Transient paradoxical closure of the larynx, occurring in the absence of any underlying structural or neurological defect, is a recognized cause of paroxysmal breathlessness and wheeze. This phenomenon, most commonly termed vocal cord dysfunction and more recently termed inducible laryngeal obstruction (ILO),1 is often misdiagnosed and mistreated as asthma.2, 3 This may be explained by the lack of a robust, accepted diagnostic methodology.4, 5
Central to the diagnosis of ILO is endoscopic visualization of the larynx in order to capture paradoxical narrowing of the laryngeal inlet occurring concurrently with compatible clinical features.6 This process is also dependent on successful exposure to a specific or relevant inducer; that is, to provoke closure. Exercise-induced laryngeal obstruction (EILO) is now recognized to be a prevalent cause of unexplained breathlessness in young athletic individuals7, 8 and is best diagnosed using the continuous laryngoscopy during exercise (CLE) test.9 The latter is performed by securing a flexible laryngoscope in the nasopharynx, thus allowing continuous visualization of laryngeal movement and only one passage of the endoscope. It also offers an opportunity for biofeedback,10 and the development of battery-powered portable laryngoscope systems has now made it possible to deliver continuous laryngoscopy in challenging environments, for example, when swimming.11
Despite these developments, very little information is published regarding the optimum methodology for the assessment of laryngeal movement during environmental-type (i.e., nonexercise) provocation. Provocation agents utilized in this context typically include relatively innocuous stimuli such as household cleaning products, odors, or scents, but certain workplace environmental triggers are also relevant.12, 13 Indeed, work-related irritant-induced laryngeal dysfunction remains an underrecognized and poorly diagnosed condition.14
We present a novel methodological approach to the diagnosis of ILO, utilizing a similar approach to CLE testing, to perform continuous laryngoscopy during provocation (CLP). In this report, we provide a description of this methodology and illustrative clinical cases to highlight the diagnostic and therapeutic benefits of the approach and outline its safety.
Hull, J. H., Walsted, E. S., Feary, J., Cullinan, P., Scadding, G., Bailey, E., & Selby, J. (2019). Continuous laryngoscopy during provocation in the assessment of inducible laryngeal obstruction. The Laryngoscope, 129(8), 1863–1866.
