Nonmotor and Extracerebellar Features in Spinocerebellar Ataxia Type 6.

BACKGROUND: Spinocerebellar ataxia type 6 (SCA6), traditionally seen as a pure cerebellar disorder, may involve broader brain degeneration. OBJECTIVE: The aim was to evaluate the nonmotor symptoms and extracerebellar signs in SCA6. METHODS: This study evaluated 18 genetically confirmed SCA6 patients using clinical scales for motor and nonmotor symptoms. Spearman's correlation test was performed to calculate the strength of association between CAG repeat length and clinical scales. RESULTS: Findings revealed frequent noncerebellar manifestations, including sensory symptoms (72.2%), fatigue (64.7%), hyperreflexia (38.9%), restless legs syndrome (28.6%), and urinary dysfunction (27.8%). Excessive daytime sleepiness and rapid eye movement sleep behavior disorder each affected 23.5% of patients. Less common signs included oculomotor abnormalities and spasticity. A significant correlation was found between CAG repeat length and sleep behavior scores (correlation coefficient: -0.609, P = 0.046). CONCLUSIONS: This study underscored the prevalence of nonmotor symptoms and extracerebellar signs in SCA6, supporting the possibility of broader neurological involvement in the disease.