Cerebellar peduncle lesion without saccadic abnormalities.

A 66-year-old woman had a unilateral infarction in the cerebellar peduncle. Saccadic eye movements were intact in this patient, while smooth-pursuit eye movements were impaired. Magnetic resonance imaging disclosed that the lesion was well localized in the superior cerebellar peduncle and the juxtarestiform body. These findings support the idea that saccade signals from the cerebellum project to the brainstem through the hook bundle, which was recently confirmed in the monkey.