Anisocoria as initial manifestation of multiple sclerosis. Use of 3 tesla magnetic resonance imaging.

A 21-year-old woman seen in this clinic with non-reactive mydriasis in the right eye that contracted with 1% pilocarpine. Cranial angio-CT and 1.5 T magnetic resonance imaging (MRI) did not detect any disease. Given a subsequent limitation of adduction, supraduction, and infarction of the right eye, a 3 T MRI was requested. This showed a lesion of the midbrain at the exit of the 3rd cranial nerve. After improvement, no new episodes were observed until 18 months later, when the patient presented with probable optic neuritis and systemic symptoms. At this time the 1.5 T MRI detected infratentorial and supratentorial demyelinating plaques. A subsequent lumbar puncture and clinic outcome confirmed the diagnosis of relapsing-remitting multiple sclerosis.