In a Japanese study, a "helmet-type cooling apparatus" was tested on 17 patients with severe ischemic stroke. An American study tested a "NASA-spinoff" helmet on six patients with severe ischemic stroke.
Ischemic strokes are caused by blood clots in blood vessels of the brain or leading to it.
The helmets may improve patient outcomes and lengthen the time treatment window for ischemic strokes.
Hypothermia low temperature is known to protect the brain from ischemic injury. However, overall surface cooling is associated with various adverse effects, said Kentaro Yamada, M.D., of the National Cardiovascular Center in Osaka, Japan.
"The largest problem of systemic surface cooling is the requirement of general anesthesia, which increases risks of respiratory and circulatory diseases," he said. "Systemic surface cooling is commonly associated with severe infections, arrhythmia, hypopotassemia (low potassium) or decrease of platelet counts, which may countervail protective effects of hypothermia."
He also noted that "in our experience of hypothermia therapy in acute stroke patients using systemic surface cooling, excellent functional recovery was obtained in 83 percent of younger patients under age 60 but only in 20 percent of elderly patients."
Scientists have tried various methods to cool the brain, including cooling the entire body, using dry ice and blowing cool air on the head. However, methods were unable to selectively cool the brain rapidly and maintain such preferential cooling over the rest of the body, said Huan Wang, M.D., assistant and resident of neurosurgery at the University of Illinois, College of Medicine, Peoria, Ill.