Changes in clinical features of multiple system atrophy in Japan

INTRODUCTION: 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. METHODS: 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). RESULTS: 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 [(123)I]-meta-iodo benzylguanidine (MIBG) myocardial scintigraphy tended to be lower in patients with MSA-P than in those with MSA-C. CONCLUSION: 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.