It is very difficult to differentiate spinal cord tumors from nonneoplastic myelopathies even with MRI. It is important to know the differential points between tumorous conditions and intramedullary nonneoplastic myelopathies in order to avoid unnecessary biopsy.

Fusiform enlargement with T2 hyperintensity of the spinal cord is seen in both tumors and nonneoplastic cord lesions. The MR findings that suggest nonneoplastic myelopathies are as follows: (1) multiple lesions with spinal cord swelling and skip area; (2) small focal, nodular, linear, or punctate enhancement in the peripheral white matter; and (3) decreased cord swelling, cord atrophy, or loss of enhancement at follow-up imaging. Spinal cord expansion in nonneoplastic myelopathies tends to be less than tumors. Spinal cord tumors including gliomas, lymphoma, and metastases usually show demarcated low-signal solid lesions within T2 hyperintensity in corresponding to enhancing region. However, nonneoplastic myelopathy shows relatively homogeneous high signal intensity on T2-weighted images regardless of enhancement (Table 10.1).

Acute transverse myelopathy (ATM) is acute inflammatory process involving both halves of the spinal cord, producing motor or sensory impairment (Choi et al. 1996). The causes of ATM are inflammatory and noninflammatory lesions, which are viral infections, multiple sclerosis (MS), postviral or postvaccinal processes such as acute disseminated encephalomyelitis, vasculitis such as systemic lupus erythematosus or Behcet’s disease, acute vascular infarction, paraneoplastic syndromes, and idiopathic. The diagnostic criteria of ATM are as follows: (1) development of sensory, motor, or autonomic dysfunction; (2) bilateral signs or symptoms; (3) clearly defined sensory level; (4) exclusion of extra-axial compressive cause by MRI; (5) inflammation with CSF examination or enhanced MR images; and (6) progression of nadir between 4 h and 21 days after the onset of symptom (Goh et al. 2011). The MR imaging appearance is quite variable, with mild spinal cord swelling, ill-defined homogeneous hyperintense regions on T2-weighted image, and isointense to hypointense regions on T1-weighted image over 3 or 4 spinal segments. Lesions occur most frequently in the thoracic cord. There are variable enhancement patterns after administration of contrast agent, including focal, diffuse, patchy, or peripheral patterns (Pardatscher et al. 1992). Follow-up MR imaging may show resolution of the abnormal signal and normalization or atrophy of spinal cord. Differentiation between ATM and MS is clinically important but is not easy with imaging alone (Table 10.3). MR imaging of the brain is a useful further study, which may reveal typical findings of MS (Campi et al. 1995). Of the patients with spinal cord MS, 90 % had intracranial MS plaques. Small, ovoid, enhancing spinal cord lesions without cord swelling have a high possibility of MS.

With MR imaging, most focal plaques of MS are less than 2 vertebral body lengths in size, occupied less than half the cross-sectional diameter of the cord, and were characteristically peripherally located with respect to a transverse cross-sectional reference (Tartaglino et al. 1995). Approximately two-thirds of the MS lesions in the spinal cord are present in the cervical region, and more than half of the patients with MS with cord plaques had multiple plaques.

Neuromyelitis optica (NMO), also known as Devic’s disease, is an autoimmune, inflammatory disorder involving the optic nerves (optic neuritis) and spinal cord (myelitis). Spinal cord lesions lead to muscle weakness of the extremities, reduced sensation, and bladder dysfunction.

Diagnosis of neuromyelitis optica requires two absolute criteria plus at least two of three supportive criteria (Makhani et al. 2013). Absolute criteria are optic neuritis and acute myelitis. Supportive criteria are brain MR findings not indicating multiple sclerosis at onset, more extensive (≥ 3 vertebral segments) T2 hyperintensity on spinal cord MRI, and NMO-IgG seropositive status. Longitudinally extensive transverse myelitis (>3 segments) is the characteristic of NMO (Table 10.4). Lesions are usually localized to the cervical and upper thoracic cord.

Acute disseminated encephalomyelitis (ADEM) is postinfectious or postvaccinated immune-mediated inflammatory disorder of the white matter. The MR findings of ADEM are similar to those of multiple sclerosis, and it is indistinguishable on single study. But the clinical course of ADEM is monophasic and relapse of the disease is rare unlike multiple sclerosis. The spinal MRI shows multifocal flame-shaped white matter lesions with slight cord swelling. The brain is almost always involved and brain MRI should be included whenever suspicious cord lesion is found.

The clinical feature of acute spinal cord infarction is motor, sensory, and autonomic disturbance of sudden onset. Infarction most often occurs in the lower thoracic cord, which is supplied by the artery of Adamkiewicz. Spinal cord infarction usually involves the anterior spinal artery territory, the gray matter of the anterior horns being more prone to ischemia than the peripheral white matter (Goh et al. 2011). On MR imaging, bilaterally symmetric foci of T2 hyperintensity are seen in the anterior column (owl-eye appearance) of the spinal cord. Sometimes, the T2 hyperintensity involves central gray matter. The peripheral white matter is usually spared. Diffusion-weighted imaging (DWI) of the spine will help make earlier and more confident diagnosis of infarction.