystic or necrotic zones. Solid portions can have variable gadolinium (Gd) contrast enhancement, ± Gd contrast enhancement in the leptomeninges from tumor dissemination. Solid portions can have restricted diffusion on diffusion-weighted imaging.


CT: Circumscribed or invasive lesions with low-intermediate attenuation, variable contrast enhancement, and frequent dissemination into the leptomeninges.

Highly malignant tumors (WHO grade IV) that are usually located in the cerebrum, pineal gland, and cerebellum and rarely occur as primary spinal tumors. These malignant tumors frequently disseminate along CSF pathways. Tumors are composed of poorly differentiated or undifferentiated cells with divergent differentiation along neuronal, astrocytic, or ependymal lines. Typically occur in patients 4 weeks to 20 years old (mean age = 5.5 years). Prognosis is poorer than that for medulloblastoma.


Atypical teratoid/rhabdoid tumor

MRI: Tumors often have intermediate signal on T1-weighted imaging (T1WI), ± zones of high signal from hemorrhage on T1WI, and variable mixed low, intermediate, and/or high signal on T2-weighted imaging. Solid portions can have prominent gadolinium (Gd) contrast enhancement, ± heterogeneous pattern, ± Gd contrast enhancement in the leptomeninges from tumor dissemination. Solid portions can have restricted diffusion on diffusion-weighted imaging.

Rare malignant tumors involving the CNS, usually occurring in the first decade (patients are usually < 3 years old). Ki-67/MIB-1 proliferation index is often high, > 50%. Associated with mutations of the INI1(hSNF5/SMARCB1) gene on chromosome 22q11.2. Histologically appear as solid tumors ± necrotic areas, similar to malignant rhabdoid tumors of the kidney. Associated with a very poor prognosis.


Metastatic tumor ( Fig. 1.100 )

MRI: Intramedullary lesion or superficial lesions with low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, + gadolinium contrast enhancement with surrounding edema (high signal on T2WI) in spinal cord or along the pial surface. Cysts are rare. Often extend two or three vertebral segments.

Rare intramedullary lesions that can present with pain, bladder or bowel dysfunction, and paresthesias. Location: Cervical spinal cord (45%), thoracic spinal cord (35%), lumbar region (8%). Usually solitary lesions, occasionally multiple. Spread hematogenously via arteries, or by direct extension into leptomeninges with invasion of pial surface or central canal of the spinal cord. Primary CNS tumors include PNET/medulloblastoma and glioblastoma. Primary tumor outside of CNS is most often lung or breast cancer.


Demyelinating Disease


Multiple sclerosis (MS) ( Fig. 1.101 and Fig. 1.102 )

MRI: Intramedullary lesion or multiple lesions in spinal cord, usually with low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging, + gadolinium (Gd) contrast enhancement in acute or early subacute demyelinating lesions. Older lesions typically do not show Gd contrast enhancement. Demyelinating lesions in MS are usually located in peripheral portions of the spinal cord, occupy < 50% of the cross-sectional area of the cord, and typically involve two vertebral segments or less. (With neuromyelitis optica, lesions can extend more than three or four vertebral segments.) Acute/subacute demyelinating lesions may mildly expand the spinal cord.

MS is the most common acquired demyelinating disease, usually affecting women (peak ages = 20–40 years). Plaques in the spinal cord can be associated with localized atrophy, most often with the relapsing/remitting type of MS. Up to 25% of patients have lesions only in the spinal cord. Other demyelinating diseases include acute disseminated encephalomyelitis (an immune-mediated demyelination occurring after viral infection), acute transverse myelitis, toxin-related demyelination (exogenous toxins from environmental exposure or ingestion, such as alcohol, solvents, etc., or endogenous toxins from metabolic disorders, such as leukodystrophies, mitochondrial encephalopathies, etc.), radiation injury, trauma, and demyelinating vascular disease.


Neuromyelitis optica

MRI: Intramedullary lesion or multiple lesions in spinal cord, usually with low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging, + gadolinium (Gd) contrast enhancement for acute or early subacute demyelinating lesions. Older lesions typically show no Gd contrast enhancement. Lesions often extend more than three or four vertebral segments. Acute/subacute demyelinating lesions may mildly expand the spinal cord.

Devic′s disease (neuromyelitis optica) is an autoimmune demyelinating disease that consists of optic neuritis and progressive demyelination of the spinal cord, with minimal or no concomitant demyelination in the brain. The presence of antiaquaporin 4 (AQP-4) antibodies is specific for neuromyelitis optica, enabling its differentiation from multiple sclerosis. Neuromyelitis optica has an incidence of 4.4 per 100,000, is more common in women than in men, and has age of onset at around 40 years. Aziathioprine and rituximab are used to treat neuromyelitis optica.


Acute disseminated encephalomyelitis (ADEM) ( Fig. 1.103 and Fig. 1.104 )

MRI: Intramedullary lesion or multiple lesions in spinal cord with low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging. Lesions are located in peripheral white matter of spinal cord, ± involvement of central portions of spinal cord (gray matter), ± mild cord expansion, + gadolinium contrast enhancement in acute/early subacute phases of demyelination.

ADEM is a noninfectious, monophasic, inflammatory/demyelinating process involving the spinal cord and/or brain that occurs several weeks after viral infection or vaccination. Occurs in children more than in adults. Incidence is 0.4/100,000. Associated with various bilateral motor and sensory deficits.


Transverse myelitis ( Fig. 1.105 )

MRI: Intramedullary lesion or multiple lesions in spinal cord with low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging (T2WI). Involves thoracic spinal cord more often than cervical spinal cord. Usually located in central portion of spinal cord, lesions typically occupy more than two-thirds of cross-sectional area of spinal cord (88%) on T2WI, commonly extend three to four vertebral segments (53%), ± mild cord expansion (47%). Gadolinium contrast enhancement (focal or peripheral) is seen in 53% of cases, usually in acute/early subacute phase of demyelination.

Transverse myelitis is a noninfectious inflammatory process involving both halves of the spinal cord as well as gray and white matter. The disorder has multiple causes: demyelination after viral infection or vaccination (possibly a variant of ADEM), autoimmune diseases/collagen vascular diseases (SLE), paraneoplastic syndromes, or atypical multiple sclerosis, or it may be idiopathic. Can be diagnosis of exclusion. Occurs in males more than in females, and patients’ mean age = 45 years. Associated with various bilateral motor and sensory deficits. Pathologic changes considered to be a combination of demyelination and arterial or venous ischemia.


Other Noninfectious Inflammatory Disease Involving the Spinal Cord


Sarcoidosis ( Fig. 1.106 and Fig. 1.107 )

MRI: Poorly marginated intramedullary zone of high signal on T2-weighted imaging, low-intermediate signal on T1-weighted imaging, usually with gadolinium contrast enhancement (patchy multifocal, peripheral > central), ± mild expansion of spinal cord, ± associated leptomeningeal enhancement along pial surface. Location: Cervical/upper thoracic > mid and lower thoracic spinal cord.

Sarcoidosis is a multisystem noncaseating granulomatous disease of uncertain etiology that involves the CNS in ~ 5–15% of cases. Rarely involves the spinal cord. Associated with severe neurologic deficits if untreated. May mimic intramedullary neoplasm.


Sjögren syndrome ( Fig. 1.108 )

MRI: Intramedullary lesion or multiple lesions in spinal cord, can have low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging, + gadolinium (Gd) contrast enhancement in acute or early subacute demyelinating lesions. Older lesions typically don′t show Gd contrast enhancement. MRI features can overlap those for multiple sclerosis.

Autoimmune disease in which a mononuclear lymphocyte infiltration can occur in one or more exocrine glands (lacrimal, parotid, submandibular, and minor salivary glands), resulting in acinar cell destruction and impaired gland function. Autoantibodies associated with Sjögren syndrome include anti-Ro (SS-A antibodies) and anti-La (SS-B antibodies). Usually occurs in adults between 40 and 60 years old, with a female predominance of over 90%. Sjögren syndrome can be a primary disorder or a secondary form associated with other autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Patients present with decreased lacrimal and salivary gland function, xerostomia, and keratoconjunctivitis sicca. Demyelinating lesions in the brain, optic nerves, cranial nerves, spinal cord, and/or peripheral nerves occur in up to 20%. Other sites damaged by the autoimmune response include the eyes, lungs, heart, kidneys, and connective tissue.


Infectious Diseases of Spinal Cord


Viral infection

MRI: Intramedullary lesion or multiple lesions in spinal cord with low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging, ± minimal cord expansion, ± mild gadolinium contrast enhancement, ± leptomeningeal enhancement (cytomegalovirus, herpes).

Direct viral infection of spinal cord. Common causes include poliovirus, echovirus, hepatitis viruses (A, B, or C), rubella virus, measles virus, mumps virus, rabies virus, West Nile virus, Coxsackie virus, herpes simplex virus (I or II), herpes zoster from reactivation of varicella-zoster virus (VSV), cytomegalovirus (CMV), human immunodeficiency virus, and JC virus.


Abscess/nonviral infectious myelitis ( Fig. 1.109 )

MRI: Early findings in myelitis and spinal cord abscess include intramedullary zone of high signal on T2-weighted imaging (T2WI) with a poorly defined peripheral zone of contrast enhancement on T1-weighted imaging. The zone of peripheral enhancement can become more well defined over time, ± residual myelomalacia, ± leptomeningeal enhancement (with Mycobacterium tuberculosis infection or syphilis). Both high-signal abnormalities on T2WI and contrast enhancement can resolve with antibiotic therapy.

Infection can result from hematogenous dissemination or spread within CSF. Organisms and infections reported to result in spinal cord abscess or nonviral myelitis include Streptococcus milleri, S. pyogenes, Mycobacterium tuberculosis, atypical mycobacteria, syphilis, Schistosoma mansoni, and fungi (Cryptococcus, Candida, and Aspergillus).


Parasitic infection ( Fig. 1.110 )

MRI: Poorly marginated intramedullary zone of high signal on T2-weighted imaging and low-intermediate signal on T1-weighted imaging, usually + gadolinium contrast enhancement. Lesions are often located in the thoracic spinal cord, ± leptomeningeal enhancement. Usually, concurrent lesions are present in brain.

Parasitic infection of the spinal cord is rare. The most common parasite to involve the spinal cord is Toxoplasma gondii in immunocompromised patients. Otherwise, toxoplasmosis rarely involves the spinal cord. Schistosoma mansoni can involve the spinal cord in immunocompetent patients in Asia/Africa. Parasitic infection is associated with rapid decline in neurologic function related to the site of the lesion in the spinal cord.


