Effects of Neuromuscular Electrical Stimulation (NMES) on salivary flow in healthy adults

BACKGROUND: Neuromuscular electrical stimulation (NMES) is a method used for enhancing suprahyoid muscle activity and is widely applied as a treatment for dysphagia. Patients often complain of saliva pooling in the pharynx during NMES. Therefore, the purpose of this study was to investigate the changes in salivary flow during NMES. MATERIAL AND METHODS: Twenty healthy adults participated in this study. Electrical stimulation was applied at constant strength for 60 minutes to the suprahyoid muscles using VitalStim®. Participants were examined under three conditions of NMES: sensory threshold plus 75% of the difference between sensory and pain thresholds (75% Stim), SensoryStim, and Sham. Saliva collections, using a 10-min spitting method, were performed seven times: before stimulation (S1), during stimulation (S2-S6), and 5 min after stimulation ended (S7). RESULTS: Significant differences were observed in saliva flow between S1 and S7, as well as S2 and S7 in 75% Stim. CONCLUSIONS: This study indicates that an increase in saliva flow was promoted after NMES. Therefore, NMES may have effects on patients with xerostomia. Key words:Neuromuscular electrical stimulation, suprahyoid muscle, sensory threshold, pain threshold, saliva flow.