Characteristics of dysarthria in patients with spinocerebellar degeneration and multiple system atrophy: a cross-sectional and longitudinal study using the Frenchay Dysarthria Assessment Second Edition (FDA-2)

Purpose: The purpose of this study was to evaluate the dysarthria of patients with spinocerebellar degeneration and multiple system atrophy (SCD/MSA) cross-sectionally and longitudinally using the Frenchay Dysarthria Assessment Second Edition (FDA-2), which provides a comprehensive assessment of dysarthria, and to clarify characteristic patterns and longitudinal changes. Materials and methods: A total of 21 patients with SCD and MSA were included. Patients’ dysarthria was assessed using the FDA-2 and the Scale for the Assessment and Rating of Ataxia (SARA) item 4(SARA speech) at intervals of ≥ 12 months. Changes over time were examined with a paired t-test and Wilcoxon’s signed-rank test. Multiple regression analysis explored determinants of speech intelligibility, with FDA-2 intelligibility as the dependent variable and respiration, lips, palate, laryngeal, and tongue subscores as predictors. Results: The number of patients according to disease types was SCA2 in 1, SCA3 in 8, SCA31 in 1, MSA-C in 8, and an undetermined disease type in 3. The examination interval was 31.1 ± 15.6 months. FDA-2 scores were lower for repetitive-movement or speech items than for rest items. Lips and palate subscores were relatively higher, whereas laryngeal and tongue subscores were lower. Over time, reflex, lips, laryngeal, tongue, and total scores declined significantly, whereas the palate, respiration, and intelligibility scores remained stable. Multiple regression identified the laryngeal subscores as the only significant predictor of intelligibility (Sβ = 0.77, p = 0.047). Conclusion: The FDA-2 revealed a distinct dysarthria profile in SCD/MSA. Longitudinal FDA-2 monitoring may facilitate early detection and targeted intervention.