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Guo H, Liu JF, Li CH, Wang JW, Li H, Gao BL. Greater hemodynamic stresses initiate aneurysms on major cerebral arterial bifurcations. Front Neurol 2023; 14:1265484. [PMID: 37900605 PMCID: PMC10601459 DOI: 10.3389/fneur.2023.1265484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Accepted: 09/19/2023] [Indexed: 10/31/2023] Open
Abstract
Objective To retrospectively investigate the hemodynamic stresses in initiating aneurysm formation on major cerebral arterial bifurcations with computational fluid dynamics (CFD) analysis. Methods The cerebral 3D angiographic data of major cerebral arterial bifurcations of the internal carotid, middle cerebral, anterior cerebral, and basilar arteries in 80 patients harboring bifurcation aneurysms and 80 control subjects with no aneurysms were retrospectively collected for the CFD analysis of hemodynamic stresses associated with aneurysm formation. Results Bifurcation angles at major bifurcations in all patients were significantly positively (P < 0.001) correlated with the age. At the center of direct flow impingement (CDFI) on the bifurcation wall, total pressure was the highest but dropped rapidly toward the branches. Wall shear stress, dynamic pressure, strain rate, and vorticity were lowest at the CDFI but they increased quickly toward the branches. The bifurcation angle was significantly (P < 0.001) enlarged in patients with bifurcation aneurysms than those without them, for all major arterial bifurcations. Most aneurysms leaned toward the smaller arterial branch or the arterial branch that formed a smaller angle with the parent artery, where the hemodynamic stresses increased significantly (P < 0.05), compared with those on the contralateral arterial branch forming a larger angle with the parent artery. Following the aneurysm development, all the hemodynamic stresses on the aneurysm dome decreased significantly (P < 0.001) compared with those at the initiation site on the bifurcation wall after virtual aneurysm removal. With the decrease of bifurcation angles, all the hemodynamic stresses decreased. Conclusion The formation of intracranial aneurysms on major intracranial arterial bifurcations is significantly associated with locally abnormally augmented hemodynamic stresses, which must be reduced.
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Affiliation(s)
| | | | - Cong-Hui Li
- Department of Neurosurgery, The First Hospital, Hebei Medical University, Shijiazhuang, Hebei, China
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Guo H, Yang ST, Wang JW, Li H, Gao BL, Li CH. High hemodynamic stresses induce aneurysms at internal carotid artery bends. Medicine (Baltimore) 2023; 102:e34587. [PMID: 37543806 PMCID: PMC10402985 DOI: 10.1097/md.0000000000034587] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/07/2023] Open
Abstract
To investigate the role of hemodynamic stresses in initiating cerebral aneurysms at bends of internal carotid artery (ICA). Sixty-one patients with 68 aneurysms at ICA bends were retrospectively enrolled as the experiment group. Among the 61 patients, 30 normal ICAs without aneurysms were chosen as the control. All patients had 3-dimensional angiography and CFD analysis. The bending angle was significantly (P < .0001) smaller in the experiment than control group (131.2º ± 14.9º vs 150.3º ± 9.5º). The dynamic pressure, shear stress, vorticity magnitude and strain rate were the least at direct flow impinging center where the total pressure was very high. The dynamic stress, shear stress, strain rate and gradients of total pressure except for gradient 1 were significantly (P < .05) greater at the aneurysm site than at all the other sites. The total pressure at the aneurysm site was greater (P < .05) than at 1 lateral location and at the distal area but smaller (P < .05) than at the proximal area. The dynamic pressure, shear stress, strain rate and gradient of total pressure at the aneurysm site were significantly (P < .001) greater than on the aneurysm dome. The hemodynamic stresses were all significantly (P < .01) greater at the aneurysm site in the experiment group than at the site corresponding to the aneurysm in the control group. Aneurysms at the ICA bends are caused by direct flow impingement and increased hemodynamic stresses, and smaller arterial bending angles result in abnormally enhanced hemodynamic stresses to initiate an aneurysm near the flow impingement area.
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Affiliation(s)
- Hao Guo
- The First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Song-Tao Yang
- Neurosurgery Department, the Affiliated Hospital of North China University of Science and Technology, Shijiazhuang, Hebei Province, China
| | - Ji-Wei Wang
- The First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Hui Li
- The First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Bu-Lang Gao
- The First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Cong-Hui Li
- The First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China
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3
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The Cerebral Arterial Wall in the Development and Growth of Intracranial Aneurysms. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12125964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A considerable number of people harbor intracranial aneurysms (IA), which is a focal or segmental disease of the arterial wall. The pathophysiologic mechanisms of IAs formation, growth, and rupture are complex. The mechanism also differs with respect to the type of aneurysm. In broad aspects, aneurysms may be considered a disease of the vessel wall. In addition to the classic risk factors and the genetic/environmental conditions, altered structural and pathologic events along with the interaction of the surrounding environment and luminal flow dynamics contribute to the aneurysm’s development and growth. In this review, we have tried to simplify the complex interaction of a multitude of events in relation to vessel wall in the formation and growth of IAs.