Vascular Lesions


Intramedullary hemorrhage ( Fig. 1.111 and Fig. 1.112 )

Hyperacute phase (4–6 hours): Hemoglobin is primarily diamagnetic oxyhemoglobin (iron Fe2+ state), with intermediate signal on T1-weighted imaging (T1WI) and slightly high signal on T2-weighted imaging (T2WI).


Acute phase (12–48 hours): Hemoglobin primarily is paramagnetic deoxyhemoglobin (iron Fe2+ state), with intermediate signal on T1WI and low signal on T2WI, surrounded by a peripheral zone of high signal (edema) on T2WI.


Subacute phase (> 2 days): Hemoglobin becomes oxidized to the iron Fe3+ state, methemoglobin, which is strongly paramagnetic. Initially, when the methemoglobin is intracellular, the hematoma has high signal on T1WI that progresses peripherally to centrally and low signal on T2WI, surrounded by a zone of high signal (edema) on T2WI. Eventually, when the methemoglobin becomes primarily extracellular, the hematoma has high signal on T1WI and T2WI. Chronic phase: Hemoglobin is extracellular methemoglobin and is progressively degraded to hemosiderin.

Can result from trauma, vascular malformations, coagulopathy, infarction, metastases, abscesses, and viral infections (herpes simplex, cytomegalovirus).


Posthemorrhagic lesions

MRI: Intramedullary zone with high signal on T2-weighted imaging (T2WI) secondary to gliosis and myelomalacia, ± localized thinning of spinal cord, ± sites of low signal on T2WI where there is methemoglobin (also with high signal on T1-weighted imaging) and/or hemosiderin deposition. Typically there is no gadolinium contrast enhancement.

Sites of prior hemorrhage can have variable appearance depending on the relative ratios of gliosis, encephalomalacia, and blood breakdown products (methemoglobin, hemosiderin, etc.).


Arteriovenous malformation (AVM) ( Fig. 1.113 )

MRI: Lesions with irregular margins that can be located in the spinal cord (white and/or gray matter), dura, or both locations. AVMs contain multiple, tortuous, tubular flow voids on T1- and T2-weighted images secondary to patent arteries with high blood flow, as well as thrombosed vessels with variable signal, areas of hemorrhage in various phases, calcifications, gliosis, and myelomalacia. The venous portions often show gadolinium contrast enhancement, ± ischemia (high signal on T2-weighted imaging in the spinal cord) related to venous congestion, ± swelling of spinal cord. Usually not associated with mass effect unless there is recent hemorrhage or venous occlusion.

Intracranial AVMs are much more common than spinal AVMs. Annual risk of hemorrhage. AVMs can be sporadic, congenital, or associated with a history of trauma. Spinal AVMs are classified into four types according to anatomic involvement. Types I and IV are arteriovenous fistulas (AVFs), which are direct shunts between arteries and veins. Types II and III are AVMs, which are connected by a collection of abnormal vessels referred to as a nidus. Type I malformations, dural AVFs, are typically located at nerve root sleeves (most common type). In type II, intramedullary AVMs, the nidus is within the spinal cord. Type III, juvenile AVM, can involve the spinal cord, intradural extramedullary space, and extradural structures. Type IV, perimedullary (pial) AVFs, are located at the surface of the spinal cord or cauda equina. Patients can present with progressive myelopathy. Perimedullary AVFs and intramedullary AVMs can present with subarachnoid and/or intramedullary hemorrhage. Most frequently occur in men, 40 to 50 years old. Treatment includes surgery and/or endovascular embolization.


Cavernous malformation ( Fig. 1.114 )

MRI: Single or multiple multilobulated intramedullary lesions that have a peripheral rim or irregular zone of low signal on T2-weighted imaging and T2*-weighted imaging secondary to hemosiderin, surrounding a central zone of variable signal (low, intermediate, high, or mixed) on T1- and T2-weighted imaging, depending on ages of hemorrhagic portions. Gradient echo techniques are useful for detecting multiple lesions.

Cavernous malformations can occur as multiple lesions in the brain, brainstem, and/or spinal cord. Family history of cavernous malformations occurs in 12% of cases, and16% of patients with cavernous malformations in the spinal cord also have cerebral lesions. Patients range in age from 2 to 80 years (mean age = 39 years). Cavernous malformations occur more commonly in the thoracic spinal cord than in the cervical spinal cord. Usually measure ~ 10 mm. Symptoms include motor and sensory deficits, pain, and bowel and bladder dysfunction. Associated with increased risk of hemorrhage and progression of symptoms. Treatment of symptomatic lesions with surgery or microsurgery can lead to clinical improvement.


Venous angioma (Developmental venous anomaly)

MRI: On postcontrast T1-weighted imaging, venous angiomas are seen as a gadolinium-enhancing vein draining a collection of small medullary veins (caput medusae). The draining vein may be seen as a signal void on T2-weighted imaging.

Considered an anomalous venous formation and typically not associated with hemorrhage. Usually an incidental finding, except when associated with cavernous malformation.


Spinal cord infarct/ischemia of arterial etiology ( Fig. 1.115 )

MRI: Four MRI patterns of abnormalities associated with spinal cord ischemia are related to the distribution of the anterior spinal artery (artery of Adamkiewicz):


1. Zones of high signal on T2-weighted imaging (T2WI) involving the anterior horns of the gray matter of the spinal cord.


2. Zones of high signal on T2WI involving both the anterior and posterior horns of the gray matter of the spinal cord.


3. Diffuse zone of high signal on T2WI involving all of the gray matter of the spinal cord and adjacent central white matter.


4. Diffuse zone of high signal on T2WI involving the entire cross-section of the spinal cord.

Arterial infarcts often occur in the territory of the anterior spinal artery, which supplies the anterior two-thirds of the spinal cord, including the white and gray matter. Ischemia or infarcts involving the spinal cord are rare disorders associated with atherosclerosis, diabetes, hypertension, abdominal aortic aneurysms, and abdominal aortic surgery. Associated with rapid onset of bladder and bowel dysfunction. Ischemia/infarction of the spinal cord is most often seen in the thoracolumbar distribution of the anterior spinal artery (artery of Adamkiewicz).


Ischemia—Venous infarction/congestion ( Fig. 1.116 )

MRI: Poorly defined intramedullary zone of low-intermediate signal on T1-weighted imaging, high signal on T2-weighted images involving gray and white matter, ± cord expansion, ± gadolinium contrast enhancement, and dilated veins on the pial surface of the spinal cord.

Venous infarction of the spinal cord is associated with dural arteriovenous fistula or malformation and thrombophlebitis. Results in coagulative necrosis of the gray and white matter of the spinal cord (subacute necrotizing myelopathy). MRI features may overlap those of arterial ischemia/infarction involving the spinal cord.


Traumatic Lesions


Spinal cord contusion ( Fig. 1.117 )

MRI: Poorly defined intramedullary zone of low-intermediate signal on T1-weighted imaging (T1WI), high signal on T2-weighted imaging (T2WI) involving gray and/or white matter, ± cord expansion, ± zones of high signal on T1WI (methemoglobin) or low signal on T2WI (intracellular methemoglobin), usually no gadolinium contrast enhancement, ± avulsed nerve roots (Erb′s palsy), ± vertebral fracture, ± disruption of posterior longitudinal ligament.

Traumatic injury of spinal cord is often secondary to a large disk herniation, vertebral fracture, vertebral subluxation/dislocation, impression by foreign body, hyperflexion/extension injury, or birth trauma.


Spinal cord transection ( Fig. 1.118 )

MRI: Foci and/or diffuse zones of high signal on T2-weighted imaging (T2WI) involving the gray and/or white matter of the spinal cord, irregular linear zone with high signal on T2WI oriented transversely or obliquely to the long axis of the spinal cord, ± gadolinium contrast enhancement.

Severe traumatic injury from acceleration/deceleration or shaking can result in transection of axons. Often associated with other injuries, such as vertebral fractures and subarachnoid or intramedullary hemorrhage.


Chronic injury ( Fig. 1.119 )

MRI: Poorly defined intramedullary zone of low-intermediate signal on T1-weighted imaging (T1WI), high signal on T2-weighted imaging (T2WI) involving gray and white matter, ± cord atrophy, ± intramedullary zones of cavitation (discrete zones of low signal on T1WI and high signal on T2WI) or macrocystic change, no gadolinium contrast enhancement, ± syringohydromyelia.

Myelomalacia that can result from prior traumatic injuries, severe spinal stenosis, severe kyphosis, spondylolisthesis, prior demyelination, or radiation injury.


Degenerative Abnormalities


Myelomalacia ( Fig. 1.120 )

MRI: Asymmetric or symmetric decrease of spinal cord volume, usually associated with abnormal increased intramedullary signal on T2-weighted imaging, and no gadolinium contrast enhancement.

Atrophy of the spinal cord can result from chronic compression related to spinal canal stenosis, prior demyelination, infection, hemorrhage, trauma, or neurodegenerative disorders, such as spinocerebellar ataxia/degeneration, Friedreich′s ataxia, etc.


Wallerian degeneration

MRI: Bilateral zones of abnormal high signal on T2-weighted imaging in lateral corticospinal tracts below the site of spinal cord injury and in the dorsal columns above the site of cord injury, usually seen 7 weeks or more after injury, and usually with no gadolinium contrast enhancement.

Wallerian degeneration represents antegrade degeneration of axons and their myelin sheaths from injury to the cell bodies or proximal portions of axons. With spinal cord damage, Wallerian degeneration is seen in the dorsal columns above the site of injury and in the corticospinal tracts below the site of injury. The size of the intramedullary lesions/abnormalities is dependent on the number of axons affected. Wallerian degeneration can involve one side of the brainstem and spinal cord related to neuronal/axonal loss in the brain from cerebral infarction or cerebral hemorrhage.


Amyotrophic lateral sclerosis

MRI: Bilateral zones with high signal on T2-weighted imaging (T2WI) and FLAIR can occasionally be seen involving the corticospinal tracts in the posterior limbs of the internal capsules, brainstem, and spinal cord, ± low signal on T2WI involving the motor cortex from iron deposition, no gadolinium contrast enhancement, ± atrophy of spinal cord.


Diffusion tensor imaging: Progressive decreases occur in the fractional anisotropy at the corticospinal tracts and corpus callosum secondary to myelin damage.

