Laryngeal Dysfunction Manifesting as Chronic Refractory Cough and Dyspnea

Abstract

Topic Importance

Laryngeal dysfunction as a cause of chronic refractory cough (CRC) and episodic dyspnea is often missed which results in unnecessary testing and delays in diagnosis. Understanding laryngeal roles in breathing and airway protection can help to appreciate the propensity to laryngeal dysfunction with aging, chronic lung disease and sleep apnea.

Review findings

The human larynx is a complex muscular structure that undertakes multiple roles of breathing, vocalization, coughing and swallowing. To undertake these activities, the larynx has a high density of sensory and motor innervation. Besides common embryological origins with the pharynx and esophagus with which many laryngeal activities are shared, somatomotor and autonomic pathways regulate emotional, cognitive and complex motor sequence-planning activities within the larynx. Due to its unique location, the larynx is susceptible to infectious and gastroesophageal reflux-related insults. Couple this with key roles in regulation of airflow and mediation of airway protective reflexes, it is not surprising that neuropathic abnormalities and muscle dysfunction can develop frequently. The expression of laryngeal dysfunction as hypersensitivity to mechanical, thermal, chemical and other stimuli leads to exaggerated airway protective reflexes (laryngeal adductor reflex and cough reflex) manifesting as dyspnea and cough.

Summary

Pulmonologists should incorporate assessment of laryngeal dysfunction during evaluation of CRC and dyspnea. Recognition of laryngeal hypersensitivity in patient with CRC can identify patients that can benefit from cough suppression therapies. Similarly, timely identification of inducible laryngeal obstruction can not only resolve episodic dyspnea but lessen need for unnecessary testing and treatments.