Regional mild hypothermia in the protection of the ischemic brain

Objective: To demonstrate that mild hypothermia can be a protective element when an ischemic onset occurs in rabbit brains. Methods: A rabbit model of focal ischemia was used to test the protection provided by mild hypothermia regionally produced by means of the placement of ice bag on the scalp of a hemicranium which has had previously its bone removed. Twenty New Zealand White rabbits were divided into two groups as follows: (A) a control group where an ischemic lesion was produced by coagulation of the middle cerebral artery and (B) a brain protected group where mild hypothermia was provided during 80 to 100 minutes after the same ischemic lesion. The brains slices were stained with 2,3,5-Triphenyletrazolium (TTC). The sections were photographed with a digital camera and the infarct volume was measured through a computer program. Results: The average of infarct volume was 70.53 mm³ in the control group. In the protected group, the average of infarct volume was 41,30 mm³ only in five animals. Five animals of this group did not demonstrate macroscopically and microscopically infarct area. Conclusions: We concluded that mild hypothermia regionally produced may protect ischemic brains of rabbits.