Methacholine challenge testing in the diagnosis of paradoxical vocal fold motion

Objective: The purpose of this study was to determine whether methacholine challenge testing (MCT) combined with serial laryngoscopy could elicit and visualize paradoxical vocal fold motion (PVFM) during asymptomatic periods and suggest laryngeal dysfunction as an etiology of episodic dyspnea. Study Design: A retrospective study of seven adult patients. Methods: Medical records of seven adult patients who were referred to an otolaryngology clinic with recurrent episodes of dyspnea or choking and underwent bronchoprovocation testing were reviewed. After initial fiberoptic laryngoscopy and pulmonary function testing (PFT), bronchoprovocation was performed using aerosolized methacholine at increasing concentrations. Each administration was followed by repeated laryngoscopy and PFT. A positive endoscopic test was marked by the visualization of paradoxical adduction of the true vocal folds during inspiration. A positive bronchoprovocation test was marked by a 20% or greater decline in the forced expiratory volume. Results: All seven patients demonstrated normal upper airway anatomy and function on initial laryngoscopy. In three patients, a positive endoscopic examination demonstrating PVFM was elicited during MCT. In three, the bronchoprovocation test was positive, and asthma was diagnosed. In one patient, both tests were negative. PVFM was seen in all patients whose chief complaint was choking (n = 2) but in only one of five patients whose chief complaint was dyspnea. Conclusions: PVFM may be elicited and observed during MCT coupled with serial laryngoscopy. This test holds promise in differentiating vocal cord dysfunction from asthma during asymptomatic periods in patients who present with recurrent episodes of refractory dyspnea.