Multiple sclerosis presenting as isolated oculomotor nerve palsy.

A 23-year old woman came to the emergency room with an isolated oculomotor nerve palsy (including pupillary dilatation) of rapid onset. Investigations and history revealed no cause. The subsequent course of events indicated a diagnosis of multiple sclerosis. While the third nerve has been shown to be involved during the course of multiple sclerosis, this is the first report of a case presenting as an isolated oculomotor nerve paralysis.