Incidental finding of fenestration of the supraclinoid internal carotid artery with appearances on magnetic resonance angiography

A case of incidentally diagnosed fenestration of the supraclinoid internal carotid artery (ICA) with an associated aneurysm is presented. We present appearances on magnetic resonance angiography, which have not been previously described. Careful interrogation of the data in volume-rendered and multiplanar reformats was required to make the diagnosis. The relationship between fenestrations and aneurysms in the anterior circulation is discussed both in general terms and with specific regard to the supraclinoid ICA. We also review the embryology of the distal ICA, which may help explain the adult anatomy of this rare lesion as a failure of caudal separation of the rostral and caudal divisions of the primitive distal ICA.     

Early changes in cerebral aneurysms in the internal carotid artery/posterior communicating artery junction

In order to obtain information about preaneurysmal changes, the junction of the internal carotid artery/posterior communicating artery (ICA/PComA) in the circles of Willis in subjects with aneurysms at sites other than the junction, and in control subjects without aneurysms, were studied by light microscopy. Small evaginations and thinnings of the media with and without dilatation were observed at the apical areas of the forks with a significantly higher incidence in the aneurysm series than in the control, suggesting some predisposing factor in subjects with aneurysms. As well as funnel-shaped dilatations previously described as the only type of ICA/PComA preaneurysmal change, other more localized types were observed. All the small evaginations and about half of the thinnings and dilatations were observed at the apex in association with a medial gap, but the other half occurred at some distance from the apex. The thinned arterial wall showed degenerative changes of the elastic lamina and media. Intimal pads were observed at the apex, the ICA/PComA lateral angle and the ICA stem/branch curve. Their combination with preaneurysmal changes was more frequent in the aneurysm series in comparison with the control. Degenerative changes of the elastic lamina and media caused by hemodynamic stress due to branching structures including intimal pads are thus presumed to be the initial lesions existing prior to aneurysm formation.     

Duplicate origin of the posterior communicating artery diagnosed by magnetic resonance angiography

Extremely rarely, a posterior communicating artery (PCoA) of “duplicate origin” occurs when two branches of the PCoA arise separately from the supraclinoid segment of the internal carotid artery (ICA) and quickly fuse to form an arterial ring. Three such cases previously reported were described as “fenestration.” We report the case of this rare variation diagnosed by magnetic resonance angiography and discuss the differentiation of PCoA of duplicate origin from PCoA fenestration, supraclinoid ICA fenestration, and hyperplastic anterior choroidal artery.     

锁孔择期手术治疗破裂的大脑中动脉瘤32例

目的探讨锁孔神经外科手术治疗后交通动脉瘤的手术技巧和适应证。方法回顾性分析32例破裂的大脑中动脉瘤病例,全部经DSA或CTA确诊,出血2周后行眉弓上锁孔开颅,显微神经外科手术动脉瘤夹闭。结果 32例全部夹闭,无1例死亡,治愈率100%。术后1周内头部CTA,动脉瘤消失,载瘤动脉通畅,动脉瘤夹固定良好。10例于术后3～6个月进行了随访（CTA或DSA）,未见复发。结论锁孔手术是治疗大脑中动脉瘤的微创治疗技术,减少了手术创伤及并发症,恰当地选择适应证和手术时机及应用显微外科技术是治疗的关键。     

