Functional electrical stimulation (FES) has been debated as an innovative treatment in the management of patients with laryngeal paralysis. In this study, we examined whether FES to the paralyzed laryngeal adductor muscles improves the voice sounds impaired by unilateral laryngeal paralysis. We confirmed that the FES to the paralyzed thyroarytenoid muscle (TA) induced the adduction of vocal fold in decerebrate cats. Electrical stimulation delivered to periaqueductal grey (PAG) induced vocalization in the cats with unilateral laryngeal paralysis. We estimated the changes in duration of voice sounds, subglottic pressure, and quality of voice during vocalization with or without FES to the paralyzed TA muscle. The duration of voice sounds was prolonged by delivering the FES to paralyzed laryngeal adductor TA muscle. The subglottic pressure increased during vocalization with FES. The intensity of voice sounds increased, and the quality of voice sounds improved with FES. These results suggested that the FES to paralyzed adductor TA muscle could be expected to improve the quality of voice sounds in the animals with unilateral laryngeal paralysis. This study indicates the possibility that FES to the paralyzed laryngeal adductor muscles is accepted as a new therapy for patients with unilateral laryngeal paralysis.
