Detection of swallowing disorders using a multiple channel surface electromyography sheet: A preliminary study

Abstract

Background/purpose: We invented a sensor sheet with multiple electromyogram electrodes, which can be easily attached to the front of the neck, to evaluate surface electromyograms (sEMG) during swallowing function. In this paper, we evaluated sEMG in healthy volunteers and dysphagia patients using the sensor sheet and discussed its potential to evaluate swallowing function.

Materials and methods: Ten healthy volunteers (age, 29.5 ± 3.9 years) and 18 clinically diagnosed dysphagia patients (age, 67.8 ± 12.1 years) were included. The sensor sheet had four pairs of electrodes, and sEMG at the suprahyoid muscles (positions A and B) and the infrahyoid muscles (positions C and D) were recorded while swallowing water, thickened water, yogurt, and jelly; sEMG findings were compared between these positions.

Results: Significant differences in the duration of muscle activity was observed when swallowing yogurt at position D and when swallowing jelly, thickened water, and water at position B (Mann-Whitney U test, p < 0.05). In healthy volunteers, muscle activation typically began from positions A or B to position D, whereas in dysphagia patients, it sometimes began from position D.

Conclusion: There were significant differences in duration and sequence patterns of four sEMG activities between healthy young volunteers and dysphagia patients in the assessment using the sensor sheet, although some technical and scientific problems remained unresolved. These results indicate that swallowing function could be evaluated using the sensor sheet.

Keywords: Electromyography; Neck muscle; Swallowing disorders.

Figure 1

Layout of sensor sheet. (a) The back side of sensor sheet; (b) Photograph with sensor sheet and attached laryngeal microphone. Eight electrodes were placed at four positions (position A: upper front of the suprahyoid muscles, position B: rear bottom of the suprahyoid muscles, position C: above the infrahyoid muscles, and position D: beneath the infrahyoid muscles). A pair of electrodes was placed in each position 30 mm apart. A laryngeal microphone was affixed to the inferior margin of the cricoid cartilage to monitor swallowing sound.

Figure 2

Analysis of sEMG.(a) Wave of muscle activity; (b) Swallowing sound. The threshold was set two-fold larger than the average sEMG amplitude of baseline interval in each position, which was the period when there was very less sEMG response for 0.5 s. The onset was defined as the time when the value of sEMG voltage exceeded a threshold, closest to the time of the largest swallowing sound, whereas the offset was defined as the time when the voltage fell below the threshold, closest to the time of the largest swallowing sound. Image is for illustration purposes.