Understanding Malignant Hyperthermia

Malignant hyperthermia (MH) is a rare reaction to certain medicines used for general anesthesia. This problem runs in families (genetic). This means it is passed down from parents to children. The problem is severe and life threatening, but it can be treated. You can take steps to help prevent it in the future. It is vital for your family members to know that they may also be likely to have MH.

Causes and symptoms of malignant hyperthermia

MH happens in people who have a gene that causes abnormal proteins to be present in the muscles. Certain anesthesia medicines react with these proteins. This leads to sudden and severe symptoms. These include:

  • Increased heart rate

  • Severe muscle contractions

  • Very high body temperature

These symptoms appear soon after the medicines are given. Less commonly, they may appear after surgery has ended.

Treatment for malignant hyperthermia

Any person being given anesthesia is closely monitored for signs of MH. If you develop signs of MH, the medicines are stopped. Steps are taken to cool your body. You may get an antidote medicine called dantrolene. This medicine is given for 24 to 48 hours. During this time, medical staff will watch you closely.

Possible complications

If the problem is not treated quickly, it can lead to breakdown of muscle tissues. The result may be cardiac arrest, brain damage, kidney failure, or even death.

When to call your healthcare provider

Get emergency medical care right away if you are likely to get MH and have any of the following symptoms:

  • Dark brown urine

  • Fever of 105°F (40.6°C) or higher

  • Muscle rigidity and stiffness

  • Unexplained bleeding

Preventing malignant hyperthermia

People who are likely to have this problem can still have surgery if they take precautions. If you have had MH, be sure to tell any healthcare provider before having any dental work or surgery. Your family members may also carry the gene for MH. Even if they had surgery without problems in the past, they should not assume they couldn’t get MH in the future. All your close family members should tell their healthcare providers that they might be likely to get MH.