Cooling Helmets May Stabilize Stroke Patients
Helmets Lower Temperature of Brain, Slowing Stroke Damage
Feb. 5, 2004 (San Diego) -- A cool head is always an asset, especially after a stroke. Thus, experimental devices that cool the heads -- and brains -- of stroke patients are some of the hottest technologies among stroke researchers.
Early studies of two such devices, both of them helmets that can be applied by emergency technicians transporting patients to hospitals, suggest that brain cooling, or hypothermia, may slow stroke damage and improve outcome, says Mark Mayberg, MD, chairman of neurosurgery at The Cleveland Clinic. Mayberg tells WebMD that the cooling treatments are one of several new technologies are rapidly being developed that will allow physicians to "take a more aggressive approach to stroke treatment" and will lengthen the window of treatment.
Results of the studies were presented at the 29th International Stroke Conference in San Diego.
Cooling Caps Minimize Damage
Huan Wang, MD, of the University of Illinois College of Medicine in Peoria, Ill., tells WebMD that he and his colleagues are testing a cooling helmet designed by NASA researchers. The cap has two layers: One is filled with a "liquid cooling heat exchanger," and the other is a pressurized lining that can be adjusted so that the cap conforms to the head and neck.
He says the cap can cool the brain surface by about 6 degrees in an hour. In animal studies, researchers were able to slow stroke damage when the brain surface temperature was dropped.
The researchers determined that cooling the brain reduced the damage that stroke does to the brain tissue by as much as 70%, Wang says in a news release.
"The goal with this therapy, therefore, is to try to improve neurological outcomes by minimizing stroke's effect," Wang says in the release. "The first step in that direction was to find a therapy that effectively cooled the brain and, judging by this study, we have."
Cooling the Body Tricky
The tricky part about cooling the brain is eventually the chill extends throughout the body and that "increases the risk of heart damage, pneumonia, and sepsis," Wang tells WebMD. He tried the cooling cap on six stroke patients, average age 68, and "five tolerated it very well," but he says it is too early to determine if the cooling treatment actually improved outcome.
In Japan, Hiroaki Naritomi, MD, of the Cardiovascular Center in Osaka, tested another helmet on 17 patients. He says six patients had good functional outcome three to 10 months after the stroke.
Larry Goldstein, MD, professor of medicine and director of the Duke University Medical Center for Cerebrovascular Disease in Durham, N.C., tells WebMD that hypothermia -- or lowering the body's temperature -- is known to slow damage and brain surgeons often "cool" brains of patients before surgery. But most previous cooling experiments have relied upon total body cooling, which is considered risky because of the risk of heart damage. Specifically targeting the head for cooling seems to be a good option, he says.
Yet Goldstein notes that there are still several problems. "Just because the brain surface is cooled doesn't mean that the deep brain is cooled," he says. Thus, strokes caused by damage in the deep brain regions may not benefit from surface cooling.
Nonetheless, Goldstein says the early results of the cooling studies are promising.