Changes in clinical features of multiple system atrophy in Japan

Multiple system atrophy (MSA) is an adult-onset progressive neurodegenerative disease that causes parkinsonism, cerebellar ataxia, and/or autonomic failure. MSA is categorized as MSA with predominant cerebellar ataxia (MSA-C) or MSA with predominant parkinsonism (MSA-P) according to the cardinal symptom at diagnosis. MSA-C has been reported to be the predominant presentation in Japan to date. However, major epidemiological studies regarding MSA in Japan were carried out before 2006; thus, the recent advancement of various imaging studies remains unclear. This study aimed to investigate the clinical characteristics of the recent MSA patients in Japan.

In this retrospective study, we divided 80 probable MSA patients into group A and group B and examined them to reveal whether the clinical features of MSA were different depending on the time periods of diagnosis (1989-2003 and 2004-2018, respectively).

The age at onset was significantly higher in MSA-P patients than in MSA-C patients (p = 0.0039) and was also higher in group B than in group A (p = 0.013). Although MSA-C was the predominant type in both groups, MSA-P was significantly more frequent in group B than in group A (p = 0.039). Although not statistically significant, the early heart/mediastinum ratio in [¹²³I]-meta-iodo benzylguanidine (MIBG) myocardial scintigraphy tended to be lower in patients with MSA-P than in those with MSA-C.

The proportion of MSA-P was likely larger than previously recorded due to the aging population in Japan and the improvement of differential diagnosis between PD and MSA-P.