A comparative study of EEG suppressions induced by global cerebral ischemia and anoxia.

Cerebral ischemia and anoxia induce sequential changes that include ionic redistribution, alteration of enzimatic reactions governing metabolism and intracellular signaling. Despite high technology instrumentation including positron emission, tomography and magnetic resonance imaging used to unravel the intricacies of cerebral blood flow and metabolism, the electroencephalography (EEG) retains a useful place in the evaluation of processes induced by cerebral ischemia, especially in experimental conditions. We have investigated in this study EEG suppression and recovery following global cerebral ischemia, obtained by "four vessel occlusion model", reperfusion and anoxia. Both cerebral ischemia and anoxia have produced a sudden diminution of electrical brain activity and flat line was recorded after 8-10 sec. in the ischemic rats, but after 35-40 sec. in the anoxic rats. After same period of time (2 min) of ischemia and anoxia EEG recovery has been faster in the ischemic rat.