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Chen B, Tao W, Li S, Zeng M, Zhang L, Huang Z, Chen F. Medial Gap: A Structural Factor at the Arterial Bifurcation Aggravating Hemodynamic Insult. J Neuropathol Exp Neurol 2022; 81:282-290. [PMID: 35312777 DOI: 10.1093/jnen/nlac017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Previous studies have reported that intracranial aneurysms frequently occur adjacent to the medial gap. However, the role of the medial gap in aneurysm formation is controversial. We designed this study to explore the potential role of the medial gap in aneurysm formation. Widened artery bifurcations with or without medial gaps were microsurgically created and pathologically stained in the carotid arteries of 30 rats. Numerical artery bifurcation models were constructed, and bidirectional fluid-solid interaction analyses were performed. Animal experiments showed that the apexes of widened bifurcations with a medial gap were prone to being insulted by blood flow compared to those without a medial gap. The bidirectional fluid-solid interaction analyses indicated that artery bifurcations with the medial gap exhibited higher wall shear stress (WSS) and von Mises stress (VMS) at the apex of the bifurcation. The disparity of stress between the gap and no-gap model was larger for widened bifurcations, peaking at 180° with a maximum of 1.9 folds. The maximum VMS and relatively high WSS were located at the junction between the medial gap and the adjacent arterial wall. Our results suggest that the medial gap at the widened arterial bifurcation may promote aneurysm formation.
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Affiliation(s)
- Bo Chen
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Wengui Tao
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Shifu Li
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Ming Zeng
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Liyang Zhang
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zheng Huang
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Fenghua Chen
- From the Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
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5
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Zhang X, Hao W, Han S, Ren CF, Yang L, Han Y, Gao B. Middle cerebral arterial bifurcation aneurysms are associated with bifurcation angle and high tortuosity. J Neuroradiol 2021; 49:392-397. [PMID: 34896148 DOI: 10.1016/j.neurad.2021.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/02/2021] [Accepted: 12/04/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE To investigate the association of middle cerebral artery (MCA) bifurcation aneurysms with bifurcation morphology. MATERIALS AND METHODS 205 patients were enrolled, including 61 patients with MCA bifurcation aneurysms and 144 non-aneurysmal subjects. Aneurysmal cases were divided into types C (aneurysm neck on extension of the parent artery centerline) and D (deviating neck). The radius of the parent artery M1 (RP) and bilateral branches (RS and RL, respectively), smaller (φS) and larger (φL) lateral angles, bifurcation angle, and arterial tortuosity from parent vessel to bilateral branches (TS and TL, respectively) were analyzed. Logistic regression and receiver operator characteristic (ROC) curve analysis were performed to identify risk factors and predictive values for MCA aneurysm presence and types. RESULTS In aneurysmal MCA bifurcations, bifurcating angle, TS, TL and RL were significantly larger (P<0.01), while φS was significantly smaller (P<0.001) than those in controls. The bifurcation angle, TS and LogitP were better morphological parameters for predicting MCA aneurysm presence with the AUC of 0.795, 0.932 and 0.951, respectively. Significant (P<0.05) differences were observed in the bifurcation angle, φL, RP, RL and TL between types C and D aneurysmal bifurcations. TL was an independent factor in discriminating types C from D aneurysms with an AUC of 0.802. CONCLUSIONS Bifurcation angle and arterial tortuosity from the parent artery to the branch forming a smaller angle with the parent artery have a higher value in distinguishing MCA aneurysmal from non-aneurysmal ones, and the tortuosity from the parent artery to the contralateral branch is the best indicator for distinguishing types C from D aneurysmal bifurcations.
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Affiliation(s)
- Xuejing Zhang
- Department of Medical Research and Neurosurgery, Shijiazhuang People's Hospital, China
| | - Weili Hao
- Department of Medical Research and Neurosurgery, Shijiazhuang People's Hospital, China
| | | | - Chun-Feng Ren
- Zhengzhou University First Affiliated Hospital, China
| | - Lei Yang
- Department of Medical Research and Neurosurgery, Shijiazhuang People's Hospital, China
| | - Yongfeng Han
- Department of Medical Research and Neurosurgery, Shijiazhuang People's Hospital, China
| | - Bulang Gao
- Department of Medical Research and Neurosurgery, Shijiazhuang People's Hospital, China.
