Diplopia in the Spinocerebellar Ataxias: Prevalence, Risk Factors, and Association with Falls

Spinocerebellar ataxias (SCAs) are inherited neurodegenerative disorders characterized by coordination, balance, and gait difficulties. Studies have independently found a high prevalence of diplopia and falls in the SCA population. This analysis aims to determine the prevalence and risk factors for diplopia in SCAs and its association with frequent falls in the SCA population. We analyzed data from participants age ≥ 18 in the Clinical Research Consortium for the Study of Cerebellar Ataxia (CRC-SCA), a multicenter natural history study of people with SCA. Pre-ataxia genetic carriers and subjects with unknown SCA types or missing demographic data were excluded. Diplopia was ascertained at baseline, and fall questionnaires were completed at baseline and follow-up visits. We measured the prevalence of diplopia overall and by SCA type and used logistic regression to identify characteristics associated with diplopia prevalence. Using mixed effects logistic regression models, we also investigated the relationship between diplopia and frequent falls (≥2 falls/12 months). Of 747 eligible CRC-SCA participants, 280 (37.5%) reported experiencing diplopia at baseline. SCA 3 (OR 4.93, 95% CI 2.76-8.78), SCA 6 (OR 2.81, 95% CI 1.46-5.40), and SCA 8 (OR 2.67, 95% CI 1.05-6.83) were associated with an increased prevalence of diplopia compared to SCA1. Diplopia was not associated with frequent falls cross-sectionally (OR 0.94, 95% CI 0.53-1.65) or longitudinally (OR 0.96, 95% CI 0.42-2.18). Diplopia is common in the SCA population and is associated with SCA type but not increased fall prevalence, functional limitation severity, ataxia severity, or disease duration.