Progressive and often rapid degeneration of upper motor neurons of the primary motor cortex and corticospinal tracts (CST), medullary brainstem nuclei, and lower motor neurons at the anterior horns of the spinal cord. Usually occurs in adults > 55 years old, with progressive muscle weakness and atrophy leading to death. Histologic findings include loss of pyramidal motor neurons in the primary motor cortex, axonal degeneration in the CST, proliferation of glial cells, and expansion of the extracellular matrix. Degeneration also involves neurons in the frontal and temporal lobes.


Poliomyelitis ( Fig. 1.121 )

MRI: Acute infection appears as localized enlargement and high signal on T2-weighted imaging (T2WI) involving the ventral horns of the spinal cord. Chronic manifestations appear as foci of high signal on T2WI in one or both of the ventral horns of the spinal cord.

Poliovirus targets the anterior horn cells in the spinal cord (ventral horns), resulting in asymmetric, flaccid paralysis. The native virus is virtually eradicated, although vaccine-associated paralytic poliomyelitis does rarely occur.


Radiation myelopathy ( Fig. 1.122 )

MRI: Focal or poorly defined zone of low-intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, ± gadolinium contrast enhancement, ± expansion of spinal cord, late phase gliosis/atrophy.

Usually occurs from 3 months to 10 years (most often between 9 to 20 months) after radiation treatment, and may be difficult to distinguish from neoplasm. Histopathologic findings include zones of axonal degeneration and demyelination, necrosis, and hyaline and/or fibrinoid degeneration of vascular endothelium. Marrow in the field of radiation treatment typically has high signal on T1-weighted imaging because of loss of red marrow (increased proportion of yellow marrow to red marrow).


Other Lesions


Syringohydromyelia ( Fig. 1.123; see also Fig. 1.14 )

MRI: Enlarged spinal cord with intramedullary fluid-filled zone that is central or slightly eccentric. Usually there is a distinct interface between the intramedullary fluid and solid portions of the spinal cord, ± septations along syrinx, ± zone of high signal surrounding syrinx (edema, gliosis). No gadolinium contrast enhancement if benign syringohydromyelia, ± enhancement if syrinx is associated with intramedullary neoplasm.

Hydromyelia is distention of the central canal of the spinal cord (lined by ependymal cells). Syringomyelia is dissection of CSF into the spinal cord (not lined by ependymal cells). Syringohydromyelia is a combination of both, and may be secondary to congenital/developmental anomalies (Chiari I or Chiari II malformation or basilar invagination), or secondary to neoplasms of the spinal cord (astrocytoma, ependymoma, or hemangioblastoma).


Vitamin B12 deficiency (Subacute combined degeneration) ( Fig. 1.124 )

MRI: Symmetric longitudinally oriented zones of high signal on T2-weighted imaging involving the dorsal and lateral columns of the spinal cord, ± restricted diffusion, ± mild expansion of the spinal cord, usually with no or minimal gadolinium contrast enhancement. Intramedullary signal abnormalities can resolve after correction of vitamin B12 deficiency.

The abnormalities involving the spinal cord caused by vitamin B12 (cobalamin) deficiency are referred to as subacute combined degeneration. Vitamin B12 is an enzymatic cofactor associated with the cytosolic enzyme methionine synthetase, which catalyzes the methylation of homocysteine to methionine, enabling the synthesis of myelin protein, DNA, lipids, and carbohydrates. Vitamin B12 deficiency can result from dietary insufficiency, malabsorption, or exposure to nitrous oxide, which inactivates the vitamin by oxidizing its cobalt component. Vitamin B12 deficiency causes myelopathy, peripheral neuropathy, cognitive impairment, and optic neuropathy. Histopathologic studies show lesions in the posterior and lateral columns of the spinal cord, as well as in the spinocerebellar and corticospinal tracts.


Superficial siderosis ( Fig. 1.125 )

MRI: Thin rims of low signal on T2-weighted and gradient echo images along the pial surface of the spinal cord and/or brain.

The low signal on T2-weighted and gradient echo images results from chronic hemosiderin deposition from prior episodes of subarachnoid hemorrhage (ruptured aneurysm, trauma, coagulopathy, vascular malformation, etc.). Subpial iron deposition is associated with free radical damage, causing neuronal injury/loss, demyelination, and reactive gliosis. Can lead to progressive neurologic deterioration (cerebellar gait ataxia, sensorineural hearing loss).

(a) Sagittal T2-weighted imaging of an 18-year-old male with a pilocytic astrocytoma (arrows) in the upper cervical spinal cord extending into the medulla that has heterogeneous high signal. (b) The lesion shows gadolinium contrast enhancement (arrow) on sagittal fat-suppressed T1-weighted imaging.
(a) Sagittal T2-weighted imaging of a 14-year-old male shows an astrocytoma in the thoracic spinal cord that has high signal (arrow). (b) The lesion shows irregular gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 78-year-old woman with an anaplastic astrocytoma in the cervical spinal cord that has high signal centrally surrounded by thin irregular zone with low signal from hemosiderin with adjacent peripheral high signal (arrow). (b) The tumor shows irregular intramedullary gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 46-year-old woman with a glioblastoma multiforme in the conus medullaris (arrow) that has high signal. (b) The lesion shows irregular intramedullary gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 49-year-old woman with an intramedullary ependymoma in the cervical spinal cord (arrow) that has high signal and (b) shows nodular intramedullary gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 27-year-old man with an intramedullary ependymoma in the cervical and upper thoracic spinal cord that has heterogeneous high signal with adjacent edema and syrinx formation (arrows). (b) The tumor shows intramedullary gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal fat-suppressed T2-weighted imaging of a 24-year-old man with neurofibromatosis type 2 who has multiple intramedullary ependymomas in the cervical spinal cord (arrows) that have high signal. (b) The tumors show gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrows).
Sagittal T2-weighted imaging of an 8-year-old female who has a ganglioglioma in the conus medullaris (arrow) that has high signal.
(a,b) Sagittal T2-weighted imaging of a 14-month-old female with a large ganglioglioma in the spinal cord that has heterogeneous slightly high signal with proximal and distal syrinx formation and peripheral edema. (c) The tumor shows gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging.
(a) Sagittal fat-suppressed T1-weighted imaging of a 26-year-old man with von Hippel-Lindau disease shows small, nodular, gadolinium-enhancing hemangioblastoma (arrows) at the dorsal surface of the cervical spinal cord. (b) There are associated poorly defined adjacent zones of intramedullary high signal on sagittal T2-weighted imaging (arrow).
(a) Sagittal T1-weighted imaging of a 47-year-old woman with von Hippel-Lindau disease shows a gadolinium-enhancing hemangioblastoma (arrow) in the thoracic spinal cord. (b) The lesion contains flow voids and heterogeneous high signal (arrow) with peripheral edema on sagittal T2-weighted imaging.
(a) Sagittal T1-weighted imaging of a 19-year-old man with a glioneuronal tumor in the cervical spinal cord that shows gadolinium contrast enhancement (arrow). (b) The tumor has heterogeneous high signal (arrow) on sagittal T2-weighted imaging, with a distal syrinx and peripheral edema with high signal.
(a) Sagittal fat-suppressed T1-weighted imaging of a 2-year-old male with a malignant glioneuronal tumor in the thoracic spinal cord that has multiple nodular zones of gadolinium contrast enhancement, as well as enhancing disseminated leptomeningeal tumor along the pial surface of the spinal cord, and (b) mixed slightly high and high intramedullary signal on sagittal T2-weighted imaging.
(a) Sagittal T2-weighted imaging of a 6-month-old female with a grade III oligodendroglioma (arrow) in the cervical and upper thoracic spinal cord that has high signal and (b) shows heterogeneous gadolinium contrast enhancement on sagittal T1-weighted imaging (arrows).
(a) Coronal fat-suppressed T1-weighted imaging of a 49-year-old woman shows multiple gadolinium-enhancing metastatic lesions in the brain from breast carcinoma. (b) Sagittal fat-suppressed T1-weighted imaging shows two gadolinium-enhancing metastatic lesions in the cervical spinal cord (arrows) that (c) have poorly defined high signal on sagittal fat-suppressed T2-weighted imaging (arrows).
(a) Sagittal and (b) axial images of a patient with multiple sclerosis show a slightly expansile “flame-shaped” intramedullary lesion with high signal (arrows) and corresponding gadolinium contrast enhancement on (c) sagittal and (d) axial fat-suppressed T1-weighted imaging (arrows) representing a zone of active demyelination.
(a) Sagittal fat-suppressed T2-weighted imaging of a 45-year-old woman with multiple sclerosis shows multiple intramedullary demyelinating lesions with high signal in the cervical and upper thoracic spinal cord. (b) Axial T2-weighted imaging shows one intramedullary zone of demyelination involving the white matter at the left lateral portion of the spinal cord (arrow).
(a) Sagittal and (b) axial T2-weighted images of an 11-year-old female with acute disseminated encephalomyelitis (ADEM) show a long, intramedullary, expansile zone of demyelination with high signal.
(a) Sagittal and (b) axial images of a 15-year-old male with acute disseminated encephalomyelitis (ADEM) show an irregular intramedullary zone of demyelination in the cervical and upper thoracic spinal cord that has irregular high signal.
(a) Sagittal and (b) axial images of a 51-year-old man with transverse myelitis involving the thoracic spinal cord (arrows) that has high signal involving more than two-thirds of the cross-sectional area of the spinal cord. (c) Axial fat-suppressed T1-weighted imaging shows gadolinium contrast enhancement of the actively demyelinating lesion (arrow).
(a) Sagittal fat-suppressed T1-weighted imaging of a 35-year-old man with sarcoidosis shows a gadolinium-enhancing intramedullary lesion in the cervical spinal cord (arrow) that has (b) high signal on sagittal T2-weighted imaging (arrow). The extent of the abnormal high signal on T2-weighted imaging is larger than the zone of gadolinium contrast enhancement.
(a) Sagittal fat-suppressed T1-weighted imaging of a 39-year-old man with sarcoidosis shows a gadolinium-enhancing intramedullary lesion involving the dorsal portion of the cervical spinal cord (arrow) that has (b) high signal on sagittal T2-weighted imaging (arrow). The extent of the abnormal high signal on T2-weighted imaging is larger than the zone of gadolinium contrast enhancement.
(a) Sagittal fat-suppressed T2-weighted imaging of a 46-year-old woman with Sjögren syndrome shows an intramedullary demyelinating lesion with high signal (arrow), and (b) a corresponding peripheral rim of gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Postsurgical sagittal T2- weighted imaging shows an abscess (arrows) with irregular, heterogeneous, slightly high and high signal in the conus medullaris, which has (b) a peripheral rim of gadolinium contrast enhancement on axial fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 38-year-old man with toxoplasmosis of the thoracic spinal cord that has high signal (arrow) and (b) shows gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
Sagittal T1-weighted imaging of a 45-year-old man shows an intramedullary hemorrhage with high signal from an arteriovenous malformation.
(a) Sagittal T1-weighted imaging and (b) sagittal fat-suppressed T1-weighted imaging of a 73-year-old woman show an intramedullary hemorrhage with high signal related to an astrocytoma.
(a) Sagittal and (b) axial T2-weighted imaging of a 39-year-old man show an arteriovenous malformation (AVM) with multiple flow voids within the spinal cord and subarachnoid space. (c) Spinal arteriogram shows the abnormally dilated and tortuous vessels of the AVM.
(a) Sagittal T1-weighted imaging of a 22-year-old woman shows an intramedullary cavernous malformation that has mostly high signal centrally surrounded by a rim of low-signal hemosiderin on (b) sagittal T2-weighted imaging and (c) axial gradient recalled echo imaging.
(a) Sagittal and (b) axial T2-weighted images show an infarct from arterial occlusion involving the central gray matter of the spinal cord, which has high signal.
(a) Sagittal T2-weighted imaging shows an intradural arteriovenous malformation with multiple flow voids in the subarachnoid space adjacent to the lower spinal cord. A poorly defined intramedullary zone of high signal involves gray and white matter, with (b) associated gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow) representing coagulative ischemic necrosis (subacute necrotizing myelopathy).
Sagittal fat-suppressed T2-weighted imaging shows an acute severe flexion fracture of the C5 vertebral body with retropulsed bone compressing the spinal cord, causing a spinal cord contusion with high intramedullary signal (arrow).
Sagittal fat-suppressed T2-weighted imaging shows a quadrangular flexion fracture of the C4 vertebra (vertical arrows) associated with tears of the interspinous ligaments with high signal and poorly defined high intramedullary signal from cord contusion, as well as a high-signal line representing transection of the spinal cord (horizontal arrow).
Sagittal T2-weighted imaging shows myelomalacia and a posttraumatic syrinx (arrow) in the cervical spinal cord related to prior fracture of the C5 vertebral body.
Sagittal fat-suppressed T2-weighted imaging of a 58-year-old man shows atrophy and poorly defined high signal in the cervical spinal cord representing a zone of myelomalacia (arrow) secondary to severe spinal canal stenosis at the C4–C5 level.
Axial T2-weighted imaging of a patient with remote poliomyelitis shows foci with high signal in the anterior horn cells of the spinal cord.
(a,b) Sagittal fat-suppressed T1-weighted imaging of a patient with breast carcinoma shows multiple, irregular, gadolinium-enhancing, metastatic lesions in the vertebral marrow that were treated with radiation. A poorly defined intramedullary zone of gadolinium contrast enhancement is seen in the spinal cord (arrow in a) with associated high signal on axial T2-weighted imaging (arrow in b) representing the site of radiation-induced myelopathy.
(a) Sagittal and (b) axial T2-weighted images of a 54-year-old woman show a syrinx with high signal expanding the cervical spinal cord.
(a) Sagittal and (b) axial T2-weighted images of a 19-year-old man with vitamin B12 deficiency (subacute combined degeneration) shows symmetric longitudinally oriented zones of high signal involving the dorsal and lateral columns of the mildly expanded spinal cord.
(a) Sagittal and (b) axial T2-weighted images of a 66-year-old woman with superficial siderosis show a thin rim of low signal along the pial surface of the spinal cord.