经翼点入路鞍区手术间隙解剖学研究

目的　为鞍区显微外科手术提供解剖学参数。方法　对 10具成人尸体头颅的鞍区手术间隙及邻近血管、神经进行解剖学观察、测量。结果　大脑中动脉M1段在距颈内动脉分叉部 18.4± 3.2mm处形成初级分叉 ,向后上方发出约 14支穿支 ,分布至基底节区。鞍结节后缘至视交叉前缘相距 5 .6± 1.1mm ,两侧视神经内侧缘间最大距离 10 .5± 1.4mm。颈内动脉从内侧壁发出 3.2支垂体上动脉 ,终止于视神经、视交叉、视束和垂体柄 ;视神经 -颈内动脉三角三边长度分别为 6 .6± 0 .6mm ,6 .9± 0 .7mm ,4 .0± 0 .4mm。颈内动脉 -小脑幕三角三边长度为 8.8± 0 .7mm ,6 .7± 0 .7mm ,4 .4± 1.0mm ,后交通动脉起自颈内动脉后外壁距分叉部 7.7± 0 .5mm ,止于大脑后动脉 ,全长 18.7± 2 .3mm ,途中发出 7.4条穿通支。脉络膜前动脉从距分叉部 4 .4± 0 .6mm处发出 ,向后方走行 ,发出细小分支 ,分布于钩回、脉络丛。前交通动脉全长 1.9± 0 .3mm ,在前交通动脉上方 0 .9± 0 .2mm ,大脑前动脉A2段前外壁发出Heubner回返动脉 ,分布于胼胝体、基底节、下丘脑及额叶脑组织。结论　应用这些间隙的解剖学测量可指导与鞍区相关的手术 ,安全显露鞍区解剖结构 ,不损伤重要的血管和神经。     

大脑前动脉的A1优势征及在前交通动脉瘤脑血管造影诊断中的意义

目的：探讨A1优势征的影像学表现及其出现率与大脑前交通动脉瘤的关系.方法：回顾性分析128例脑动脉瘤数字减影脑血管造影的影像学资料.以大脑前交通动脉瘤作为试验组,其他部位的动脉瘤作为对照组.结果：128例病人中,共139个动脉瘤.前交通动脉瘤49个,后交通动脉瘤41个,基底动脉瘤29个,大脑中动脉瘤14个,颈内动脉瘤6个.A1优势征58例,A1对称75例.结论：前交通动脉瘤Al优势征多见,其出现率与其他部位脑动脉瘤之间存在显著差异（P＜0.05）.     

Wall Shear Stress and Pressure Distribution on Aneurysms and Infundibulae in the Posterior Communicating Artery Bifurcation

A growing number of cases of rupture at an infundibulum, progression of infundibulum to a frank aneurysm, and subarachnoid hemorrhage (SAH) in the posterior communicating artery (PCoA) have been reported. Using patient-specific geometric models of the supraclinoid internal carotid artery (ICA) with PCoA infundibulum or aneurysm, high-resolution computational fluid dynamics simulations were performed by solving the Navier–Stokes equations with a spectral/hp element method. Simulation results show that the flow impinges at the distal wall of infundibulum near the outside of the ICA bend and creates a region of higher pressure (4–5 mmHg) surrounded by a band of a high wall shear stress (WSS) (20–30 N/m² on average). At the proximal end of the infundibulum, another stagnation area is formed characterized by low WSS (<1 N/m²) and high oscillating shear index. This impingement region seems to coincide with the locations of the rupture of infundibulae or progression to aneurysms. In addition, the pulsatile flow becomes unstable due to the presence of aneurysms or aneurysm-like infundibulae, and this leads to WSS temporal fluctuations inside the aneurysm, which may accelerate the degenerative processes in the vessel walls.     

Points to consider when evaluating three-dimensional digital subtraction angiography of intracranial aneurysms and their effects on treatment

Background/aimIn this study, we aimed to investigate what should be regarded as potential determinants of treatment strategies when evaluating 3D digital subtraction angiography (DSA) images.Material and methodsOur inclusion criteria were as follows: (1) presence of at least one intracranial aneurysm demonstrated by conventional angiography, (2) having both 2D and 3D images, and (3) being over 18 years old. First, two-dimensional (2D) and then 3D angiography images of 226 aneurysms of 150 patients were scanned. Morphological characteristics such as size, configurations, relationship with parent artery, baby counts, and other incidental findings were determined.ResultsOf the 226 aneurysms, 11 (4.9%) were only detected on 3D images. Four of these 11 additional aneurysms were believed to be babies of other aneurysms seen in 2D images. Middle cerebral artery (MCA) M1 segment was the most common localization in terms of missed aneurysms. Of the 28 aneurysms located in the communicating segment of the internal carotid artery, the absolute locations of 7 (25%) could not be detected in 2D images or detected in the wrong location. Of the 24 aneurysms located in the ophthalmic segment, the origin of 8 (33%) could not be clearly identified in 2D images. Truncus relationships of MCAs bifurcation/trifurcation aneurysms were seen in 41 of 63 aneurysms (65%) on 2D images, whereas all were confirmed on 3D images. Fenestrations not seen in 2D images were identified in 3D images of 4 patients (3%).ConclusionThe superiority of 3D images compared to 2D images in determining the morphologic characteristics of intracranial aneurysms has been known for a long time. The contribution of 3D images to the treatment can be summarized as evaluating the parent artery relationship, revealing the number and shapes of aneurysm babies more clearly, detecting fenestrations, and shortening procedure time by finding the correct working angle.     

