Malignant Hyperthermia in the News

By Denise Mann; reviewed by V. Leroy Young, MD

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Malignant hyperthermia is rare, but it can be deadly. Recent media reports about the death of an 18-year-old undergoing breast enhancement surgery has thrust malignant hyperthermia into the spotlight, but what is it? Are you at risk? And how can you best protect yourself and your loved ones from malignant hyperthermia?

What Is Malignant Hyperthermia?

Malignant hyperthermia is a rare but potentially fatal complication of general anesthesia when it is combined with certain inhaled agents. These agents are all used rather frequently in cosmetic surgeries because they are inexpensive, effective and easy to deliver. Malignant hyperthermia is a biochemical reaction marked by intense muscle contractions that lead to a state of rigor (rigidity in muscle tissue), hyperthermia (abnormally high fever) and muscle breakdown.

Here's what happens: People who are genetically susceptible to malignant hyperthermia produce abnormal proteins inside their muscle cells. These proteins, in turn, trigger the release of excess calcium when the person inhales certain common anesthetics. The increased calcium activates sustained muscle contractions and greatly increases the amount of energy the body uses. This leads to a corresponding increase in heat production (hyperthermia).

Eventually, these overactive muscle cells run out of energy and die. When they die, high levels of potassium and a protein are released into the bloodstream and cause a cascade of dangerous events, including muscle damage, cardiac arrest, brain damage, massive internal bleeding, kidney and other organ failure and death. These events can occur even when proper treatment is administered.

Malignant hyperthermia is not always fatal. In fact, death rates have been dropping steadily. In the 1960s and 1970s, the mortality rate was 80 percent, and now it is close to 10 percent.

How Many People Get Malignant Hyperthermia?

As mentioned above, the good news is that malignant hyperthermia is relatively rare. There are no exact figures, because no standardized reporting system or registry exists to track malignant hyperthermia. It is estimated that anywhere from one in 5,000 to one in 100,000 administrations of general anesthesia with triggering agents will result in malignant hyperthermia.

At least 80 different genetic defects are linked to malignant hyperthermia, one reason it is so rare. New research in the September 2008 issue of Anesthesiology shows that a genetic mutation located in the body's skeletal muscles may cause malignant hyperthermia. The MH-associated mutation in the ryanodine receptor 1 (RYR1) gene was isolated from a single Austrian family, but the researchers point out that its identification could help others in the future.

"Proving the causative role of a new mutation enables researchers to include it in the list of MH mutations and makes the genetic test more reliable," the researchers conclude. "This is an important step toward establishing an inexpensive and minimally invasive genetic test for diagnosing MH. This new mutation should, therefore, be included in the current list of MH-causing mutations."

The condition is also associated with inherited muscle disorders such as muscular dystrophy, a progressive muscle-wasting disease.

In data presented recently at a meeting on patient safety in plastic surgery of the head and neck, no cases of malignant hyperthermia were seen among 1.1 million cosmetic surgeries. Two cosmetic surgery-related cases have occurred since January 2007, including the Florida teen who developed malignant hyperthermia while undergoing breast augmentation surgery.

Are You at Risk for Malignant Hyperthermia?

Maybe. A person is considered at risk if they have previously experienced malignant hyperthermia or if a close family member has developed the condition while under general anesthesia.

In fact, children and siblings of a person who had malignant hyperthermia have a 50 percent increased risk of also being susceptible to malignant hyperthermia. These individuals should wear medical alert bracelets.

Unfortunately, most people are not aware of their risk until a parent or sibling develops malignant hyperthermia while under anesthesia.

Diagnostic Tests for Malignant Hyperthermia

A muscle biopsy of the thigh muscle is the gold standard when it comes to diagnosing malignant hyperthermia. The biopsy analyzes how a piece of the muscle responds to one of the triggering anesthetics.

This test can cost more than $6,000 and is available only at a small number of medical centers.

A genetic blood test is available, but its accuracy has yet to be confirmed.

