Exercise-induced laryngeal obstruction: a common and overlooked cause of exertional breathlessness.

Abstract

A commonly-encountered clinical scenario in primary care involves an adolescent or young adult, with no past medical history, presenting with wheeze and breathlessness, occurring in association with exercise.1 However, the differential diagnosis for this presentation is broad. Such patients are often diagnosed with exercise-induced asthma and prescribed a short-acting bronchodilator.1 Recently there has been increasing recognition that an alternative diagnosis should be considered,2 specifically a condition termed exercise-induced laryngeal obstruction (EILO), a phenomenon in which closure of the larynx occurs during high-intensity exercise. This narrowing causes a significant reduction in airflow, thereby precipitating breathlessness and wheeze. Some have termed this condition exercise-induced vocal cord dysfunction (VCD), although the narrowing most frequently occurs at a level above the vocal cords (that is, involves supra-glottic structures) and thus EILO is an appropriate descriptor. The reason EILO develops in some individuals is currently unclear. A primary function of the glottis is to defend the airway, and thus the larynx resides in a primed status that favours closure. The larynx is richly innervated and may become hypersensitive upon repeated exposure to laryngeal irritants. Moreover, the forces and pressure change that are manifest across the larynx during intense exercise appear to play a role in precipitating laryngeal closure. Distinguishing between exercise-induced bronchoconstriction and EILO can be diagnostically challenging, particularly in a primary care setting. The aim of this short article is thus not to provide a complete review of EILO, but to highlight pertinent features for focus in a clinic-based assessment, and …