Intracranial Aneurysms Occur More Frequently at Bifurcation Sites That Typically Experience Higher Hemodynamic Stresses

Alfano, Jaclyn M; Kolega, John; Natarajan, Sabareesh K.; Xiang, Jianping; Paluch, Rocco A.; Levy, Elad I.; Siddiqui, Adnan H.; Meng, Hui

doi:10.1227/neu.0000000000000016

Cited by 81 publications

(59 citation statements)

References 38 publications

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“…4,5,13,14 Alfano et al 4 showed a significant association between a vessel bifurcation where aneurysms are frequent (ie, the ACoA complex, middle cerebral artery bifurcations, and ICA/posterior communicating artery junction) and high WSS. Studies on glass models revealed that the magnitude of hemodynamic stress increases proportionally to the bifurcation angle and asymmetry of the branch diameter.…”

Section: Discussionmentioning

confidence: 99%

“…However, we still do not know why intracranial aneurysms develop preferentially in certain arterial bifurcations, namely in the internal carotid artery (ICA)/posterior communicating artery junction, anterior communicating artery (ACoA) complex, and middle cerebral artery bifurcation. 4 This issue was partially addressed in glass model studies, showing that the magnitude and distribution of hemodynamic stress on the vessel bifurcation depend not only on blood flow but also on the bifurcation angle and flow pulsatility. 5,6 Also, our previous study showed that occurrence of cerebral aneurysms in the arteries constituting pathways of collateral circulation in patients with the occlusion of brachiocephalic vessels is not always related to the increase in blood velocity.…”

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confidence: 99%

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Morphological, Hemodynamic, and Clinical Independent Risk Factors for Anterior Communicating Artery Aneurysms

Kaspera¹,

Ładziński²,

Larysz³

et al. 2014

Stroke

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Background and Purpose-The pathogenesis of cerebral aneurysms still raises some controversies. The aim of this study was to identify morphological, hemodynamic, and clinical independent risk factors for anterior communicating artery (ACoA) aneurysm development. Methods-Computed tomography angiography and transcranial color-coded sonography were performed in 77 patients with a nonbleeding ACoA aneurysm and in 73 controls. Symmetry of A1 segments of the anterior cerebral arteries, angles between A1 and A2 segments, tortuosity, diameter, mean velocity (V m ), pulsatility index, and volume flow rate in both A1 segments were determined. Moreover, all study participants completed a survey on their medical history. Multivariate backward stepwise logistic regression analysis was performed to identify independent risk factors for ACoA aneurysm development. Results-Smoking, hypertension, asymmetry of A1 segments, the angle between A1 and A2 segments, A1 segment diameter, V m , pulsatility index, and volume flow rate turned out to be associated with the occurrence of ACoA aneurysms on univariate analysis. Multivariate analysis identified smoking (odds ratio, 2.036; 95% confidence interval, 1.277-3.245), asymmetry of A1 segments >40% (odds ratio, 2.524; 95% confidence interval, 1.275-4.996), pulsatility index (odds ratio, 0.004; 95% confidence interval, 0.000-0.124), and the angle between A1 and A2 segments ≤100° (odds ratio, 4.665; 95% confidence interval, 2.247-9.687) as independent strong risk factors for ACoA aneurysm development. Conclusions-The risk of ACoA aneurysm formation is determined by several independent clinical, morphological, and hemodynamic factors. The strongest independent risk factors include smoking, asymmetry of A1 segments >40%, low blood flow pulsatility, and the angle between A1 and A2 segments ≤100°. (Stroke. 2014;45:2906-2911.)

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Morphological, Hemodynamic, and Clinical Independent Risk Factors for Anterior Communicating Artery Aneurysms

Kaspera¹,

Ładziński²,

Larysz³

et al. 2014

Stroke

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“…22,24 Through detailed hemodynamics-histology mapping, we found that IA initiation at the BT (defined by regions of IEL loss) was associated with high WSS combined with positive WSS gradient above a threshold. 24,33 This hemodynamic condition, often associated with bifurcation apices, 34 has been recognized to independently cause de novo IA formation. 21,22,24,35 Kono et al 36 further provided clinical evidence that de novo BT aneurysms could be triggered by unphysiologically high local WSS and WSS gradient generated by proximal stenoses.…”

Section: Discussionmentioning

confidence: 99%

Aneurysmal Remodeling in the Circle of Willis after Carotid Occlusion in an Experimental Model

Tutino

Mandelbaum

Choi³

et al. 2013

J Cereb Blood Flow Metab

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Carotid occlusions are associated with de novo intracranial aneurysm formation in clinical case reports, but this phenomenon is not widely studied. We performed bilateral carotid ligation (n ¼ 9) in rabbits to simulate carotid occlusion, and sham surgery (n ¼ 3) for control. Upon euthanasia (n ¼ 3 at 5 days, n ¼ 6 at 6 months post ligation, and n ¼ 3 at 5 days after sham operation), vascular corrosion casts of the circle of Willis (CoW) were created. Using scanning electron microscopy, we quantified gross morphologic, macroscopic, and microscopic changes on the endocasts and compared findings with histologic data. At 5 days, CoW arteries of ligated animals increased caliber. The posterior communicating artery (PCom) increased length and tortuosity, and the ophthalmic artery (OA) origin presented preaneurysmal bulges. At 6 months, calibers were unchanged from 5 days, PComs further increased tortuosity while presenting segmental dilations, and the OA origin and basilar terminus presented preaneurysmal bulges. This exploratory study provides evidence that flow increase after carotid occlusion produces both compensatory arterial augmentation and pathologic remodeling such as tortuosity and saccular/fusiform aneurysm. Our findings may have considerable clinical implications, as these lesser-known consequences should be considered when managing patients with carotid artery disease or choosing carotid ligation as a therapeutic option.

