Multiphasic disseminated encephalomyelitis presenting as alternating hemiplegia.

Two cases of alternating hemiparesis are reported, one in a black Sudanese woman, the other in a Saudi man, who had two episodes of alternating hemiparesis separated in time by six and three years respectively. Based on the typical appearance of the MRI and the results of brain biopsy, the diagnosis of multiphasic disseminated encephalomyelitis was made rather than that of multiple sclerosis. This entity is also differentiated from recurrent disseminated encephalomyelitis, where the relapses are symptomatically stereotyped although the appearance of the MRI is similar and in which new lesions do not occur. Because of the unusual appearance of these MRI lesions, brain biopsy is often performed but recognising their relevance should obviate that need.