STUMP PRESSURE, THE CONTRALATERAL CAROTID-ARTERY, AND ELECTROENCEPHALOGRAPHIC CHANGES

Electroencephalographic (EEG) monitoring and measurement of stump pressure are the most widely employed methods of assessing the risk of cerebral ischemia during carotid endarterectomy. The status of the contralateral carotid artery has also been thought to influence the need for placing a shunt. The relationship of EEG monitoring, stump pressure, and the contralateral carotid artery has not been completely delineated. We retrospectively reviewed these three variables in 113 patients undergoing 124 carotid endarterectomies. The contralateral artery was classified as occluded, stenotic (greater than 50% decrease in diameter), or nonstenotic. There was a 48% incidence of EEG changes with contralateral occlusion, 18% with stenosis, and 21% with nonstenotic arteries (p = 0.014). There was a 73% incidence of EEG changes when the stump pressure was less than 25 mm Hg, 32% when the stump pressure was 25 to 50 mm Hg, and 2% when the stump pressure was greater than 50 mm Hg (p < 0.001). There was no significant difference in the mean stump pressure for patients with occlusion (43.8 mm Hg), stenosis (44.7 mm Hg), or nonstenotic contralateral arteries (51.3 mm Hg). All patients with contralateral occlusion and a stump pressure less than 25 mm Hg had EEG changes. No patient with a stump pressure greater than 50 mm Hg and a patent contralateral artery had EEG changes. Although the incidence of EEG changes in the majority of patients was not accurately predicted by the stump pressure and the status of the contralateral carotid artery, stump pressure less than or equal to 50 mm Hg was sensitive, identifying 97% of patients with EEG changes.