Malignant Hyperthermia

Malignant hyperthermia is a serious problem that can happen after some types of anesthesia drugs are given. It causes a dangerous spike in body temperature, along with stiff or twitching muscles, a fast heartbeat, and other unpleasant symptoms. If not treated quickly, malignant hyperthermia can be life-threatening.

Often, a person's risk for malignant hyperthermia comes from a gene they inherit from their parents. Sometimes, though, a random change happens in the genes, also putting them at risk. A blood test, called genetic testing, can show if someone has a gene that makes them more likely to have this reaction. This inherited condition is known as malignant hyperthermia susceptibility (MHS).

If someone experiences malignant hyperthermia, doctors will use medicine like dantrolene (available under various brand names like Dantrium, Revonto, and Ryanodex). They also use methods to cool the body down, such as ice packs, and provide other supportive care to help the person recover.

Malignant hyperthermia is a rare but serious condition that usually doesn't show any warning signs until someone is exposed to certain anesthetic drugs. There are no noticeable symptoms of the condition beforehand.

The first signs and symptoms of malignant hyperthermia often appear during or shortly after surgery, while under anesthesia or recovering. These can include:

• Severe muscle stiffness or spasms: Your muscles might feel very tight and painful.
• Trouble breathing: Your breathing could become very fast and shallow, making it hard for your body to get enough oxygen and leading to dangerously high levels of carbon dioxide in your blood.
• Fast heartbeat: Your heart might beat much faster than usual.
• Irregular heartbeat: Your heart might beat in an abnormal rhythm.
• High body temperature: Your body temperature can rise dangerously high. This is a very serious sign.
• Excessive sweating: You might sweat a lot.
• Skin changes: Your skin might look blotchy or have an uneven color, sometimes described as "mottled."

In some unusual cases, people prone to malignant hyperthermia may experience a reaction to intense physical activity in hot, humid conditions, during a viral illness, or after taking cholesterol-lowering medications (statins). It's important to note that these are less common triggers.

Even if you have no reaction the first time you're exposed to certain anesthetics, you could still have a reaction if you need them again in the future. Fortunately, there are other types of anesthetics that are safe to use for people with a risk of malignant hyperthermia. Your doctor will work with you to find the safest and most appropriate options.

If a family member has a history of malignant hyperthermia, you need to tell your doctor and the anesthesiologist (the doctor who gives anesthesia) before any surgery or procedure that requires anesthesia. This is crucial because different medicines can be used instead of the usual ones, to keep you safe. Malignant hyperthermia is a serious reaction to certain anesthetic drugs. Letting your medical team know about this risk allows them to choose safer alternatives to prevent complications.

Malignant hyperthermia is a serious condition that can happen to people with a genetic predisposition. This predisposition, called malignant hyperthermia susceptibility (MHS), is caused by a change in a person's genes (a mutation). Essentially, certain genes can make someone more likely to have a dangerous reaction to specific anesthetic drugs.

This genetic predisposition usually means a person inherited the faulty gene from one of their parents. In some cases, the gene change happens spontaneously, not inherited.

There are a few different genes that can be involved in MHS. The most common one is called RYR1. Less frequently, CACNA1S and STAC3 genes are affected. These gene changes make a person more susceptible to a dangerous reaction when exposed to certain anesthetic drugs. This reaction can be very severe and even life-threatening. It's important to note that having a gene mutation doesn't mean you will definitely get malignant hyperthermia. It just means you have a higher risk.

Having a family history of malignant hyperthermia (MHS) increases your risk of developing the condition.

MHS is a genetic disorder, meaning it's passed down through families. If one of your parents has the gene change linked to MHS, you have a 50% chance of inheriting it. This is called "autosomal dominant inheritance." This means you only need to inherit one altered gene from a parent to be at risk. Having other relatives with MHS also increases your risk. The more affected relatives you have, the higher the likelihood that you might also have the condition.

Your risk of malignant hyperthermia is also higher if you or a close relative have:

• A history of a suspected malignant hyperthermia reaction during surgery or other procedures under anesthesia. This means if you or a family member had a serious reaction to anesthesia in the past, your risk is greater.
• A history of muscle breakdown (rhabdomyolysis). Rhabdomyolysis can occur due to intense physical exertion in hot, humid weather or from taking certain medications, like statins. If you or a relative have experienced this, your risk of malignant hyperthermia is elevated.
• Inherited muscle diseases or disorders. Some muscle problems are passed down through families and can increase the chance of malignant hyperthermia. This includes inherited muscle conditions.

In short, a family history of MHS or related conditions like severe reactions to anesthesia, muscle breakdown, or inherited muscle disorders can significantly increase your risk of developing malignant hyperthermia. If you have concerns, it's important to talk to your doctor.

Untreated malignant hyperthermia can lead to serious problems. This rare condition causes muscles to break down rapidly, a process called rhabdomyolysis. This muscle breakdown can damage the kidneys, potentially causing kidney failure. It can also affect the body's ability to clot blood, leading to bleeding problems. In severe cases, malignant hyperthermia can be fatal.

If you or any of your close family members have a history of a serious reaction to anesthesia (called malignant hyperthermia), or if anyone in your family has had problems with anesthesia in the past, be sure to tell your doctor or anesthesiologist before any surgery or procedure that needs anesthesia.

Knowing about your family history helps your anesthesiologist choose anesthesia drugs that are less likely to cause a problem. This way, they can better manage your risk.

Malignant hyperthermia is diagnosed by looking at signs and symptoms, closely watching you during and right after anesthesia, and running lab tests to check for problems.

If you have risk factors for malignant hyperthermia, your doctor might suggest tests to see if you're more likely to get it (susceptibility testing). These tests can include genetic testing or a muscle biopsy.

Genetic Testing:

Genetic testing looks for a specific change in your genes that makes you prone to malignant hyperthermia. A small sample of your blood is taken and sent to a lab. The lab checks for the presence of a gene mutation that's linked to a condition called malignant hyperthermia susceptibility. Finding this mutation means you have a higher chance of developing malignant hyperthermia if exposed to triggers.

Muscle Biopsy (Contraction Test):

Sometimes, your doctor might recommend a muscle biopsy if you have a risk for malignant hyperthermia. During a muscle biopsy, a small piece of muscle tissue is removed surgically and sent to a lab. In the lab, the muscle sample is exposed to certain chemicals that can trigger malignant hyperthermia. This helps researchers see how your muscle reacts to these triggers.

Crucially, this test needs to be performed on the fresh muscle tissue right after it's removed. This means you might need to travel to a specialized medical center that can do the biopsy quickly.