Quantification of electromyographic activity during REM sleep in Chinese narcolepsy patients and healthy controls: a...

This study aimed to assess and quantify rapid eye movement (REM) sleep electromyographic (EMG) activity in narcolepsy patients.

The study involved 95 participants, including 25 with narcolepsy type 1 (NT1), 36 with narcolepsy type 2 (NT2), and 34 healthy controls (HC). We visually analyzed phasic, tonic, and "any" muscle activity for the submentalis (SM) and phasic for the anterior tibialis (AT) by both 3-s REM mini-epochs (3sRME) and 30-s REM epochs (30sRE) methods. Group metrics of EMG activity indices in 3sRME and positive REM sleep without atonia (RWA) indices in 30sRE (AASM rules) were analyzed. Receiver operating characteristic (ROC) curves determined the best cutoff thresholds for narcolepsy.

All median SM and AT EMG activity indices in 3sRME were significantly higher in NT1 and NT2 compared to HC (P < 0.05). In the 30sRE method, positive RWA with phasic SM, total SM, and combined SM + AT indices were significantly higher only in NT1 versus HC in all analyses. The 3sRME phasic AT index had the highest area under the curve (AUC) of 0.884 (cutoff > 1.74%) for narcolepsy, 0.920 (cutoff > 2.03%) for NT1, and 0.859 (cutoff > 1.74%) for NT2. In the 30sRE method, the positive RWA with combined SM + AT index had the highest AUC of 0.691 (cutoff > 4.37%) for narcolepsy.

The study demonstrated increased levels of REM sleep EMG activity in narcoleptic patients compared to HC, with more pronounced abnormalities in NT1 than NT2, suggesting its potential as an alternative biomarker for narcolepsy.