MedlinePlus Medical Encyclopedia: Malignant hyperthermia

Skip navigation


Medical Encyclopedia
Other encyclopedia topics:	A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9

Malignant hyperthermia

Contents of this page:
Alternative names Definition Causes, incidence, and risk factors Symptoms Signs and tests	Treatment Expectations (prognosis) Complications Calling your health care provider Prevention

Alternative names

Hyperthermia - malignant; Hyperpyrexia - malignant

Definition Return to top

Malignant hyperthermia is a group of inherited muscle problems characterized by muscle breakdown following certain stimuli -- such as anesthesia, extremes of exercise (particularly in hot conditions), fever, or use of stimulant drugs. The problems associated with this condition result from over-excitable muscles that contract uncontrollably, severe fever, abnormal heart rhythms, and kidney failure.

Causes, incidence, and risk factors Return to top

Malignant hyperthermia is inherited as an autosomal dominant trait (it requires only one affected parent for a child inherit the condition). It 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 break-down products of muscle may damage the kidneys and cause acute renal failure. The urine may turn dark due to released muscle pigments (see rhabdomyolysis).

Malignant hyperthermia can be fatal if not treated immediately. It can be prevented by administration of appropriate drugs before anesthesia.

Symptoms Return to top

Rapid rise in temperature following administration of anesthesia
Muscle rigidity and stiffness following administration of anesthesia
Dark brown coloration to urine
Muscle ache without obvious exercise to explain sore muscles
Family history of malignant hyperthermia or unexplained death during anesthesia

Signs and tests Return to top

Blood chemistry (see chem-20) shows increased blood levels of creatine phosphokinase (CPK), potassium, uric acid, phosphate.
Myoglobin in the urine is elevated.
Muscle biopsy using an in vitro contracture test may show abnormal results in response to certain drugs such as caffeine and halothane (an anesthetic).
Muscle biopsy may show abnormal muscle, such as central cores, in some types.
Genetic testing such as ryanodine receptor (RYR1) may show gene abnormalities.
Phosphorus magnetic resonance spectroscopy, a research test, may show abnormal muscle function.

Treatment Return to top

The best course of action for this condition is prevention. If a general anesthetic is to be given, pretreatment with dantrolene sodium is recommended. If you have a family history of anesthesia-induced problems it is imperative to alert your surgeon and anesthesiologist.

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

Intravenous and oral fluids as well as certain medications are essential for maintaining kidney function during an acute episode.

Expectations (prognosis) Return to top

Episodes of the disorder can often be prevented. Repeated episodes or untreated episodes can cause kidney failure. Untreated episodes can be fatal. Fortunately, the use of the drug dantrolene has made fatalities much less common.

Complications Return to top

Rhabdomyolysis, a kidney injury caused by excess myoglobin
Renal failure
Myopathy (weak muscles) or muscular dystrophy
Death

Calling your health care provider Return to top

If you know that you or a member of your family has had problems with general anesthesia, or if you know you have a family history of malignant hyperthermia, be sure to notify both the surgeon and the anesthesiologist before having any surgery.

Prevention Return to top

It is important to recognize susceptible patients before giving them 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.

It is important to avoid stimulant drugs such as cocaine, amphetamine (speed) and ecstasy (an amphetamine derivative) as they may produce malignant hyperthermia-like problems in susceptible individuals.

Genetic counseling is recommended for anyone with a family history of myopathy, muscular dystrophy or malignant hyperthermia.

Update Date: 8/19/2003

Updated by: Douglas R. Stewart, M.D., Division of Medical Genetics, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.