Pharyngoglottal Closure Reflex: Characterization in Healthy Young, Elderly and Dysphagic Patients with Predeglutitive Aspiration

Abstract

Background: Mechanism(s) of aspiration, a common complication of oropharyngeal dysphagia, is not completely elucidated. Since the pharyngoglottal closure reflex induces vocal cord adduction in healthy young humans, it may help prevent aspiration during premature spill of oral content. Objective: The objective of this study was to characterize this reflex in normal young and elderly humans and dysphagic patients with predeglutitive aspiration; a potential group for developing abnormalities of this reflex. Methods: We used a concurrent video endoscopic and manometric technique for recording of the vocal cords’ response to pharyngeal water stimulation. We first studied 9 young (26 ± 2 years) and 9 elderly (77 ± 14 years) healthy volunteers to characterize and determine the effect of aging on the pharyngoglottal closure reflex. Subsequently, we studied 8 patients (65 ± 16 years) with predeglutitive aspiration and 7 age-matched controls to characterize this reflex among patients with compromised airway safety during swallowing. Results: The threshold volume of water for triggering both glottal closure and reflexive pharyngeal swallow in the elderly volunteers for rapid pulse injection was significantly larger than that for the young (p < 0.05). Neither glottal closure reflex nor pharyngeal reflexive swallow could be induced in any of the dysphagic patients with volumes of injected water as large as 1 ml. In contrast, in all age-matched controls, both the pharyngoglottal reflex and reflexive pharyngeal swallow were stimulated with threshold volumes of 0.3 ± 0.07 and 0.6 ± 0.05 ml, respectively. Conclusions: Pharyngeal stimulation by water induces vocal cord adduction in humans; the pharyngoglottal closure reflex. Although preserved, a significantly larger volume of water is required to stimulate this reflex by rapid pulse injection in the elderly, suggesting some deterioration in this age group. The pharyngoglottal closure reflex induced by rapid pulse injection is absent in dysphagic patients with predeglutitive aspiration, suggesting its contribution to airway protection against aspiration.