A 53 year old man was stung behind the knees by five wasps, subsequently identified as belonging to the species Vespula germanica (commonly known as “yellow jackets”). Within a few minutes, he became dizzy, began to wheeze, and collapsed. He responded rapidly to intramuscular epinephrine administered by the attending paramedics, but showed a persistent sinus tachycardia during the subsequent hospital admission. Thus, when he was discharged the following day, he was put on sotalol for 1 week.

He had been stung by a wasp 1 year previously, suffering only extensive local swelling. There was no personal or family history of atopic disease or of reactions to ingested or topical allergens.

He remained free of symptoms for the next 5 weeks, but then developed rapid onset, severe, and painful muscular twitching throughout his limbs, profuse generalised sweating, and insomnia. For 3 weeks prior to his second hospital admission, he was treated with a combination of amitriptyline 10 mg nightly and gabapentin 300 mg thrice daily without effect.

On examination, the patient was afebrile but had hyperhidrosis and tachycardia. He appeared emotionally labile. There were continuous coarse fasciculations throughout all limbs, most markedly in the deltoid and quadriceps bilaterally. The limb tone was normal, with preserved power and normal sensation.

Serum creatine kinase (CK) level on admission was 10 756 IU/l. Serum urea and creatinine levels were normal and no urinary …