Table 1.4 Dural and intradural extramedullary lesions




  • Congenital and Developmental




    • Meningocele



    • Dural dysplasia/ectasia



    • Dorsal dermal sinus



    • Dermoid



    • Epidermoid



    • Neurenteric cyst



    • Fibrolipoma of the filum terminale



  • Neoplasms




    • Ependymoma



    • Schwannoma (Neurinoma)



    • Meningioma



    • Neurofibroma



    • Paraganglioma



    • Teratoma



    • Hemangioma



    • Hemangioblastoma



    • Hemangiopericytoma



    • Solitary fibrous tumors (SFTs)



    • Primitive neuroectodermal tumor



    • Leptomeningeal neoplastic disease



    • Lymphoma



    • Leukemia



    • Primary melanocytic tumors of the central nervous system



  • Infection




    • Bacterial infection



    • Fungal infection



    • Viral infection



  • Noninfectious Dural and Leptomeningeal Disorders




    • Sarcoidosis



    • Guillain-Barré syndrome



    • Chronic inflammatory demyelinating polyneuropathy



    • Radiculitis



    • Adhesive arachnoiditis



    • Arachnoiditis ossificans



    • Granulomatosis with polyangiitis (Wegener′s granulomatosis)



    • Idiopathic hypertrophic pachymeningitis



  • Vascular Lesions




    • Arteriovenous malformations (AVMs)



    • Hemorrhage within CSF (Subarachnoid hemorrhage)



    • Subdural hemorrhage



  • Acquired Lesions




    • Perineural cysts/Tarlov cysts



    • Arachnoid cyst



    • Pseudomeningocele



    • CSF leak/fistula



    • Spinal cord herniation



    • Intradural herniated disk



    • Calcifying pseudoneoplasm of the neuraxis (CAPNON)





































































































































































































Dural and intradural extramedullary lesions

Lesions

Imaging Findings

Comments

Congenital and Developmental


Meningocele (See Fig. 1.27 and Fig. 1.346 )

MRI: Protrusion of CSF and meninges through a vertebral defect caused by either surgical laminectomy or congenital anomaly. Sacral meningoceles can extend anteriorly through a defect in the sacrum.

Acquired meningoceles are more common than meningoceles resulting from congenital dorsal bony dysraphism. Anterior sacral meningoceles can result from trauma or can be associated with mesenchymal dysplasias (neurofibromatosis type 1, Marfan syndrome, syndrome of caudal regression).


Dural dysplasia/ectasia (See Fig. 1.45 and Fig. 1.46 )

MRI: Scalloping of the dorsal aspects of the vertebral bodies, dilatation of optic nerve sheaths, dilatation of intervertebral and sacral foraminal nerve sheaths, and lateral meningoceles.

Dural ectasia is defined as expansion of the dural sac, often in association with herniation of nerve root sleeves through foramina. In addition to occurring in neurofibromatosis type 1 (NF1) and Marfan syndrome, dural ectasia can also occur with Ehlers-Danlos syndrome, ankylosing spondylitis, scoliosis, and trauma. Dural dysplasia is associated with NF1.


Dorsal dermal sinus (See Fig. 1.23 )

MRI: Thin tubular structure with low signal on T1-weighted imaging extending internally from a dimple in the dorsal skin of the lower back, with or without extension into the spinal canal through the median raphe or spina bifida, with or without associated dermoid or epidermoid in the spinal canal (50%).

Epithelium-lined fistula that extends from a dimple in the dorsal skin surface (± hairy nevus, hyperpigmented patch, or hemangioma at ostium of the dimple) toward and/or into the spinal canal. Results from lack of normal developmental separation of superficial ectoderm from neural ectoderm. Lumbar > thoracic > occipital regions. Potential source of infection involving spine and spinal canal.


Dermoid ( Fig. 1.126 )

MRI: Well-circumscribed spheroid or multilobulated intradural lesion, usually with high signal on T1-weighted images and variable low, intermediate, and/or high signal on T2-weighted imaging, no gadolinium contrast enhancement, ± fluid–fluid or fluid–debris levels. Lumbar region is the most common location of spinal dermoid.


CT: Well-circumscribed spheroid or multilobulated intradural lesions, usually with low attenuation, ± fat–fluid or fluid–debris levels. Can be associated with dorsal dermal sinus.

Nonneoplastic congenital or acquired ectodermal-inclusion cystic lesions filled with lipid material, cholesterol, desquamated cells, and keratinaceous debris, usually with mild mass effect on adjacent spinal cord or nerve roots, ± related clinical symptoms. Occurs in adults, and in males slightly more than in females. Can cause chemical meningitis if dermoid cyst ruptures into the subarachnoid space.


Epidermoid

MRI: Well-circumscribed, spheroid or multilobulated, intradural, ectodermal-inclusion cystic lesions with low-intermediate signal on T1-weighted imaging and high signal on T2- and diffusion-weighted imaging. Mixed low, intermediate, or high signal on FLAIR images, and no gadolinium contrast enhancement. Can be associated with dorsal dermal sinus.


CT: Well-circumscribed, spheroid or multilobulated, extra-axial ectodermal-inclusion cystic lesions with low-intermediate attenuation.

Nonneoplastic extramedullary epithelial-inclusion lesions filled with desquamated cells and keratinaceous debris, usually with mild mass effect on adjacent spinal cord and/or nerve roots, ± related clinical symptoms. May be congenital (± associated dorsal dermal sinus, spina bifida, hemivertebrae) or acquired (late complication of lumbar puncture). Occurs in males and females equally often.


Neurenteric cyst ( Fig. 1.127; see also Fig. 1.31 )

MRI: Well-circumscribed, spheroid, intradural, extra-axial lesion, with low, intermediate, or high signal on T1-weighted imaging (related to protein concentration) and on T2-weighted imaging, and usually shows no gadolinium contrast enhancement. CT: Circumscribed, intradural, extra-axial structure with low-intermediate attenuation. Usually no contrast enhancement.

Neurenteric cysts are malformations in which there is a persistent communication between the ventrally located endoderm and the dorsally located ectoderm secondary to developmental failure of separation of the notochord and foregut. Obliteration of portions of a dorsal enteric sinus can result in cysts lined by endothelium, fibrous cords, or sinuses. Observed in patients < 40 years old. Location: thoracic > cervical > posterior cranial fossa > craniovertebral junction > lumbar. Usually midline in position and often ventral to the spinal cord or brainstem. Associated with anomalies of the adjacent vertebrae.


Fibrolipoma of the filum terminale (See Fig. 1.26 )

MRI: Thin linear zone of high signal on T1-weighted imaging along the filum terminale, usually less than 3 mm in diameter, with normal position of conus medullaris (typically not associated with tethering of spinal cord).

Asymptomatic incidental finding with incidence of ~ 5%. The distal end of the conus is normally positioned.


Neoplasms


Ependymoma ( Fig. 1.128 and Fig. 1.129 )

MRI: Intradural, circumscribed, lobulated lesions at conus medullaris and/or cauda equina/filum terminale, rarely in sacrococcygeal soft tissues. Lesions usually have low-intermediate signal on T1-weighted imaging (T1WI) and intermediate-high signal on T2-weighted imaging (T2WI), ± foci of high signal on T1WI from mucin or hemorrhage, ± peripheral rim of low signal (hemosiderin) on T2WI, ± tumoral cysts (high signal on T2WI). Ependymomas shows varying degrees of Gd-contrast enhancement.


