Malignant hyperthermia
Hyperthermia - malignant; Hyperpyrexia - malignant; MHMalignant hyperthermia (MH) is a disease that causes a fast rise in body temperature and severe muscle contractions when someone receives general anesthesia with one or more of the following drugs: halothane, isoflurane, sevoflurane, desflurane or succinylcholine. MH is a genetic disorder passed down through families.
General anesthesia
General anesthesia is treatment with certain medicines that puts you into a deep sleep so you do not feel pain during surgery. After you receive the...
Read Article Now Book Mark ArticleHyperthermia means high body temperature. Malignant hyperthermia is not the same as hyperthermia from other medical emergencies such as heat stroke or infection.
Heat stroke
Heat emergencies or illnesses are caused by exposure to extreme heat or sun. Heat illnesses can be prevented by being careful in hot, humid weather....
Read Article Now Book Mark ArticleCauses
MH is inherited. Only one parent has to carry the gene for the disease for a child to inherit the condition.
It may occur with some other inherited muscle diseases, such as multiminicore myopathy and central core disease.
Symptoms
Symptoms of MH include:
- Bleeding
- Dark brown urine (due to a muscle protein called myoglobin in the urine)
- Muscle ache without an obvious cause, such as exercise or injury
- Muscle rigidity and stiffness
Muscle rigidity
Muscle cramps are when a muscle gets tight (contracts) without you trying to tighten it, and it does not relax. Cramps may involve all or part of on...
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Exams and Tests
MH is often discovered after a person is given anesthesia during surgery.
There may be a family history of MH or unexplained death during anesthesia.
The person may have a fast and often irregular heart rate.
Irregular heart rate
An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregul...
Read Article Now Book Mark ArticleTests for MH may include:
- Blood clotting studies (PT, or prothrombin time; PTT, or partial thromboplastin time)
PT, or prothrombin time
Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. It measures the functio...
Read Article Now Book Mark ArticlePTT, or partial thromboplastin time
Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. It measures the functio...
Read Article Now Book Mark Article - Blood chemistry panel, including CK (creatinine kinase, which is higher in the blood when muscle is destroyed during a bout of the illness)
- Genetic testing to look for defects in the genes that are linked with the disease
- Muscle biopsy
Muscle biopsy
A muscle biopsy is the removal of a small piece of muscle tissue for examination.
Read Article Now Book Mark Article - Urine myoglobin (testing for muscle protein in the urine)
Urine myoglobin
The myoglobin urine test is done to detect the presence of myoglobin in urine. Myoglobin can also be measured with a blood test.
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Treatment
During an episode of MH, a medicine called dantrolene is often given. Wrapping the person in a cooling blanket can help reduce fever and the risk for serious complications.
To preserve kidney function during an episode, the person may receive fluids through a vein.
Support Groups
These resources can provide more information about MH:
- Malignant Hyperthermia Association of the United States -- www.mhaus.org
- National Organization for Rare Disorders -- rarediseases.org/rare-diseases/malignant-hyperthermia
- US National Library of Medicine - MedlinePlus website -- medlineplus.gov/genetics/condition/malignant-hyperthermia/
Outlook (Prognosis)
Repeated or untreated episodes can cause kidney failure. Untreated episodes can be fatal.
Possible Complications
These serious complications can occur:
- Amputation
- Breakdown of muscle tissue
- Swelling of the hands and feet and problems with blood flow and nerve function (compartment syndrome)
Compartment syndrome
Acute compartment syndrome is a serious condition that involves increased pressure in a muscle compartment. It can lead to muscle and nerve damage a...
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- Abnormal blood clotting and bleeding
- Heart rhythm problems
- Kidney failure
- Buildup of acid in the body fluids (metabolic acidosis)
Metabolic acidosis
Metabolic acidosis is a condition in which there is too much acid in the body fluids.
Read Article Now Book Mark Article - Fluid buildup in the lungs
- Weak or deformed muscles (myopathy or muscular dystrophy)
Muscular dystrophy
Muscular dystrophy (MD) is a group of inherited disorders that cause muscle weakness and loss of muscle tissue, which get worse over time.
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When to Contact a Medical Professional
If you need surgery, tell both your surgeon and anesthesiologist before surgery if:
- You know that you or a member of your family has had problems with general anesthesia
- You know you have a family history of MH
Using certain medicines can prevent the complications of MH during surgery.
Prevention
Tell your health care provider before having surgery with general anesthesia, if you or anyone in your family has MH.
Avoid stimulant drugs such as cocaine, amphetamine (speed), and ecstasy. These drugs may cause problems similar to MH in people who are prone to this condition.
Genetic counseling is recommended for anyone with a family history of myopathy, muscular dystrophy, or MH.
References
American Association of Nurse Anesthesiology. Malignant hyperthermia crisis preparedness and treatment: position statement. 10. issuu.com/aanapublishing/docs/11_-_malignant_hyperthermia_crisis_preparedness_an. Updated April 2018. Accessed July 16, 2023.
Yepuri N, Pruekprasert N, Cooney RN. Surgical complications. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 21st ed. St Louis, MO: Elsevier; 2022:chap 12.
Zhou J, Nozari A, Bateman B, Allen PD, Pessah IN. Neuromuscular disorders including malignant hyperthermia and other genetic disorders. In: Gropper MA, ed. Miller's Anesthesia. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 35.
Review Date: 6/12/2023
Reviewed By: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.