Swallowing Exercise Evaluated Using High-Density Surface Electromyography in Patients with Head and Neck Cancer: Supplementary Analysis of an Exploratory Phase II Trial.

Background and Objectives: Muscle strength evaluation using high-density surface electromyography (HD-sEMG) was recently developed for the detailed analysis of the motor unit (MU). Detection of the spatial distribution of sEMG can detect changes in MU recruitment patterns resulting from muscle-strengthening exercises. We conducted a prospective study in 2022 to evaluate the safety and feasibility of transcutaneous electrical sensory stimulation (TESS) therapy using an interferential current device (IFCD) in patients with head and neck squamous cell carcinoma (HNSCC) undergoing chemoradiotherapy (CRT), and reported the safety and feasibility of TESS. We evaluated the efficacy of swallowing exercises in patients with HNSCC undergoing CRT and determined the significance of sEMG in evaluating swallowing function. Materials and Methods: In this supplementary study, the patients performed muscle-strengthening exercises five days a week. The association of the effects of the exercises with body mass index, skeletal muscle mass index, HD-sEMG, tongue muscle strength, and tongue pressure were evaluated. Results: We found significant correlations between the rate of weight loss and skeletal muscle mass index reduction and the rate of change in the recruitment of the MU of the suprahyoid muscle group measured using HD-sEMG. Conclusions: We believe that nutritional supplementation is necessary in addition to muscle strengthening during CRT.