A Study of Interhemispheric Diaschisis:Reduction of Cerebral Blood Flow in Both Hemispheres Following Unilateral Middle Cerebral Artery Occlusion in Cats

Abstract

To demonstrate the effect of interhemispheric diaschisis in acute unilateral cerebral infarction, the changes of regional cerebral blood flow (rCBF) following experimental occlusion of one middle cerebral artery(MCA) for up to 16 hours were investigated in an unanesthetized cat model using the technique of transorbital snare ligature implanted in the intact cranium. rCBF of both MCA territories and both marginal zones were measured simultaneously by the hydrogen clearance technique. 25 cats were divided into 2 groups according to the size of infarct; Group A, infarct larger than 10% of ipsilateral coronal sectional surface of hemisphere and Group B, smaller than 10%. DUring the initial stage of ischemia, significant decrease in rCBF of the contralateral hemisphere was observed in both groups, however, in Group A, rCBF gradually increased toward preocclusion level. In Group B, rCBF decreased further and remained low till the 16th hour after occlusion. These results suggested that mild ischemic Group B would take advantage of interhemispheric diaschisis during the late phase of infarct development as well as the substantial collateral flow from the surrounding anterior and posterior cerebral artery territories.