Chronic cough as the sole presenting manifestation of bronchial asthma

Abstract

Six patients with chronic cough, without history of dyspnea or wheezing, had normal base-line spirometry but hyper-reactive airways, as demonstrated with methacholine. Maintenance therapy with bronchodilators promptly eliminated the cough in all patients. Three to 12 months later therapy was discontinued for three days, cough returned, and detailed pulmonary-function studies were carried out. Again, base-line values were normal, but after methacholine one-second forced expiratory volume decreased an average of 40% in the patients as compared to 3% in normal controls (P<0.001). The point of identical flow was increased by methacholine to 43.5% of vital capacity in the patients, as compared to 6% in normal controls (P<0.001), and the alveolar plateau was 4.8 DELTAN2 per liter, as compared to 1.4 in normal controls (P<0.01). Specific airway conductance was lowered in patients and controls, but the post-methacholine value was significantly lower in the patients. On the basis of their persistently hyper-reactive airways, inducible diffuse airway bronchoconstriction and excellent response to bronchodilator therapy, these patients appear to have a variant form of asthma in which the only presenting symptom is cough.