Malignant hyperthermia is a life-threatening disorder, usually triggered by medications given during a general anesthetic. These medications include succinylcholine (a muscle relaxant) and inhaled anesthetics (gases).

Only certain individuals are susceptible to malignant hyperthermia. This is thought to be due to a genetic mutation and is inherited as an autosomal dominant trait. It is described as a mutation on the ryanodine receptor and affects calcium distribution in the muscle cells.

If malignant hyperthermia is triggered, it leads to an uncontrolled release of calcium in the cells which causes muscle rigidity and symptoms including an increased temperature, increased carbon dioxide production, increased heart rate, arrhythmias and a metabolic acidosis.

Malignant hyperthermia is a medical emergency and requires rapid treatment with dantrolene, cooled intravenous fluids, sedation and treatment of the metabolic acidosis. The therapy helps to cool the person and balance the acid-base status of the blood.

When you are seen by your anesthesiologist before surgery he/she will always ask you if there is a family history of problems with anesthesia, and this is the reason why. If there is a family history of malignant hyperthermia, this information will change the anesthetic plan for you. We will still be able to safely provide anesthesia, but we will use a “non-triggering anesthetic” where we avoid giving any drugs that can cause malignant hyperthermia, and we take special precautions with our anesthesia equipment to prevent triggering anesthetic gases from reaching your body.

People with a history of malignant hyperthermia are able to undergo regional anesthesia (nerve blocks, spinals, and epidurals) without a problem.

If there is a positive family history or you have had an episode of malignant hyperthermia, there is testing you should have done called a muscle biopsy. Also if you do have a positive family history of malignant hyperthermia you should wear a Medic Alert bracelet stating so. Please inform your anesthesiologist of any concerns you have about malignant hyperthermia prior to your surgery.

Madison Anesthesiology Consultants, LLP is committed to continued research for Malignant Hyperthermia and contributes to this important effort annually. For more information about Malignant Hyperthermia, resources on this topic are available in the Resources section.