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Malek AM, Hippelheuser JE, Lauric A. Vortex formation and associated aneurysmogenic transverse rotational shear stress near the apex of wide-angle cerebral bifurcations. J Neurosurg 2021:1-12. [PMID: 34715656 DOI: 10.3171/2021.6.jns204385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 06/15/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Aneurysm formation preferentially occurs at the site of wide-angle cerebral arterial bifurcations, which were recently shown to have a high longitudinal positive wall shear stress (WSS) gradient that promotes aneurysm formation. The authors sought to explore the other components of the hemodynamic environment that are altered with increasing bifurcation angle in the apical region and the effects of these components on WSS patterns on the vessel wall that may modulate aneurysm genesis and progression. METHODS Parametric models of symmetrical and asymmetrical bifurcations were created with increasing bifurcation angles (45°-240°), and 3D rotational angiography models of 13 middle cerebral artery (MCA) bifurcations (7 aneurysmal, 6 controls) were analyzed using computational fluid dynamics. For aneurysmal bifurcations, the aneurysm was digitally removed to uncover hemodynamics at the apex. WSS vectors along cross-sectional planes distal to the bifurcation apex were decomposed as orthogonal projections to the cut plane into longitudinal and transverse (tangential to the cross-sectional plane) components. Transverse rotational WSS (TRWSS) and TRWSS gradients (TRWSSGs) were sampled and evaluated at the apex and immediately distal from the apex. RESULTS In parametric models, increased bifurcation angle was associated with transverse flow vortex formation with emergence of an associated apical high TRWSS with highly aneurysmogenic positive TRWSSGs. While TRWSS decayed rapidly away from the apex in narrow-angle bifurcations, it remained greatly elevated for many radii downstream in aneurysm-prone wider bifurcations. In asymmetrical bifurcations, TRWSS was higher on the aneurysm-prone daughter vessel associated with the wider angle. Patient-derived models with aneurysmal bifurcations had wider angles (149.33° ± 12.56° vs 98.17° ± 8.67°, p < 0.001), with significantly higher maximum TRWSS (1.37 ± 0.67 vs 0.48 ± 0.23 Pa, p = 0.01) and TRWSSG (1.78 ± 0.92 vs 0.76 ± 0.50 Pa/mm, p = 0.03) compared to control nonaneurysmal bifurcations. CONCLUSIONS Wider vascular bifurcations are associated with a novel and to the authors' knowledge previously undescribed transverse component rotational wall shear stress associated with a positive (aneurysmogenic) spatial gradient. The resulting hemodynamic insult, demonstrated in both parametric models and patient-based anatomy, is noted to decay rapidly away from the protection of the medial pad in healthy narrow-angle bifurcations but remain elevated distally downstream of wide-angle aneurysm-prone bifurcations. This TRWSS serves as a new contribution to the hemodynamic environment favoring aneurysm formation and progression at wide cerebral bifurcations and may have clinical implications favoring interventions that reduce bifurcation angle.
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Affiliation(s)
- Adel M Malek
- 1Department of Neurosurgery, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts
| | - James E Hippelheuser
- 1Department of Neurosurgery, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts
| | - Alexandra Lauric
- 1Department of Neurosurgery, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts
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7
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Laarman MD, Ruigrok YM, Nierstrasz RCS, Spliet WGM, Van Hecke W, Algra A, Rinkel GJE. Histological Differences of the Vascular Wall Between Sites With High and Low Prevalence of Intracranial Aneurysm. J Neuropathol Exp Neurol 2019; 78:648-654. [PMID: 31058997 DOI: 10.1093/jnen/nlz036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Intracranial aneurysms (IAs) develop more often on bifurcations compared with the rest of the circle of Willis (CoW). We investigated histological differences between 2 high IA prevalence sites (anterior communicating artery [AcomA] and basilar tip) and 2 corresponding low IA prevalence sites (anterior cerebral artery [ACA] and basilar artery [BA]) using histological sections of 10 CoWs without IAs. Medial defect density in the AcomA was 0.24 medial defects/mm compared with 0.02 for the A1 part and 0.03 for the A2 part of the ACA. In the basilar tip we found 0.15 medial defects/mm compared with 0.14 in the BA. Vascular smooth muscle cells (VSMCs) were more often disorganized in both high-prevalence sites (AcomA: 10/10, basilar tip: 5/10) compared with low-prevalence sites (both ACA and BA: 1/10). Intima thickening was more severe in the high-prevalence sites. Vascular wall thickness was not significantly different between high- and low-prevalence sites, but had a larger variance in high- compared with low-prevalence sites (AcomA vs ACA: p = 6.8E-12, basilar tip vs BA: p = 0.02). Disorganized VSMCs at high-prevalence sites likely result in a higher susceptibility to hemodynamic stress, leading to more vascular remodeling (such as intima thickening), which could increase the likelihood of IA formation.
