What is malignant hyperthermia and why can it be dangerous during anesthesia?

Malignant hyperthermia is a rare, potentially lethal condition characterized by severe muscle rigidity and a rapid increase in body temperature that occurs in susceptible individuals when exposed to certain anesthetic agents, such as halothane, or muscle relaxants like succinylcholine.1

It is dangerous during anesthesia because it triggers an abnormal release of calcium into the muscle fiber's sarcoplasm. This excess calcium causes the muscles to contract and become rigid while simultaneously stimulating the mitochondria to burn glycogen, which generates intense heat.1

The condition is life-threatening because the patient's central body temperature can rise rapidly; death may occur suddenly if the temperature exceeds 43 °C (110 °F). Because the condition is often inherited as an autosomal dominant trait, it is critical to identify susceptibility before surgery. If an attack occurs, the anesthetic must be stopped immediately, the patient must be cooled, and specific medications that prevent calcium release are administered to manage the crisis.1