Effectiveness of the sequential 4-channel NMES compared with conventional 2-channel NMES for the treatment of dysphagia in a prospective double-blind randomized controlled study

Background: To date, conventional swallowing therapies and 2-channel NMES are standard treatments for dysphagia. The precise mechanism of 2-channel neuromuscular electrical stimulation (NMES) treatment has yet to be determined, and controversy remains over the efficacy. The sequential 4-channel NMES was newly developed based on the normal contractile sequence of swallowing-related muscles. Objective: To evaluate and compare the rehabilitative effectiveness of sequential 4-channel NMES with that of conventional 2-channel NMES.Methods: In this prospective randomized case-control study, 23 subjects with dysphagia were enrolled. Twelve subjects with 4-channel NMES group and eleven subjects with 2-channel NMES group completed the intervention. Pretreatment and posttreatment evaluations were performed with the videofluoroscopic dysphagia scale (VDS), penetration-aspiration scale (PAS), MD Anderson dysphagia inventory (MDADI), functional oral intake scale (FOIS), and Likert scale.Results: The sequential 4-channel NMES group significantly improved the VDS (oral, pharyngeal, and total), PAS, FOIS, and MDADI (emotional, functional, and physical scale) compared with pretreatment data. The 2-channel NMES group significantly improved the VDS (oral, pharyngeal, and total) and MDADI (emotional, physical scale), but not the PAS and FOIS compared with pretreatment data. When the two groups were directly compared, the 4-channel NMES group showed significant improvement in oral and total VDS.Conclusions: Sequential 4-channel NMES activating the suprahyoid, thyrohyoid, and other infrahyoid muscles with proper interval time can be a new effective treatment for dysphagia.Trial registration : clinicaltrial.gov, registration number: NCT03670498, registered 13 September 2018, https://clinicaltrials.gov/ct2/show/NCT03670498?term=NCT03670498&draw=2&rank=1