An Experimental Study on Cerebral Recirculation in Acute Regional Cerebral Infarction

Kim, Hyun Jip; Jung, Hee Won; Han, Dae Hee; Sim, Bo Sung

Abstract

Cerebral revascularization has been popular since the introduction of microsurgical technique into the neurosurgery. But there is still no satisfactory measures in the treatment of acute cerebral infarction caused by obstruction of the major cerebral artery. It was also reported that early restoration of blood flow into the infracted area frequently aggravated the cerebral infarction. The purpose of this experiment is to establish an experimental animal model for temporary occlusion of the middle cerebral artery, and to estimate the tolerable duration of cerebral ischemia without occurrence of hemorrhagic infarction and severe cerebral edema after restoration of blood flow. For temporary arterial occlusion, 80 nylon snare was prepared around the proximal middle cerebral artery through transorbital approach. 48 hours after operation, alert cats were subjected to temporary occlusion of the artery. Occlusion of the artery for 1, 2, 4, or 6 hours was followed by recirculation for 2 hours. Immediately after sacrifice, 2% solution of triphenyl tetrazolium chloride was injected into common carotid arteries. Clinical observation was done during the whole procedure of the experiment. And brain was examined grossly for cerebral infarction, hemispheric swelling and hemorrhagic infarction. The results were as follows; 1) With transorbital snare technique for temporary occlusion of the middle cerebral artery, relatively constant cerebral infarction could be produced in cats. 2) The initial clinical findings were characteristic and similar in all cats whose middle cerebral arteries were occluded. These consisted of contralateral hemiparesis, rapid circling and tonic deviation of the head and neck toward the side of arterial occlusion. After 5-20 minutes rapid circling gait and tonic deviation disappeared, but hemiparesis and slow circling gait continued throughout the experiment. 3) In contrast to stable clinical states in animals of 8 hour occlusion group and recirculation groups after 1 or 2 hours of arterial occlusion, over half of cats whose middle cerebral arteries were occluded for 4 hours or more became clinically aggravated after recirvulation(p<0.05). 4) There was a tendency that the infarcted area unstained with 2% solution of triphenyl tetrazolium chloride was progressively enlarged as the duration of arterial occlusion increased, but the difference was not stastically significant(p>0.05). 5) Cerebral hemispheric swelling in cats of recirculation groups became progressively increased as the duration of arterial occlusion increased(p<0.05), and had close correlation with clinical findings. 6) In cats whose middle cerebral arteries were occluded for 6 hours, the rate of gross hemorrhagic infarction increased abruptly.