Non-MS recurrent demyelinating diseases.

The introduction of MRI has shown that the acute, recurrent (R), and multiphasic (M) forms of disseminated encephalomyelitis (DEM) are more common than suspected in adults, and that their MR images are sufficiently characteristic in most instances to make differentiation from multiple sclerosis (MS) possible. In addition, a number of clinical features of DEM are rarely seen in MS: fever, malaise, nausea, vomiting, positional vertigo, convulsions, aphasia, meningism, bilateral optic neuritis, and CSF leukocytosis and elevated protein. CSF oligoclonal bands are usually absent. It is remarkable that confusion between R- and MDEM and MS persists despite the numerous published reports on recurrent DEM dating back 70 years, many illustrating the characteristic MRIs. There are many case reports of DEM erroneously diagnosed as MS, Schilder's, Marburg's, Devic's, and Baló's disease, and, in particular brain tumors. It is probable that acute DEM is occasionally mistaken for a clinically isolated symptom of MS. Possible mechanisms for recurrence include localization at the site of a previous injury to the nervous system, or by the phenomenon of molecular mimicry. The importance of differentiating R- and MDEM from MS is greater today due to the recommendation that immunodulatory treatment be initiated in patients with a clinically isolated syndrome, or when the occurrence of a second clinical episode establishes the diagnosis of MS.