Electrophysiological Difference in Obstructive Sleep Apnea with and without REM sleep Behavior Disorder: Cardiopulmonary Coupling Analysis

Abstract

Objectives: Although rapid eye movement behavior disorder (RBD) and obstructive sleep apnea syndrome (OSA) have different pathophysiology, RBD patients with OSA appeared to have more stable sleep compared to patients with OSA and to verify it by cardiopulmonary coupling (CPC) method. Methods: The polysomnography (PSG) data of 138 subjects with OSA (AHI ≥ 15), RBD with OSA (AHI ≥ 15), RBD, normal control (N=32, 26, 29, 51, respectively) were collected. For conducting case control study between RBD with OSA and patients with OSA only, a total of 32 OSA controls, matched for age, AHI and BMI were recruited. CPC parameters were obtained using CPC analyzer in Rem Logic. Sleep spectrogram by CPC analyses revealed the percentage of stable tidal volume [high-frequency coupling (HFC), 0.1–0.4 Hz] and fluctuation tidal volume [lowfrequency coupling (LFC), 0.01 Hz to 0.1 Hz)] during sleep. Results: Although there was no significant Apnea-Hypopnea index (AHI) difference between RBD with OSA and OSA group (AHI 29.1 ± 15.6/hr vs. 34.1 ± 18.9, p=0.332), there was significant difference in CPC measurements. In RBD-OSA group showed lower LFC (35.9 ± 16.8 vs. 49.7 ± 21.3, p=0.010) than OSA group. Unlike higher AHI in RBD with OSA than RBD group (29.1 ± 15.6/hr vs. 3.2 ± 1.6, p<0.001), there was no significant difference in CPC study. Both OSA group and RBD with OSA group showed higher LFC (OSA vs. normal: 49.7 ± 21.3 vs. 28.4 ± 13.3, p<0.001, RBD with OSA vs. normal: 35.9 ± 16.8 vs. 28.4 ± 13.2 p=0.035) and lower HFC (OSA vs. normal: 37.5 ± 20.0 vs. 56.2 ± 16.2, p<0.001, RBD with OSA vs. normal: 46.8 ± 20.8 vs. 56.2 ± 16.2, p=0.031) when compared with normal control group, respectively. Conclusions: In terms of autonomic-respiratory interaction, RBD with OSA showed similar CPC profile (higher LFC and lower HFC than normal) to OSA group but less severe than pure OSA group. It suggests that RBD may have a protective effect on OSA.