An electrophysiological investigation of deglutition in man

Abstract

This article describes a combined electrophysiological and mechanical method used to measure laryngeal movements and related submental EMG activity during swallowing. The mechanical upward and downward movements of the larynx were detected using a piezoelectric sensor while the submental integrated EMG (SM-EMG) was recorded. Measurements were performed in 29 human subjects. The interval between the onsets of the two sensor signal deflections was used as a measure of the time the larynx remained in its superior position during swallowing. In 10 subjects, the cricopharyngeus muscle (CP) of the upper esophageal spinchter showed a continuous tonic EMG activity except during swallowing. All the parameters measured were influenced by the type and volume of the bolus material. The method presented in this study proved its usefulness in the study of the physiology of deglutition as well as in its objective clinical evaluation in patients with dysphagia.

Modulation of Upper Esophageal Sphincter (UES) Relaxation and Opening During Volume Swallowing

“…One school of thought holds that tonic CP deactivation and UES opening occurs simultaneously due to brainstem-mediated neural inhibition originating in the CPG [3,5,14,15]. An alternate school of thought is that the suprahyoid muscles are primarily involved in UES opening and that traction within the suprahyoid muscle group leads to CP deactivation [1,7,16,17].…”

Noninvasive Monitoring of Breathing and Swallowing Interaction

“…Once the pharyngeal phase is initiated, the chain of events is irreversible. The entire oropharyngeal sequence takes only 0.6 to 1.0 second, and this duration is remarkably constant in humans (Ertekin, Pehlivan et al 1995).…”

“…All the muscles in this complex contract simultaneously to initiate a swallow and function as laryngeal elevators (Miller 1982). Consequently, submental surface EMG activity provides considerable information about the onset and duration of the oropharyngeal swallowing phase, as contraction of the SM complex pulls the hyoid bone into an anterosuperior position, thereby elevating the larynx and initiating the other reflexive changes that constitute the pharyngeal phase of swallowing (Donner, Bosma et al 1985;Dodds, Logemann et al 1990;Ertekin, Pehlivan et al 1995). However, pharyngeal and laryngeal EMG recording during swallowing was difficult to perform noninvasively and usually required the insertion of a needle electrode.…”

“…Most of the initial EMG studies of swallowing used needle electrodes to record intramuscular EMG activity (Doty and Bosma 1956;Perlman, Palmer et al 1999). Ertekin et al (Ertekin, Pehlivan et al 1995) were the first to describe an electrophysiological method for investigating swallowing in humans. Recent advances in the management of respiratory failure have considerably improved the survival of patients with neuromuscular disease (Finder, Birnkrant et al 2004).…”

Reflex influences on oropharyngeal swallowing

“…Second late burst is called rebound burst and appears after the CP-EMG pause. [23,46] Rebound burst activity is always observed with each swallow, therefore it should belong to the sequential muscle activation of CPG. But foreburst can not be found in each normal subject, and therefore may be related with protective reflexes.…”