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Affiliation(s)
- Melanie D Laarman
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht.,Hubrecht Institute-KNAW and University Medical Center Utrecht
| | - Ynte M Ruigrok
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht
| | - Renske C S Nierstrasz
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht
| | - Wim G M Spliet
- Department of Pathology, University Medical Center Utrecht
| | - Wim Van Hecke
- Department of Pathology, University Medical Center Utrecht.,Princess Máxima Center for Pediatric Oncology
| | - Ale Algra
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht.,Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Gabriël J E Rinkel
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht
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Zhang XJ, Li CH, Hao WL, Zhang DH, Gao BL. The Optimality Principle Decreases Hemodynamic Stresses for Aneurysm Initiation at Anterior Cerebral Artery Bifurcations. World Neurosurg 2019; 121:e379-e388. [PMID: 30266713 DOI: 10.1016/j.wneu.2018.09.112] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/12/2018] [Accepted: 09/15/2018] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To investigate hemodynamic stresses on anterior cerebral artery bifurcation apex and possible mechanism of the optimality principle in protecting bifurcation wall from supercharged hemodynamic stresses. METHODS Three-dimensional angiographic datasets of 122 patients with anterior communicating artery (Acom) aneurysms, 21 patients with non-Acom aneurysms, and 220 control subjects with no aneurysms were used. Radii of parent (r0) and daughter branches (r1 and r2) were measured, and bifurcations obeying the optimality principle required optimal caliber control of r0n = r1n + r2n, with the junction exponent n approximating 3. Radius ratio = r03/(r13 + r23) and n were compared between aneurysmal and control bifurcations. Blood flow was simulated for analysis of hemodynamic stresses. RESULTS Acom bifurcations in subjects without Acom aneurysms displayed optimal caliber radius, with mean radius ratio of 0.99 and n of 3.25, whereas Acom aneurysmal bifurcations had significantly lower radius ratio, 0.62 (P < 0.05), but higher n, 4.23 (P < 0.05). Peak wall shear stress and corresponding total pressure were significantly smaller for bifurcations obeying than disobeying the optimality principle (P < 0.001 and P < 0.05, respectively). Total pressures in the direct impinging center, peak wall shear stress distance, and anterior cerebral artery bifurcation angle all were significantly smaller for bifurcations obeying than disobeying the optimality principle (P < 0.05 and P < 0.001, respectively). CONCLUSIONS Normal anterior cerebral artery bifurcations obey the optimality principle whereas bifurcations with Acom aneurysms do not. Disobeying the optimality principle presents significantly enhanced hemodynamic stresses to possibly damage the bifurcation wall for aneurysm initiation.
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Affiliation(s)
- Xue-Jing Zhang
- Department of Neurosurgery, The First Hospital, Hebei Medical University, Shijiazhuang, China; Department of Medical Research, Shijiazhuang First Hospital, Hebei Medical University, Shijiazhuang, China
| | - Cong-Hui Li
- Department of Neurosurgery, The First Hospital, Hebei Medical University, Shijiazhuang, China
| | - Wei-Li Hao
- Department of Medical Research, Shijiazhuang First Hospital, Hebei Medical University, Shijiazhuang, China
| | | | - Bu-Lang Gao
- Department of Neurosurgery, The First Hospital, Hebei Medical University, Shijiazhuang, China; Department of Medical Research, Shijiazhuang First Hospital, Hebei Medical University, Shijiazhuang, China.
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9
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Feng X, Ji W, Qian Z, Liu P, Kang H, Wen X, Xu W, Li Y, Jiang C, Wu Z, Liu A. Bifurcation Location Is Significantly Associated with Rupture of Small Intracranial Aneurysms (<5 mm). World Neurosurg 2016; 98:538-545. [PMID: 27888082 DOI: 10.1016/j.wneu.2016.11.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 11/11/2016] [Accepted: 11/12/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND AND OBJECTIVE Patients with small (<5 mm) unruptured intracranial aneurysms (UIAs) are at risk of subarachnoid hemorrhage, but risk assessment of these patients remains controversial in daily clinical practice. We aimed to identify the risk factors of aneurysmal rupture in these patients. METHODS We retrospectively analyzed consecutive patients with small UIAs who were admitted to our center between February 2009 and December 2014. The enrolled patients were divided into ruptured and unruptured groups. The risk factors for aneurysmal rupture were determined using multivariate logistic regression analysis. RESULTS A total of 548 patients with 618 small intracranial aneurysms (267 ruptured and 351 unruptured) were included. Univariate analysis showed that rupture of small aneurysms was related to sex, age, smoking, hypertension, aspect ratio, size ratio, irregular shape, aneurysm width, height, and neck diameter, and location at bifurcation or posterior circulation. Multivariate logistic regression showed that rupture was associated with bifurcation location (odds ratio [OR], 5.409; 95% confidence interval [CI], 3.656-8.001; P < 0.001), size ratio (OR, 3.092; 95% CI, 2.002-4.774; P < 0.001), location (OR, 2.624; 95% CI, 1.428-4.824; P = 0.002), hypertension (OR, 1.698; 95% CI, 1.1140-2.527; P = 0.009), and age at diagnosis of UIA (OR, 1.826; 95% CI, 1.225-2.723; P = 0.003). CONCLUSIONS This study showed that 70.4% of small ruptured intracranial aneurysms (<5 mm) were located at parent artery bifurcations and that bifurcation location was a significant independent factor for the risk of rupture of small UIAs (<5 mm). Prophylactic treatment should be recommended for small UIAs in this location.
