OCULOMOTOR ABNORMALITIES AND MRI FINDINGS IN IDIOPATHIC CEREBELLAR-ATAXIA

Extensive oculomotor testing and quantitative MRI evaluation was perfo rmed in seven patients with idiopathic cerebellar ataxia without extra cerebellar symptoms (IDCA-C) and in ten patients with additional extra cerebellar symptoms (IDCA-P). The most severe oculomotor deficits were disturbed smooth pursuit, optokinetic nystagmus and suppression of th e vestibule-ocular reflex (VOR). The symptoms correlated well and cons istently with the amount of atrophy of the flocculus and the dorsal ve rmis. These correlations, however, were not specific, and deficits als o correlated with the amount of atrophy of other cerebellar structures . No correlation was found between saccade velocity and brainstem atro phy or between saccade metrics and atrophy of the dorsal vermis. Altho ugh patients with IDCA-P had more severe oculomotor deficits than pati ents with IDCA-C, the pattern of the oculomotor disturbances was the s ame for both groups. Thus, eye movement analysis alone is not sufficie nt to distinguish between patients with pure cerebellar ataxia and tho se with additional extracerebellar symptoms.