Predictors of clamp-induced electroencephalographic changes during carotid endarterectomies.

OBJECTIVE

Electroencephalograms (EEGs) detect clamp-induced cerebral ischemia during carotid endarterectomy (CEA) and thus impact management and minimize the risk of perioperative stroke. We hypothesized that age, preoperative neurologic symptoms, ≥70% contralateral carotid and bilateral vertebral stenosis increase the probability of clamp-induced EEG changes, whereas ≥70% unilateral carotid stenosis does not.

METHODS

This is an observational cohort study of 299 patients who underwent CEA with EEG monitoring at a single large urban academic medical center in 2009. Univariate and multivariate logistic regression were used.

RESULTS

Seventy percent or greater ipsilateral carotid stenosis decreases the odds of clamp-induced neurophysiologic dysfunction (odds ratio [OR] = 0.43, 95% confidence interval [CI] [0.18, 0.99], P = 0.04) after adjustment for symptomatic status, degree contralateral carotid or vertebral stenosis, and age. Preoperative neurologic symptoms, ≥70% contralateral carotid stenosis, and bilateral extracranial vertebral stenosis independently increase these odds (OR 2.62, 95% CI [1.32, 5.18], P = 0.005; OR 2.84, 95% CI [1.27, 6.34], P = 0.01; and OR 3.58, 95% CI [1.02, 12.53], P = 0.04, respectively), after adjustment for the other factors. Age ≥70 years has no significant impact.

CONCLUSIONS

Preoperative neurologic symptoms, ≥70% contralateral carotid, and bilateral vertebral stenosis increase the probability of clamp-induced ischemia as detected by intraoperative EEG, while ≥70% ipsilateral carotid stenosis decreases it.