Dear
I am writing to let you know about the potential susceptibility to malignant hyperthermia in our family. We have discovered a genetic trait, which could have a potentially tragic effect on even distant relatives if they require surgery under general anesthesia.
We learned about this when ____________________ was given a commonly used general anesthetic and then had a life-threatening reaction. Although we didn’t realize it, _________________ was at risk for developing this reaction because of an unusual hereditary muscle disorder.
This disorder, a syndrome called malignant hyperthermia (MH), occurs when a susceptible individual is given the drugs that “trigger” MH. The triggering drugs are gas anesthesia and succinylcholine, a muscle relaxant. (Don’t be overly concerned about the word “malignant” – MH has nothing to do with cancer.) MH makes a person susceptible to developing a chain reaction of symptoms.
The reaction, which may (but does not always) occur, includes a variety of symptoms: muscle rigidity; dramatic changes in the acid content of the blood (which can cause irritation to the heart and possible cardiac arrest); increased amounts of carbon dioxide expelled by rapid and deep breathing (hyperventilation); breakdown of muscle, as indicated by very dark urine; and high body temperature (a late sign).
This syndrome is reversible if the operating team is prepared and acts quickly. Moreover, the syndrome is preventable if the doctor knows in advance of the patient’s potential MH susceptibility and takes certain precautions, such as the use of non-triggering anesthetic agents. Non-triggering agents, such as local or intravenous anesthesia, are very good alternatives which can be safely used in MH-susceptible individuals.
Although MH is uncommon in the general population, the odds are quite high for family members of known susceptible patients to also have the trait. Most susceptible parents transmit the trait to about half of their offspring. It’s very important to note that more than 50% of MH-susceptible patients had general anesthesia on at least one occasion (uneventfully) before they even knew they were susceptible. You should not assume you are safe because you have had uneventful anesthetics.
The enclosed pamphlets are published by the Malignant Hyperthermia Association of the United States (MHAUS), a non-profit educational organization dedicated to promoting optimum care and scientific understanding of MH and related disorders. MHAUS membership numbers in the thousands and includes medical professionals from many disciplines, as well as MH-susceptible individuals and their families. MHAUS provides a variety of information materials such as newsletters and educational brochures about MH and what you can do. If you become a member of MHAUS, you can have ready access to all this information.
Right now there are several steps you should take:
- Please let me know about any anesthetic reactions (eg. muscle damage or high fever during or after an anesthetic) you or others in the family have experienced. Has anyone in the family died “mysteriously” during or following surgery? This information can help determine which family line carries the MH trait.
- Notify your own doctors about your potential susceptibility. MHAUS can provide you with literature to share with your doctor. You may also want to consider discussing whether current diagnostic testing options to evaluate your susceptibility to MH are appropriate.
- Notify school nurses and teachers and make a note in your children’s medical records.
- Contact hospitals in your area to be sure that they stock the antidote drug, Dantrium IV/Dantrolene sodium for injection, and that they are prepared to care for your family in an emergency. MHAUS has a form letter you can use for this purpose.
- Consider obtaining a medical ID tag such as a bracelet or necklace. MHAUS has a Medical ID Program of it’s own with the MH Hotline phone number already engraved on each tag.
At present, there are two diagnostic testing options to evaluate susceptibility to MH: one is a muscle contracture test, and it first requires a muscle biopsy performed only at specialized centers; the other option requires a blood sample for genetic testing. You should talk with your doctor to see which test is recommended for you; genetic testing is appropriate only under certain circumstances. MHAUS can send you more information about the tests, as well as provide a list of the testing sites in the United States. In addition, MHAUS can put you in touch with an MH expert to discuss questions that you might have. If you would like more information, please contact MHAUS, PO Box 1069, Sherburne NY 13460-1069, or call 1-800-986-4287 or access their website at www.mhaus.org.
If you establish that you are, indeed, MH-susceptible, you should talk with your doctor about registering yourself with the North American MH Registry of MHAUS as an MH-susceptible individual. You may contact the Registry at the Mercy Hospital of Pittsburg, 1400 Locust St, 8th Floor-Ermire Bldg RM 822/823, Pittsburg PA 15129 or call 1-888-274-7899 or by their website www.mhreg.org.
Sincerely,
