Introduction: Subtle cognitive dysfunction occurs in approximately 25% of patients within 24 hours of carotid endarterectomy (CEA). One of the purported mechanisms of this early cognitive dysfunction (eCD) is global hypoperfusion due to inadequate collateral circulation during carotid artery cross clamping. We sought to determine whether poor collateral circulation within the circle of Willis (CoW), as determined by pre-operative computed tomography angiography (CTA) or magnetic resonance angiography (MRA), can predict eCD following CEA.

Methods: Patients who underwent CEA at a single institution between 2004 and 2012 and who had pre-operative MRA or CTA imaging were included in this study. Imaging was analyzed and patients were stratified according to posterior communicating (P.comm) artery status (radiographic visualization of =1 normal P.comm versus no normal P.comms). Univariate analyses (Chi-squared and Wilcoxon rank-sum) were performed using prospectively collected data for each patient, including pre-operative and post-operative neuropsychometric evaluation within 24 hours of CEA. Variables demonstrating a p-value <0.20 were included in a stepwise logistic regression model to identify predictors of eCD following CEA.

Results: Forty-two CEA patients had pre-operative MRA or CTA imaging available for analysis. Four patients were excluded due to intra-operative EEG changes indicative of cerebral ischemia and subsequent carotid shunt placement. Variables included in the multivariate model of eCD were prior myocardial infarction (p=0.04), peripheral vascular disease (p=0.09), and radiographic absence of both P.comms (p=0.007). In the final multivariate logistic regression model, radiographic absence of both P.comms was the only significant predictor of eCD (OR: 0.104; 95% CI: 0.015 - 0.699; p=0.020).

Conclusions: Pre-operative identification of inadequate collateral circulation in the CoW may allow for prediction of patients who will experience eCD after CEA. Additional studies are necessary to further characterize the effect of CoW integrity on post-CEA eCD.

Patient Care: The ability to accurately predict which patients will experience cognitive dysfunction after carotid endarterectomy will allow for a more comprehensive assessment of the relative risks and benefits of this surgical procedure.

Learning Objectives: By the conclusion of this session, participants should be able to describe the potential prognostic significance of radiographically evident collateral vessels in the circle of Willis in patients undergoing carotid endarterectomy.

References: Heyer, Eric J, Ruchey Sharma, Anita Rampersad, Christopher J Winfree, William J Mack, Robert A Solomon, George J Todd, Paul C McCormick, James G McMurtry, Donald O Quest, Yaakov Stern, Ronald M Lazar, and E Sander Connolly. 2002. “A controlled prospective study of neuropsychological dysfunction following carotid endarterectomy..” Archives of neurology 59(2): 217–222. Mocco, J, David A Wilson, Ricardo J Komotar, Joseph Zurica, William J Mack, Hadi J Halazun, Raheleh Hatami, Robert R Sciacca, E Sander Connolly, and Eric J Heyer. 2006. “Predictors of neurocognitive decline after carotid endarterectomy..” Neurosurgery 58(5): 844–850.