Edema and Necrosis in Experimental Cerebral Infarction

Some cerebral edema always accompanies ischemic infarction and contributes to symptoms in a substantial number of human cases.¹Although the edema usually is greater with large than with small infarcts,²morphologic correlation sometimes is poor. This raises the question in ischemic lesions whether there is a stage of prenecrotic swelling or of swelling independent of necrosis; the corollary question is whether swelling itself contributes to the eventual size of the brain infarct. To investigate this we attempted to induce in rats graded anoxicischemic cerebral lesions; small animals were chosen in order to have sufficient numbers to analyze results. Because of the well-known narrow margin in rats between producing no brain lesion at all and producing death by anoxia, a modification of Levine's³technique combining carotid ligation with anoxic exposure was employed. Whereas Levine (and Spector⁴) exposed animals to severe hypoxia for variable periods of time