Single central nervous system lesions can simulate multiple sclerosis.

Three cases are reported in which an initial misdiagnosis of multiple sclerosis was made. In each of these a single central nervous system lesion with space occupying effect was present. These lesions caused confusion because multiple closely running neurological tracts were affected, and there was relapse and remission in the neurological signs and symptoms produced. We conclude that such cases need careful assessment to determine whether a single structural lesion could explain the presentation. Early imaging may show remediable lesions or prevent unnecessary steroid therapy.