Progressive necrotic myelopathy: clinical course in 9 patients.

OBJECTIVE: To review the clinical, laboratory, and radiological findings of 9 patients who had progressive idiopathic myelopathy with evidence of spinal cord necrosis. DESIGN AND METHODS: We reviewed personally examined cases of myelopathy that fulfilled the following criteria: (1) regional loss of reflexes, flaccidity, and muscle atrophy; (2) magnetic resonance imaging showing a shrunken or cavitated cord without evidence of arteriovenous malformation; (3) electromyogram showing denervation over several contiguous spinal cord sgements with preservation of sensory potentials in some cases; and (4) the absence of evidence of systemic disease or neoplasm.
RESULTS: The illness began in these patients after the age of 40 years, with prominent burning or tingling limb pain, occasionally with radicular features or with less well-defined back, neck, or abdominal pain. Leg or infrequently arm weakness appeared concurrently or soon after the onset of pain. The most distinctive feature was a saltatory progression of symptoms, punctuated by both acute and subacute worsenings approximately every 3 to 9 months, culminating in paraplegia or tetraplegia. The distinguishing clinical findings, together indicative of destruction of gray matter elements of the cord, were limb atrophy, persistent areflexia, and flaccidity. The concentration of cerebrospinal fluid protein was typically elevated between 500 g/L and 1000 g/L, without oligoclonal bands, accompanied infrequently by pleocytosis. Magnetic resonance imaging showed features suggesting cord necrosis, specifically swelling, T2-weighted hyperintensity, and gadolinium enhancement over several spinal cord segments, succeeded months later by atrophy in the same regions. Necrosis of the cord was found in biopsy material from one patient and postmortem pathology in another case, but inflammation and blood vessel abnormalities were absent. Only 2 patients had prolonged visual evoked responses. The disease progressed despite immune-modulating treatments although several patients had brief epochs of limited improvement.
CONCLUSIONS: The saltatory course, prolonged visual evoked responses in 2 patients, and a cranial abnormality on magnetic resonance imaging in another, raised the possibility of a link to multiple sclerosis. However, the normal cranial magnetic resonance imaging scans in 6 other patients, uniformly absent oligoclonal bands, and poor response to treatment were atypical for multiple sclerosis. On the basis of shared clinical and laboratory features, idiopathic progressive necrotic myelopathy is indistinguishable from a limited form of Devic disease.