Duchenne muscular dystrophy and malignant hyperthermia--two case reports.

The case histories are presented including the anaesthetic and postoperative management, of two children, a two-year-old with undiagnosed Duchenne muscular dystrophy (DMD) and a three-year-old with known DMD. The child with undiagnosed DMD had no symptoms of DMD and had received halothane twice before, without succinylcholine, with no apparent difficulty. Following an uneventful induction of anaesthesia with halothane, nitrous oxide and O2, succinylcholine resulted in bilateral masseter muscle spasm and then, in rapid sequence, ventricular tachycardia and cardiac arrest. Resuscitation was difficult, prolonged and associated with hyperkalaemia (K+ = 12.57 mEq X L-1), severe metabolic and respiratory acidosis, high peripheral venous pressure and massive hepatosplenomegaly, but not hyperthermia. The patient was finally resuscitated but died two days later. Skeletal muscle biopsy results were consistent with malignant hyperthermia. The second patient was known to have DMD but did not receive prophylactic or intraoperative dantrolene nor have his anaesthetic machine flushed with oxygen for an extended period prior to induction of anaesthesia. This child was anaesthetized with fentanyl and N2O and, with the exception of a high intraoperative heart rate (155-160 beats X min-1), had an uncomplicated anaesthetic and operation (intraoperative axillary temperatures ranged between 36.8-37.9 degrees C). Postoperatively his temperature rapidly increased to 38.8 degrees C and then 40.3 degrees C and he became metabolically acidotic. Intravenous administration of dantrolene for 48 hours reduced the temperature and allowed normal recovery and discharge. A postoperative muscle biopsy was consistent with DMD.(ABSTRACT TRUNCATED AT 250 WORDS)