Long-term clinical course and extracerebellar manifestations of hereditary spinocerebellar degeneration.

INTRODUCTION: Hereditary spinocerebellar degeneration (hSCD) comprises a heterogeneous group of inherited neurodegenerative diseases characterized by slowly progressive ataxia and various extracerebellar manifestations. This study aimed to investigate the long-term clinical course of hSCD, including quantitative information on disease progression. METHODS: We enrolled 42 consecutive patients with various hSCD genotypes and followed them for a mean of 9 years. We used the International Cooperative Ataxia Rating Scale (ICARS) to assess ataxia, and we evaluated the extracerebellar manifestations. RESULTS: The mean annual increase in the ICARS score was 2.6 ± 5.9 points/year, with no significant differences detected among genotypes in exploratory subgroup comparisons. At baseline, half of the patients had extracerebellar manifestations, including pyramidal signs (31.0%), sensory disturbances (21.4%), and autonomic symptoms (16.7%). The frequency of these manifestations increased with disease progression. The presence of extracerebellar manifestations at baseline was associated with greater increases in the ICARS scores over time and an earlier onset of wheelchair dependence. Brain perfusion analysis revealed that reduced blood flow to the precentral gyrus at baseline was associated with the manifestation of pyramidal signs at the endpoint. CONCLUSION: As the disease progressed, extracerebellar manifestations gradually appeared. These manifestations may reflect more widespread neurodegeneration and may help identify patients at higher risk of clinical deterioration. Careful assessment and appropriate management of both cerebellar and extracerebellar manifestations may be clinically important for optimizing patient outcomes.