Severe muscular rigidity at birth: malignant hyperthermia syndrome?

A case of severe muscular rigidity in a premature male infant born by Caesarean Section under general anaesthesia is described. A probable diagnosis of malignant hyperthermia was supported by the clinical symptoms of muscular rigidity and cyanosis, a creatinine phosphokinase of 24,630 I.U. (Normal 0--100) and a urinary myoglobin of 248 mg/l (normal 6--35). The muscle tone and laboratory values slowly returned to normal over a period of days. Anaesthetic management for a ventriculoperitoneal shunt performed at seven weeks of age included pre and postoperative treatment with dantrolene. No crisis occurred at this time. The parents, who have normal CPK and a negative family history, were advised to treat the child as if he had malignant hyperthermia until such time as a definitive diagnosis can be made.