Disease Severity and Its Associations With Non-Ataxic Signs, Cognition, Mobility, and Balance In Spinocerebellar Ataxia: A Cross-Sectional Study

Abstract

Background: Spinocerebellar ataxias (SCA) are progressive neurodegenerative disorders. Severity ratings are commonly used to describe disease progression, yet how ataxia severity relates to extracerebellar (non-ataxic) signs, cognitive screening, mobility, and balance remains incompletely understood.

Objective: To examine associations between ataxia severity and non-ataxic signs, cognition, mobility, and balance in SCA and to explore the influence of functional stage.

Methods: In this cross-sectional study, 42 individuals with SCA were assessed with the Scale for the Assessment and Rating of Ataxia (SARA), Inventory of Non-Ataxia Signs (INAS), Berg Balance Scale (BBS), Timed Up and Go (TUG), and Mini-Mental State Examination (MMSE). Participants were classified by Klockgether stage (stage 1 vs stage 2). Associations with SARA were tested using Spearman’s rho; partial correlations controlled for Klockgether stage.

Results: Stage 2 showed higher SARA scores and worse function than stage 1, with lower BBS scores and longer TUG times (all p<0.001). INAS was higher in stage 2 but not significant (p=0.056), and MMSE did not differ (p=0.780). SARA correlated with INAS (rho=0.385; p=0.012), BBS (rho=−0.852; p<0.001), and TUG (rho=0.773; p<0.001), but not with MMSE (rho=0.167; p=0.289). After adjustment, associations remained for BBS (rho=−0.752; p<0.001) and TUG (rho=0.642; p<0.001), but not for INAS (rho=0.266; p=0.089).

Conclusion: Greater ataxia severity was strongly associated with poorer balance and mobility, supporting the combined use of SARA with BBS and TUG to characterize functioning and guide physiotherapy planning. Lack of association with MMSE should not be interpreted as absence of cognitive impairment; domain-specific cognitive testing and longitudinal studies are warranted.