Oculomotor Abnormalities in Cerebellar Degeneration

Despite the classical treatises by Holmes [1] and later by Cogan [2] on “specific” cerebellar eye signs, most clinicians during the past decades have been very cautious in relating observed eye-movement disorders to cerebellar lesions. This caution acknowledged the fact that frequently in cerebellar disease there is a coexisting involvement of brain-stem structures, making the clear correlation of signs and symptoms to cerebellar lesions rather difficult. However, over the last 25 years a host of clinical and neurophysiological data (the latter mostly derived from single-unit recordings and ablation studies [3], as well as anatomical tracing techniques), have cast some light on this dilemma. Meanwhile, we can at least try to attribute specific oculomotor subfunctions and related eye-movement abnormalities to distinct parts of the cerebellum [for more recent reviews see 4–7].