Assessment of Primary Collateral Grades Based on the Integrity of Willis' Circle: Predicting the Prognosis of Acute Intracranial Internal Carotid Artery Occlusion Before Thrombectomy.

OBJECTIVE: Endovascular mechanical thrombectomy (EVMT) has shown significant efficacy in improving neurological functions in patients with intracranial internal carotid artery occlusion (IICAO), but its clinical outcomes are variable. We examined the relationship between favorable clinical outcomes after EVMT in IICAO and a set of predictors. METHODS: In this retrospective study, 189 patients with IICAO treated by EVMT at 3 centers from November 2015 to December 2020 were included and analyzed. Non-contrast computed tomography and computed tomography angiography were evaluated on admission. The morphology of IICAO was categorized into Ia, Ib, L, or T types, depending on the involvement of the posterior communicating artery origin, proximal anterior cerebral artery, and middle cerebral artery. The Willis' circle was categorized as integrated or compromised Willis' circle. In combination with the involvement of the IICAO and the integrity of Willis' circle, we used the primary collateral grade (PCG) to describe the presence of functional Willisian collaterals. Baseline data including demographics, characteristics, vascular risk factors, and initial National Institutes of Health Stroke Scale scores were collected. Hemorrhagic transformation was evaluated using the 24-hour non-contrast computed tomography after EVMT. Favorable outcomes based on modified Rankin scale, were defined as 0-2 at 90 days. RESULTS: A total of 189 patients were included (median age, 69 years; 126 male [66.7%]). 104 patients [55.0%] showed reperfusion after EVMT, but 72 patients [38.1%] achieved favorable outcomes at 90 days. The mortality rate of type Ib was significantly higher than that with type Ia (χ2 = 14.21, P = 0.001). The outcome with different structure of Willis' circle was not statistically different between the 2 groups. A multivariate logistic regression analysis showed that IICAO T-type (odds ratio, 0.028 [95% confidence interval: 0.323-3.829], P = 0.042) and PCG 2 (odds ratio 9.427[95% confidence interval:1.863-47.698], P = 0.007) were predictors of favorable outcomes. CONCLUSIONS: Evaluation of PCG by determining the type of IICAO and the integrity of Willis' circle may serve as a valuable indicator for the prognosis and as an essential reference for screening patients before EVMT.

Assessment of the cortical artery using computed tomography angiography for bypass surgery in moyamoya disease.

Computed tomography angiography (CTA) is often used to assess the vascular status in moyamoya disease. The purpose of the study is to identify the characteristics of cortical arteries (M4) of moyamoya disease on CTA; the clinical significance of which is also discussed. A total of 38 hemispheric sides of 27 patients with moyamoya disease were included in this study. The number of M4 was visualized on CTA using cortical surface imaging and compared between the moyamoya disease group and the non-moyamoya disease group or the control group. Then, the clinical and radiological factors associated with the number of M4, the distribution of M4, and collateral circulation were examined. The number of M4 was lower in the moyamoya disease group than in the non-moyamoya disease group and in the control group (p < 0.05). There are few predictive clinical factors of the number of M4 except male sex. The prefrontal artery, precentral artery, central artery, and angular artery had a significantly higher prevalence in moyamoya disease (p < 0.05). The durocortical and periventricular anastomosis had a significantly higher prevalence in moyamoya disease (p < 0.05). The prevalence and distribution pattern of cortical arteries in moyamoya disease differed from that of the non-moyamoya disease group, and the distribution patterns of M4 might be influenced by collateral circulation. It is thus essential to recognize M4 to assess the recipient artery so as to ensure superficial temporal artery-middle cerebral artery bypass.

Effects of carotid endarterectomy or stenting on arterial diameters in the circle of Willis.

BACKGROUND: In patients with internal carotid artery (ICA) stenosis, the circle of Willis (CoW) is the primary collateral pathway. We compared luminal diameters in the CoW before and after carotid revascularization and compared the effects of carotid endarterectomy (CEA) and stenting on these diameters. METHODS: At a single center in the International Carotid Stenting Study, 139 patients with symptomatic ICA stenosis of 50% or more were randomized to stenting (n = 81) or CEA (n = 58). The diameters of all segments of the CoW were assessed on computed tomography angiography (CTA), before and 30 days after revascularization. All evaluations were performed blinded to treatment allocation and order of CTA. RESULTS: A .10-mm increase (95% confidence interval [CI], .02-.17; 7%; P = .01) in diameter after revascularization occurred in the ipsilateral precommunicating anterior cerebral artery (A1), whereas both the ipsilateral and contralateral posterior communicating arteries decreased in diameter by .12 mm (95% CI, .04-.21; 14%; P = .01) and .08 mm (95% CI, .00-.17; 10%; P = .05), respectively. The increase in diameter of the A1 was larger after stenting (.15 mm; 95% CI, .07-.24; P = .001) than after CEA (.02 mm; 95% CI, -.11 to .15; P = .79). Only in patients treated with CEA, the diameters of the contralateral A1 and ipsilateral precommunicating posterior cerebral artery were reduced after revascularization. CONCLUSIONS: Carotid revascularization improves anterior collateralization and reduces reliance on posterior collateral pathways via the CoW. Carotid stenting and endarterectomy appear to have different early effects on collateralization.

Microneurosurgical training model in fresh cadaveric cow brain: a laboratory study simulating the approach to the circle of Willis.

BACKGROUND: Residents of neurosurgery need many years to develop microneurosurgical skills, and laboratory training models are essential for developing and refining surgical skills before clinical application of microneurosurgery. A simple simulation model is needed for young residents to learn how to handle microneurosurgical instruments, and to perform safe dissection of intracranial vessels and nerves. METHODS: The material consists of a 2-year-old fresh cadaveric cow cranium. A 4-step approach was designed to dissect the internal carotid artery and its proximal branches, the optic nerve, the optic chiasm, and the pituitary stalk. RESULTS: The model simulates standard microneurosurgery using a variety of approaches to vessels and neural structures in and around the circle of Willis of the human brain. CONCLUSION: The cadaveric cow brain, besides being cost-effective, represents a fairly useful method to accustom residents of neurosurgery, especially junior residents, to dissecting intracranial vessels and nerves, and it simulates intracranial microneurosurgical procedures performed in the human brain.

[CT-angiography for diagnostic assessment of intracranial vascular aneurysms]. / Die CT-Angiographie zur diagnostischen Beurteilung intrakranieller Gefässaneurysmen.

Intracranial aneurysms bear a high risk of morbidity and mortality especially when they have become symptomatic due to rupture or represent a space occupying lesion. Therefore operative treatment is aimed at the obliteration of the aneurysm to eliminate the risk of hemorrhage. Planning of treatment requires a diagnostic resolution capable of showing aneurysms and their anatomic relationship to the adjacent structures. Due to technical advances computed tomography has reached a diagnostic accuracy sufficient to plan aneurysm treatment. This report describes the present state of three-dimensional spiral-CT angiography (3D-spiral-CTA) and our protocol to examine the arteries of the Circle of Willis for the presence and microanatomy of aneurysms. The experience of 46 patients with 64 aneurysms is reported and the diagnostic value of the method in comparison to conventional angiography is evaluated.