Malignant hyperthermia is a disease that causes a fast rise in body temperature and severe muscle contractions when someone with the disease gets general anesthesia. It 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.
Malignant hyperthermia is inherited. Only 1 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.
Symptoms of malignant hyperthermia include:
- Dark brown 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
Exams and Tests
Malignant hyperthermia is often discovered after a person is given anesthesia during surgery.
There may be a family history of malignant hyperthermia or unexplained death during anesthesia.
The person may have a fast and often irregular heart rate.
Tests for the condition may include:
- Blood clotting studies (PT, or prothombin time; PTT, or partial thrombloplastin time)
- Blood chemistry panel, including CPK (creatinine phosphokinase, 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
- Urine myoglobin (muscle protein)
During an episode of malignant hyperthermia, 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.
Malignant Hyperthermia Association of the United States -- www.mhaus.org. This organization's website has a special page for patients and families that includes information and support.
Repeated or untreated episodes can cause kidney failure. Untreated episodes can be fatal.
These serious complications can occur:
- Breakdown of muscle tissue
- Swelling of the hands and feet and problems with blood flow and nerve function (compartment syndrome)
- 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 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 malignant hyperthermia
Using certain medicines can prevent the complications of malignant hyperthermia during surgery.
Tell your health care provider if you or anyone in your family has malignant hyperthermia, especially before having surgery with general anesthesia.
Avoid stimulant drugs such as cocaine, amphetamine (speed), and ecstasy. These drugs may cause problems similar to malignant hyperthermia in people who are prone to this condition.
Genetic counseling is recommended for anyone with a family history of myopathy, muscular dystrophy, or malignant hyperthermia.
Hyperthermia - malignant; Hyperpyrexia - malignant
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Update Date 4/30/2015
Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.