Suxamethonium, masseter spasm and later malignant hyperthermia.

A 25-year-old man admitted with severe upper torso trauma displayed masseter muscle spasm after suxamethonium given during resuscitation. Anaesthesia was initially maintained with intravenous agents during transfer and X-ray angiography. However, during surgery to correct a brachial artery injury, malignant hyperthermia was triggered when isoflurane was given, 2.5 h after the suxamethonium. He responded to treatment, including dantrolene administration. Peak serum and urine myoglobin were 12,947 micrograms.l-1 and 54,571 micrograms.l-1, respectively, while maximum serum creatinine kinase was 17,300 IU. The patient made an uneventful recovery and later proved positive for malignant hyperthermia susceptibility on muscle contracture tests.