Facet Osteoarthritis and Synovitis—Cervical




Clinical Presentation


The patient is an 80-year-old female with severe neck pain, neck stiffness, right C4 radiculopathy, and suboccipital headaches. The patient has limited range of neck rotation.




Imaging Presentation


Radiographs of the spine revealed multilevel cervical spondylosis deformans, disc space narrowing. There is also narrowing of left C1-2 facet joint and multilevel facet and uncinate process hypertrophy. Bone scan reveals increased activity in the upper cervical spine on the left and mid cervical spine on the right ( Fig. 34-1 ) . Magnetic resonance (MR) imaging reveals a small effusion in the left C1-2 facet joint, thickened parafacetal soft tissues at C3-4 on the right, and enhancement of the parafacetal soft tissues posterior to the left C1-2 facets, surrounding the right C3-4 facets and in the right C3-4 neural foramen ( Figs. 34-2 to 34-6 ) .




Figure 34-1


Cervical Facet Synovitis Left C3-4 and Right C1-2.

99mTc—methylene diphosphonate (MDP) radionuclide bone scan, posterior view. Increased activity is demonstrated in the upper left ( short arrow ) and mid-right ( long arrow ) cervical spine.



Figure 34-2


Cervical Facet Synovitis Left C3-4 and Right C1-2.

Same patient as in Figure 34-1 . Coronal fat-saturated T2-weighted MRI of the cervical spine. T2 hyperintense facet joint effusion ( short arrow ), left C1-2 level. Right C3-4 facet hypertrophy and T2 hyperintense signal is demonstrated in and adjacent to the right C3-4 facets ( long arrow ). C1 = left lateral mass of C1. C2, C3, and C4 vertebral bodies labeled. D = Dens.



Figure 34-3


Right C3-4 Facet Synovitis.

Axial fat-saturated T2-weighted MRI at the C3-4 level in same patient as in Figures 34-1 and 34-2 . T2 hyperintense signal is demonstrated in the right C3-4 facets, right parafacetal soft tissues ( arrows ) and right uncinate process ( U ), representing edema and/or active inflammation.



Figure 34-4


Right C3-4 Facet Synovitis.

Axial T1-weighted MR image at C3-4 level, corresponding to Figure 34-3 , shows thickened right parafacetal soft tissues ( arrows ) surrounding irregular hypertrophic right C3-4 facets.



Figure 34-5


Right C3-4 Facet Synovitis.

Axial contrast-enhanced fat-saturated T1-weighted MRI at C3-4 level corresponding to Figures 34-3 and 34-4 . The thickened parafacetal soft tissues ( arrows ) enhance intensely representing inflammation. Enhancing inflammatory tissue is also located in the right C3-4 neural foramen. The right uncinate process ( U ) also enhances and therefore is involved with the inflammatory process.



Figure 34-6


Left C1-2 Osteoarthritis and Active Left C1-2 Facet Synovitis.

Left parasagittal contrast-enhanced fat-saturated T1-weighted MRI through cervical spine in same patient as in Figures 34-1–34-5 . The left C1-2 zygapophyseal (facet) joint is narrowed and hypertrophic bone is visible along its anterior ( long arrow ) and posterior margin ( short arrow ). The posterior C1-2 parafacetal soft tissues enhance intensely ( short arrow ).




Discussion


The cervical facet (zygapophyseal) joints are true diarthrodial joints, containing synovial fluid and lined by hyaline cartilage ( Fig. 34-7 ) . The cervical facets are oriented in an oblique coronal plane, which helps prevent translation of the cervical vertebrae along the anteroposterior axis ( Figs. 34-7 and 34-8 ). The degree of orientation of the cervical facet joints in the oblique coronal plane varies according to the cervical level (see Fig. 34-7 ). The C2 vertebra is unique because of the odontoid process but also because the lateral arch of C2 anatomically is like no other vertebra. The lateral atlantoaxial joint, that is, the C1-2 facet joint, is positioned more anteriorly than the cervical facets below the C1-2 level (see Fig. 34-7 ). The superior articular facet of C2 is nearly horizontally oriented and is positioned relatively far forward and superior to the inferior articular process of C2. The lateral arch of C2 is very unique because it is in reality an elongated articular pillar that embodies both the C2 pedicle and C2 pars interarticularis. The cervical neural foramen is located anterior to the cervical articular pillars and superior articular process and is bounded anteromedially by the uncinate process (see Fig. 34-8 ). The cervical neural foramen contains a ventral nerve root, the dorsal root ganglion, foraminal veins, and a small amount of fat. The vertebral artery traverses the anterior portion of the cervical neural foramen; at the vertebral body level, the vertebral artery courses through the transverse foramen. The dorsal root ganglion lies in a small concave depression along the anterior surface of the superior articular process. The cervical facet joints have a relatively thick capsule laterally (see Fig. 34-8 ). The cervical neural foramina are bounded superiorly and inferiorly by pedicles ( Fig. 34-9 ) .




Figure 34-7


Sagittal Cryomicrotome Image of Cadaver Specimen, Obtained Through Level of Cervical Articular Pillars.

