Alternate Names: Hyperthermia - malignant; Hyperpyrexia - malignant

Causes and Risks: Malignant hyperthermia is inherited as an autosomal dominant trait (it requires only one affected parent to inherit the condition). The condition may be associated with muscular diseases such as muscular dystrophy and central core disease.

Malignant hyperthermia is often noted for the first time during administration of anesthesia. The anesthetized patient rapidly develops a high fever and muscle rigidity. During these episodes, muscle tissue is destroyed and the released muscle pigments (myoglobin) may damage the kidneys and cause acute renal failure (see rhabdomyolysis). Malignant hyperthermia can be fatal if not treated immediately. It can be prevented by administration of appropriate drugs before anesthesia.

Prevention: It is important to recognize susceptible patients before anesthesia. Clues may be obtained from the family history or previous episodes. Episodes of malignant hyperthermia may be prevented by giving dantrolene sodium before anesthesia.

Symptoms:

• rapid rise in temperature following administration of anesthesia
• muscle rigidity and stiffness following administration of anesthesia

Signs and Tests:

• blood chemistry (see chem-20), CK is elevated
• myoglobin - urine
• biopsy - muscle

Treatment: The main goal of treatment is prevention. If a general anesthetic is to be given, pretreatment with dantrolene sodium is recommended.

For an episode of malignant hyperthermia, antipyretics (fever-reducing medications such as acetaminophen) and a cooling blanket can help reduce acute episodes of fever.

Intravenous fluids and medications may be needed to maintain kidney function.

Prognosis: Episodes of the disorder can often be prevented. Untreated episodes can be fatal.

Complications:

• rhabdomyolysis
• renal failure
• fatal outcome

If you know that you or a member of your family had problems with general anesthesia (or if you know you have a family history of malignant hyperthermia) be sure to notify the surgeon AND THE ANESTHESIOLOGIST before having any surgery.