Annals of Otology, Rhinology & Laryngology 114(6):478-487. © 2005 Annals Publishing Company. All rights reserved. Timing of Glottic Closure During Swallowing: A Combined Electromyographic and Endoscopic Analysis

Objectives: We performed a case series to enhance our understanding of the coupling between neuromuscular events and glottic closure. Methods: We performed combined flexible video laryngoscopy and electromyography in 4 healthy human subjects. Hooked-wire electrodes were placed in the superior pharyngeal constrictor, longitudinal pharyngeal, cricopharyngeus, thyroarytenoid, genioglossus, suprahyoid, and posterior cricoarytenoid muscles, A flexible endoscope tip was posi-tioned in the oropharyngeal-hypopharyngeal region. The subjects performed multiple trials each of lO-mL normal and super-supraglottic liquid swallows. Results: Arytenoid movement consistently preceded full glottic closure and was associated with cessation of activity of the posterior cricoarytenoid muscle. In 89 % of normal swallows, the glottis was partially open in the video frame before bolus passage. The maximum amount of thyroarytenoid electromyographic activity occurred during endoscopic white-out. When subjects executed a super-supraglottic swallow, early thyroarytenoid activity coincided with arytenoid con-tact. Conclusions: The initial medialization of the arytenoids is due to a decrease in motor tone of the posterior cricoarytenoid muscle. Full glottic closure typically occurs late in the process of swallowing, with activation of the thyroarytenoid muscle. Shifting of arytenoid medialization and glottic closure earlier in the super-supraglottic swallow indicates that glottic closure is under significant voluntary control. Key Words: deglutition, electromyography, endoscopy, larynx