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Affiliation(s)
- Xin Feng
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wenjun Ji
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zenghui Qian
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Peng Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Huibin Kang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xiaolong Wen
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wenjuan Xu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Youxiang Li
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Chuhan Jiang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zhongxue Wu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Aihua Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
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10
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Basic Principles of Hemodynamics and Cerebral Aneurysms. World Neurosurg 2016; 88:311-319. [DOI: 10.1016/j.wneu.2016.01.031] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 01/03/2016] [Accepted: 01/05/2016] [Indexed: 11/18/2022]
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11
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Tütüncü F, Schimansky S, Baharoglu MI, Gao B, Calnan D, Hippelheuser J, Safain MG, Lauric A, Malek AM. Widening of the basilar bifurcation angle: association with presence of intracranial aneurysm, age, and female sex. J Neurosurg 2014; 121:1401-10. [DOI: 10.3171/2014.8.jns1447] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Arterial bifurcations represent preferred locations for aneurysm formation, especially when they are associated with variations in divider geometry. The authors hypothesized a link between basilar apex aneurysms and basilar bifurcation (α) and vertebrobasilar junction (VBJ) angles.
Methods
The α and VBJ angles were measured in 3D MR and rotational angiographic volumes using a coplanar 3-point technique. Angle α was compared between age-matched cohorts in 45 patients with basilar artery (BA) aneurysms, 65 patients with aneurysms in other locations (non-BA), and 103 nonaneurysmal controls. Additional analysis was performed in 273 nonaneurysmal controls. Computational fluid dynamics (CFD) simulations were performed on parametric BA models with increasing angles.
Results
Angle α was significantly wider in patients with BA aneurysms (146.7° ± 20.5°) than in those with non-BA aneurysms (111.7° ± 18°) and in controls (103° ± 20.6°) (p < 0.0001), whereas no difference was observed for the VBJ angle. A wider angle α correlated with BA aneurysm neck width but not dome size, which is consistent with CFD results showing a widening of the impingement zone at the bifurcation apex. BA bifurcations hosting even small aneurysms (< 5 mm) had a significantly larger α angle compared with matched controls (p < 0.0001). In nonaneurysmal controls, α increased with age (p < 0.0001), with a threshold effect above 35 years of age and a steeper dependence in females (p = 0.002) than males (p = 0.04).
Conclusions
The α angle widens with age during adulthood, especially in females. This angular widening is associated with basilar bifurcation aneurysms and may predispose individuals to aneurysm initiation by diffusing the flow impingement zone away from the protective medial band region of the flow divider.
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12
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Validation of compliance zone at cerebral arterial bifurcation using phantom and computational fluid dynamics simulation. J Comput Assist Tomogr 2014; 38:480-4. [PMID: 24681853 DOI: 10.1097/rct.0000000000000056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE A zone compliant to pulsatile flow (compliance zone) showing evagination and flattening at the apex of the cerebral arterial bifurcation was documented in our previous report using electrocardiogram-gated computed tomographic and magnetic resonance angiography. We aimed to validate the existence of compliance zones and examine their relationship to local thin-elastic walls. METHODS We examined different bifurcating vascular models: a phantom with a thin elastic region at the apex and computational fluid dynamics models with either an elastic or rigid region at the apex of a bifurcation. RESULTS In the phantom, the elastic region at the apex of the bifurcation showed evagination and flattening in time with the pulsatile circulating fluids. The size of the evaginations increased when the outlet side was tilted down below the level of the flow-generating pump. Pulsatile evagination could be simulated in the computational fluid dynamics model with an elastic region at the bifurcation apex, and the pressure gradient was highest in the evaginating apex in peak systolic phase. CONCLUSIONS We were able to demonstrate a compliance zone, which responds to pressure gradients, experimentally, in the form of a thin elastic region at an arterial bifurcation.
