MRI of an infant with Fisher syndrome.

A 15-month-old female infant with nystagmus, gait disturbance, diminished reflexes, ophthalmoplegia, and facial paresis was diagnosed as having Fisher syndrome. Magnetic resonance imaging revealed a transient, high-signal-intensity lesion on the left side of the cerebellum on T2-weighted images. The ataxia of Fisher syndrome is not compatible with polyneuritis, but can be explained by a cerebellar lesion, as seen in this case.