Doctors induce comas to fight brain disorders
For years, medical researchers have been looking for ways to induce coma in patients with brain disorders in the hopes of stopping the clock and giving the body time to recover. The goal is to create a temporary state of metabolic shutdown, much like what occurs during hibernation.
This approach has been considered for patients with a wide variety of conditions, such as strokes, seizures, and head trauma, but success has been limited.
Last fall, in a case that drew national attention, doctors in Wisconsin induced a seven-day coma in a 15-year-old girl with rabies, a virus that mercilessly assaults the brain and is almost invariably fatal. The patient, Jeanna Giese, survived and she has been recovering remarkably over the past several months. The case has raised hopes that inducing coma may have important applications for neurological diseases after all.
At a theoretical level, the idea of inducing coma to treat certain neurological diseases makes perfect sense. For many of the diseases, tissue damage occurs over a short and defined period of time. If it were somehow possible to put the brain to sleep during that critical time period, it would make sense that doctors could limit the damage.
Dr. David Warner, a neuroanesthesiologist at Duke University, has been studying the use of induced coma to treat strokes in lab animals. During a stroke, blood flow is cut off, depriving brain tissue of nutrients, such as glucose and oxygen.
''[A stroke] reduces the gas supply to the brain," Warner said. ''Like a car, if the brain is using its energy supplies more slowly, the fuel will last longer."
According to Warner, however, induced coma seems to be beneficial in only a few selected clinical situations (mostly trauma patients), and even then the benefits are marginal. But, he said, there is promise for the future.
The case in Wisconsin highlights some new potential uses for this technique.
Dr. Rodney Willoughby, an infectious disease specialist at the Children's Hospital of Wisconsin and the lead doctor in the Wisconsin case, explained that rabies is a perfect disease to treat with induced coma.
The rabies virus, which is usually transmitted from animals such as dogs or bats -- as was the case with Giese -- causes little direct damage to the brain. Rather, it induces abnormal brain activity, which leads to usually lethal complications.
Not only should blocking this abnormal brain activity minimize the complications, but at the same time it should provide the immune system with time to rid the body of the virus, Willoughby said.
French researchers actually tried to treat rabies with ''artificial hibernation" decades ago, but the idea was not successful at the time for unclear reasons. The idea was largely forgotten until Willoughby and his team used it last fall.
''[What] her physicians were trying to do, in casual parlance, was to give the brain a break," said Dr. Charles Rupprecht, a rabies expert from the Centers for Disease Control and Prevention who was involved in the Wisconsin case.
While more work will be needed to show that the case was not simply a fluke, the tremendous success of the Wisconsin doctors had has garnered the attention of experts in the field.
Willoughby, who has taken an interest in new applications for induced anesthesia, speculated that ''this approach might apply to diseases in which there is not a lot of direct damage to brain cells." In particular, he said he believes it might have unrecognized uses in patients with congenital metabolic diseases, drug and alcohol intoxication, other infectious and immunologic disorders of the brain, and asphyxia (inadequate oxygen intake), in which damage results not so much from the actual disease itself but rather from the body's response to the disease. Inducing coma might slow down that response.
Warner agreed that the Wisconsin case has suggested some interesting new applications for induced coma in the treatment of disease, though he believes Giese, who recently returned to school part time, ''may have been just one very lucky individual."