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Wang J, Tan HQ, Zhu YQ, Li MH, Li ZZ, Yan L, Cheng YS. Complex hemodynamic insult in combination with wall degeneration at the apex of an arterial bifurcation contributes to generation of nascent aneurysms in a canine model. AJNR Am J Neuroradiol 2014; 35:1805-12. [PMID: 24788130 DOI: 10.3174/ajnr.a3926] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The detailed mechanisms of cerebral aneurysm generation remain unclear. Our aim was to investigate whether specific hemodynamic insult in combination with arterial wall degeneration leads to the development of aneurysms in a canine model. MATERIALS AND METHODS New branch points in the common carotid artery were created in 18 dogs. Nine animals subsequently received elastase insult at the arterial bifurcation apex (elastase-treated bifurcation group); the control bifurcation group (n=9) received saline, and 3 dogs received an elastase insult to both straight common carotid arteries (elastase-treated straight group). Angiographic and hemodynamic analysis was performed immediately and 12 and 24 weeks' postsurgery; histologic response was evaluated at 12 and 24 weeks. RESULTS Angiography revealed nascent aneurysms (mean, 3.2±0.4 mm) at the arterial bifurcation apices in 5/9 models of the elastase-treated bifurcation group (versus 0 in the control bifurcation group and elastase-treated straight group) without any observed aneurysm rupture. Histologic analysis revealed internal elastic lamina discontinuity, elastic fiber disruption, a thinner muscular layer, reduced smooth-muscle cell proliferation, increased inflammatory cell (macrophage) infiltration, and expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in the media of the elastase-treated bifurcation group compared with that in either the control bifurcation group or the elastase-treated straight group (P<.001). Hemodynamic analysis after surgery indicated that the apex experienced extremely low wall shear stress and flow velocity and the highest relative and total pressure in the elastase-treated bifurcation group, while the values returned to normal after arterial wall remodelling. CONCLUSIONS In our study, combined hemodynamic insult and arterial wall degeneration at arterial bifurcations are required for the generation of aneurysms in a canine model.
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Affiliation(s)
- J Wang
- From the Department of Diagnostic and Interventional Radiology (J.W., H.-Q.T., Y.-Q.Z., M.-H.L., L.Y., Y.-S.C.), Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - H-Q Tan
- From the Department of Diagnostic and Interventional Radiology (J.W., H.-Q.T., Y.-Q.Z., M.-H.L., L.Y., Y.-S.C.), Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Y-Q Zhu
- From the Department of Diagnostic and Interventional Radiology (J.W., H.-Q.T., Y.-Q.Z., M.-H.L., L.Y., Y.-S.C.), Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - M-H Li
- From the Department of Diagnostic and Interventional Radiology (J.W., H.-Q.T., Y.-Q.Z., M.-H.L., L.Y., Y.-S.C.), Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Z-Z Li
- School of Mechanical Engineering (Z.-Z.L.), Shanghai Jiao Tong University, Shanghai, China
| | - L Yan
- From the Department of Diagnostic and Interventional Radiology (J.W., H.-Q.T., Y.-Q.Z., M.-H.L., L.Y., Y.-S.C.), Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Y-S Cheng
- From the Department of Diagnostic and Interventional Radiology (J.W., H.-Q.T., Y.-Q.Z., M.-H.L., L.Y., Y.-S.C.), Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
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Wright SN, Kochunov P, Mut F, Bergamino M, Brown KM, Mazziotta JC, Toga AW, Cebral JR, Ascoli GA. Digital reconstruction and morphometric analysis of human brain arterial vasculature from magnetic resonance angiography. Neuroimage 2013; 82:170-81. [PMID: 23727319 PMCID: PMC3971907 DOI: 10.1016/j.neuroimage.2013.05.089] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/15/2013] [Accepted: 05/16/2013] [Indexed: 01/26/2023] Open
Abstract
Characterization of the complex branching architecture of cerebral arteries across a representative sample of the human population is important for diagnosing, analyzing, and predicting pathological states. Brain arterial vasculature can be visualized by magnetic resonance angiography (MRA). However, most MRA studies are limited to qualitative assessments, partial morphometric analyses, individual (or small numbers of) subjects, proprietary datasets, or combinations of the above limitations. Neuroinformatics tools, developed for neuronal arbor analysis, were used to quantify vascular morphology from 3T time-of-flight MRA high-resolution (620 μm isotropic) images collected in 61 healthy volunteers (36/25 F/M, average age=31.2 ± 10.7, range=19-64 years). We present in-depth morphometric analyses of the global and local anatomical features of these arbors. The overall structure and size of the vasculature did not significantly differ across genders, ages, or hemispheres. The total length of the three major arterial trees stemming from the circle of Willis (from smallest to largest: the posterior, anterior, and middle cerebral arteries; or PCAs, ACAs, and MCAs, respectively) followed an approximate 1:2:4 proportion. Arterial size co-varied across individuals: subjects with one artery longer than average tended to have all other arteries also longer than average. There was no net right-left difference across the population in any of the individual arteries, but ACAs were more lateralized than MCAs. MCAs, ACAs, and PCAs had similar branch-level properties such as bifurcation angles. Throughout the arterial vasculature, there were considerable differences between branch types: bifurcating branches were significantly shorter and straighter than terminating branches. Furthermore, the length and meandering of bifurcating branches increased with age and with path distance from the circle of Willis. All reconstructions are freely distributed through a public database to enable additional analyses and modeling (cng.gmu.edu/brava).
