Malignant Hyperthermia

Malignant hyperthermia (MH) or malignant hyperpyrexia is a rare life-threatening condition that is usually triggered by exposure to certain drugs used for general anesthesia; specifically, the volatile anesthetic agents and the neuromuscular blocking agent, succinylcholine. In susceptible individuals, these drugs can induce a drastic and uncontrolled increase in skeletal muscle oxidative metabolism, which overwhelms the body's capacity to supply oxygen, remove carbon dioxide, and regulate body temperature, eventually leading to circulatory collapse and death if not treated quickly.

Susceptibility to MH is often inherited as an autosomal dominant disorder, for which there are at least 6 genetic loci of interest, most prominently the ryanodine receptor gene (RYR1). MH susceptibility is phenotypically and genetically related to central core disease (CCD), an autosomal dominant disorder characterized both by MH symptoms and myopathy. MH is usually revealed by anesthesia, or when a family member develops the symptoms. There is no simple, straightforward test to diagnose the condition. When MH develops during a procedure, treatment with dantrolene sodium is usually initiated; dantrolene and the avoidance of anesthesia in susceptible people have markedly reduced the mortality from this condition.