DALLAS, Sept. 1 -- Lowering the body temperature by about one degree within a few hours of a stroke can reduce brain damage and the risk of death, according to a study in this month's Stroke: Journal of the American Heart Association. Researchers in Copenhagen, Denmark, pumped cool air into a thermal blanket to induce mild hypothermia (low body temperature) in 17 awake patients soon after they suffered strokes, then maintained the cooler body temperatures for six hours. Those receiving the cooling therapy had a six-month survival rate nearly twice that of a control group of 56 patients who weren't treated with hypothermia.
This study is the first to investigate hypothermia's effect in awake patients and compare their recovery with untreated controls.
"By showing that hypothermia can be successfully used without anesthesia, we have suggested a method of treatment that appears to be low in cost and applicable in most hospitals involved in stroke treatment," says Lars Kammersgaard, M.D., lead author of the study. "If future trials support our findings, the majority of stroke patients may be able to benefit from this treatment in the near future."
Before this study, Kammersgaard says, intervention with hypothermia has been examined only on a limited basis, and putting patients under full anesthesia has always been part of the cooling procedure. However, the researchers in this group were able to work with conscious patients by giving them injections of a drug to control shivering associated with the cooling treatment. On average, body temperatures were reduced by 1.3 degrees Celsius- from 36.8 to 35.5 degrees and some reduction continued for up to four hours after treatment was discontinued.
"By reducing the body temperature in the stroke patient, the brain receives cooled blood," Kammersgaard says. "Animal studies involving hypothermia strongly suggest that decreased brain temperature causes less destruction of brain tissue."
Kammersgaard says there is also evidence to support the idea that people who have low body temperature at the time of hospital admission tend to have lower mortality and better overall outcomes after a stroke.
Kammersgaard's group has documented in animal studies that a decrease of just one degree Celsius in the body temperature of stroke patients at admission is related to smaller regions of brain injury and an 80 percent reduction in the risk of death after stroke.
Because of the relatively small number of patients involved, Kammersgaard emphasizes that no firm conclusions can be drawn from this study. But a much larger randomized clinical trial involving 1,000 stroke patients in Denmark, Norway and Sweden is currently being organized using the same type of treatment.
"Hypothermia seems to have the strongest potential of any stroke treatment, but further study is necessary to determine the full extent of its benefits," he says. "In the present study, for example, we were not able to conclude how much effect hypothermia has on the degree of paralysis in stroke patients, but this will be addressed when the new study is launched within the next few months."
Co-authors include: B.H. Rasmussen, M.D.; H.S. Jorgensen, DMSci.; J. Reith, M.D.; U. Weber, M.D.; and T. S. Olsen, DMSci.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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