[Devic's optic neuromyelitis. Follow-up of the evolution of the medullary lesions using magnetic resonance].

The nosology of Devic's optic neuromyelitis (NMOD) is controversial. Although classically considered to be a variety of multiple sclerosis, there are a number of differentiating characteristics which would permit classification as a separate condition. The evolution of changes in the medulla, as shown by magnetic resonance, is described in a patient with recurrent episodes of myelitis and optic neuritis. In successive exacerbations widening of the medulla was seen, with the appearance of areas of cavitation which later gave rise to atrophy of the medulla. During an 18 year follow-up period the symptoms were only of visual and medullary pathology, on magnetic resonance no other lesions were found in other parts of the central nervous system. The condition corresponded to Devic's optic neuromyelitis (NMOD). Whether it is a variant type of multiple sclerosis or a distinct entity, NMOD shows differentiating characteristics.