Case of the month. September 1996--new onset hemiparesis.

A 44 year old woman developed left hemiparesis. CT scan showed a contrast enhancing lesion in the right periventricular area. A stereotactic biopsy was performed. The initial impression was that of an astrocytic neoplasm, however the presence of perivascular lymphocytes and numerous foamy macrophages led to consultation. Special studies demonstrated demyelination and lymphocytic infiltrate with relative axonal preservation consistent with multiple sclerosis. Additional history from the patient revealed a flu-like illness one week prior to the hemiparesis and a history of transitory visual problems, possibly early manifestations of her multiple sclerosis.