Surface electromyographic and electroglottographic studies in normal subjects under two swallow conditions: normal and during the Mendelsohn manuever.

Surface electromyography (EMG) has been used successfully in teaching patients swallow maneuvers in clinical settings. The present study aims to determine if surface EMG can reliably demonstrate differences in muscle activity between the normal swallow and the Mendelsohn maneuver and whether there is a close temporal relationship between submental muscles and laryngeal elevation as demonstrated by electroglottography (EGG). Surface EMG was measured from five muscle groups (superior and inferior orbicularis oris, masseter, submental and infrahyoid) in 20 normal subjects under two swallowing conditions: normal and during performance of the Mendelsohn maneuver. A significant difference in EMG activity from the submental muscle group between the normal swallow and the Mendelsohn maneuver indicates that EMG at this location can be used reliably to differentiate between these two swallow conditions. The onset of submental activity and laryngeal elevation occurred within 10 ms of each other. The offset of submental activity and the return of the larynx to its resting position occurred within 24 ms of each other. Regarding the temporal relationship among the five muscle groups, the sequence of the most frequent muscle initiation was orbicularis oris inferior. orbicularis oris superior, masseter. submental muscle group, and infrahyoid muscle group. The sequence of the most frequent muscle termination was orbicularis oris superior, orbicularis oris inferior, masseter, submental muscle group, and infrahyoid muscle group in both normal swallow and the Mendelsohn maneuver.