Standardization of Stimulus Location for Functional Electrical Stimulation of Swallowing

Many nerves and muscles are involved in the swallowing process; hence neuromuscular disorders cause dysphagia resulting in aspiration pneumonia. A critical movement in the pharyngeal phase of swallowing is hyolaryngeal elevation to help protect the airway and open a relaxed upper esophageal sphincter. Functional electrical stimulation (FES) is expected to improve the function of muscles acting on the hyolaryngeal motion, which may contribute to airway protection in dysphagic patients. However, it is difficult to select the stimulus locations that effectively assist laryngeal elevation without the expertise in the anatomy of swallowing-related muscles. Therefore, this study investigated the method to standardize the selection of the stimulus locations based on the dimensions of the larynx. In addition, the effect of stimulus intensity on the amount of laryngeal elevation was evaluated.