Structural changes in the airways: cause or effect of chronic cough?

Patients with a chronic cough have asthma or "asthma-related" diagnoses such as cough variant asthma or non-asthmatic eosinophilic bronchitis usually responsive to inhaled corticosteroid therapy, or non-asthma-related diagnoses including "idiopathic" or "unexplained" cases. Both of these conditions involve airway inflammation. More recently, structural changes or remodeling of the lower airways, which have been considered characteristic of classic asthma with wheezing, have also been demonstrated in patients with chronic cough, irrespective of its cause. In this article, the presence, pathogenesis, and possible consequences of such structural changes in patients with chronic cough are reviewed. Although whether chronic cough leads to structural changes or structural changes is a cause of chronic cough is difficult to determine, the concomitance of both mechanisms may lead to a positive feedback mechanism or a vicious cycle of cough persistence.