A 13 year old boy was referred for evaluation of his troublesome asthma symptoms. He had a six month history of episodic acute dyspnoea on minimal exertion—for example, climbing stairs. Between episodes he could exercise maximally without difficulty. Dyspnoea was accompanied by a loud inspiratory noise, described as “wheeze” but not cough. The episodes occurred only at school, lasted for five to 10 minutes, and resolved completely.

He was diagnosed with asthma when he was 2 years old because of nocturnal cough, and he had been treated with inhaled steroids until recently. His father reported that his son’s pulse raced in the morning. On examination he was well. His height and weight both lay on the 75th centile. He had no stigmata of chronic lung disease, such as fingernail clubbing or chest wall deformity. He had a hoarse voice.

The results of chest radiography and pulmonary function testing were normal. Electrocardiography showed a sinus tachycardia of 120 beats per minute. A diagnosis of vocal cord dysfunction was made and the boy was referred for speech therapy.

One month later he developed nausea and vomiting, and was noted …