To the Editor: These two cases, which occurred many years ago, illustrate a useful clinical sign in the diagnosis of tetanus.

An elderly man was admitted to hospital after crushing his finger in a stable door. He commented in passing that when he whistled across the park to his wife that morning, she had not heard him. However, she had heard him the previous two mornings. He was a professional whistler on the radio and, when asked, still appeared to produce a good strong whistle. As it is the high pitch that carries long distances, I pondered the causes of selective pitch loss. I suspected the "risus sardonicus" of tetanus. He was subsequently confirmed to have tetanus and survived.

Years later, a middle-aged woman with right hypochondral pain and presumed cholelithiasis presented to a country hospital for a cholecystogram. I chatted to her about her bandaged hand — she said that she had cut it on a jam tin in her house, but that her general practitioner was treating it, and all her vaccinations were up-to-date. Some hours later she complained that her abdominal pain was worse and had moved. I believed that the pain was probably related to movement of gallstones, but was more interested in her hand wound, of which she was dismissive. I asked her to whistle. It was a good whistle, but she commented, "It's not my whistle, I whistle the cows into the bales." Recalling my previous patient with the altered whistle, I diagnosed tetanus and arranged her urgent transfer to a consultant at Sydney Hospital (Sir Kenneth Noad). Indeed, she did have tetanus, and developed laryngeal spasm requiring emergency tracheotomy and 2.5 weeks in a respirator. Sir Kenneth later thanked me for saving the patient's life.

The alteration of a person's whistle in tetanus can be explained as an early effect of the increased tone in facial muscles, which causes the classic risus sardonicus. As tetanus toxin must travel from peripheral nerve terminals to the nerve-cell body in the brainstem or spinal cord to exert its effects, muscles of the jaw, face and head, with their shorter axonal pathways, are often involved before those of the trunk and extremities.1