CT: Lesions usually have intermediate attenuation, ± hemorrhage.

Ependymomas at conus medullaris or cauda equina/filum terminale usually are myxopapillary, and are thought to arise from the ependymal glia of the filum terminale. There is a slight male predominance. Usually, ependymomas are slow-growing neoplasms associated with long duration of back pain, sensory deficits, motor weakness, and bladder and bowel dysfunction, ± chronic erosion of bone, with scalloping of vertebral bodies and enlargement of intervertebral foramina.


Schwannoma (Neurinoma) ( Fig. 1.130 and Fig. 1.131 )

MRI: Circumscribed spheroid or ovoid extramedullary lesions, with low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging (T2WI), and usually prominent gadolinium (Gd) contrast enhancement. High signal on T2WI and Gd contrast enhancement can be heterogeneous in large lesions due to cystic degeneration and/or hemorrhage.


CT: Lesions have intermediate attenuation, + contrast enhancement. Large lesions can have cystic degeneration and/or hemorrhage.

Schwannomas are encapsulated neoplasms arising asymmetrically from nerve sheath that contain differentiated neoplastic Schwann cells. They are the most common type of intradural extramedullary neoplasm, usually present in adults with pain, radiculopathy, paresthesias, and lower extremity weakness. Immunoreactive to S-100. Multiple schwannomas are seen in neurofibromatosis type 2 (NF2), which is an autosomal dominant disease involving a gene mutation at chromosome 22q12. In addition to schwannomas, patients with NF2 can also have multiple meningiomas and ependymomas. The incidence of NF2 is 1/37,000 to 1/50,000 newborns. Age at presentation = 22 to 72 years (mean age = 46 years). Peak incidence is in the fourth to sixth decades. Many patients with NF2 present in the third decade with bilateral vestibular schwannomas.


Meningioma ( Fig. 1.132 and Fig. 1.133 )

MRI: Extradural or intradural extramedullary lesion, with intermediate signal on T1-weighted imaging, intermediate-slightly high signal on T2-weighted imaging, and usually prominent gadolinium contrast enhancement, ± calcifications.


CT: Lesions usually have intermediate attenuation, + contrast enhancement, ± calcifications.

Usually benign neoplasms, meningiomas typically occur in adults (> 40 years old), and in women more than in men. Composed of neoplastic meningothelial (arachnoidal or arachnoid cap) cells. Immunoreactive to epithelial membrane antigen. Meningiomas are usually solitary and sporadic, but can also occur as multiple lesions in neurofibromatosis type 2. Can result in compression of adjacent spinal cord and nerve roots; rarely are invasive/malignant.


Neurofibroma ( Fig. 1.134 )

MRI: Lobulated ovoid or spheroid extramedullary lesions, ± irregular margins, ± extradural extension of lesion with dumbbell shape, ± erosion of foramina, ± scalloping of dorsal margin of vertebral body (chronic erosion or dural ectasia in neurofibromatosis type 1). Lesions have low-intermediate signal on T1-weighted imaging, high signal on T2-weighted imaging (T2WI), + prominent gadolinium (Gd) contrast enhancement. High signal on T2WI and Gd contrast enhancement can be heterogeneous in large lesions.


CT: Lesions usually have intermediate attenuation, + contrast enhancement, erosion of adjacent bone.

Unencapsulated neoplasms involving nerve and nerve sheath, neurofibromas are a common type of intradural extramedullary neoplasm, often with extradural extension. These benign tumors contain mixtures of Schwann cells, perineural-like cells, and interlacing fascicles of fibroblasts associated with abundant collagen. Unlike schwannomas, neurofibromas lack Antoni A and B regions and cannot be separated pathologically from the underlying nerve. Most frequently occur as sporadic, localized, solitary lesions, less frequently as diffuse or plexiform lesions. Multiple neurofibromas are typically seen with neurofibromatosis type 1, which is an autosomal dominant disorder (1/2,500 births) caused by mutations of the neurofibromin gene on chromosome 17q11.2. Usually present in adults with pain, radiculopathy, paresthesias, and lower extremity weakness.


Paraganglioma ( Fig. 1.135 )

MRI: Spheroid, ovoid, lobulated, intradural, extramedullary lesion with intermediate signal on T1-weighted imaging (T1WI) and intermediate-high signal on T2-weighted imaging (T2WI), ± tubular zones of flow voids, + prominent gadolinium contrast enhancement, ± foci of high signal on T1WI from mucin or hemorrhage, ± peripheral rim of low signal (hemosiderin) on T2WI, usually located in region of cauda equina and filum terminale.


CT: Lesions usually have intermediate attenuation, + contrast enhancement.

Benign encapsulated neuroendocrine tumors that arise from neural crest cells associated with autonomic ganglia (paraganglia) throughout the body. Lesions, also referred to as chemodectomas, are named according to location (glomus jugulare, tympanicum, vagale). Rarely occur in spine as intradural extramedullary lesions within the lumbar thecal sac.


Teratoma ( Fig. 1.136 )

MRI: Circumscribed lesions with variable low, intermediate, and/or high signal on T1- and T2-weighted imaging, ± gadolinium contrast enhancement. May contain calcifications and cysts, as well as fatty components.


CT: Circumscribed lesions with variable low, intermediate, and/or high attenuation, ± contrast enhancement. May contain calcifications and cysts, as well as fatty components.

The second most common type of germ cell tumor, teratomas occur most often in children, and in males more than in females. There are benign and malignant types. Mature teratomas have differentiated cells from ectoderm, mesoderm (cartilage, bone, muscle, and/or fat), and endoderm (cysts with enteric or respiratory epithelia). Immature teratomas contain partially differentiated ectodermal, mesodermal, or endodermal cells.


Hemangioma ( Fig. 1.137 )

MRI: Circumscribed or poorly marginated structures (< 4 cm in diameter) with intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging (T2WI) and fat-suppressed T2WI, typically with gadolinium contrast enhancement.


CT: Hemangiomas have mostly intermediate attenuation, + contrast enhancement.

Hemangiomas are benign lesions of soft tissue or bone composed of capillary, cavernous, and/or venous malformations. Considered to be a hamartomatous disorder. Intraosseous hemangiomas in the vertebrae occur as incidental findings in up to 10% of patients. Hemangiomas rarely occur in the spinal cord or as intradural extramedullary lesions. Can be associated with back and radicular pain. Occur in patients 1 to 84 years old (median age = 33 years).


Hemangioblastoma (See Fig. 1.96 )

MRI: Small gadolinium-enhancing nodule ± cyst, or larger lesion with prominent heterogeneous enhancement ± flow voids within lesion or at the periphery. Intermediate signal on T1-weighted imaging, intermediate-high signal on T2-weighted imaging, and occasionally evidence of recent or remote hemorrhage.


CT: Small contrast-enhancing nodule ± cyst, or larger lesion with prominent heterogeneous enhancement, ± hemorrhage.

Slow-growing, vascular tumors (WHO grade I) that involve the cerebellum, brainstem, and/or spinal cord. Can extend into the spinal subarachnoid space. Tumors consist of numerous thin-walled vessels as well as large, lipid-containing, vacuolated stromal cells that have variably sized hyperchromatic nuclei. Mitotic figures are rare. Stromal cells are immunoreactive to VEGF, vimentin, CXCR4, aquaporin 1, carbonic anhydrase, S-100, CD56, neuron-specific enolase, and D2–40. Vessels typically react to a reticulin stain. Tumors occur as a result of sporadic mutations of the VHL gene or as a result of an autosomal dominant germline mutation of the VHL gene on chromosome 3p25–26 that causes von Hippel-Lindau (VHL) disease. In VHL disease, multiple CNS hemangioblastomas occur, as well as clear-cell renal carcinoma, pheochromocytoma, endolymphatic sac tumor, neuroendocrine tumor, pancreatic adenoma, and epididymal cystadenoma. VHL disease occurs in adolescents and young and middle-aged adults.


Hemangiopericytoma

MRI: Extradural or intradural extramedullary lesions that can involve vertebral marrow. Lesions are often well circumscribed, with intermediate signal on T1-weighted imaging, intermediate to slightly high signal on T2-weighted imaging, and prominent gadolinium contrast enhancement (may resemble meningiomas), ± associated erosive bone changes.

Rare malignant tumors of presumed pericytic origin that contain variously shaped pericytic cells (oval, round, spindlelike) and adjacent irregular branching vascular spaces lined by endothelial cells. Mildly immunoreactive to CD34, with frequent mitoses and necrosis. Frequency of metastases is greater than that for meningiomas. Usually occur in soft tissues and less frequently in bone. Account for < 1% of primary soft tissue tumors. Most tumors occur in young adults (90–95%), only 5–10% occur in children, and more commonly found in males than in females. Hemangiopericytomas are sometimes referred to as angioblastic meningioma or meningeal hemangiopericytoma.


Solitary fibrous tumors (SFTs) ( Fig. 1.138 )

MRI: SFTs often have circumscribed margins and can be extramedullary, intramedullary, or both. Often have low to intermediate signal on T1- and proton density-weighted imaging, low, intermediate, and/or slightly high signal on T2-weighted imaging (T2WI), and heterogeneous slightly high to high signal on fat-suppressed T2WI. Usually show gadolinium contrast enhancement.

Rare, benign, spindle-cell, mesenchymal neoplasms that occur in a wide range of anatomic sites, including the extremities, and rarely the cranial or spinal meninges. SFTs typically show a branching vascular pattern similar to that of hemangiopericytoma, resemble pleural SFTs, and usually are strongly immunoreactive to CD34. SFTs account for less than 2% of soft tissue tumors. Median patient age ranges from 50 to 60 years. Treatment is typically surgery. Patients usually have a favorable prognosis.


Primitive neuroectodermal tumor ( Fig. 1.139 )

MRI: Circumscribed or poorly margined lesions, with low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging, ± cystic or necrotic zones, variable gadolinium (Gd) contrast enhancement, ± disseminated Gd contrast enhancement in the leptomeninges. Solid portions can have restricted diffusion on diffusion-weighted imaging.


CT: Variable abnormal intradural contrast enhancement, ± dissemination into the leptomeninges.

