“Uncle Joe woke up from minor surgery packed in ice.”
That’s more than interesting family gossip. It’s an ominous clue that Joe’s relatives are at risk for a rare, inherited condition that can make their bodies overheat enough to kill them if they receive certain types of anesthesia — a clue that every family member should tell their doctors.
Now scientists are preparing to offer the first genetic testing for this condition, called malignant hyperthermia, that may help affected families begin to tell which relatives really are at risk.
The test also may help shed light on whether people at risk of malignant hyperthermia in the operating room may be at higher-than-normal risk of exercise-induced heat stroke.
That problem has been gaining attention since the 2001 death of a 12-year-old North Carolina boy. He survived malignant hyperthermia while having a broken arm set, and collapsed months later after a football game.
The first gene test won’t be perfect, cautions Dr. Sheila Muldoon of the Uniformed Services University of the Health Sciences, who helped develop it. Scientists don’t yet know if they’ve found all the genetic mutations involved.
But until now, relatives of someone thought to have suffered malignant hyperthermia have had to assume they were at risk, or undergo a very painful muscle biopsy to prove it.
'I want to know'
The gene test, to be offered through the University of Pittsburgh by fall, will require a spot of blood or a swab from inside the cheek. If a malignant hyperthermia survivor has one of 16 mutations the test detects — and roughly a third are expected to — then scientists should be able to tell if his or her relatives inherited the condition.
“I have a son who’s almost a year old, and what happens if no one knows” he’s susceptible, asks Alex Gross of Bethesda, Md., who spent a week in a coma after suffering malignant hyperthermia during surgery for a noncancerous inner-ear tumor in 2002. “I want to know.”
Malignant hyperthermia occurs when certain anesthesia drugs — including a family of inhaled gases, such as isoflurane and sevoflurane, that are top choices for children — trigger a life-threatening attack in a genetically susceptible patient. The drugs set off a state of super-metabolism that breaks down muscles and raises body temperature as high as 110 degrees.
Malignant hyperthermia once killed most victims, but today death is very rare because anesthesiologists watch for early signs and usually reverse symptoms with quick use of a drug called dantrolene.
But more surgery now is performed in physicians’ offices, which often don’t stock dantrolene, cautions Dr. Henry Rosenberg of the Malignant Hyperthermia Association. He points to patients who have died during cosmetic surgery as a result.
'Waking up in ice'
Recovery can be arduous, so knowing if a relative has the condition is important.
“We don’t want to get the average person all anxious,” Rosenberg cautions; malignant hyperthermia is pretty rare. It’s thought to occur anywhere from one in 5,000 to one in 50,000 surgeries that use the triggering anesthetics. Still, no one knows how many people are at risk.
Interestingly, there are geographic clusters. Malignant hyperthermia is so common in Wisconsin and parts of Michigan that many anesthesiologists keep lists of at-risk family names to check new patients against, Rosenberg says. Studies in Grenoble, France, suggest as many as one in 3,000 people there are susceptible.
The key message for anyone about to undergo surgery is simple: Ask if any relative ever had an unusual or bad anesthesia reaction — Rosenberg often hears the “waking up in ice” story — and tell your anesthesiologist. He or she can pick an anesthetic that won’t trigger malignant hyperthermia.
