Objective: To investigate whether REM sleep without atonia (RWA) is associated with sleep architecture in patients with multiple system atrophy (MSA).

Background: In MSA patients, REM sleep behavior disorder (RBD) is a very common sleep disorder and characterized by the absence of muscle atonia during REM sleep, resulting in acting out of dreams. In PD patients, RBD is associated with the severe clinical manifestations of both motor symptoms and non-motor symptoms, such as autonomic symptoms and cognitive functions. RWA is a core feature of RBD, evaluated by polysomnography (PSG) and detected even in the subclinical RBD stage, which manifests RWA in the absence of the clinical history of RBD. However, little is known about whether the presence of RWA affects sleep architecture in MSA.

Method: This cross-sectional study involved 69 clinically diagnosed MSA patients (female = 39), including 42 MSA-C and 27 MSA-P patients who completed the overnight-PSG were retrospectively reviewed for the presence of RWA and sleep architecture based on the PSG recordings. The patients were divided into two groups according to the presence of RWA. Statistical evaluations were assessed using the Welch’s test, the Chi-squared test, and the Spearman’s correlation.

Results: Of the 69 patients, 62 (89.9 %) showed RWA on PSG. Gender and disease duration were not different between MSA patients with or without RWA, although the age at the onset of MSA was different between the groups (58.7±8.3 years old vs 68.1±7.2, p=0.01). Regarding sleep architecture, there were statistically significant difference between the groups in the total sleep time (TST; 359.9±82.5 min. vs 258.1±88.5, p=0.022), the sleep efficiency (68.8±14.8 % vs 49.7±16.5, p=0.02), the wake after sleep onset (WASO; 118.5±66.8 min. vs 214.0±88.8, p=0.029), and the percentages of stage N3 sleep (7.4±7.5 % vs 2.4±4.8, p=0.035). The percentage of other non-REM sleep stages (N1 and N2) and REM sleep stage did not differ between the groups. There were no correlations between these variables and the age at the onset of MSA.

Conclusion: Our study revealed RWA is detected in most MSA patients. Furthermore, MSA patients with RWA is associated with the longer TST and slow-wave sleep (stage N3 sleep), shorter WASO, and greater sleep efficiency compared to those without, implying that the presence of RWA is associated with sleep architecture.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/relationship-between-rem-sleep-without-atonia-and-sleep-architecture-in-multiple-system-atrophy/