Highly malignant tumors (WHO grade IV) that are usually located in the cerebrum, pineal gland, and cerebellum, and rarely occur as primary intramedullary or extramedullary spinal tumors. The tumors frequently disseminate along CSF pathways. Tumors are composed of poorly differentiated or undifferentiated cells with divergent differentiation along neuronal, astrocytic, or ependymal lines. Typically occur in patients from 4 weeks to 20 years old (mean age = 5.5 years). Prognosis is poorer than that for medulloblastoma.


Leptomeningeal neoplastic disease ( Fig. 1.140 and Fig. 1.141 )

MRI: Single or multiple nodular enhancing lesions ± focal or diffuse abnormal subarachnoid enhancement along pial surface of the spinal cord. Low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging. Leptomeningeal tumor is best seen on postcontrast images.


CT: Single or multiple nodular subarachnoid lesions or thickened nerve roots on postmyelographic CT images.

Gadolinium contrast enhancement in the subarachnoid space (leptomeninges) usually is associated with significant pathology (neoplasm versus inflammation and/or infection). Primary CNS neoplasms commonly associated with subarachnoid dissemination include primitive neuroectodermal tumors (such as medulloblastoma, pineoblastoma, etc.), glioblastoma, ependymoma, and choroid plexus carcinoma. Metastases can occur within the CSF due to direct extension through the dura, by hematogenous dissemination, or via the choroid plexus. The most frequent primary neoplasms outside the CNS with subarachnoid metastases are lung carcinoma, breast carcinoma, melanoma, lymphoma, and leukemia.


Lymphoma ( Fig. 1.142 and Fig. 1.143 )

MRI: Single or multiple nodular enhancing lesions ± focal or diffuse abnormal subarachnoid enhancement along pial surface of the spinal cord. Low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging. Leptomeningeal tumor is best seen on postcontrast images.


CT: Single or multiple nodular subarachnoid lesions or thickened nerve roots on postmyelographic CT images.

Primary CNS lymphoma is more common than secondary, usually in adults > 40 years old. Lymphoma accounts for 5% of primary brain tumors and 0.8–1.5% of primary intracranial tumors. B-cell lymphoma is more common than T-cell lymphoma. Intracranial lymphoma involves the leptomeninges in secondary lymphoma more often than in primary lymphoma.


Leukemia ( Fig. 1.144 )

MRI: Single or multiple nodular enhancing lesions ± focal or diffuse abnormal subarachnoid enhancement along pial surface of the spinal cord. Low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging. Leptomeningeal tumor is best seen on postcontrast images.


CT: Single or multiple nodular subarachnoid lesions or thickened nerve roots on postmyelographic CT images.

Leukemias are neoplastic proliferations of hematopoietic cells. Myeloid sarcomas (also referred to as chloromas or granulocytic sarcomas) are focal tumors composed of myeloblasts and neoplastic granulocyte precursor cells, and occur in 2% of patients with acute myelogenous leukemia. Leukemic lesions can involve the dura, leptomeninges, brain, and spinal cord.


Primary melanocytic tumors of the central nervous system ( Fig. 1.145 )

MRI: Leptomeningeal lesions have irregular margins, low-intermediate or high signal (secondary to increased melanin) on T1-weighted imaging in the sulci, intermediate-slightly high signal on T2-weighted imaging, high signal on FLAIR, and leptomeningeal gadolinium contrast enhancement, ± hydrocephalus, ± vermian hypoplasia, ± arachnoid cysts, ± Dandy-Walker malformation. Intra-axial lesions usually < 3 cm in brain parenchyma/brainstem (anterior temporal lobes, cerebellum, thalami, inferior frontal lobes). Intra-axial lesions have intermediate-slightly high signal on T1-weighted imaging secondary to increased melanin, ± decreased signal on T2-weighted imaging, ± gadolinium contrast enhancement.


CT: May show subtle hyperdensity secondary to increased melanin, ± vermian hypoplasia, ± arachnoid cysts.

Primary melanocytic tumors of the CNS represents a spectrum of benign to malignant pigmented tumors in adults and children. In children, neurocutaneous melanosis is a rare nonfamilial disorder with focal and/or diffuse proliferation of melanocytes in leptomeninges associated with large and/or numerous cutaneous nevi. Presents in infants and young children. Immunoreactive to HMB-45, MART-1, and S-100. Cutaneous nevi are typically benign. Melanocytes in the leptomeninges change into CNS melanoma in 40–50%. Meningeal melanocytoma is a benign, rare, pigmented tumor consisting of leptomeningeal melanocytes that typically occur in the posterior cranial fossa or spinal canal in patients with a mean age of 42 years.


Infection


Bacterial infection ( Fig. 1.146 )

MRI: Single or multiple nodular enhancing subarachnoid lesions or enhancement along the pial margin of the spinal cord and/or nerve roots. Low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging. Leptomeningeal inflammation is often best seen on postcontrast images.

Gadolinium contrast enhancement in the subarachnoid space (leptomeninges) usually is associated with significant pathology (inflammation and/or infection versus neoplasm). Leptomeningeal inflammation and/or infection can result from pyogenic, fungal, or parasitic diseases, as well as tuberculosis. Pyogenic arachnoiditis can result from extension of intracranial meningitis, epidural abscess, or vertebral osteomyelitis, or it may be a complication of surgery or immunocompromised status.


Fungal infection

MRI: Single or multiple nodular enhancing subarachnoid lesions or enhancement along the pial margin of the spinal cord and/or nerve roots. Low-intermediate signal on T1-weighted imaging and intermediate-high signal on T2-weighted imaging. Leptomeningeal inflammation is often best seen on postcontrast images.

The fungi most commonly associated with leptomeningitis are Crytococcus neoformans, Cladophialophora bantiana, and Coccidioides immitis. Other fungi that infect the meninges include Aspergillus spp. , Candida albicans, Histoplasma capsulatum, Mucor, and Rhizopus. Fungal leptomeningitis usually occurs in immunocompromised patients.


Viral infection

MRI: Enlarged nerves with slightly high signal on T2-weighted imaging (T2WI) and fat-suppressed T2WI, ± gadolinium contrast enhancement.

Primary viral infections (cytomegalovirus, Coxsackie virus, echovirus, hepatitis viruses (A, B, or C), rubella virus, measles virus, mumps virus, rabies virus, Herpes simplex 1 or II viruses, varicella zoster virus, Epstein-Barr virus, human immunodeficiency virus, and West Nile virus) can cause direct infection of the intradural nerves.


Noninfectious Dural and Leptomeningeal Disorders


Sarcoidosis ( Fig. 1.147 )

MRI: Smooth and/or nodular gadolinium (Gd) contrast enhancement can be seen in the leptomeninges and/or dura. Lesions in the spinal cord can show poorly marginated intramedullary zones with low-intermediate signal on T1-weighted imaging, slightly high to high signal on T2-weighted imaging and FLAIR, and usually Gd contrast enhancement, + localized mass effect and peripheral edema.


CT: Smooth and/or nodular contrast enhancement can be seen in the leptomeninges and/or dura.

Sarcoidosis is a multisystem noncaseating granulomatous disease of uncertain cause that can involve the CNS in 5 to 15% of cases. If untreated, it may be associated with severe neurologic deficits, such as encephalopathy, cranial neuropathies, and myelopathy. Diagnosis of neurosarcoid may be difficult when the neurologic complications precede other systemic manifestations in the lungs, lymph nodes, skin, bone, and/or eyes.


Guillain-Barré syndrome ( Fig. 1.148 )

MRI: Gadolinium (Gd) contrast enhancement of one or more intradural thoracolumbar nerve roots, ± nerve root enlargement, ± aggregation of one or more intradural nerve roots, ± Gd contrast enhancement of cranial nerves.

Rapidly progressive peripheral inflammatory/demyelinating polyneuropathy characterized by progressive ascending weakness of the extremitries with areflexia. Incidence of 2/100,000. Often preceded by respiratory or gastrointestinal infection in prior month. CSF analysis shows elevated protein levels. Lymphocytic and macrophagic aggregates occur around endoneural vessels in association with nerve demyelination. EMG shows slowing or blocking of nerve conduction.


Chronic inflammatory demyelinating polyneuropathy (CIDP) or chronic acquired immune-mediated multifocal demyelinating neuropathy ( Fig. 1.149 )

MRI: Most frequently involves the nerves of the lumbar plexus and cauda equina, and infrequently involves the brachial plexus. Diffuse enlargement of multiple nerves with slightly high signal on T2-weighted imaging (T2WI) and fat-suppressed T2WI, with variable mild-moderate gadolinium contrast enhancement. Localized zones of nodular thickening may be seen within the enlarged nerves. Enlarged nerves can be bilateral and symmetric or asymmetric. Abnormally enlarged nerves can extend from the ventral rami to the lateral portions of the brachial plexus.

Acquired immune-mediated progressive/recurrent polyneuropathy that occurs more commonly in adults than in children. Prevalence of up to 7/100,000. Usually involves the spinal nerves, ± proximal nerve trunks of the brachial plexus. Patients present with relapsing or progressive symmetric proximal and distal muscle weakness without or with sensory loss. Diagnosis is based on biopsy and clinical and electrophysiologic examinations. EMGs show slowed conduction velocities from demyelination. Cycles of demyelination and remyelination produce enlarged nerves with inflammatory infiltrates (lymphocytes, macrophages). Can occur in association with IgG or IgA monoclonal gammopathy, inflammatory bowel disease, hepatitis C infection, HIV infection, diabetes, Sjögren syndrome, and lymphoma. Immunosuppressive medications can be used for treatment.


Radiculitis

MRI: Gadolinium contrast enhancement of one or more intradural nerve roots, ± nerve root enlargement, ± aggregation of one or more intradural nerve roots.

Gadolinium contrast enhancement of intradural nerves can be seen in two-thirds of asymptomatic volunteers, possibly secondary to enhancement of vessels adjacent to the nerves, but can also result from compression of nerve roots by disk herniation or from inflammation/infection (cytomegalovirus infection in AIDS patients, Guillain-Barré syndrome, sarcoid, etc.).


Adhesive arachnoiditis ( Fig. 1.150 )

MRI: Clumping of nerve roots within the thecal sac, and/or peripheral positioning of nerve roots within the thecal sac, “empty sac” sign, and usually not associated gadolinium contrast enhancement.


CT: Aggregation of nerve roots within the thecal sac, and/or peripheral positioning of nerve roots within the thecal sac, and “empty sac” sign on postmyelographic CT images.

Adhesive arachnoiditis is a chronic disorder that results in aggregation of nerve roots within the thecal sac or adhesion of nerve roots to the inner margin of the thecal sac. Can result from prior surgery, hemorrhage, radiation treatment, meningitis, or myelography with Pantopaque.


