Cerebral embolism during elective carotid endarterectomy treated with tissue plasminogen activator: utility of intraoperative EEG monitoring.

Electroencephalography (EEG) is routinely used during elective carotid endarterectomy (CEA) for monitoring cerebral perfusion. The period most frequently associated with cerebral hypoperfusion is the one during the clamping of the carotid artery. We present a case whereby acute hypoperfusion, as detected by ipsilateral hemispheric slowing and attenuation of the fast frequencies on EEG, was detected in the period prior to clamping of the carotid artery. The acute changes were caused by a cerebral embolism. Following emergent treatment with intraoperative thrombolytic therapy with intra-arterial tissue plasminogen activator (t-PA) the EEG changes reversed fully. We discuss the utility of intraoperative EEG monitoring in the detection and treatment of cerebral embolism. The ability of EEG to intraoperatively measure the function of the at-risk cerebral cortex makes it not only a useful tool in detecting acute changes such as from a large embolism, but also in guiding necessary treatment by offering direct feedback in the absence of reliable imaging and clinical examination.