Experimental studies of ischemic brain edema

Abstract

A new model of cerebral embolism in Wistar rats in which recirculation of the blood flow in ischemic areas can be introduced by means of removal of embolus in an easy way was designed. Large cerebral infarction in the territory of the right middle cerebral artery was induced by the embolization of a silicone rubber cylinder attached to a nylon surgical thread which was positioned at the segment where the right internal carotid artery branches into the middle cerebral artery. Recirculation in the ischemic area was performed successfully by removal of the cylcinder by simply pulling thread out from the artery. Influence of the recirculation on water contents and histological changes in the brains were investigated. Water contents in the brains increased from 77.62% in controls to 79.48% in the experimental group 12 hours after embolization. Recirculation for 2 hours after the various duration of ischemia enhanced the water contents significantly as compared to the brains receiving embolism for the same duration without recirculation. Reflow of the blood into the infarcted area resulted in increased vascular permeability leading to more severe edematous spongy changes in the brains and extravasation of erythrocytes and granulocytes from the small vessels in the infarcted area.