Arachnoiditis ossificans ( Fig. 1.151 )

CT: Irregular zones with high attenuation in the subarachnoid space.

Chronic inflammatory disorder that results in metaplastic ossification changes in the subarachnoid space, usually in the thoracic and lumbar regions. Can be associated with prior infection, hemorrhage, myelography, or surgery.


Granulomatosis with polyangiitis (Wegener′s granulomatosis) ( Fig. 1.152 )

MRI: Poorly defined zones of soft tissue thickening with low-intermediate signal on T1-weighted imaging, slightly high to high signal on T2-weighted imaging, and gadolinium contrast enhancement involving dura, ± bone invasion and destruction, ± extension into the adjacent soft tissues.

Multisystem disease with necrotizing granulomas in the respiratory tract, focal necrotizing angiitis of small arteries and veins of various tissues, and glomerulonephritis. Typically, positive immunoreactivity to cytoplasmic antineutrophil cytoplasmic antibody (c-ANCA). Can involve the paranasal sinuses, nasopharynx, orbits, brain, spinal cord, and cranial and/or spinal dura. Treatment includes corticosteroids, cyclophosphamide, and anti-TNF agents.


Idiopathic hypertrophic pachymeningitis ( Fig. 1.153 )

MRI: Thickened spinal and/or cranial dura with linear and/or nodular gadolinium contrast enhancement, ± spinal cord compression with intramedullary high signal on T2-weighted imaging.

Rare idiopathic disorder in which there is chronic inflammatory hypertrophy of cranial and/or spinal dura. Usually is a diagnosis of exclusion. Patients often present in the sixth or seventh decades with clinical complaints of local pain, ± progressive radiculopathy and myelopathy. The etiology is unknown, but it may be related to trauma, infection, autoimmune disease (rheumatoid arthritis, granulomatosis with polyangiitis, inflammatory pseudotumor, IgG4 disease), and neoplasms. Pathologic findings include the presence of fibrous tissue, mature lymphocytes and plasma cells, and epithelioid histiocytes in dura without evidence of bacteria, fungi, or vasculitis. Treatment includes immunosuppressant therapy and surgical decompression.


Vascular Lesions


Arteriovenous malformations (AVMs) ( Fig. 1.154 )

MRI: Lesions with irregular margins that can be located in the spinal cord (white and/or gray matter), dura, or both locations. AVMs contain multiple, tortuous, tubular flow voids on T1- and T2-weighted imaging secondary to patent arteries with high blood flow, as well as thrombosed vessels with variable signal, areas of hemorrhage in various phases, calcifications, gliosis, and myelomalacia. The venous portions often show gadolinium contrast enhancement. There may or may not be ischemia (high signal on T2-weighted imaging in the spinal cord) related to venous congestion, ± swelling of spinal cord. Usually not associated with mass effect unless there is recent hemorrhage or venous occlusion.


MRA and CTA: Time-resolved techniques for contrast-enhanced MRA and CTA can show arterial and venous phases of blood flow through AVMs.

Intracranial AVMs are much more common than spinal AVMs. Annual risk of hemorrhage. AVMs can be sporadic/spontaneous (60%) or associated with a history of trauma (40%). Spinal AVMs are classified into four types according to anatomic involvement. Types I and IV are arteriovenous fistulas (AVFs), which are direct shunts between arteries and veins. Types II and III are AVMs, which are connected by a collection of abnormal vessels referred to as a nidus. Type I malformations, dural AVFs, are typically located at nerve root sleeves (most common type). Type II are intramedullary AVMs, where the nidus is within the spinal cord. Type III, juvenile AVMs, can involve the spinal cord, intradural extramedullary space, and extradural structures. Type IV, perimedullary (pial) AVFs, are located at the surface of the spinal cord or cauda equina. Patients can present with progressive myelopathy. Perimedullary AVFs and intramedullary AVMs can present with subarachnoid and/or intramedullary hemorrhage. Most frequently occur in men, 40 to 50 years old. Treatment includes surgery and/or endovascular embolization.


Hemorrhage within CSF (Subarachnoid hemorrhage) ( Fig. 1.155 and Fig. 1.156 )

MRI: Hemorrhage into the CSF can cause prominent, transient, amorphous enhancement in the spinal leptomeninges/subarachnoid space. The subarachnoid hemorrhage can have low-intermediate signal on T1-weighted imaging and high signal on T2-weighted imaging similar to CSF.

Hemorrhage into CSF from cranial or spinal surgery, trauma, vascular malformation, anticoagulation, or neoplasm can result in leptomeningeal enhancement from chemical irritation (within 2 weeks of surgery). Usually resolves after 2–3 weeks.


Subdural hemorrhage ( Fig. 1.157 and Fig. 1.158 )

MRI: Smooth-marginated collection between the inner margin of the dura and outer margin of the spinal arachnoid layer, which has intermediate to high signal on T1-weighted imaging (T1WI) in the early phases and low, intermediate, or high signal on T2-weighted imaging (T2WI). After 2 weeks, subdural collections often have low signal on T1WI and T2WI related to hemoglobin degradation.


CT: Subdural collection that can have high attenuation in the acute phase that progressively decreases with time.

Collection of blood between the spinal dura and outer margin of the spinal arachnoid layer. Can result from trauma, surgery, extension from intracranial subdural hemorrhage, anticoagulation, or complications from lumbar punctures, epidural or spinal anesthesia, and acupuncture.


Acquired Lesions


Perineural cysts/Tarlov cysts ( Fig. 1.159 and Fig. 1.160 )

MRI: Well-circumscribed cysts with MRI signal comparable to CSF involving nerve root sleeves and associated with chronic erosive changes involving adjacent bony structures. Sacral (± widening of sacral foramina) > lumbar nerve root sleeves. Usually range from 15 to 20 mm in diameter, but can be larger.

CT: Circumscribed lesion with CSF attenuation, ± erosion of adjacent bone. CSF-filled cystic dilatations that occur between the perineurium and endoneurium of nerve roots. Most frequently involve the sacral nerve roots, but can occur at any spinal level. Usually are asymptomatic, incidental findings on MRI and CT on 4.6% of exams.


Arachnoid cyst ( Fig. 1.161 and Fig. 1.162 )

MRI: Well-circumscribed, intradural, extramedullary lesions with low signal on T1-weighted imaging and high signal on T2-weighted imaging similar to CSF, with no gadolinium contrast enhancement.


CT: Circumscribed lesion with CSF attenuation surrounded by thin wall, ± erosion of adjacent bone.

Nonneoplastic, congenital, developmental, or acquired extra-axial lesions filled with CSF, usually with mild mass effect on adjacent spinal cord or nerve roots. Can be intradural (type III) or extradural ± communication with the intrathecal subarachnoid space. Extradural cysts without nerve root fibers are referred to as type I cysts, and extradural cysts containing spinal nerve root fibers are referred to as type II cysts. Most spinal arachnoid cysts are located adjacent to the dorsal aspect of the thoracic spinal cord, with a mean cranial-caudal extent of four vertebral levels. Cysts located ventral to the spinal cord also occur but are uncommon. Can be asymptomatic or associated with compression of the spinal cord and/or nerve roots. Treatment is surgical excision and/or fenestration.


Pseudomeningocele ( Fig. 1.163 )

MRI: Extrathecal CSF collection with high signal on T2-weighted imaging, usually with circumscribed thin margins, ± thin marginal gadolinium contrast enhancement, ± nerve roots extending into pseudomeningocele.


CT myelography can identify extravasated iodinated contrast and site of dural tear.

Extravasated localized collection of extradural CSF that results from a dural tear secondary to trauma, spinal surgery, percutaneous thecal sac puncture, or congenital defect. A fibrous capsule is usually present at the margins of the pseudomeningocele. The CSF within the pseudomeningocele can persist or eventually resorb. Communication of the pseudomeningocele with the thecal sac may persist or spontaneously seal.


CSF leak/fistula ( Fig. 1.164 )

MRI: Extrathecal CSF collection with high signal on T2-weighted imaging (T2WI), ± hyperdynamic localized flow void on T2WI at site of dural defect from hyperdynamic CSF flow across the dural defect. Margins of fluid collection can be irregular due to dissection into adjacent soft tissue.


CT myelography can identify extravasated iodinated contrast and site of dural tear.

Extravasated collection of extradural CSF with irregular margins that results from a dural tear secondary to trauma, spinal surgery, percutaneous thecal sac puncture, or congenital defect. A CSF fistula represents a communication of CSF from the thecal sac to another anatomic cavity or adjacent soft tissue. Can be associated with intracranial hypotension, posture-related headaches, nausea, vomiting, neck pain, and photophobia. Treatment includes epidural blood patch and/or surgical repair.


Spinal cord herniation ( Fig. 1.165 )

MRI: A focal anterior kink of the spinal cord is typically seen on sagittal T2-weighted imaging (T2WI), along with widening of the dorsal subarachnoid space. Axial T2WI shows an anteriorly positioned and deformed spinal cord that protrudes through an anterior dural defect.


Postmyelographic CT: A focal anterior kink in the spinal cord, with widening of the dorsal subarachnoid space, is typically seen. No filling defects are seen in the dorsal subarachnoid space.

Uncommon clinical disorder in which the spinal cord herniates through an anterior or anterolateral dural defect in the upper to mid thoracic spine, often between the T4 and T7 levels. The cause of the dural defect is usually unknown. Usually occurs in adults 20 to 80 years old (mean age = 50 years). Clinical findings result from tethering of the spinal cord and include numbness, pain, decreased temperature sensation in the lower extremities, gait disturbances, incontinence, and Brown-Sequard syndrome (ipsilateral upper motor neuron paralysis, decreased proprioception, and contralateral decreased pain and temperature sensation). Surgical closure of the dural defect can relieve symptoms.


Intradural herniated disk

MRI: Amorphous structure with intermediate signal on T1-weighted imaging and variable and/or mixed signal (intermediate, high) on T2-weighted imaging. Occasionally there is gadolinium contrast enhancement if the lesion becomes vascularized (by ingrowth of fibrovascular material).

Disk herniations rarely extend through dura into the thecal sac.


Calcifying pseudoneoplasm of the neuraxis (CAPNON)

MRI: Lesions have low signal on T1-weighted imaging and on T2-weighted imaging (T2WI) related to the dense zone of calcification seen on CT, ± peripheral slightly high signal on T2WI, ± peripheral rim of gadolinium contrast enhancement.


CT: Lesions have varying amounts of calcification and soft tissue attenuation.