Current Knowledge of and Perspectives about the Pathogenesis of Blood Blister-like Aneurysms of the Internal Carotid Artery: A Review of the Literature

Blood blister-like aneurysms (BBAs) are rare and usually appear at nonbranching sites in the supraclinoid portion of the internal carotid artery (ICA). Because it is difficult to obtain histological specimens of the aneurysm wall and because experimental models are challenging to establish, the pathogenesis of BBAs remains uncertain. In this paper, we reviewed the diagnostic, radiological, and pathophysiological characteristics of patients with BBAs. We also summarized the existing evidence and potential mechanisms related to the causes of BBAs. Current evidence indicates that atherosclerosis and dissection are the main prerequisites for the formation of BBAs. Hemodynamics may play a role in the process of BBA formation due to the unique vascular anatomy of the supraclinoid ICA. Further research on histopathology and hemodynamics is warranted in this field.     

EARLY CHANGES IN CEREBRAL ANEURYSMS IN THE INTERNAL CAROTID ARTERY/POSTERIOR COMMUNICATING ARTERY JUNCTION

In order to obtain information about preaneurysmal changes, the junction of the internal carotid artery/posterior communicating artery (ICA/PComA) in the circles of Willis in subjects with aneurysms at sites other than the junction, and in control subjects without aneurysms, were studied by light microscopy.
Small evaginations and thinnings of the media with and without dilatation were observed at the apical areas of the forks with a significantly higher incidence in the aneurysm series than in the control, suggesting some predisposing factor in subjects with aneurysms. As well as funnel-shaped dilatations previously described as the only type of ICA/PComA preaneurysmal change, other more localized types were observed. All the small evaginations and about half of the thinnings and dilatations were observed at the apex in association with a medial gap, but the other half occured at some distance from the apex. The thinned arterial wall showed degenerative changes of the elastic lamina and media. Intimal pads were observed at the apex, the ICA/PComA lateral angle and the ICA stem/branch curve. Their combination with preaneurysmal changes was more frequent in the aneurysm series in comparison with the control.
Degenerative changes of the elastic lamina and media caused by hemodynamic stress due to branching structures including intimal pads are thus presumed to be the initial lesions existing prior to aneurysm formation.     

Anatomic evaluation of the carotid artery bifurcation in cadavers: implications for open and endovascular therapy

Knowledge of carotid bifurcation (CB), common carotid artery (CCA) and its branches and their recognition during diagnostic imaging are also important for vascular surgical procedures in the region, such as carotid endarterectomy or radical neck dissection, catheterization and aneurysms. The surgical anatomy of the carotid arteries was studied in 20 cadavers. Micrometric values of the CB and its relation with surrounding structures, measurements belonging to the external carotid artery (ECA) and internal carotid artery (ICA), and metric data, such as lower face including the greater horn, laryngeal prominence have been evaluated by making linear measures. The diameter of the CCA at the CB under 2 cm and CB diameter was measured as 8.1 +/- 2.24 mm and 12.79 +/- 2.87 mm, respectively. Evaluating data related to the ICA and the ECA in samples, the aspect was measured the ICA and the ECA in the CB discrimination point as 21.52 +/- 20.53 degrees . In the most location of the ECA origin according to the ICA has been determined as medial position in 35 specimens. The origin of the superior thyroid artery (STA) was found to be at the same level with the CB in 40% and below it in 25% specimens. This study has provided measured objective criteria for the arterial features of the neck region, which are crucial during surgery. The origins of the branches of the CCA act as key landmarks for adequate and appropriate placement of the cross-clamp on the carotid arteries.     

