Postexercise muscle cramping associated with positive malignant hyperthermia contracture testing

Malignant hyperthermia is a rare hypermetabolic disorder of skeletal muscle that usually manifests after administration of certain anesthetic drugs, such as halothane and succinylcholine Chloride.(3,4,6) The disorder is caused by an abnormality in calcium homeostasis in muscle.(3,4,6) Before dantrolene sodium was introduced, perioperative malignant hyperthermia episodes were approximately 70% fatal.(3) Patients are generally asymptomatic while awake, although there have been reported cases of this disorder being triggered when the patient was awake.(7,8) We describe a young athlete who developed severe muscle cramping after exercise in hot, humid weather; the athlete tested positive for malignant hyperthermia susceptibility.