Prediction of malignant infarction: perifocal neurochemical monitoring following prolonged MCA occlusion in cats.

Neurochemical monitoring in the ischemic core predicts malignancy in focal ischemia in cats. Since perifocal regions are more suitable for clinical microdialysis (MD) applications, we tested whether monitoring at such site predicts also malignancy.--Laser Doppler (LD) probes, pressure microsensors, and MD/HPLC measured cerebral blood flow (CBF), intracranial pressure (ICP), and extracellular glutamate (Glu), respectively. The middle cerebral artery was occluded (MCAO) for 3 hours followed by 6 hours reperfusion. Additionally, LD measured CBF in ischemic core.--MCAO reduced CBF in the core in all below 25% of control. In animals exhibiting malignancy (eye dilatation during reperfusion), MCAO decreased CBF in the perifocal site to around 35%. CBF primarily recovered following recirculation but decreased thereafter as ICP rose due to progressive edema formation. Glu increased concomitantly. In cats exhibiting a benign course, MCAO decreased CBF in the perifocal site to around 55%. Recirculation normalized CBF, and Glu did not increase. During MCAO, Glu differences between both groups were not significant.--Glu determinations in perifocal sites taken during MCAO do not predict fatal outcome. This contrasts with determinations in the core. After reperfusion, Glu elevation in perifocal sites may serve as a rather late predictor of malignancy.