Continuous electroencephalographic monitoring during carotid endarterectomy.

Four hundred and twenty-seven carotid endarteriectomies were performed on 377 patients. The electroencephalogram was used as the sole determinant for the use of a carotid shunt in 386 carotid endarterectomies. With clamping of the internal carotid artery, 51 (13%) had electroencephalographic changes. The most common electroencephalographic change (60%) was rapid, ipsilateral attenuation of background activity. In the 30 day follow up period there were 3 deaths (0.7%) and 11 strokes (2.5%). Two patients (0.5%) had intraoperative strokes. The combined morbidity and mortality was 2.8% (12 of 427). Neurologic complications increased significantly with contralateral carotid occlusion. The electroencephalogram correlated well with neurological deficits occurring in surgery, but stump pressures neither correlated with neurological deficits nor electroencephalographic changes. Continuous electroencephalographic monitoring during carotid endarterectomy is an effective method of determining significant cerebral ischemia and the need for a carotid shunt.