MIDDLE CEREBRAL-ARTERY OCCLUSION WITHOUT CRANIECTOMY IN RATS - WHICH METHOD WORKS BEST

Background and Purpose: Our purpose was to assess the effectiveness of middle cerebral artery occlusion in producing acute focal ischemia in the rat by the use of Koizumi's and Longa's methods, in which occlusion is achieved by passing a nylon thread into the internal carotid artery. Methods. Cerebral blood flow was measured by using the hydrogen clearance method, and the brains were examined histologically to assess ischemic damage. Results: By Koizumi's method profound reduction in cerebral blood flow was achieved in 28 of 30 rats (93%). The mean cerebral blood flow in the middle cerebral artery territory was 10.7 (95% confidence interval, 9.9-11.5) ml/100 g per minute. By Longa's method reduction in cerebral blood flow was achieved in only 29 of 52 rats (56%), and in these animals mean cerebral blood flow was 33 (95% confidence interval, 28.3-33.7) ml/100 g per minute (p<0.001 compared with Koizumi's method). Cerebral blood flow was reduced to < 16 ml/100 g per minute in only seven animals (24%). Conclusions: By Koizumi's method the depth of ischemia is more profound, occlusion is achieved in a much higher proportion of cases, and the incidence of perforation of the intracranial internal carotid is much less frequent than by Longa's method.