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Compensatory Effects of Sequential 4-Channel Neuromuscular Electrical Stimulation for the Treatment of Acute, Subacute, and Chronic Dysphagia in a Prospective, Double-Blinded Randomized Clinical Trial

Background. The precise mechanism of 2-channel neuromuscular electrical stimulation (NMES) treatment is unknown, and controversy remains over its efficacy. The sequential 4-channel NMES was newly developed based on normal contractile sequences of swallowing-related muscles. Objective. To assess the clinical efficacy of sequential 4-channel NMES during swallowing. Methods. In this prospective RCT, 52 inpatients with dysphagia (acute, subacute, and chronic state) after stroke, brain tumor, or encephalitis were enrolled. Participants who underwent a videofluoroscopic swallowing study (VFSS) and clinical evaluation were enrolled and were randomly assigned to the 4-channel NMES or sham group. The 4-channel NMES and sham groups swallowed thin and honey-like fluids under NMES (sequential stimulation on suprahyoid and infrahyoid) and sham stimulation, respectively. The procedures were evaluated with the VFSS. Pre- and post-treatment evaluations were performed with the videofluoroscopic dysphagia scale (VDS), penetration–aspiration scale (PAS), Likert scale, and kinematic analysis. Results. The 4-channel NMES group showed significantly greater improvements than the sham group with respect to oral VDS, pharyngeal VDS, total VDS, and PAS (P < .05). Furthermore, the Likert scale for satisfaction, easiness, and discomfort for swallowing showed favorable results for the 4-channel NMES group (P < .05). In the kinematic analysis, the peak speed point, distance, and velocity of hyoid movement were significantly greater in the 4-channel NMES group (P < .05). Conclusions. Sequential 4-channel NMES activating the suprahyoid, thyrohyoid, and other infrahyoid muscles during swallowing showed significant clinical improvement with respect to VDS, PAS, and kinematic analysis. Therefore, sequential 4-channel NMES is a potential new functional electrical stimulation system for the treatment of dysphagia.