Association of dysphagia severity in multiple system atrophy with the specific binding ratio on dopamine transporter SPECT

Dysphagia in multiple system atrophy (MSA) is life-threatening and is caused by parkinsonism with cerebellar ataxia as a contributing factor. The present study investigated the relationship between dysphagia severity in MSA and the specific binding ratio (SBR) on dopamine transporter (DaT) SPECT using the Hyodo score, a qualitative scale for use with fiberoptic endoscopic evaluation of swallowing (FEES). Hyodo score's ability to predict aspiration during a FEES examination of 88 patients with MSA was first tested. Then the clinical characteristics, Hyodo score, and SBR of patients with either predominant parkinsonism (MSA-P; n = 11) or cerebellar ataxia (MSA-C; n = 25) who underwent FEES and DaT SPECT simultaneously were compared. Logistic regression demonstrated that the Hyodo score was a significant predictive factor of aspiration (p = 0.003). The MSA-P group had a significantly higher Hyodo score (p = 0.026) and lower SBR (p = 0.011) than the MSA-C group while neither group demonstrated any significant difference in disease duration at the FEES examination. Linear regression demonstrated a significant, inverse correlation between the Hyodo score and SBR in the MSA-P (p = 0.044; r = −0.616) and MSA-C (p = 0.044; r = −0.406) groups. When the effect of SBR was removed by analysis of covariance, no significant difference in the Hyodo score remained between the groups. Our results suggested an association between presynaptic changes in nigrostriatal dopaminergic neurons and dysphagia severity in MSA which largely contributes to the difference in dysphagia severity between MSA-P and MSA-C. •We investigated the relationship between dysphagia severity in MSA and the SBR on DaT SPECT.•The utility of Hyodo score for assessing dysphagia severity in MSA was found.•A significant correlation of Hyodo score with SBR was observed in both MSA-P and MSA-C.•The correlation contributes to the difference in dysphagia severity between MSA-P and MSA-C.•Dysphagia severity in MSA was associated with the presynaptic changes of nigrostriatal neurons.