CAPNONs are rare, slow-growing, nonneoplastic, calcified lesions (also referred to as fibro-osseous lesions) that can occur anywhere in the CNS, as well as involve bone and/or dura. Lesions contain variable amounts of fibrous stroma, chondromyxoid matrix with pallisading spindle, epithelioid, and/or multinucleated cells, and ossifications.

(a) Sagittal fat-suppressed T1-weighted imaging of a 27-year-old woman shows an intradural dermoid at the L2 level that has high signal (arrow) and (b) low signal on sagittal T2-weighted imaging (arrow).
(a) Sagittal fat-suppressed T1-weighted imaging of a 7-year-old female shows a neurenteric cyst anterior to the spinal cord that has high signal related to the elevated protein content within the lesion (arrows). (b) The lesion (arrows) has low signal on sagittal fat-suppressed T2-weighted imaging.
(a) Sagittal T2-weighted imaging of a 24-year-old man shows an ependymoma that has mixed intermediate, low, and high signal (arrow) and (b) shows gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 33-year-old man with a large grade II ependymoma in the lower spinal canal that has high signal (arrows) and (b) shows heterogeneous gadolinium contrast enhancement on sagittal T1-weighted imaging (arrows). The tumor remodels and scallops the dorsal margins of the L3–L5 vertebral bodies and sacrum.
(a) Sagittal T2-weighted imaging of a 31-year-old woman with an intradural extramedullary schwannoma impressing on the ventral margin of the conus medullaris and cauda equina that has mixed intermediate and high signal (arrow) and (b) shows gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
Sagittal fat-suppressed T1-weighted imaging of a 26-year-old woman with neurofibromatosis type 2 who has multiple, small, gadolinium-enhancing, intradural schwannomas.
(a) Coronal fat-suppressed T2-weighted imaging of a 41-year-old woman with an intradural extramedullary meningioma (arrows) that has intermediate signal and (b) shows gadolinium contrast enhancement on coronal fat-suppressed T1-weighted imaging (arrow). The meningioma indents the right lateral aspect of the spinal cord.
(a) Sagittal T2-weighted imaging of a 79-year-old woman with an intradural extramedullary calcified meningioma that has low signal (arrow) and (b) shows heterogeneous gadolinium contrast enhancement on sagittal T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 19-year-old woman shows a neurofibroma that has intermediate signal (arrows) and shows gadolinium contrast enhancement on (b) sagittal and (c) axial fat-suppressed T1-weighted imaging (arrows). The lesion has both intradural and extradural portions.
(a) Sagittal T2-weighted imaging of a 51-year-old man shows an intradural paraganglioma at the L4 level that has heterogeneous mostly intermediate signal (arrow) and (b) shows gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T1-weighted imaging of a 77-year-old woman shows an intradural teratoma at the dorsal surface of the conus medullaris that has mixed intermediate and high signal (arrow). (b) The high signal of the fat-containing portions of the lesion on T1-weighted imaging is nulled on sagittal fat-suppressed T2-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 21-year-old woman with an intradural capillary hemangioma at the L3–L4 level has slightly high signal (arrow) and (b) shows gadolinium contrast enhancement on sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 75-year-old man with an intradural, extramedullary, solitary fibrous tumor at the C4–C5 level that has low and intermediate signal (arrow) and shows gadolinium contrast enhancement on (b) sagittal and (c) axial fat-suppressed T1-weighted imaging (arrows). The tumor compresses the left side of the spinal cord, which is displaced leftward with intramedullary edematous changes.
(a) Coronal T2-weighted imaging of a 25-year-old woman with a primary, intradural, extramedullary primitive neuroectodermal tumor (PNET) located to the left of the lower spinal cord that has intermediate signal (arrow) and (b) gadolinium contrast enhancement on sagittal T1-weighted imaging (arrow). Disseminated subarachnoid tumor is seen as gadolinium contrast enhancement along the pial surface of the spinal cord.
(a) Sagittal and (b) axial T2-weighted images of a 48-year-old man with melanoma and leptomeningeal metastases seen as irregularly thickened intradural lumbar nerves that show abnormal gadolinium contrast enhancement on (c) axial fat-suppressed T1-weighted imaging.
(a) Sagittal T2-weighted imaging of a patient with intracranial astrocytoma who has leptomeningeal metastases, seen as irregular zones with intermediate signal within the lumbar thecal sac (arrows) and that show irregular gadolinium contrast enhancement on (b) sagittal fat-suppressed T1-weighted imaging.
(a) Sagittal T2-weighted imaging of a 72-year-old woman with non-Hodgkin lymphoma who has a leptomeningeal tumor, seen as irregular zones with intermediate signal involving multiple lumbar nerves, and that shows irregular gadolinium contrast enhancement on (b) sagittal fat-suppressed T1-weighted imaging.
(a) Sagittal T2-weighted imaging of a 71-year-old man with non-Hodgkin lymphoma who has a nodular leptomeningeal tumor with intermediate signal at the L4–L5 level (arrow) and that shows gadolinium contrast enhancement on (b) sagittal fat-suppressed T1-weighted imaging (arrow).
(a) Sagittal T2-weighted imaging of a 15-year-old male with acute lymphocytic leukemia and leptomeningeal tumor seen as irregularly thickened intradural lumbar nerves, which show extensive diffuse subarachnoid gadolinium contrast enhancement on (b) sagittal fat-suppressed T1-weighted imaging.
Sagittal T1-weighted image of a patient with leptomeningeal melanocytosis shows nodular and linear zones with high signal along the pial surface of the spinal cord.
(a) Sagittal and (b) axial T1-weighted images of a 50-year-old woman with streptococcal meningitis show irregular thickening and gadolinium contrast enhancement of multiple lumbar nerve roots.
Sagittal fat-suppressed T1-weighted images of a 52-year-old woman with neurosarcoid show multiple nodular foci of gadolinium contrast enhancement (a) along the spinal cord and (b) within the lumbar thecal sac. Foci of gadolinium contrast enhancement are also seen along the pial surface of the pons and within the fourth ventricle (a).
(a) Sagittal and (b,c) axial fat-suppressed T1-weighted images of an 11-year-old female with Guillain-Barré syndrome show gadolinium contrast enhancement involving the lumbar nerve roots.
(a,b) Axial fat-suppressed T1-weighted imaging of a 57-year-old woman with chronic inflammatory demyelinating polyneuropathy (CIDP) shows enlargement of multiple lumbar and sacral nerves, which show gadolinium contrast enhancement.
(a) Sagittal and (b) axial T2-weighted images of a patient with adhesive arachnoiditis show clumping of nerve roots within the thecal sac. (c) Axial T2-weighted imaging shows peripheral positioning of nerve roots within the lower thecal sac—“empty sac” sign.
Axial CT without intrathecal contrast of a 37-year-old man shows irregular zones with high attenuation in the subarachnoid space (arrow) representing arachnoiditis ossificans.
Sagittal fat-suppressed T1-weighted imaging of a 56-year-old woman who has granulomatosis with polyangiitis (Wegener′s granulomatosis) shows localized thickened gadolinium contrast enhancement of the dura (arrows) from necrotizing granulomas.
Sagittal fat-suppressed T1-weighted imaging of a 43-year-old woman shows thick dural gadolinium contrast enhancement (arrows) from idiopathic hypertrophic pachymeningitis.
(a) Sagittal T2-weighted imaging of a 39-year-old woman with an intradural vascular malformation shows multiple flow voids surrounding the lower spinal cord. (b) Sagittal gadolinium-enhanced 3D time-of-flight MRA shows the malformation receiving its blood supply from posterior lumbar arteries.
(a) Axial CT of a 10-month-old male shows high-attenuation hemorrhage in the fourth ventricle from a cerebellar arteriovenous malformation. (b) Sagittal T1-weighted imaging shows central aggregation of the lumbar nerve roots within the thecal sac. The CSF in the thecal sac has low signal. (c) Postcontrast fat-suppressed sagittal T1-weighted imaging shows diffuse gadolinium contrast enhancement in the lumbar thecal sac from dilute subarachnoid hemorrhage causing chemical irritation. The enhancement caused by subarachnoid hemorrhage typically resolves in 2–3 weeks, as it did for this patient.
Sagittal T2-weighted imaging of a 56-year-old woman shows subarachnoid hemorrhage dorsal to the spinal cord, which has mixed low, intermediate, and high signal (arrows).
(a) Sagittal fat-suppressed T1-weighted imaging and (b) axial T1-weighted imaging of a 42-year-old woman show a subdural hemorrhage with high signal (arrow) in the anterior portion of the thecal sac.
(a) Sagittal and (b) axial T2-weighted images of a 20-year-old man show a subdural hemorrhage with low-intermediate signal (arrows) in the posterior portion of the thecal sac. A thin low-signal line representing the outer arachnoid membrane separates the subdural hemorrhage from the subarachnoid CSF with high signal. The subdural hemorrhage had low signal on T1-weighted imaging similar to CSF (not shown).
(a) Sagittal fat-suppressed T2-weighted imaging and (b) axial T2-weighted imaging of a 50-year-old man show perineural cysts/Tarlov cysts (arrows) that have high signal similar to CSF.
(a) Coronal T1-weighted imaging and (b) coronal T2-weighted imaging of a 45-year-old woman show multiple large Tarlov cysts, which are associated with chronic erosion and expansion of the sacral foramina.
(a) Sagittal T1-weighted imaging and (b) sagittal T2-weighted imaging of a 49-year-old man show an intradural arachnoid cyst (arrows) that has CSF signal and compresses the dorsal margin of the spinal cord
(a) Sagittal and (b) axial T2-weighted images of a 35-year-old woman show an extradural arachnoid cyst with high signal (arrows), which displaces the thecal sac anteriorly. The arachnoid cyst is associated with chronic bony erosion and expansion of the spinal canal.
(a) Sagittal and (b) axial T2- weighted images of a 35-year-old woman who had multilevel laminectomies complicated by a pseudomeningocele (arrows), which is seen as a dorsal extrathecal CSF collection with high signal containing herniated nerve roots.
(a) Sagittal fat-suppressed T2-weighted imaging and (b) axial T2-weighted imaging of a 58-year-old man who had lumbar laminectomies complicated by a dural tear, with high-signal CSF dissecting into the dorsal soft tissues. A signal void caused by high CSF flow across the dural tear is seen (arrows).
(a) Sagittal T2-weighted imaging shows a focal anterior kink involving the spinal cord (arrow) with widening of the dorsal subarachnoid space. (b) Axial T2-weighted imaging shows an anteriorly positioned and deformed spinal cord, which protrudes through an anterior dural defect (arrow).

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May 24, 2020 | Posted by in NEUROLOGICAL IMAGING | Comments Off on Spine

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