眶上外侧-纵裂入路处理前交通动脉瘤的临床应用解剖

目的　研究经眶上外侧-纵裂入路至前交通动脉复合体区的显微解剖,为临床应用该入路夹闭前交通动脉瘤提供解剖学依据。 方法　选取20具（40侧）成人尸头模拟经眶上外侧-纵裂入路,显微镜下观察前交通动脉复合体区的暴露情况,测量并记录相关数据。 结果　经眶上外侧-纵裂入路可较好地暴露前交通动脉复合体,尤其是前交通动脉的上区和后上区,且在暴露时对同侧额叶及直回的牵拉明显减轻。前交通动脉长度为（2.80±1.12）mm,中间外径为（1.79±0.82）mm,其距视交叉前缘中点距离为（4.59±2.22）mm。 结论　眶上外侧-纵裂入路具有手术视野好、脑组织损伤小等特点,对于上突型和后上突型前交通动脉瘤的暴露十分有益。     

CT angiographic depiction of a supraclinoid ICA fenestration mimicking aneurysm,confirmed with catheter angiography

Fenestrations (segmental duplications) of the intracranial arteries are rare anomalies that have been associated with aneurysms. Fenestrations of the supraclinoid ICA are extremely rare, with only a few reported cases. We present a supraclinoid ICA fenestration, which on axial CTA images initially mimicked an aneurysm, but was correctly delineated as a fenestration on multiplanar reformatted and 3D reconstructed images. Confirmation was made with conventional angiography. To our knowledge, this represents the first time that this rare variant has been identified with cross-sectional imaging. A review of the literature including proposed embryology is provided.     

LEO+Baby单支架辅助弹簧圈栓塞前交通动脉瘤的有效性及安全性

目的评价专为小血管设计的低剖面、自膨式LEO+Baby单支架辅助弹簧圈栓塞前交通动脉瘤的有效性和安全性。方法回顾性分析应用LEO+Baby单支架辅助弹簧圈栓塞技术治疗的52例前交通动脉瘤患者的临床资料,统计患者基本信息、影像学资料、手术情况及并发症情况。结果52例前交通动脉瘤患者应用LEO+Baby支架51枚,1例患者支架导管到位困难,转开颅手术治疗,其余均操作成功,成功率为98%(51/52);术后即刻造影动脉瘤完全栓塞42例,瘤颈残留9例。术中动脉瘤破裂1例,支架内血栓形成3例,术中弹簧圈脱出1例。术后随访6~12个月,改良Rankin量表(mRS)评分为4~5分2例,2~3分5例,随访无死亡病例。46例患者术后6个月DSA复查结果显示完全栓塞率89.1%(41/46),其余5例未行DSA复查;无支架相关并发症及动脉瘤再破裂出血发生。头颅CT显示,无迟发性脑梗死、脑出血发生。结论应用LEO+Baby单支架辅助弹簧圈栓塞前交通动脉瘤操作成功率和安全性高、围术期并发症少且短期预后良好。     

实验性大鼠脑血管痉挛动物模型制备

目的探索实验性SD大鼠蛛网膜下隙出血（SAH）脑血管痉挛模型制备方法。方法尾动脉取血,立体定位仪下枕大池二次注血,印度墨水灌注测量大脑中动脉、颈内动脉和基底动脉直径,Morris水迷宫行为学测试,测定血中内皮素-1、一氧化氮合酶含量。结果 SAH组脑血管明显变细,Morris水迷宫显示有学习记忆能力减退,大脑中动脉、颈内动脉和基底动脉直径分别为（169.33±8.67）mm、（227.33±14.25）mm、（226.33±5.99）mm;内皮素-1和一氧化氮合酶分别为（214.36±10.49）g/L、（211.15±16.99）U/mL,与对照组比较有统计学差异。结论本实验方法能够制备蛛网膜下隙出血后脑血管痉挛模型。     

Histopathologic characteristics of a saccular aneurysm arising in the non-branching segment of the distal middle cerebral artery

