A Questionnaire-Based Study on Clinical REM Sleep Behavior Disorder and Subtypes in Multiple System Atrophy

Objectives: Studies documenting the association between rapid eye movement sleep behavior disorder (RBD) and subtypes of multiple system atrophy (MSA) are rare. In this study, we investigated the presence of clinical RBD in MSA patients and compared the prevalence and severity of RBD in patients with MSA-P and MSA-C subtypes. Methods: We evaluated 54 consecutive patients presenting with MSA and hospitalized in the neurology ward of Beijing Hospital from February 2012 to June 2020. The healthy control (HC) group consisted of 100 healthy individuals who came to our hospital for physical examination. The clinical diagnosis of RBD was based on the minimal diagnostic criteria of International Classification of Sleep Disorders, revised. The severity of clinical RBD was rated on a digital scale from 0 to 3. The patients were divided into 2 subgroups: MSA-P and MSA-C. The MSA and HC groups were compared in terms of frequency of clinical RBD. The MSA-P and MSA-C subgroups were compared with each other for age, sex, onset age, disease duration, and features of clinical RBD. The correlation between severity of clinical RBD and clinical characteristics of MSA was analyzed in the patient groups. Results: The frequency of clinical RBD in MSA and HC groups was 70.4% (38/54) and 5% (5/100), respectively. The difference between 2 groups was significant (chi(2) = 74.453, p = 0.000). Among the patients, 57.4% (31/54) had the MSA-P subtype. There were no significant differences between MSA-P and MSA-C subtypes in the prevalence (chi(2) = 1.734, p = 0.188) and severity (chi(2) = 1.776, p = 0.412) of clinical RBD. The onset of clinical RBD during the premotor period was not different between the subtypes of MSA, either in patients' number of preceding the onset of motor symptoms (chi(2) = 0.581, p = 0.446) or the preceding time (Z = -0.550, p = 0.582). For the MSA-C patients, there was a negative correlation between the score of severity of the RBD scale and RBD preceding motor symptoms (r = -0.482, p = 0.020). Conclusion: In our study, the prevalence of clinical RBD is unrelated to the subtypes of MSA. The onset of clinical RBD during the premotor period was not different between subtypes of MSA. However, we found that the severity of RBD occurring before the motor symptoms was more than that occurring after the motor symptoms in MSA-C patients. Our results showed that MSA-P and MSA-C patients may have a probable indicator for the similar pathologic mechanism of the disease and its sleep problems.