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Affiliation(s)
- Susan N. Wright
- Krasnow Inst. for Advanced Study, George Mason Univ., Fairfax, VA, USA
| | - Peter Kochunov
- Univ. of Texas, Health Science Center in San Antonio, USA
| | - Fernando Mut
- Center for Computational Fluid Dynamics, George Mason Univ., Fairfax, VA, USA
| | | | - Kerry M. Brown
- Krasnow Inst. for Advanced Study, George Mason Univ., Fairfax, VA, USA
| | | | | | - Juan R. Cebral
- Krasnow Inst. for Advanced Study, George Mason Univ., Fairfax, VA, USA
- Center for Computational Fluid Dynamics, George Mason Univ., Fairfax, VA, USA
| | - Giorgio A. Ascoli
- Krasnow Inst. for Advanced Study, George Mason Univ., Fairfax, VA, USA
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15
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Sadasivan C, Fiorella DJ, Woo HH, Lieber BB. Physical factors effecting cerebral aneurysm pathophysiology. Ann Biomed Eng 2013; 41:1347-65. [PMID: 23549899 DOI: 10.1007/s10439-013-0800-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 03/21/2013] [Indexed: 12/21/2022]
Abstract
Many factors that are either blood-, wall-, or hemodynamics-borne have been associated with the initiation, growth, and rupture of intracranial aneurysms. The distribution of cerebral aneurysms around the bifurcations of the circle of Willis has provided the impetus for numerous studies trying to link hemodynamic factors (flow impingement, pressure, and/or wall shear stress) to aneurysm pathophysiology. The focus of this review is to provide a broad overview of such hemodynamic associations as well as the subsumed aspects of vascular anatomy and wall structure. Hemodynamic factors seem to be correlated to the distribution of aneurysms on the intracranial arterial tree and complex, slow flow patterns seem to be associated with aneurysm growth and rupture. However, both the prevalence of aneurysms in the general population and the incidence of ruptures in the aneurysm population are extremely low. This suggests that hemodynamic factors and purely mechanical explanations by themselves may serve as necessary, but never as necessary and sufficient conditions of this disease's causation. The ultimate cause is not yet known, but it is likely an additive or multiplicative effect of a handful of biochemical and biomechanical factors.
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Affiliation(s)
- Chander Sadasivan
- Department of Neurological Surgery, Stony Brook University Medical Center, 100 Nicolls Road, HSC T12, Room 080, Stony Brook, NY 11794-8122, USA
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16
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Ohara K, Kimura T, Karasawa T, Tokuyama H, Wakino S, Hayashi K, Itoh H, Okada Y. A large coronary aneurysm and its probable precursor lesions in a patient with autosomal dominant polycystic kidney disease: An implication for the process of aneurysmogenesis. Pathol Int 2012; 62:758-62. [DOI: 10.1111/pin.12007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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A remodelling metric for angular fibre distributions and its application to diseased carotid bifurcations. Biomech Model Mechanobiol 2011; 11:869-82. [DOI: 10.1007/s10237-011-0358-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 10/25/2011] [Indexed: 10/15/2022]
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18
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Current status of computational fluid dynamics for cerebral aneurysms: The clinician’s perspective. J Clin Neurosci 2011; 18:1285-8. [DOI: 10.1016/j.jocn.2011.02.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 01/31/2011] [Accepted: 02/05/2011] [Indexed: 11/19/2022]
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Echocardiogram-gated computed tomographic and magnetic resonance angiographies for the detection of pulsatile expansion at the intracranial arterial bifurcation. J Comput Assist Tomogr 2010; 34:842-6. [PMID: 21084898 DOI: 10.1097/rct.0b013e3181ecc265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To identify the pulsatile small vascular lesion by echocardiogram (ECG)-gated computed tomographic (CT) and magnetic resonance (MR) angiographies. METHODS Seven patients who exhibited small evagination at the cerebral artery bifurcations on 3-dimensional (3D) time-of-flight MR angiogram were enrolled. They were examined by conventional/ECG-gated CT angiogram (n = 6) and ECG-gated MR angiogram (n = 5). Echocardiogram-gated MR angiogram was performed with 3D time of flight, triggered after each time window. From ECG-gated CT and MR angiograms, consecutive 10-phase images within a single cardiac cycle were obtained. RESULTS The pulsatile change of evagination was demonstrated on both ECG-gated CT angiogram (5 of 6 patients) and ECG-gated MR angiogram (all 5 patients). Flattening of the evagination during the diastolic phase was observed in 4 of 6 ECG-gated CT angiograms and 3 of 5 ECG-gated MR angiograms. Of note was a patient with a tiny evagination (<2 × 1 mm); pulsatile change was demonstrated only by ECG-gated MR angiogram. CONCLUSION The pulsatile expansion of evagination at the cerebral artery bifurcation can be demonstrated on ECG-gated CT/MR angiograms.
