ABSTRACT
BACKGROUND: Dysphagia diagnosis is limited by our inability to evaluate the underlying neuromuscular pathology of swallowing. A novel approach using pharyngeal surface electromyography (PsEMG) has been reported in the literature. OBJECTIVE: Three exploratory projects were undertaken to provide data toward the validation of PsEMG as a clinical measure of pharyngeal physiology. The first evaluates laterality of electrode placement in the pharynx. The second and third evaluate PsEMG using a circumferential and unidirectional electrode, respectively, during swallowing maneuvers. METHODS: In experiment 1, a catheter housing 3 manometric sensors and 1 bipolar PsEMG electrode was randomly inserted in each nares of 10 participants. Moving jaw radiographs were taken, and the PsEMG electrode was measured in millimeters from midline. In experiments 2 and 3, the catheter was placed in 22 and 40 research participants, respectively. Waveform characteristics were collected during swallowing maneuvers. The 2 experiments differed by type of electrode (circumferential, unidirectional) and swallowing maneuver (noneffortful and effortful swallow; noneffortful, effortful, and tongue-hold swallow). RESULTS: Midline electrode placement occurred on 20% of trials with deviation of up to 14.7 mm on all other trials. Maneuver-specific differences in amplitude were not detected with PsEMG; unacceptable levels of intrasubject and intersubject variability were identified. Temporal relationships of PsEMG and pharyngeal manometric pressure appeared appropriate. The unidirectional electrode revealed a unique bimodal PsEMG pattern that may reflect sequential contraction of muscles of the posterior pharyngeal wall. CONCLUSIONS: The current PsEMG design and procedures do not validly measure pharyngeal muscle activity. Recommendations for improved methods are provided.
