Computerized electroencephalogram monitoring and carotid artery shunting

During carotid artery surgery, ischemic electroencephalogram (EEG) changes were detected by computerized analysis in 27 of 225 carotid clamping intervals. All but 7 of these changes resolved spontaneously before the restoration of blood flow. Restored flow was associated, after variable delay, with an improved EEG pattern in 6 of 7 cases. Of 27 EEG episodes, there were 5 cases in which the EEG event persisted for 10 minutes or longer. All 5 patients developed new neurological deficits; none of the other patients did. It is suggested that all patients undergoing carotid artery surgery be monitored with EEG and that a shunt be placed if a persistent EEG change is noted.