Dorsal midbrain syndrome in multiple sclerosis.

Complaining only of vertical diplopia, a 34-year-old woman had pupillary light-near dissociation, upward gaze paresis, convergence-retraction nystagmus, and skew deviation. Cranial computerized tomography excluded a space-occupying lesion. Additional history and examination established the diagnosis of clinically definite multiple sclerosis. Dorsal midbrain syndrome due to multiple sclerosis rare.