Objectives/hypothesis: Exercise-induced vocal cord dysfunction is difficult to diagnose because the paradoxical vocal cord adduction should be observed during exercise. Our goal was to develop and validate a new diagnostic method for exercise-induced vocal cord dysfunction by combining continuous fiberoptic laryngoscopy with a bicycle ergometry test.
Methods: Thirty consecutive patients referred to a laryngologist because of suspicion of exercise-induced vocal cord dysfunction and 15 healthy controls underwent the exercise test until dyspnea or exhaustion rated as 18-19/20 on the Borg scale. Laryngeal findings, electrocardiography, blood pressure, heart rate, and respiratory rate were monitored, and forced expiratory flow in the first second was measured before and after the exercise. The medical history was assessed by use of a structured questionnaire.
Results: Among the 30 patients, 27 (90%) performed the test successfully, as did all controls. Diagnostic signs of inspiratory stridor, supraglottic collapse, and vocal cord adduction appeared in five (19%) patients but in none of the controls. Of the 30 patients referred, the laryngologist considered 25 to be suspect. Of them, 9 (36%) showed signs diagnostic or highly suspect for exercise-induced vocal cord dysfunction. Of the 15 patients whose dyspnea could be induced during the test, nine (60%) were suspected of having exercise-induced vocal cord dysfunction.
Conclusions: Fiberoptic videolaryngoscopy during bicycle ergometry was a well-tolerated and relatively easily established diagnostic tool that could induce dyspnea in more than one half the patients examined. If the symptom of dyspnea appeared, the most frequent diagnosis was exercise- induced vocal cord dysfunction.