Optimal cerebral monitoring during carotid endarterectomy: Neurologic response under local anesthesia

Abstract

A prospective series of carotid endarterectomies were performed with patients given local anesthesia in an attempt to determine the efficacy of intraoperative EEG monitoring and/or stump pressure measurements in predicting the need for carotid shunting. Carotid artery stump pressure was measured and EEG changes noted; however, neither low stump pressure nor EEG changes influenced the decision for shunt insertion. A shunt was only used if a neurologic deficit developed during carotid clamping. A total of 134 carotid endarterectomies were done in 121 patients. Sixty-six patients were men and 55 were women with ages ranging from 41 to 88 years. Indications included transient ischemic attacks in 57 (43%), prior stroke in 25 (19%), vertebrobasilar symptoms in nine (6%), and asymptomatic patients with high-grade stenosis, 43 (32%). Thirteen patients (9.7%) developed neurologic deficits following carotid clamping and had shunts inserted. All deficits cleared following shunt insertion. Nine of the 13 had EEG changes, but in four, EEGs were unchanged despite the occurrence of clear-cut neurologic changes. Stump pressure in the 13 patients ranged from 14 to 78 mm Hg. Ten were greater than 24 mm Hg and three were more than 50 mm Hg. In 121 operations no neurologic deficits occurred during carotid clamping and no shunts were inserted. In 13 of these operations, significant EEG changes were noted. Stump pressures in these 13 with EEG changes ranged from 15 to 120 mm Hg. In seven, stump pressure was greater than 50 mm Hg. There were no deaths in the series. Two (1.5%) temporary and one (0.7%) permanent postoperative deficits occurred. One of the temporary and the one permanent deficit occurred in patients with intraoperative EEG changes and neurologic deficits requiring shunting. Results of the study suggest that neither EEG monitoring nor stump pressure measurement identify all patients who require intraoperative shunts. The development of a neurologic deficit with carotid clamping in the conscious patient appears to be a more reliable indicator for shunt placement. © 1985.