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Malignant hyperthermia: Causes, Symptoms, Risk Factors, Diagnosis, Treatment, Prevention and Complications

Sep 27, 2023

Malignant hyperthermia

Malignant hyperthermia is a serious adverse reaction to several anaesthetic medications. This extreme response frequently involves symptoms such as an abnormally high body temperature, rigid muscles or spasms, a quick heartbeat, and others. Malignant hyperthermia consequences might be lethal if not treated right away.

The gene that makes you susceptible to malignant hyperthermia is often inherited, while it can occasionally arise as the result of a random genetic change. If you have a gene that is affected, genetic testing will indicate it. Malignant hyperthermia Susceptibility (MHS) is the name of this hereditary condition.

Malignant hyperthermia can be treated with supportive care, dantrolene (Dantrium, Revonto, Ryanodex), and other methods of reducing body temperature.

Until you are exposed to certain anaesthetic medicines, you often don't show any indications or symptoms of being at risk of malignant hyperthermia.

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Causes Of Malignant Hyperthermia

A genetic disease called malignant hyperthermia susceptibility (MHS), which is brought on by a gene change (mutation), can result in malignant hyperthermia. The defective gene raises your risk of developing malignant hyperthermia when you are exposed to specific anaesthetic medications which trigger a response.

 The affected gene is most frequently inherited, typically from one affected parent. Less frequently, a random gene alteration causes the affected gene rather than an inherited condition.

MHS may be caused by various genes. RYR1 is the gene that is frequently affected. CACNA1S and STAC3 are two less often affected genes.

Symptoms Of Malignant Hyperthermia

Malignant hyperthermia can present with a variety of symptoms during surgery, anaesthesia, or the early postoperative recovery period. Among them are:

  • Muscular spasms or severe rigidity
  • Problems with rapid, shallow breathing and difficulties with low oxygen and high carbon dioxide
  • Rapid heartbeat
  • Irregular heartbeat
  • Dangerously high body temperature
  • Sweating excessively
  • Skin that is uneven or patchy in appearance

Rarely, individuals at risk for malignant hyperthermia have experienced symptoms following intense physical activity in conditions of high temperatures or humidity, when suffering from a viral infection, or when using statin drugs for reducing cholesterol.

Risk factors Of Malignant hyperthermia

Having a family member with MHS increases your risk of developing a genetic condition.

To be affected by this condition (autosomal dominant inheritance pattern), only one altered gene from a parent is required. You have a 50% risk of developing MHS if one of your parents carries the gene alteration that results in the disease.

Additionally increased is your likelihood of having MHS if you have other family members who are suffering from MHS. Additionally, if you or a close family has:

  • History of an incident that may have involved malignant hyperthermia while under anaesthetic
  • History of rhabdomyolysis, a condition in which exercising in conditions of severe heat and humidity or while taking a statin medicine can cause the breakdown of muscle tissue.
  • Specific muscle conditions and diseases brought on by hereditary gene alterations
  • You still run the chance of developing malignant hyperthermia if you receive certain anaesthesia medicines in the future even if you don't experience a severe reaction the first time you take them. Alternatively, you could utilise other anaesthetics that don't cause a reaction.

Diagnosis Of Malignant Hyperthermia

Diagnostic criteria for malignant hyperthermia include signs and symptoms, observation during and immediately after anaesthesia, and blood tests to look for complications.

Testing for susceptibility

If you have risk factors, it may be advised to undergo susceptibility testing to see whether you have a higher risk of developing malignant hyperthermia. A muscle biopsy test or genetic testing are both options for testing.

  • Genetic test: Genetic testing can detect the gene change (mutation) that makes you susceptible to malignant hyperthermia. Your blood is collected for a sample, which is then submitted to a lab for Examination. An individual with a hereditary disease known as malignant hyperthermia susceptibility (MHS) will have a gene alteration that can be detected by genetic testing.
  • Muscle biopsy (test of contractility): If you run the danger of developing malignant hyperthermia, your doctor could occasionally advise a muscle biopsy. In this test, a small portion of muscle tissue is surgically extracted and sent to the lab for examination. To find out how the muscle contracts, the specimen is subjected to substances that will cause malignant hyperthermia in the laboratory. It is essential to travel to a specialised muscle biopsy laboratory since this test must be performed on muscle tissue as soon as it has been removed.

Treatment Of Malignant Hyperthermia

It's important that you inform your doctor and anesthesiologist before receiving anaesthesia if you or a member of your family has malignant hyperthermia susceptibility (MHS) or if you believe you may be at risk for the condition. Your anaesthesia may involve the use of medications that don't cause malignant hyperthermia.

Malignant hyperthermia should be treated right away with the following:

  • Medication: The reaction is treated by preventing the release of calcium into muscles with a medication known as dantrolene (Dantrium, Revonto, Ryanodex). To treat problems associated with chemical balance in the body (metabolic imbalance), additional drugs may be prescribed.
  • Oxygen: Through a face mask, you might be given oxygen. Most often, oxygen is administered via a tube inserted into the trachea.
  • Cooling the body: You can use ice packs, cooling blankets, a fan with cold mist, and chilled intravenous (IV) fluids to help in lowering your temperature.
  • Extra fluids: Through an intravenous (IV) line, you could potentially get extra fluids.
  • Support services: It may be necessary for you to spend a day or two in intensive care to monitor your temperature, blood pressure, heart rate, respiration, and reaction to treatment. To monitor the severity of any muscle deterioration and potential kidney injury, many lab tests will be performed periodically. Typically, a hospital stay is required until the lab test results start to come back. Malignant hyperthermia typically disappears after a few days of receiving treatment.

Following-up care

Exercise in excessive heat and humidity could result in another reaction if you have already suffered malignant hyperthermia as a result of specific anaesthesia medicines. Discuss what precautions you need to take with your healthcare professional.

To find out if you have a genetic condition that puts you at risk for malignant hyperthermia, consult with your doctor about whether you should also undergo genetic testing. Ask members of the close family to also think about undergoing genetic testing.

Wear a medical alert necklace or bracelet if you suffer from the genetic condition MHS, which increases your chance of developing malignant hyperthermia. This informs medical professionals of your risk, particularly during an emergency when you might not be able to communicate.

Prevention Of Malignant Hyperthermia

Before having surgery or undergoing any operation requiring anaesthesia, let your doctor or anesthesiologist know if you have a family history of malignant hyperthermia or a relative who has issues with anaesthesia.

Your anesthesiologist may recommend staying away from some anaesthesia medicines by evaluating your risk of malignant hyperthermia.

Complications Of Malignant Hyperthermia

Malignant hyperthermia has the potential to cause serious problems, including:

  • Rhabdomyolysis is an uncommon disease that results in the breakdown of muscle cells.
  • Kidney failure or damage
  • Clotting and bleeding problems
  • Death

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