The effect of the collateral cerebrovascular circulation on tolerance to carotid artery cross-clamping and on early outcome after carotid endarterectomy: complications.

Abstract

Background: Carotid endarterectomy (CEA) is an effective surgical intervention that decreases the risk of stroke in patients with severe symptomatic carotid artery stenosis. The Circle of Willis (CoW) serves as the primary source of contralateral blood supply in situations of ipsilateral blood supply deficiency; therefore, it has been suggested that CoW's anatomy affects CEA outcomes. Objective: The aim of this study was to evaluate the associations between the cerebral collateral circulation, a positive awake test for intraoperative neurologic deficit after carotid cross-clamping (CC) under local or regional anesthesia (LRA) and postoperative adverse neurologic events. Methods: A systematic review was conducted searching MEDLINE, Cochrane and Web of Science databases for studies that assessed the cerebral circulation, including CoW variations, using neuroimaging techniques in patients who underwent carotid CC for endarterectomy under LRA. Data were extracted and analyzed systematically, as appropriate. Results: Eight eligible studies involving CC in 1313 patients, of whom 1258 underwent 1261 carotid endarterectomies, were included in the systematic review. The incidence of positive awake test among the CEA patients ranged from 4.4% to 19.7%. Overall, patients with anterior circulation insufficiency had a positive awake test ranging from 5% to 91%, while patients with posterior circulation insufficiency had a positive awake test ranging from 27% to 74%. Additionally, patients with incomplete CoW did not exhibit a statistically significant direct correlation with the presence of neurological deficits. A positive awake test in patients with contralateral carotid stenosis or occlusion ranged from 5.8% to 100%, with a meta-analytical incidence of 79.9%. Data were insufficient to evaluate the effect of the collateral circulation on early outcome after CEA. Conclusion: The presence of an incomplete CoW alone did not affect the incidence of intraoperative neurologic deficit and data were insufficient to evaluate its effect on outcomes after CEA, performed under LRA. The findings suggest that more than one abnormality of the CoW or contralateral carotid stenosis/occlusion likely predicts a positive intraoperative awake test. Additional research with consistent and internationally defined methodology is required to predict intolerance to carotid CC with the goal to consider alternative management (carotid artery stenting or medical therapy) for patients at high risk for CC intolerance.