Surface electromyographic studies of swallowing in normal subjects: A review of 440 adults. Report 3. Qualitative data

Abstract

Objective Surface electromyographic studies were performed on 440 normal adults to describe and evaluate different types of normal swallows clinically useful for ENT department. Study design Prospective observational study of healthy volunteers. Methods EMG recordings were made using stick-on surface electrodes. Rectified and filtered EMG signals were evaluated. Parameters evaluated include the graphic configuration of activity of the orbicularis oris, masseter, submental group, and infrahyoid muscles, the last 2 covered by platysma, during single swallowing and continuous drinking. Four tests were examined: voluntary saliva swallows, voluntary separate swallows as normal, voluntary separate swallows of excessive amount of water (20 mL), drinking of 100 mL of water. Graphic recording of activity of the above-mentioned muscles during swallowing and drinking were evaluated for groups of adults of different ages. Results There are several types of normal swallows as seen at the surface EMG records. There was no difference between EMG recordings of male and female swallows. Only group of elderly patients (age 70+) shows age-induced differences in recorded swallows. There are two main types of normal swallow: single-share and double-share swallows. The oral phase of swallowing, being under conscious control, is very variable and should not be taken into consideration during evaluation of records. Final oral, pharyngeal, and initial esophageal stages of swallowing can be defined and evaluated at the rectified and filtered surface EMG record. Conclusion The normal muscle activity during swallows and drinking has several graphic patterns which can be identified and described similar to EKG records when surface EMG is rectified and filtered. The method of EMG recording is quick and simple, and can be used for screening and evaluation purposes in outpatient and inpatient ENT departments. These parameters represent activities required for normal deglutition, and can be used to identify abnormalities in ENT patients, and provide a basis for comparison of swallowing performance both within and between patients. These normal data form a valuable basis for future comparison with patients in pre- and postoperative stages and in EMG monitoring during ENT treatment.