New concepts of cerebellar control of eye movements

We can now, at least tentatively, relegate some oculomotor functions to particular portions of the cerebellum and thus infer which cerebellar structures are malfunctioning in the presence of particular groups of oculomotor signs. The dorsal cerebellar vermis and underlying fastigial nuclei function in the control of saccade amplitude. Consequently, saccadic inaccuracy (dysmetria) and macrosaccadic oscillations are signs of pathology in the dorsal vermis/fastigial nuclei. The floccular-nodular lobe functions in the control of a number of retinal image-stabilizing reflexes, including smooth pursuit, visual modulation of the vestibulo-ocular reflex, and holding positions of gaze. Defective smooth tracking, impaired fixation suppression of caloric-induced nystagmus, and gaze-evoked nystagmus are signs of vestibulocerebellar lesions. Furthermore, the elaboration of long-term, adaptive changes in saccadic and vestibular performance depends on these same structures. Consequent defects are persistent oscillopsia and imbalance.