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Nixon AM, Gunel M, Sumpio BE. The critical role of hemodynamics in the development of cerebral vascular disease. J Neurosurg 2010; 112:1240-53. [DOI: 10.3171/2009.10.jns09759] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Atherosclerosis and intracranial saccular aneurysms predictably localize in areas with complex arterial geometries such as bifurcations and curvatures. These sites are characterized by unique hemodynamic conditions that possibly influence the risk for these disorders. One hemodynamic parameter in particular has emerged as a key regulator of vascular biology—wall shear stress (WSS). Variations in geometry can change the distribution and magnitude of WSS, thus influencing the risk for vascular disorders. Computer simulations conducted using patient-specific data have suggested that departures from normal levels of WSS lead to aneurysm formation and progression. In addition, multiple studies indicate that disturbed flow and low WSS predispose patients to extracranial atherosclerosis, and particularly to carotid artery disease. Conversely, in the case of intracranial atherosclerosis, more studies are needed to provide a firm link between hemodynamics and atherogenesis. The recognition of WSS as an important factor in cerebral vascular disease may help to identify individuals at risk and guide treatment options.
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Affiliation(s)
| | - Murat Gunel
- 2Neurosurgery, Yale University School of Medicine, New Haven, Connecticut
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Jeong SK, Kwak HS, Cho YI. Middle cerebral artery fenestration in patients with cerebral ischemia. J Neurol Sci 2008; 275:181-4. [PMID: 18801495 DOI: 10.1016/j.jns.2008.07.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 07/23/2008] [Accepted: 07/31/2008] [Indexed: 11/25/2022]
Abstract
BACKGROUND We report five cases of middle cerebral artery (MCA) fenestration that might have caused cerebral infarction or ischemia. CASE REPORT Unilateral fenestration of the MCA was observed in five patients with artery-relevant cerebral infarction or ischemia. Enhanced magnetic resonance imaging (MRI) and three-dimensional MR angiography (MRA) were performed in the patients, and a division of the lumen after fenestration was observed using virtual arterial endoscopy. In one patient, MRA and virtual endoscopy showed an obstruction in one limb of the fenestration. The MCA fenestrations were observed in the proximal portion in three cases and the intermediate portion in two cases, and there was no associated aneurysm near or far from the fenestration. METHODS The five patients underwent both contrast-enhanced magnetic resonance imaging (MRI) and 3D MRA. Virtual arterial endoscopy was then performed to visualize the division of the lumen, a landmark of fenestration. CONCLUSIONS The association between cerebral ischemia and MCA fenestration in the five cases suggests that the fenestration disturbing local flow hemodynamics seems to cause cerebral ischemia, even a direct causative relationship should be elucidated further.
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Affiliation(s)
- Seul-Ki Jeong
- Department of Neurology & Research Institute of Clinical Medicine, Chonbuk National University Medical School & Hospital, San 2-20, Geumam-dong, Deokjin-gu, Jeonju, Chonbuk, South Korea (561-180).
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Thomas AJ, Germanwala AV, Vora N, Prevedello DM, Jovin T, Kassam A, Horowitz M. Dual Origin Extracranial Vertebral Artery: Case Report and Embryology. J Neuroimaging 2008; 18:173-6. [DOI: 10.1111/j.1552-6569.2007.00182.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Hariton I, deBotton G, Gasser TC, Holzapfel GA. Stress-modulated collagen fiber remodeling in a human carotid bifurcation. J Theor Biol 2007; 248:460-70. [PMID: 17631909 DOI: 10.1016/j.jtbi.2007.05.037] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 05/06/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
This work concerns with the implementation of a new stress-driven remodeling model for simulating the overall structure and mechanical behavior of a human carotid bifurcation. By means of an iterative finite element based procedure collagen fiber direction and maximal principal stresses are computed. We find that the predicted fibers' architecture at the cylindrical branches and at the apex of the bifurcation correlates well with histological observations. Some insights about the mechanical response of the sinus bulb and the bifurcation apex are revealed and discussed. The results are compared with other, isotropic and orthotropic, models available in the literature.
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Affiliation(s)
- I Hariton
- The Pearlstone Center for Aeronautical Studies, Department of Mechanical Engineering, Ben-Gurion University, Beer-Sheva 84105, Israel
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