Stage-specific interactions among PLM, RBD, and OSAHS in parkinson's disease and MSA.

BACKGROUND

Sleep disturbances in synucleinopathies often manifest as periodic limb movements (PLM), REM sleep behavior disorder (RBD), and obstructive sleep apnea–hypopnea syndrome (OSAHS), yet their interplay remains unclear. We explored prevalence, severity, and stage-specific interactions in multiple system atrophy (MSA) and Parkinson's disease (PD).

METHODS

Thirty‐four MSA and 264 PD patients underwent overnight polysomnography (56 parameters) and completed an institution-specific nocturnal behavior questionnaire comprising 16 binary items, used to screen sleep-related complaints and nocturnal behaviors for correlation with PSG findings. Univariate analyses and quantile regression—selected to accommodate skewed distributions and to uncover stage‐ and severity‐specific associations across the full range of AHI, RWA, and PLM values—probed sleep stage–dependent relationships among respiratory indices, chin/submental EMG activity, and limb movements.

RESULTS

MSA exhibited more severe disturbances than PD: RBD prevalence 47.1% vs 17.8% (p < 0.001), OSAHS prevalence 47.1% vs 30.7% (p = 0.055), RWA prevalence 11.8% vs 2.3% (p = 0.006), PLM prevalence 61.8% vs 25.0% (p < 0.001). Median PLM count and REM‐stage EMG activity were higher in MSA (139 vs 11.5 movements; 15.8% vs 1.2% RWA; both p < 0.001). Quantile regression showed respiratory events correlated with NREM PLM only at upper severity quintiles, while REM‐stage RWA predicted PLM consistently across quintiles. PD subgroup analysis revealed graded REM‐dominant phenotypes, with PD + RBD showing highest REM EMG (82.5%) and PLM burden (median 44.0).

CONCLUSIONS

PLM in synucleinopathies may arise secondarily from REM disinhibition and NREM respiratory arousals. Distinct profiles in MSA versus PD reflect differential neurodegeneration and support integrated diagnostic and therapeutic approaches.