Differences in dysphagia between spinocerebellar ataxia type 3 and type 6

Spinocerebellar ataxias (SCAs) are a group of neurodegenerative disorders frequently associated with autosomal dominant inheritance. SCA type 3 (SCA3) and SCA type 6 (SCA6) are the most common forms in Japan as well as the rest of the world. SCA3 affects multiple nervous systems while SCA6 affects mainly the cerebellar system. Dysphagia is clinically important since aspiration pneumonia is the most common cause of death in patients with SCA. We retrospectively studied dysphagia in 7 patients with SCA3 and 13 with SCA6 by videofluoroscopic examination of swallowing (VF). This is a larger series of patients with SCA6 than in previous studies, which had inconsistent results. Dysphagia was evaluated according to the scale established by the Japanese Society of Dysphagia Rehabilitation and the dysphagia outcome severity scale, an internationally used scale. The former separately evaluates oral and pharyngeal phases, while the latter concurrently grades both phases. Dysphagia according to the Japanese scale was mild but statistically significant in SCA6 and severe in SCA3. DOSS indicated abnormalities in SCA3 but not in SCA6. The swallowing abnormalities in SCA3 or SCA6 did not parallel the duration of disease or physical disability, suggesting that even patients with early disease or with well-preserved physical functions were at risk for aspiration. Our patients with dysphagia received percutaneous endoscopic gastrostomy-tube feeding at an appropriate time and underwent rehabilitation of swallowing. No patient had aspiration pneumonia. In conclusion, evaluation of swallowing ability by VF is essential for preventing aspiration in patients with SCA.