Changes in Evoked Potentials in Focal Cerebral Cortical Ischemia in the Rat

ABSTRACT

OBJECTIVE: To investigate the changes of motor and somatosensory evoked potentials found in focal cerebral cortical ischemia induced by endothelin-1 (ET-1), one of the common models of cerebral infarct in rats. METHOD: A total of twenty Sprague-Dawley rats were studied. Focal cerebral cortical ischemia was induced by steterotaxic injection of ET-1 into forelimb region of cerebral cortex. Pellet retrieval test, motor evoked potential (MEP), and somatosensory evoked potential (SEP) were compared before and after cerebral ischemia. The location and extent of cerebral ischemia were confirmed histologically. RESULTS: Success rate of pellet retrieval test decreased significantly after induction of cerebral ischemia, demonstrating sensorimotor deficit in the contralateral forelimb. The latency and amplitude of MEP did not changed significantly despite weakness of forelimb. However, SEP showed reversal of the positive peaks. CONCLUSION: The results suggest that the changes of MEP and SEP in focal cerebral cortical ischemia are different from those in cerebral ischemia by large artery occlusion. When evaluating MEP and SEP in focal cerebral ischemia model, interpretation of evoked potentials should be cautious.