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“…Animal studies conducted by Hashimoto et al 10 and Hazama et al 11 clearly showed that hemodynamic stress leads to degenerative changes of internal elastic lamina and muscularis media of arterial wall immediately adjacent to the apex of bifurcation. However, it is still not clear why aneurysms occur in some preferential site, like ACom complex, PCom complex and MCA bifarcation 12 . This issue was partially addressed in glass model studies, showing that the magnitude and distribution of hemodynamic stress on the vessel bifurcation depend not only on blood flow but also on the bifurcation angle and flow pulsatility [13][14] .…”

Section: Introductionmentioning

confidence: 99%

Risk Factors and Morphological Differences of Ruptured Saccular Aneurysm in Different Sites of Anterior Circulation in Patients Presenting with Subarachnoid Haemorrhage

Mahmud¹,

Habib

Khan

et al. 2018

J. Natl Inst. Neurosci Bangladesh

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Background: All sites of intracranial aneurysms have always been considered together in most of the studies of risk factors of aneurysm rupture. Therefore, it is not known whether some risk factors predispose to aneurysm rupture at a particular location. Morphologies also vary in accordance to different sites of the aneurysm. Objective: The purpose of the present study was to observe the differences in the risk factors, the size, aspect ratio and size ratio among the anterior circulation aneurysms. Methodology: This hospital based cross-sectional study carried out in the Department of Neurology at Dhaka Medical College Hospital (DMCH), Dhaka during July 2013 to June 2015 for a period of two (02) years. Patients with subarachnoid haemorrhage caused by ruptured anterior circulation saccular aneurysms admitted in the Departments of Neurology, Internal Medicine and Neurosurgery Departments at Dhaka Medical College Hospital (DMCH), Dhaka and the Department of Neurointervention at National Institute of Neurosciences and Hospital, Dhaka were enrolled in this study. Patients' ≥18 years of age with subarachnoid haemorrhage caused by anterior circulation aneurysm which was confirmed by computed tomogram (CT-scan) and/or CSF study and digital subtraction angiography were included in this study. The risk factors were identified by interviewing the patients and the morphology were measured from the digital subtraction angiogram. Results: A total number of 85 patients with ruptured saccular anterior circulation aneurysm were enrolled in this study. In this study anterior communicating artery aneurysm (ACom) was the most frequent site of aneurysm (42%). The mean age of the patients with ACom aneurysm (51.72 ± 9.26 years) was significantly higher than posterior communicating artery (47.5 ± 8.2 years) aneurysm and middle cerebral artery (MCA) (43.41 ± 8.0 years) aneurysm. Above the age of 50 ACom aneurysm was the most frequent aneurysm (OR 5.5, p<0.05). Among the female Posterior communicating artery (PCom) aneurysm (46.7%) was the most frequent aneurysm and among the male ACom aneurysm (37.5%) was the most frequent aneurysm. Family history was exclusive in MCA aneurysm (3.5%). The mean size of MCA (7.79 ± 0.71 cm) was higher than ACom (6.12 ± 2.7cm) aneurysm and PCom (6.5 ± 2.4 cm) aneurysm and proportion of aneurysm >10 mm was also higher among the middle cerebral artery (35.6%) aneurysms. The size ratio was significantly higher in ACom (3.08±1.23) and MCA (3.04±0.97) aneurysm. ACom (76.4%) and MCA (83.3%) had also more frequent high risk size ratio. Conclusion: In conclusion anterior circulation aneurysms differ in respects of risk factors and morphology.

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Intracranial Aneurysms Occur More Frequently at Bifurcation Sites That Typically Experience Higher Hemodynamic Stresses

Abstract: IAs occur more frequently at cerebral bifurcations that typically experience higher hemodynamic shear stress and stronger flow acceleration, conditions previously shown to promote aneurysm initiation in animals.

Cited by 81 publications

References 38 publications

Morphological, Hemodynamic, and Clinical Independent Risk Factors for Anterior Communicating Artery Aneurysms

Morphological, Hemodynamic, and Clinical Independent Risk Factors for Anterior Communicating Artery Aneurysms

Aneurysmal Remodeling in the Circle of Willis after Carotid Occlusion in an Experimental Model

Risk Factors and Morphological Differences of Ruptured Saccular Aneurysm in Different Sites of Anterior Circulation in Patients Presenting with Subarachnoid Haemorrhage

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