Date of Degree
MA (Master of Arts)
Speech Pathology and Audiology
The use of neuromuscular electrical stimulation (NMES) for the treatment of swallowing disorders has become increasingly popular, yet little is known about its long-term effects on muscle physiology. This study indirectly assessed suprahyoid muscle physiology using electromyography (EMG) during a jaw-opening task that was completed before training, immediately after training, and two-weeks after training. Comparisons were made in muscle performance between control participants who engaged in effortful swallowing training and participants who received conjunctive NMES during effortful swallow training. All participants completed four weeks of swallowing exercises conducted five days a week (20 sessions) and consisting of 120 swallows each session. Results revealed that participants collectively improved their peak force production following training, but peak force and EMG median frequency did not vary as a function of training method. The observed high variability in median frequency between trials in addition to the documented improvement in function without a measured change in physiology suggests the need to consider alternate electrode placements during EMG or other tools of assessment. These findings suggests that both effortful swallow training and long-term conjunctive NMES with effortful swallowing improves jaw-opening strength of healthy adults, though adding NMES to the treatment was no more effective than training without it. Further research is necessary to determine the effects of long-term NMES training on swallowing physiology in vivo using other indirect measurements, or direct measurements such as muscle biopsy if possible.
Neuromuscular Electrical Stimulation (NMES) involves using an electric current to contract muscles. This therapeutic tool is used in the treatment of swallowing disorders. However, little is known about the long-term effects of NMES on swallowing muscle physiology. Due to the structure of suprahyoid muscles which support safe swallowing and jaw-opening, using a tool such as surface electromyography (EMG) to study muscle physiology is preferred. Surface EMG involves placing electrodes on the skin which detect muscle activity below the skin.
This study compared participants who effortfully swallowed teaspoons of water (control) to participants who effortfully swallowed teaspoons of water while also receiving electrical stimulation to the swallowing muscles (experimental). All participants completed four weeks of training. Participants pushed their jaw down on a metal bar while wearing EMG electrodes on their swallowing muscles. This task was performed before testing, following four weeks of training, and after a two-week break from training. The results of this study showed that participants improved their force production over time regardless of their training method, but force production and EMG median frequency did not change as a result of their training method.
This research improves our understanding of new treatments for swallowing disorders. There was an improvement in function without a measured change in physiology, meaning that strength of jaw-opening improved. Future work should consider alternate placements of electrodes or other tools of assessment. Further research is needed to better understand the effects of long-term electrical stimulation training on swallowing muscle physiology.
publicabstract, Deglutition, Dysphagia, Effortful Swallow, Electrical Stimulation, NMES, Treatment
Copyright 2015 Brandon Scott Eddy