What Is It?
Malignant hyperthermia is a severe reaction to a dose of anesthetics. The reaction is sometimes fatal. It is caused by a rare, inherited muscle abnormality. Infrequently, extreme exercise or heat stroke can trigger malignant hyperthermia in someone with the muscle abnormality.
In people with the muscle abnormality, muscle cells have an abnormal protein on their surfaces. This abnormal protein does not affect muscle function until the muscles are exposed to a drug that can trigger a reaction.