EXTRATHORACIC AIRWAY DYSFUNCTION IN COUGH ASSOCIATED WITH GASTROESOPHAGEAL REFLUX

Background: Cough associated with gastroesophageal reflux (GER) may or iginate in extrathoracic airway receptors made hypersensitive by acid- induced mucosal injury. Objective: We investigated the role of larynge al disease and dysfunction in the pathogenesis of GER-associated cough in nonasthmatic patients. Methods: Seven patients with GER-associated cough were compared with 7 patients with GER but no cough. The patien ts underwent fiberoptic endoscopy for assessment of laryngitis and eso phagitis (expressed by scores); esophageal manometry; 24-hour pH monit oring; lung function tests; and histamine inhalation challenge with as sessment of bronchial threshold (concentration provoking 10% fall in F EV1 [PC10]), extrathoracic airway threshold (concentration provoking 2 5% fall in the maximal midinspiratory flow [PC25MIF50]), and cough thr eshold (concentration provoking 5 or more coughs PCcough). The patient s were reevaluated after 3 months of medical treatment for GER. Result s: Patients with cough, compared with those without cough, had signifi cantly higher laryngitis scores (P =.002), lower esophageal sphincter pressures, longer time with pH below 4 (P =.003), greater number of ep isodes of reflux longer than 5 minutes (P =.016), longer esophageal cl earance time (P =.048), and significantly lower PC25MIF50 (P =.005) an d PCcough (P =.008) values. Laryngitis score was significantly inverse ly related to either PCcough (P <.001) or PC25MIF50 (P <.01) but not t o PC10. Laryngitis score, PC25MIF50, and PCcough were all closely rela ted to GER severity. After GER treatment, laryngitis, PC25MIF50, and P Ccough were all significantly improved. Conclusions: These findings su ggest that GER-associated cough is strongly associated with laryngeal disease and dysfunction consequent to acid reflux injury in nonasthmat ic patients.