Sir.—I was interested to read the article "Hidden Asthma in Childhood" by Dr König (Journal 1981;135:1053-1055). It has been known for some time that a cough may be the only manifestation of asthma1; at Royal Manchester (England) Children's Hospital, a cough has been a common symptom of both perennial and seasonal asthma.
The cough characteristically occurs, or is worse, at night, with rising in the morning, exercise, excitement, exposure to the cold, or crying. The cough may be chronic, occurring daily for several months or years, or it may appear only on exposure to allergies or associated with an upper respiratory tract infection. Sometimes, the cough is similar to that of pertussis and can only be distinguished by its response to bronchodilators. Results of chest examination are almost always normal, except that sometimes bilateral Harrison's sulci may be observed. The resting peak expiratory flow rate and forced