A thin layer of pearly white hyaline cartilage lines the articulating surfaces of the cervical facet joints ( black arrows ). A thick layer of hyaline cartilage lines the margins of the lateral atlantoaxial joint ( AA ) and the occipital-atlantal joint, located between the occipital condyle ( C ) and the lateral mass of C1. The lateral atlantoaxial joint ( AA ) is positioned more anteriorly than the cervical facets below the C1-2 level. The superior articular facet ( S ) of C2 is nearly horizontally oriented and is positioned anterosuperior to the inferior articular process ( I ) of C2. The lateral arch of C2 is an elongated articular pillar ( P ) which embodies the C2 pedicle and C2 pars interarticularis. AP = articular pillar of C6. D = C7 dorsal root ganglion, which lies in concave depression along anterior surface of C7 superior articular process. V = vertebral artery located anterior to cervical dorsal root ganglia. V1 = vertebral artery at C1 level. O = obliquus capitis inferior muscle.



Figure 34-8


Axial Cryomicrotome Image in Cadaver, C4-5 Neural Foramen and Intervertebral Disc Level.

The cervical facet joints ( FJ ) are lined by hyaline cartilage and have a relatively thick cord-like capsule laterally ( arrowheads ). The cervical neural foramen is bounded posteriorly by the superior articular process ( S ) and the uncinate process ( U ) anteromedially. The neural foramen contains the dorsal root ganglion ( D ), ventral nerve root ( VR ), intraforaminal veins, and a minimal amount of fat. The vertebral artery ( V ) forms the anterior boundary of the cervical neural foramen laterally. ID = intervertebral disc, I = inferior articular facet, T = CSF within thecal sac. EDV = epidural veins.



Figure 34-9


Cervical Neural Foramina.

Curved oblique 3D reformatted CT image through the medial portion of the left cervical neural foramina. The cervical neural foramen medially is bounded by the uncinate process ( U ) anteriorly, the superior articular process ( S ) posteriorly and by a pedicle ( P ) above and below. AP = articular pillar of C4. C2 = C2 vertebral body.


The cervical facets undergo osteoarthritic degeneration in a similar manner as the lumbar facet joints and other synovial-lined joints. Abnormal acute or repeated stress upon the facet joint initiates a series of biomechanical events that cause an inflammatory process that involves the synovial lining of the joint, eventually leading to erosion of the facet articular cartilage, cortical facet erosions, facet joint narrowing, and cortical thickening ( Fig. 34-10 ) . Cystic erosions or geodes may occur in the facets similar to those that occur in other joints involved by osteoarthritis (see Fig. 34-10; Fig. 34-11 ). Eventually the facet capsules become thickened and redundant. In the cervical region, joint capsular inflammation and capsular thickening occurs, which is most obvious in the lateral facet capsule. Pain-sensitive nerve endings (nociceptors) exist in the facet capsules and synovium. Simultaneously, bony spurs develop along the margins of the facet joint and the articular processes enlarge overall, as a reactive response to the chronic inflammatory osteoarthritic process (see Figs. 34-10 and 34-11 ).




Figure 34-10


Cervical Facet Osteoarthritis, Joint Degeneration.

Sagittal CT image through left cervical lateral C1 and C2 lateral masses, cervical articular pillars and facet joints. Marked narrowing of C2-3 facet joint ( long black arrow ) secondary to advanced degenerative joint disease. Narrowed C3-4 and C4-5 facet joints contain gas ( short black arrows ). Osteophytes are seen ( white arrows ) along posterior margin of C3-4 and C4-5 facet joints.



Figure 34-11


Cervical Facet Osteoarthritis, Joint Degeneration.

Same patient as in Figure 34-10 . Coronal CT image through cervical articular pillars. Markedly narrowed bilateral C2-3 and right C3-4 facet joint spaces ( short white arrows ). Intra-articular gas ( long arrows ) is located within the narrowed left C3-4 and C4-5 facet joints. Gas is also located within erosions or geodes ( black arrows ) in the inferior articular process of C3 on the left. C1 = left lateral mass of C1.


These enlarged facets are readily visible on routine radiographs, computed tomography (CT) and MR images ( Figs. 34-10 to 34-13 ). The enlarged (hypertrophic) cervical facets contribute to cervical foraminal stenosis along with uncinate process enlargement related to degeneration of the uncovertebral joints ( Figs. 34-12 and 34-13 ) . Hypertrophic facets and uncinate processes can also narrow the transverse foramen and thereby cause localized narrowing of the vertebral arteries (see Fig. 34-12 ). Enlarged cervical facets do not encroach significantly upon the vertebral (central) canal as is commonly the situation in the lumbar region. Therefore, cervical facet hypertrophy does not contribute appreciably to cervical central canal stenosis. Cervical central canal stenosis occurs in the anteroposterior (AP) dimension and is secondary to disc bulging or protrusion, posterior vertebral osteophytes, thickened posterior longitudinal ligament, and thickened ligamentum flava.




Figure 34-12


Cervical Facet and Uncinate Process Hypertrophy.

Axial CT image C4-5 neural foramen. Severe right neural foraminal stenosis ( white arrow ) compared to relatively normal sized left neural foramen. The foraminal stenosis is due to uncinate process hypertrophy ( U ) and facet hypertrophy ( F ). The hypertrophic facet is also encroaching slightly upon the vertebral artery in the right transverse foramen ( T ). S = minimally hypertrophic left superior articular process.

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Aug 25, 2019 | Posted by in NEUROLOGICAL IMAGING | Comments Off on Facet Osteoarthritis and Synovitis—Cervical
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