Signs and Symptoms of Malignant Hyperthermia

The following symptoms are what your surgeon or anesthesiologist would look for during and after surgery:

  • High output of end-tidal carbon dioxide (CO2). CO2 levels are measured routinely during anesthesia by measuring the concentration in the exhaled gases.
  • Severe muscle rigidity, including jaw clenching and difficulty opening the mouth
  • Muscle breakdown, which manifests as cola-colored urine
  • Increased heart rate or heart rhythm abnormalities
  • High body temperature, which can jump to as high as 110 degrees
  • Excessive acid in the body fluids

Some signs and symptoms occur four to six hours after a person has woken up from anesthesia. These may include:

  • Sweating
  • Night sweats
  • Cramping
  • Fatigue
  • Nausea
  • Dizziness
  • Spotted, blotchy skin
  • Change in diet
  • Increased thirst
  • Headaches
  • Low grade fever
  • Heat intolerance
  • Elevated blood pressure
  • Stress, anxiety

Triggering Agents for Malignant Hyperthermia

In someone who is susceptible to malignant hyperthermia, triggering agents, when used with general anesthesia, include:

  • Sevoflurane
  • Desflurane
  • Isoflurane
  • Halothane
  • Enflurane
  • Methoxyflurane

Succinylcholine, a muscle relaxant, is also not safe for susceptible individuals.

Safer Anesthetics for People Susceptible to Malignant Hyperthermia

Barbiturates, benzodiazepines (such as Valium) and narcotics like fentanyl are safer than inhaled anesthetics in people who are susceptible to malignant hyperthermia.

Preventing the Consequences of Malignant Hyperthermia

The key to treatment is early recognition. Doctors must identify the signs of malignant hyperthermia early for treatment to be maximally effective. It is not enough to monitor bodty temperature, as this is one of the later signs of malignant hyperthermia.

Early signs may include heart rhythm abnormalities and jaw muscle rigidity. If a doctor suspects malignant hyperthermia, he or she should check for rigidity in the limbs, abdominal muscles and chest muscles.

Malignant Hyperthermia Treatment

Doctors treat malignant hyperthermia by packing the body in ice to cool it down, after injecting a powerful muscle relaxant called dantrolene.

Dantrolene can stop the uncontrolled release of calcium if it is administered in the right amount of time. Most hospitals have an adequate supply of dantrolene on hand. But some doctors' offices or ambulatory surgical centers do not, as dantrolene is costly and has only a three-year shelf life.

Dantrolene is also not easy to administer. Doctors must administer multiple vials in rapid-fire sequence for it to be effective. Currently the U.S. Food and Drug Administration is fast-tracking for approval a new version of dantrolene. The new version is said to enhance the medication's reconstitution time to 20 seconds or less. Reconstitution refers to the restoration of a drug to an original form after it has been altered for preservation and storage. The quicker the agent is reconstituted, the quicker it can be administered.

How to Protect Yourself Against Malignant Hyperthermia When Undergoing Cosmetic Surgery

Tell your cosmetic surgeon right away if:

  • Anyone in your family has ever developed malignant hyperthermia.
  • Anyone in your family ever spiked a fever right after waking up from general anesthesia.
  • Any deaths in your family occurred during or shortly after anesthesia.
  • You have ever had an episode or had cola-colored urine, which could be a sign of muscle breakdown.
  • You or a family member ever had heat stroke.
  • Anyone in your family ever died during or after exercising.

Before cosmetic surgery, ask your surgeon:

  • Will an anesthesiologist be on hand during the surgery?
  • Do you have an adequate supply of dantrolene?
  • Does your staff know how to administer the dantrolene?

About the Reviewer of This Article

V. Leroy Young, MD, is nationally recognized as an expert on breast augmentation and implants, and he is experienced in all types of aesthetic and reconstructive surgery. He serves on and/or chairs numerous committees of the American Society of Plastic Surgeons and the American Society for Aesthetic Plastic Surgery. Dr. Young practices at Body Aesthetic Plastic Surgery and Skin Care Center in St. Louis.

Sources:

Patient safety in cosmetic surgery of the head and neck. 4/12/2008, New York City

V. Leroy Young, American Society of Plastic Surgeons (ASPS) Tutorial. Diagnosis & Treatment of Malignant Hyperthermia. Presented at the annual meeting of the American society for Aesthetic Plastic Surgery. San Diego, Calif. May 2-6, 2008

Kaufmann A., Kraft B., Michalek-Sauberer A., Weigl L.G. Novel ryandine receptor mutation that may cause malignant hyperthermia. Anesthesiology. In press.

Additional information from the Malignant Hyperthermia Association of the United States.