Aging Influences on Pharyngeal Anatomy and Physiology: The Predisposition to Pharyngeal Collapse

Abstract

Obstructive sleep apnea is a common disorder with important sequelae.1–7 Aging substantially increases the risk of obstructive apnea,8–11 although the mechanisms underlying this predisposition remain unclear.8,12–15 Most current evidence suggests that obstructive apnea results from an interaction of the anatomy of the upper airway with the control of pharyngeal dilator muscles.4 Afflicted patients have compromised pharyngeal anatomy with reduced airway lumen.16–19,20 Through reflex mechanisms that drive activation of dilator muscles, pharyngeal patency is well maintained during wakefulness.21–23 However, these protective reflexes are diminished during sleep, thereby leading to collapse of the pharyngeal airway in anatomically predisposed people.24 Thus, aging could predispose to apnea via changes in pharyngeal anatomy and biomechanics or via deterioration in the function of pharyngeal dilator muscles.25–31 By combining magnetic resonance imaging techniques with pharyngeal physiological assessments, we sought to determine the structural and functional basis for the increased propensity for airway collapse among older persons. We included normal and near-normal controls to avoid the confounding influences of repetitive pharyngeal collapse as might occur with sleep apnea.