The Effect of Moderate Hypothermia on Infarct Size and Early Change of Regional Cerebral Glucose Uptake in Permanent Focal Cerebral Ischemia in the Rat.

Kim, Bong Soo; Choi, Kil Soo

Original Article

Journal of Korean Neurosurgical Society 1997;26(6): 772-779.

Bong Soo Kim, Kil Soo Choi

Department of Neurosurgery, College of Medicine, Seoul National University, Seoul, Korea.

ABSTRACT

Using a rat model, this study examined the cerebral protective effect of moderate hypothermia and evaluated the effect on early local metabolic change of permanent focal cerebral ischemia. The middle cerebral artery(MCA) of the rat was approached subtemporally and was occluded, and its surface was cooled. Cerebral infarct size was measured at 1, 4 and 7 days after MCA occlusion in non-treated(n=27), 2-hour hypothermia(n=27) and 3-hour hypothermia(n=27) group, respectively, and regional cerebral glucose uptake(rCGU) was determined at 1 and 4 hour after MCA occlusion in the non-treated(n=8) and 3-hour hypothermia(n=8) group, respectively. Infarct size measured at 1, 4 and 7 days after MCA occlusion was 22.2%+/-4.4%, 14.3%+/-6.6%, 13.7%+/-5.3% in the non-treated group, 19.6%+/-10.0%, 12.5%+/-6.2%, 12.0%+/-6.9% in the 2-hour hypothermia group and 12.9%+/-5.6%, 8.3%+/-3.3%, 8.2%+/-2.3% in the 3-hour hypothermia group. In the 2-hour hypothermia group, no significant size reduction was seen, but in the 3-hour hypothermia group, infarct size had decreased to half of that of the non-treated group(p<0.05). This protective effect was observed untill 1 week after MCA occlusion. rCGU in the non-treated group measured at 1 hour after MCA occlusion had increased in the periphery of the ischemic core, but at 4 hours, periischemic hypermetabolism had disappeared and the area of low metabolism in the center had become larger. rCGU in the 3-hour hypothermia group measured at 1 hour after MCA occlusion(BT 26degreesC) showed a uniform decrease in all regions, supressing temporary periischemic hypermetabolism, and at 4 hours(BT 37degreesC) after occlusion, hypermetabolism was not prominent and the area of low metabolism in the center had narrowed. This study indicates that 3 hour moderate hypothermia immediately after MCA occlusion significantly reduces infarct size, and that this protective effect was associated with suppression of periischemic hypermetabolism occurring around 1 hour after MCA occlusion.

Key Words: Permanent focal cerebral ischemia; Hypothermia; Infarct size; Regional cerebral glucose uptake; Periischemic hypermetabolism