Results of electroencephalographic monitoring during 369 consecutive carotid artery revascularizations

A continuous intraoperative EEG monitoring was performed in 369 consecutive carotid artery revascularizations (CARs) (321 patients) to minimize the intraoperative neurological morbidity. There were 227 carotid endarterectomies and patch graft angioplasty (198 patients), 79 carotid eversion endarterectomies (70 patients) and 58 internal carotid artery reimplantations into the common carotid artery (48 patients). Indications for CARs were TIAs (141, 43.9%), amaurosis fugax (60, 18.6%) and fixed or partial nonprogressing stroke (14, 4.3%). One hundred and six patients (33.1%) were asymptomatic. EEG abnormalities consistent with cerebral ischemia occurred in 97 (26.3%) operations. The indwelling shunt (IS) was used in 73 cases; in the remaining 24 (24.7%), IS was not used on purpose because the surgical procedure was carried out successfully within 5-6 min after the appearance of EEG changes. All patients awoke from the anesthesia without any neurological deficit. Five patients presented with a major stroke within postoperative day 1 and 2, and 1 patient died on postoperative day 10. In 2 of these cases, the intraoperative EEG monitoring was absolutely normal and the IS was not used: the carotid occlusion was due to technical errors. The most striking finding of this series is the absence of false-negative results in continuous EEG monitoring. EEG monitoring appears an available and useful method for the detection of cerebral ischemia secondary to carotid cross-clamping and contributes to put at zero the intraoperative complications of the surgical procedure.