Currently, the characteristics of aneurysms arising in the distal middle cerebral artery (dMCA) are not well understood. Here, we report the case of a 56-year-old woman with a ruptured saccular aneurysm in the M2 segment of the middle cerebral artery (MCA). The patient presented with a disturbance of consciousness, and computed tomography revealed a subarachnoid hemorrhage that angiography disclosed as a result of a saccular-type aneurysmal dilatation in the M2 segment of the left MCA. We excluded infection, inflammation, trauma, and neoplasia as causes of the aneurysm. Pathologic examination confirmed a ruptured saccular aneurysm of the dMCA that was unrelated to a branching zone. The aneurysmal wall was composed primarily of αSMA-positive and calponin/desmin-negative spindle cells and lacked internal elastic lamina, which was completely disrupted at the neck of the aneurysm. There was a strong positive immunoreactivity for matrix metalloproteinases (MMPs) 1, 2, and 9 in the spindle cells of the aneurysmal wall. In contrast, tests for MMP-8 were negative. The parent artery showed thickening of both the intima and media, with preservation of the internal elastic lamina. Atherosclerosis was not detected in either the parent artery or aneurysm. These findings suggest that an overexpression of MMPs may contribute to the development of saccular aneurysms in regions of the arterial trunk unrelated to branching zones.     

The posterior part of the human cerebral arterial circle (CAC): arterial caliber from gestational weeks 13 to 24

Numerous studies have reported that all components of the cerebral arterial circle in the 4-month-old human fetus are more slender than adult vessels, and of equal caliber. After that period, a degree of caliber differentiation is present, especially at the level of the posterior communicating arteries. The aim of this study was to determine arterial diameters in the posterior part of the fetal cerebral arterial circle from the 4th month (IV) to the 6th (VI). One hundred and seventy-two fetal cerebral arterial circles were examined by means of a surgical microscope. It was determined that average diameters of the left (right) pre-communicating parts of the posterior cerebral artery ranged from 0.30 +/- 0.03 (0.29 +/- 0.02) mm in month IV, to 0.36 +/- 0.04 (0.36 +/- 0.03) mm during month V and up to 0.55 +/- 0.22 (0.50 +/- 0.18) mm in month VI. The average diameters of the left (right) posterior communicating artery ranged from 0.24 +/- 0.02 mm (0.25 +/- 0.02) in month IV, to 0.30 +/- 0.03 mm (0.29 +/- 0.05) during month V and up to 0.38 +/- 0.08 (0.44 +/- 0.10) in month VI. Gender differences between posterior cerebral artery and posterior communicating artery diameters were not significant. Average posterior cerebral artery diameters were significantly larger than posterior communicating artery diameters in months IV and V, but not in month VI. It was established that caliber differentiation in the posterior part of the cerebral arterial circle began from gestational month IV, and that gender differences in arterial diameters were not significant until month VI of gestation.     

The diameters of common carotid artery and its branches in newborns

The common carotid artery (CCA) bifurcation is of clinical importance due to its vascular access site for intravascular intervention. Additionally, it is also one of the most common sites of atherosclerotic plaque formation. There are numerous studies on the diameters of CCA, internal carotid artery (ICA), and external carotid artery (ECA) in adults, but few studies on newborns. Cadaver and angiographic studies have shown dimensional variations in the carotid arteries within/between individuals and also between different sexes. It is well known that the initial lesions of atherosclerosis begin very early in fetal life. Therefore, it is important to know the anatomical details of the CCA and its branches. In the present study, the neck regions of 20 (11 males and 9 females) fixed newborn cadavers were dissected. The CCAs were cut below the bulb of the carotid bifurcation further; ICA and ECA were cut above the bulb of the carotid bifurcation. The internal diameters of the CCA, ICA, and ECA were measured using a light microscopy. ECA/CCA, ICA/CCA, ICA/ECA ratios, and outflow to inflow area ratio were calculated. The mean outflow to inflow area ratio was 1.14±0.28. Our results highly correlated with the defined optimal ratio (1.15). The ECA/CCA, ICA/CCA, and ICA/ECA ratios were 0.78±0.12, 0.71±0.13, and 0.93±0.16, respectively. There were no statistically significant differences between male and female and also between right and left sides. These findings are of importance in understanding the anatomy of carotid artery during newborn period.     

