Visual oculomotor abnormalities and vestibulo-ocular reflex dynamics in polyglutamine spinocerebellar ataxias (Review)

Spinocerebellar ataxias (SCAs) are a group of autosomal dominant neurodegenerative diseases that are characterized by cerebellar ataxia. The most common types of SCAs are caused by polyglutamine (polyQ)-encoding cytosine-adenine-guanine repeat expansions. Autosomal dominant SCAs share similar pathophysiological mechanisms. The cerebellum plays an important role in the generation and control of eye movement, and neuropathological findings indicate that cerebellar degeneration is commonly present in polyQ-SCAs. As a result, various patterns of oculomotor impairment are present in most SCA subtypes. The present review summarizes the visual oculomotor abnormalities and vestibulo-ocular reflex dynamics of the most common polyQ-SCAs, as well as their genetic, clinical and neuropathological features. In conclusion, the systemic evaluation of eye movement features is useful in the differential diagnosis of polyQ-SCAs.