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Frequently Asked Questions
Please select a question from the list below.
- Can MH symptoms be induced by stress, overheating or excessive exercise?
- Are MH-susceptible individuals at risk for symptoms/episode if exposed to triggering agents while working in an operating room or similar environment?
- Is MH always hereditary?
- If I have had an episode of malignant hyperthermia, who else is at risk?
- Is MH linked to other serious medical problems?
- Can an MH susceptible person donate blood or organs?
- How aware are hospitals and ER personnel of MH? If I went to a hospital other than my normal one, could I feel confident?
- I realize adults susceptible to MH should wear a medical ID tag. Should my children wear medical ID tags as well?
- What is the purpose of the North American MH Registry of MHAUS?
- Is hospitalization of an MHS for oral surgery warranted?
- How accurate is the muscle biopsy?
- How important is it to have a muscle biopsy if someone in the family has MH?
- What is the progress of development for a simple blood test for MH?
- I think I might have MH. What can I do?
Can MH symptoms be induced by stress, overheating or excessive exercise?
The symptoms of heat exertion and heat stroke are remarkably similar to MH. However, the vast majority of people who suffer heat-related illness are not MH susceptible. In a few cases, MH susceptibility has been diagnosed by muscle biopsy in patients who have suffered from heat stroke (non-fatal), and some experts believe that heat stroke may occur more often in MH-susceptible individuals. This is an area of intense interest and investigation. The general advice for MH susceptibles and others is to be prudent in their exposure to excessive heat and exercise in hot environments.
Are MH-susceptible individuals at risk for symptoms/episode if exposed to triggering agents while working in an operating room or similar environment?
There are no cases reported of MH patients having problems on exposure to waste anesthetic gases while working in the OR. The usual operating room procedures maintain low, trace amounts of the potent volatile anesthetics in the air. During a mask induction, someone within two feet or so of the face of the patient may be exposed to somewhat greater concentrations of gas, but that can be easily avoided. Further, the volatile agents are heavier than air and drift down to the floor, where ventilation systems efficiently clear the vapors. In addition, data from pig studies indicate that very low concentrations of anesthetics do not trigger MH in these highly susceptible animals. There has been only one report of muscle cramps and fatigue in a person who worked in a factory where he was exposed to chemicals whose structure is similar to that of potent inhalation agents.
Is MH always hereditary?
MH is considered a dominantly inherited disorder in humans. All closely related members of a family in which MH has occurred must also be considered MH susceptible and managed accordingly, unless proven otherwise. It should be noted that those who have had previous anesthetics without problem cannot be certain they are not at risk; MH-related deaths have occurred even though patients have undergone multiple prior uneventful surgeries. Certainly any family with a history of anesthetic deaths or complications should make this known to the anesthesiologist before undergoing surgery. Additionally, they should register their MH susceptibility with the North American MH Registry of MHAUS, Pittsburgh, PA by calling 412-692-5464 or toll free 888-274-7899.
If I have had an episode of malignant hyperthermia, who else is at risk?
Malignant hyperthermia is inherited in humans in a pattern termed "autosomal dominant." This means that each child or sibling of an MH susceptible person has a 50% chance of being susceptible. The risk of MH susceptibility diminishes further out on the family tree, proportional to the dilution of the relationship. For example, an aunt or an uncle would have a 25% risk of MH susceptibility. MH susceptibility does not "skip" generations. Muscle biopsy testing is the only way to determine for certain the susceptibility status. Hence, when an acute MH episode occurs in a family member, all family members, including cousins, should be alerted to their potential risk as well.
Is MH linked to other serious medical problems?
MH itself is not usually associated with other serious medical problems, such as hypertension, diabetes or similar diseases. MH or MH-like events however, have occurred in those with underlying muscle diseases, such as muscular dystrophy and myotonia. Such people typically display muscle weakness. MH has been linked to a rare disorder of muscle called Central Core Disease and a rarer muscle syndrome called King Denborough Syndrome. Additionally, individuals with certain forms of muscular dystrophy may develop life-threatening disturbances and muscle destruction with exposure to the triggering agents for MH. The crisis may resemble MH in many ways, but is not considered "true" MH. In patients with Duchenne muscular dystrophy (classic muscular dystrophy), succinylcholine, a trigger agent for MH, should always be avoided or muscle breakdown may occur.