Structural MRI of carotid artery atherosclerotic lesion burden and characterization of hemispheric cerebral blood flow before and after carotid endarterectomy

Collateral circulation plays a major role in maintaining cerebral blood flow (CBF) in patients with internal carotid artery (ICA) stenosis. CBF can remain normal despite severe ICA stenosis, making the benefit of carotid endarterectomy (CEA) or stenting difficult to assess. Before and after surgery, we assessed CBF supplied through the ipsilateral (stenotic) or contralateral ICA individually with a novel hemisphere-selective arterial spin-labeling (ASL) perfusion MR technique. We further explored the relationship between CBF and ICA obstruction ratio (OR) acquired with a multislice black-blood imaging sequence. For patients with unilateral ICA stenosis (n = 19), conventional bilateral labeling did not reveal interhemispheric differences. With unilateral labeling, CBF in the middle cerebral artery (MCA) territory on the surgical side from the ipsilateral supply (53.7 +/- 3.3 ml/100 g/min) was lower than CBF in the contralateral MCA territory from the contralateral supply (58.5 +/- 2.7 ml/100 g/min), although not statistically significant (p = 0.09). The ipsilateral MCA territory received significant (p = 0.02) contralateral supply (7.0 +/- 2.7 ml/100 g/min), while ipsilateral supply to the contralateral side was not reciprocated. After surgery (n = 11), ipsilateral supply to the MCA territory increased from 57.3 +/- 5.7 to 67.3 +/- 5.4 ml/100 g/min (p = 0.03), and contralateral supply to the ipsilateral MCA territory decreased. The best predictor of increased CBF on the side of surgery was normalized presurgical ipsilateral supply (r(2) = 0.62, p = 0.004). OR was less predictive of change, although the change in normalized contralateral supply was negatively correlated with OR(excess) (=OR(ipsilateral) - OR(contralateral)) (r(2) = 0.58, p = 0.006). The results demonstrate the effect of carotid artery stenosis on blood supply to the cerebral hemispheres, as well as the relative role of collateral pathways before surgery and redistribution of blood flow through these pathways after surgery. Unilateral ASL may better predict hemodynamic surgical outcome (measured by improved perfusion) than ICA OR.     

影响颅内小型动脉瘤破裂的影像解剖特征分析

目的 探讨颅内小型动脉瘤的破裂与其影像解剖特征的关系,建立动脉瘤破裂风险评分的预测模型,为颅内小型动脉瘤破裂高危患者的早期识别干预提供参考。方法 回顾性分析2015年1月—2020年5月郑州大学附属郑州中心医院经头颈CT血管造影或全脑血管造影证实的182例颅内小型动脉瘤(最大径＜5 mm)患者的临床资料,其中男62例、女120例,年龄31~83(56.85±11.51)岁,动脉瘤破裂组95例、未破裂组87例。两组患者动脉瘤的部位、形状、有无子囊、生长方向及相关解剖学参数等临床特征和影像解剖特征的比较采用单因素分析方法;动脉瘤破裂的独立危险因素分析采用多因素logistic分析方法,建立动脉瘤破裂的影像解剖特征的预测模型。结果 两组患者基线资料比较差异均无统计学意义(P值均＞0.05)。单因素分析显示,两组间动脉瘤部位、瘤壁形状、子囊、入射夹角、瘤高与瘤颈的比值(AR)差异均有统计学意义(P值均＜0.05)。多因素logistic回归分析显示,有子囊、入射夹角＞117.75°、AR值＞1.65是动脉瘤破裂的独立危险因素(P值均＜0.01)。根据logistic预测模型,其动脉瘤破裂风险评分(R),受试者操作特征曲线下面积为0.812(95%可信区间0.750~0.874,P＜0.01),R=2为最佳截断值,灵敏度72.6%,特异度78.2%。结论 颅内小型未破裂动脉瘤患者符合以下两种及两种以上影像解剖特征者,即动脉瘤位于颈内动脉后交通段或前交通动脉、瘤壁不规则、有子囊、入射夹角＞117.75°、AR值＞1.65等,为动脉瘤破裂的高危人群。