What is the definition of Malignant Hyperthermia?

Malignant hyperthermia (MH) is a disease that causes a fast rise in body temperature and severe muscle contractions when someone with MH gets general anesthesia. MH is passed down through families.

Hyperthermia means high body temperature. This condition is not the same as hyperthermia from medical emergencies such as heat stroke or infection.

What are the alternative names for Malignant Hyperthermia?

Hyperthermia - malignant; Hyperpyrexia - malignant; MH

What are the causes for Malignant Hyperthermia?

MH is inherited. Only one parent has to carry 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.

What are the symptoms for Malignant Hyperthermia?

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
• Rise in body temperature to 105°F (40.6°C) or higher

What are the current treatments for Malignant Hyperthermia?

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 of serious complications.

To preserve kidney function during an episode, the person may receive fluids through a vein.

What are the support groups for Malignant Hyperthermia?

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
• NIH Genetics Home Reference -- ghr.nlm.nih.gov/condition/malignant-hyperthermia

What is the outlook (prognosis) for Malignant Hyperthermia?

Repeated or untreated episodes can cause kidney failure. Untreated episodes can be fatal.

What are the possible complications for Malignant Hyperthermia?

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)
• Death
• Abnormal blood clotting and bleeding
• Heart rhythm problems
• Kidney failure
• Buildup of acid in the body fluids (metabolic acidosis)
• Fluid buildup in the lungs
• Weak or deformed muscles (myopathy or muscular dystrophy)

When should I contact a medical professional for Malignant Hyperthermia?

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.

How do I prevent Malignant Hyperthermia?

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 Anesthetists. Malignant hyperthermia crisis preparedness and treatment: position statement. www.aana.com/docs/default-source/practice-aana-com-web-documents-(all)/malignant-hyperthermia-crisis-preparedness-and-treatment.pdf?sfvrsn=630049b1_8. Updated April 2018. Accessed May 6, 2019.

Kulaylat MN, Dayton MT. Surgical complications. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 20th ed. Philadelphia, PA: Elsevier; 2017:chap 12.

Zhou J, Bose D, Allen PD, Pessah IN. Malignant hyperthermia and muscle-related disorders. In: Miller RD, ed. Miller's Anesthesia. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 43.