Collateral Ability of the Circle of Willis in Patients With Unilateral Internal Carotid Artery Occlusion

Abstract

Background and Purpose-The circle of Willis is regarded as the major source of collateral flow in patients with severe carotid artery disease. The purpose of the present study was to assess whether the presence of border zone infarcts is related to the collateral ability of the circle of Willis in symptomatic (transient ischemic attack, minor stroke) and asymptomatic patients with unilateral occlusion of the internal carotid artery (ICA). Methods-Fifty-one patients (35 symptomatic, 16 asymptomatic) and 53 control subjects were investigated. Patients had unilateral occlusion of the ICA and contralateral ICA stenosis between 0% and 69%.

Heterogeneity in Infarct Patterns and Clinical Outcomes Following Internal Carotid Artery Occlusion

“…Researchers have examined the primary and ophthalmic collateral systems without success in explaining the difference in infarct extent. [6][7][8][9] It is possible that coexistent middle cerebral artery (MCA) occlusion modifies the clinical outcome and infarct patterns of patients with ICA occlusion. This has not been well characterized previously.…”

“…In the setting of ICA occlusion (below the carotid T junction where the A1 segment and MCA stem from the ICA) but preserved anterior communicat- ing artery, the cross-flow from the nonoccluded side to the occluded ICA can provide blood to the MCA territory. 8,18 This is not possible if the ICA occlusion occurs at the carotid T junction. Additionally, blood flowing from the posterior cerebral artery (PCA) via the posterior communicating artery can act as another source for the occluded ICA (if the ICA occlusion is below the origin of the posterior communicating artery).…”

“…Additionally, blood flowing from the posterior cerebral artery (PCA) via the posterior communicating artery can act as another source for the occluded ICA (if the ICA occlusion is below the origin of the posterior communicating artery). 8,19,20 When there is occlusion of both the ICA and MCA, there is no rescue from the primary collateral system via the anterior or posterior communicating arteries to the MCA territory, and combined ICA and MCA occlusion results in infarcts resembling MCA infarcts. The ophthalmic artery has been proposed previously to be a secondary collateral system, but in clinical studies its presence has not been shown to modify outcome or infarct pattern.…”

Fetal and Primitive Type of Circle of Willis with Unilateral Trifurcation of Internal Carotid Artery

“…The most common topological variations include missing communicating vessels, fused vessels, string-like vessels, and presence of extra vessels [3]. These topological variations may affect the ability to maintain cerebral perfusion, which may increase the risk of stroke and transient ischemic attack in patients with atherosclerosis [4]. Existence of a relationship between the variations in the circle of Willis and the sites of aneurysms of arteries also postulated earlier [5].…”

Prediction of Borderzone Infarction by CTA in Patients Undergoing Carotid Embolization for Carotid Blowout

“…9 Balloon test occlusion (BTO) is the optimal testing method that can simulate the collateral reserve of the circle of Willis, which is associated with hypoperfusion-related borderzone infarction after PCO. [10][11][12] However, the suitability of BTO during emergent PCO for CBS is contentious, and the complication rate of BTO has been reported to be as high as 3.2%, which might be even higher for patients with CBS in whom heparin infusion is contraindicated.…”