Eye movements in Friedreich's ataxia.

Twenty-four patients with well-documented Friedreich's ataxia underwent quantitative oculomotor testing. A consistent pattern of eye movement abnormalities was observed. This pattern included fixation instability, inaccurate saccades with normal peak velocity, impaired smooth pursuit and optokinetic slow phases, decreased vestibulo-ocular reflex gain, and impaired visual-vestibular interaction. This pattern corresponds to the known pathologic changes of Friedreich's ataxia and can be useful in the differential diagnosis of cerebellar atrophy.