Surface electromyographic studies of swallowing in normal subjects: a review of 440 adults. Report 1. Quantitative data: timing measures.

OBJECTIVE: Surface electromyographic studies were performed on 440 normal adults to establish normative database for duration of muscle activity during swallowing and drinking clinically useful for outpatient ENT department. STUDY
DESIGN: Prospective observational study of healthy volunteers.
METHODS: Parameters evaluated during swallowing include the timing of activity of the orbicularis oris, masseter, submental, and infrahyoid muscle groups covered by platisma. Five tests were examined including voluntary single swallows of saliva ("dry" swallow), voluntary single water swallows as normal, voluntary single swallows of excessive amount of water (20 mL), continuous drinking of 100 mL of water (duration and number of swallows), monitoring of spontaneous swallowing of saliva during 1 hour period. The duration of oral, pharyngeal, and initial esophageal stages of swallowing (mean + SD) were measured for groups of adults of different age (18-30, 31-40, 41-50, 51-60, 61-70, 70+ years old).
RESULTS: Normative data for duration of muscle activity during single swallowing and continuous drinking are established for healthy adults. The duration of swallows and drinking in all tests showed insignificant increase with the age except for the geriatric group, in which this tendency is statistically significant (1-dimensional analysis of variance, SPSS, Chi-square criterion, 95% confidence interval). There was no statistically significant difference between male and female adults duration of muscle activity during single swallowing and continuous drinking in all age groups (P >/= 0.05). The relevance and clinical utility of new and alternative measures, in particular, are discussed.
CONCLUSION: Surface EMG of swallowing is a simple and reliable noninvasive method for screening evaluation of swallowing with low level of discomfort during the examination. Stage-by-stage evaluation of duration can be very important for topical diagnosis of etiology of dysphagia. The normative timing of events data can be used for evaluation of complaints and symptoms, as well as for comparison purposes in preoperative and postoperative stages and in EMG monitoring during ENT treatment. These parameters represent stages 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.