Effect of surface neuromuscular electrical stimulation on labial and lingual muscles in healthy volunteers

Neuromuscular electrical stimulation (NMES) may have potential as a treatment for muscle weakness as it may improve strength when applied to the orofacial muscles. However, before incorporating this procedure into clinical practice, research is needed to investigate its effects on lingual and facial muscles of speech and mastication. The aim of this study was to determine what effect(s) submental and labial NMES would have on lingual and labial muscle strength in healthy participants. Fourteen healthy adults (27-49 years old) were assigned to two groups (treatment and control). A pretreatment and post-treatment test using the Iowa Oral Performance Instrument was used to measure the strength of labial and lingual muscles in both groups. Participants in the treatment group received labial and submental NMES while performing a structured labial, buccal, and lingual exercise program. In contrast, participants in the control group completed the same oral motor exercise program without stimulation. Results: On comparing the total change in labial and lingual strength between the two groups, an increase in total labial strength was found in the treatment group compared with the control group. However, the control group showed an increase in total lingual strength compared with the treatment group. Results for all measurements were not statistically significant. This study concluded that NMES may be a promising modality to combine with labial and buccal exercises for improvement of muscle strength.