Polysomnographic biomarkers for persisting (isolated) REM sleep without atonia in patients with obstructive sleep...

The relationship between obstructive sleep apnea (OSA) and REM sleep without atonia (RSWA) is complex and not fully understood. While RSWA may prevent upper airway collapse during REM sleep, it can also mimic REM sleep behavior disorder (RBD) and be a potential biomarker for neurodegeneration. This study aims to identify the prevalence, characteristics, and predictors of persistent isolated RSWA (iRSWA) following positive airway pressure (PAP) therapy in OSA patients.

A retrospective analysis was conducted on 297 patients with both OSA and RSWA who underwent polysomnography (PSG) with PAP titration. RSWA was assessed using both visual and automated methods. Clinical and PSG parameters were compared between patients with and without persistent RSWA after PAP titration. Statistical analyses, including receiver operating characteristic (ROC) curve analysis, were performed to identify significant predictors of persistent RSWA.

Persistent RSWA was observed in 41.5 % of patients. Older age (p = 0.006), higher periodic limb movement index (PLMSI) (p = 0.034), and lower apnea-hypopnea index (AHI) (p = 0.048) were significantly associated with persistent RSWA. ROC analysis identified four key PSG biomarkers - RSWA duration/REM duration, RSWA duration/total apnea-hypopnea duration (tAHD) in REM sleep, tAHD in REM sleep/REM duration, and REM atonia index - that strongly predicted persistent RSWA (OR = 10.714, p = 0.024).

A substantial portion of RSWA observed in OSA patients (approximately 40 %) was not directly related to OSA and persisted despite PAP therapy. These findings suggest that persistent RSWA may indicate iRSWA, a potential prodromal biomarker for neurodegenerative disorders. The identified PSG biomarkers may improve differentiation between iRSWA and OSA-related RSWA, aiding in early diagnosis and prognostic evaluation.