Correlation between clinical severity and disability in patients with spinocerebellar ataxia types 2 and 7 using the SARA, INAS, and WHODAS 2.0 scales.

Abstract

Introduction: Spinocerebellar ataxias (SCA) constitute a heterogeneous group of neurodegenerative diseases with an autosomal dominant inheritance pattern. The SCA2 and SCA7 subtypes have a significant prevalence in Mexico, characterized by progressive cerebellar degeneration and other neurological signs that affect the patient's functionality. Objective: To determine the correlation between clinical severity and the level of perceived disability in patients with a molecular diagnosis of SCA2 and SCA7. Methodology: An observational, cross-sectional, and analytical study was conducted on a cohort of patients from Mexico City and Veracruz. The following scales were applied: Scale for the Assessment and Rating of Ataxia (SARA) for motor severity; Inventory of Non-Ataxia Signs (INAS) for non-ataxic manifestations; and the World Health Organization Disability Assessment Schedule (WHODAS 2.0) for functional disability. Statistical analysis included Spearman correlation tests and comparisons between ataxia subtypes. Results: A positive correlation and statistical significance were observed between SARA and WHODAS 2.0 scores in both subtypes (p<0.05), with the severity of the cerebellar syndrome emerging as the main predictor of disability. The clinical characterization of SCA2 was distinguished by a higher prevalence of hyporeflexia and sensory symptoms compared to SCA7, where pyramidal and oculomotor signs prevailed. Perceived disability showed no significant correlation with years of progression, but it did correlate with the clinical stage of the disease. Conclusions: The SARA scale constitutes a robust tool for predicting functional impact on daily activities. The variability in the profiles of non-ataxic signs between SCA2 and SCA7 suggests the need to implement individualized neurorehabilitation protocols according to the genotype to effectively mitigate disability.

Keywords: SCA2, SCA7, Clinical scales, Functional disability.