OCULAR MOTOR DISORDERS ASSOCIATED WITH CEREBELLAR LESIONS - PATHOPHYSIOLOGY AND TOPICAL LOCALIZATION

A number of ocular motor abnormalities can be correlated with damage i n specific parts of the cerebellum, especially the vestibulocerebellum (flocculus, paraflocculus, nodulus, uvula), and the dorsal vermis and the underlying (posterior) fastigial nuclei. These abnormalities of e ye movements reflect both immediate, on-line and long-term adaptive fu nctions of the cerebellum. Various types of image-stabilizing reflexes are in the province of the flocculus (and probably paraflocculus) inc luding pursuit, vestibulo-ocular reflex (VOR) cancellation, and holdin g the eye steady for fixation, both immediately after saccades and in eccentric positions of gaze. The nodulus (and ventral uvula) modulates << low-frequency >> aspects of vestibular responses and hence control s the duration (time constant) of the VOR. The dorsal vermis and under lying (posterior) fastigial nuclei participate in the control of the s ize of the saccadic pulse of innervation and hence saccadic accuracy. Here we review the eye signs that reflect abnormalities of these clear ly defined cerebellar functions. We will also discuss less well locali zed but presumed cerebellar eye signs and consider a potential role fo r the cerebellum in the control of both dynamic and static ocular alig nment.