Continuous intraoperative EEG monitoring during carotid surgery.

Continuous intraoperative EEG monitoring and stump pressure measurements were studied during 85 carotid revascularizations performed in 40 symptomatic cerebrovascular patients and in 32 asymptomatic subjects with a cervical bruit. The decision to place a temporary shunt was made on the basis of intraoperative EEG abnormalities regardless of stump pressure values. 11 patients with contralateral carotid lesions showed marked EEG alterations, at the moment of clamping, which returned to normal after the placement of an indwelling shunt. Stump pressure values showed a wide variation and a poor correlation with intraoperative EEG changes. In the early postoperative period there were no deaths; no new neurological deficits were detected. In the follow-up there was only 1 asymptomatic carotid rethrombosis, not revealed by the EEG, which was suspected by Doppler sonography and confirmed by angiography. The authors conclude that EEG gives valuable information about cerebral functions during carotid revascularization and can reduce the intraoperative complications of the procedure. Stump pressure measurement cannot be used alone as a safe indicator of cerebral ischemia during carotid cross-clamping.