Intrinsic laryngeal muscle activity in response to autonomic nervous system activation

Abstract

To determine whether the intrinsic laryngeal muscles exhibit a response to induced autonomic nervous system (ANS) activation, and to characterize responses that may occur. Prospective within-subjects study. A cold pressor (CP) task was used to trigger a whole-body ANS response in eight vocally normal adult females. Surface electromyography of the trapezius muscle and bipolar hook-wire electromyography of intrinsic laryngeal muscles, as well as cardiovascular measures of heart rate (HR) and blood pressure (systolic [SBP] and diastolic [DBP]), were used to characterize participants' response to CP exposure compared to at-rest baseline. Cardiovascular response to the CP task was confirmed for subjects via HR or blood pressure measures. Post hoc Bonferroni analysis confirmed statistically significant increases in HR (P = .027), SBP (P < .001), and DBP (P < .001) during the CP task as compared to baseline. Concurrent increases in muscle activity were generally observed in trapezius, posterior cricoarytenoid, bilateral thyroarytenoid/lateral cricoarytenoid muscle complex, and bilateral cricothyroid muscles for each subject. Three individuals elected to repeat the CP task and displayed the same pattern of laryngeal response as observed in their first exposure. Results for repeated baseline measures obtained after the cessation of the CP task were compared to pre-CP baseline. Overall laryngeal activation remained even after the cardiovascular response was attenuated. Results are consistent with the suggestion that human laryngeal muscles exhibit an elevated level of activation concurrent with ANS activation, and endorse the putative link between laryngeal muscle tension and acute stress. Findings are replicable within a subset of three individuals.