Magnetic resonance imaging findings in 22 cases of myelitis: comparison between patients with and without multiple sclerosis.

We reviewed the magnetic resonance imaging (MRI) database of the Dent Neurologic Institute to study the abnormal findings in myelitis. We identified 22 patients, and compared non-MS-related acute transverse myelitis (ATM, n = 9), to myelitis associated with multiple sclerosis (MS-myelitis, n = 13). The ATM patients were significantly older than MS patients at the time of the myelitis diagnosis (mean age 46 vs 35, p < 0.05). ATM appeared as a "longitudinal myelitis", with fusiform cord expansion on T1-weighted images and intramedullary increased signal on T2-weighted images, each involving multiple spinal levels (mean = 7-8). However, MS-myelitis lesions appeared focal, involving significantly fewer spinal levels (mean = 1-2, p < 0.001), although the lesions were equally likely to expand the cord. Four (42%) of the ATM lesions showed abnormal, variable enhancement, whereas none of the MS myelitis lesions enhanced. Cranial MRI was more likely to be normal in ATM (78%) than in MS-myelitis patients (15%, p < 0.001). Although readily distinguishable from lesions due to MS, the various etiologies for ATM, including post-infectious (n = 2), post-vaccination (n = 3), and idiopathic (n = 4) were indistinguishable on MRI. The MRI findings of an extensively lesioned, swollen cord, suspicious for an intramedullary tumor and providing a temptation for a biopsy, may reflect a non-neoplastic inflammatory disorder.