Detailed Information on Malignant Hyperthermia

Malignant Hyperthermia is a genetic disorder of skeletal muscle, discriminated by a hypermetabolic state, triggered by all volatile anesthetics and suxamethonium. In people with the muscle abnormality, a gene mutation causes muscle cells to have an abnormal protein on their surfaces. The mutation does not affect muscle function significantly until the muscles are exposed to one of several drugs that can trigger a reaction. When a person with this condition is exposed to one of these drugs, calcium stored in muscle cells is released, causing the muscles to contract and stiffen at the same time, causing a dramatic and dangerous increase in body temperature.

Medications known to cause malignant hyperthermia are succinylcholine, which is a muscle relieves used during surgery, and certain breath anesthetics, including halothane (Fluothane), enflurane (Ethrane), isoflurane (Forane), methoxyflurane (Penthrane), sevoflurane (Ultane) and desflurane (Suprane). Malignant hyperthermia most often occurs during or after surgery, it can occur wherever anesthetic medications are used, such as in emergency rooms, dental offices, surgeons' offices and intensive care units.

Although the symptoms can be delayed for up to 12 hours. Most cases of malignant hyperthermia occur in children and adults younger than 30. It has been estimated to arise once in every 15,000 surgeries in children and less often in adults. The current treatment of choice is the intravenous administration of dantrolene, the only known antidote, discontinuation of triggering agents, and supportive therapy directed at correcting hyperthermia, acidosis, and organ dysfunction. Treatment must be instituted rapidly on clinical suspicion of the onset of malignant hyperthermia.

Dantrolene is a muscle relaxant that appears to work directly on the ryanodine receptor to prevent the release of calcium. The use of a drug called dantrolene during incidents of malignant hyperthermia has greatly reduced the number of deaths. Fluids given by IV and mouth, as well as certain medications, are essential for maintaining kidney function during an acute episode. If you or anyone in your family has malignant hyperthermia, it is very important to tell your doctor. Genetic counseling is recommended for anyone with a family history of myopathy, muscular dystrophy, or malignant hyperthermia.