Peripheral and central mechanisms of cough hypersensitivity

Abstract

Overview of cough and cough hypersensitivity syndromeCough is an important physiological response to airway irritation but can become excessive and problematic in disease. The characteristic cough motor pattern is relatively simple, consisting of an initial inspiration, a brief expiration against a closed glottis and finally forced expiration with the glottis open (1,2). This motor pattern generates large airflow velocities that effectively clear the airways of irritant material. Accordingly, cough plays an essential role in maintaining airway patency in both health and disease. However, despite the simplicity of an observable cough, the underlying neural mechanisms that lead to the production of a cough motor pattern can be quite complex. Firstly, cough can be initiated purely reflexively, mediated by the detection of irritant stimuli in the airway tree by vagal sensory nerve fibres leading to cough induction via the brainstem without any conscious control or regulation (3,4). Additionally, cough can occur with varying levels of volitional or cognitive control. Indeed, cough can be initiated at will, with or without any sensory input from the airways, and it can also be effectively suppressed, both consciously and subconsciously, even at times of strong peripheral sensory drive (5,6). This highlights some of the complexities in understanding the neural processes that control coughing, which is further complicated by multiple types of sensory neurons and receptors in the airways for detecting different Review Article on the 3rd International Cough Conference

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Blood eosinophils as a predictor of treatment response in adults with difficult-to-treat chronic cough

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