Can an MH susceptible person donate blood or organs?
Yes. There is no harm in an MHS person donating blood or organs. MHS is not "carried" in the blood or organs.
How aware are hospitals and ER personnel of MH? If I went to a hospital other than my normal one, could I feel confident?
No definite answer can be given to this question, since we do not have specific information about every hospital. Major medical centers and teaching hospitals are likely to be prepared to respond to MH. Anesthesiologists and nurse anesthetists are more likely to be aware of MH than other medical specialists. If you are MHS, you should carry with you information, such as the MHS wallet card and the MH Hotline telephone number. In addition, wear a medical ID tag (available from MHAUS) and notify health care givers of your susceptibility.
I realize adults susceptible to MH should wear a medical ID tag. Should my children wear medical ID tags as well?
The safest approach for MHS children is to wear an ID bracelet. In an emergency situation, you might not be available and your child might not be able to provide the necessary information to medical personnel.
What is the purpose of the North American MH Registry of MHAUS?
The North American MH Registry is a division of MHAUS. The purpose of the registry is to collect specific information regarding an MH episode and to analyze data from such episodes in order to better understand the patterns of manifestation of MH and to provide information to family members as to the susceptibility status of relatives when known. The primary aims of MHAUS are to provide information and education regarding malignant hyperthermia to healthcare providers and patients in order to reduce the risk of an MH tragedy. MHAUS also supports research into the preventive diagnosis and treatment of malignant hyperthermia.
Is hospitalization of an MHS for oral surgery warranted?
Minor oral surgery, performed on an outpatient basis under local anesthesia, has been shown to be safe for MHS individuals. General anesthesia using intravenous medications or nitrous oxide only is also safe. However, any facility that performs surgery or anesthesia using MH trigger agents should be prepared to monitor the patient and treat an MH crisis, including having an adequate supply of dantrolene.
How accurate is the muscle biopsy?
The accuracy of the muscle biopsy has been evaluated at various biopsy centers. The test is extremely sensitive in detecting MH (i.e., no false negatives). Specificity is somewhat less accurate. Up to 15% of patients who are diagnosed as MH positive are not MH susceptible. However, the sensitivity and specificity are comparable with other known tests in medicine, and biopsy remains the most accurate diagnostic test available.
How important is it to have a muscle biopsy if someone in the family has MH?
The muscle biopsy is the only reliable diagnostic test for MH at the present time. If it is not possible to perform this test, members of the family should be considered MH susceptible and managed accordingly. The muscle biopsy is important for ruling out MH susceptibility in various family members and their offspring because if a patient is MH negative, their offspring will also be MH negative. However, if they are MH positive, their offspring have a 50% chance of being MH susceptible.
What is the progress of development for a simple blood test for MH?
Muscle biopsy is presently the only reliable test of MH susceptibility. By understanding the genetics of malignant hyperthermia at a molecular level, our hope is to be able to determine whether a patient harbors the gene(s) for malignant hyperthermia. Such a test would be very specific, accurate and would employ blood cells. Unfortunately, the genetics of malignant hyperthermia is very complicated and, so far, at least 40 genes have been shown to be involved in MH susceptibility. MHAUS is diligently doing research in this area in an effort to establish a lab for the development of a molecular genetic test for susceptibility to MH.
I think I might have MH. What can I do?
Evaluation at an MH clinic requires referral through your family physician. You may be asked to release information about previous anesthetics, particularly if a reaction occurred during the anesthetic. This information is necessary for the MH specialist to provide the most appropriate advice for you. In some instances, MH can be excluded because of this information, but in other cases, a muscle biopsy might be needed. Your MH specialist can provide specific individual advice.
