Restorative effect of sequential 4-channel neuromuscular electrical stimulation in obstructive sleep apnea: a feasibility study.

Background: Dysphagia and sleep apnea share a common pathophysiology in that they involve the genioglossus muscle, which is important for chewing and swallowing. Sequential 4-channel neuromuscular electrical stimulation (NMES) based on the normal sequences of the suprahyoid and infrahyoid muscles has been shown to induce effective contractions of the genioglossus, styloglossus, and hyoglossus muscles. These effects may benefit patients with obstructive sleep apnea (OSA). This study aimed to evaluate the feasibility, safety, and efficacy of sequential 4-channel NMES in OSA.

Methods: This prospective, single-center, pilot study enrolled patients aged 19-60 years with moderate to severe OSA. All participants performed home-based sequential 4-channel NMES for 60 min per session, 5 times a week, for 8 weeks during the daytime. Polysomnographic studies and clinical evaluations were conducted before and after the treatment. The primary outcome was the change in the Apnea-Hypopnea Index (AHI) from baseline. Secondary outcomes included polysomnography results such as the Oxygen Desaturation Index (ODI), snore events and percentage, saturation parameters, and the respiratory arousal index, as well as patient-reported outcomes including the Epworth Sleepiness Scale, the Korean version of the Pittsburgh Sleep Quality Index, Likert scales for satisfaction and discomfort, and the EQ-5D-5 L.

Results: A total of ten participants completed the intervention and the follow-up evaluation. Eight weeks after the application of sequential 4-channel NMES, mean AHI reduced from 28.5 to 27.6 events/h, ODI decreased from 23.1 to 20.5 events/h, and snore percentage decreased from 38.1 to 32.3%, although none of these changes reached statistical significance. The mean duration and percentage of sleep time with oxygen saturation < 90% in polysomnography decreased from 38.7 min to 12.9 min (3.4%), also without statistical significance. And patient-reported outcomes improved after treatment, but these changes were not statistically significant.

Conclusions: This study was the first to investigate sequential 4-channel NMES as a therapeutic option for patients with OSA. Given its feasibility and efficacy, 4-channel NMES warrants investigation in a larger, definitive trial in the future.