Effects of circle of Willis anatomic variations on angiographic and clinical outcomes of coiled anterior communicating artery aneurysms

Identifying hemodynamic factors associated with the rupture of anterior communicating artery aneurysms based on global modeling of blood flow in the cerebral artery network

Anterior communicating artery (ACoA) aneurysms are more prone to rupture compared to aneurysms present in other cerebral arteries. We hypothesize that systemic blood flow in the cerebral artery network plays an important role in shaping intra-aneurysmal hemodynamic environment thereby affecting the rupture risk of ACoA aneurysms. The majority of existing numerical studies in this field employed local modeling methods where the physical boundaries of a model are confined to the aneurysm region, which, though having the benefit of reducing computational cost, may compromise the physiological fidelity of numerical results due to insufficient account of systemic cerebral arterial hemodynamics. In the present study, we firstly carried out numerical experiments to address the difference between the outcomes of local and global modeling methods, demonstrating that local modeling confined to the aneurysm region results in inaccurate predictions of hemodynamic parameters compared with global modeling of the ACoA aneurysm as part of the cerebral artery network. Motivated by this finding, we built global hemodynamic models for 40 ACoA aneurysms (including 20 ruptured and 20 unruptured ones) based on medical image data. Statistical analysis of the computed hemodynamic data revealed that maximum wall shear stress (WSS), minimum WSS divergence, and maximum WSS gradient differed significantly between the ruptured and unruptured ACoA aneurysms. Optimal threshold values of high/low WSS metrics were determined through a series of statistical tests. In the meantime, some morphological parameters of aneurysms, such as large nonsphericity index, aspect ratio, and bottleneck factor, were found to be associated closely with aneurysm rupture. Furthermore, multivariate logistic regression analyses were performed to derive models combining hemodynamic and morphological parameters for discriminating the rupture status of aneurysms. The capability of the models in rupture status discrimination was high, with the area under the receiver operating characteristic curve reaching up to 0.9. The findings of the study suggest that global modeling of the cerebral artery network is essential for reliable quantification of hemodynamics in ACoA aneurysms, disturbed WSS and irregular aneurysm morphology are associated closely with aneurysm rupture, and multivariate models integrating hemodynamic and morphological parameters have high potential for assessing the rupture risk of ACoA aneurysms.

Classification of anterior communicating aneurysms on a basis of endovascular treatments

BACKGROUND AND PURPOSE

The anterior communicating artery (Acoma) aneurysms are difficult to understand because of their anatomical variations. This study reported a new classification of Acoma aneurysms on a basis of endovascular treatments.

METHODS

This retrospective study enrolled consecutive 94 patients harbored 100 Acoma aneurysms treated with coil embolization. All Acoma aneurysms were classified into 5 orientations (straight, superior, inferior, anterior, and posterior) based on the axis connecting A1 origin and the base of the aneurysm. Aneurysm characteristics, endovascular treatments, angiographic, and clinical outcomes were evaluated using this classification.

RESULTS

According to this classification, there were 64 (64%) straight, 16 (16%) inferior, 16 (16%) superior, 2 (2%) anterior, and 2 (2%) posterior projection aneurysms. There were significant differences between different groups in aneurysm height (p=0.009) and aneurysm neck size (p = 0.003), and in endovascular treatments (p=0.006). There was a significant difference in the proportion of rupture presentation among the three groups of straight, inferior, and superior (p = 0.019). There was no difference in the results of postoperative angiography (p = 0.090). An excellent functional outcome with an mRS ≤1 was achieved in 91 (96.8%) patients.

CONCLUSIONS

This classification of Acoma aneurysms based on the axis connecting A1 origin and the base of the aneurysm is associated with aneurysm height, aneurysm neck size, and in need for stent-assisted therapy. Endovascular embolization can provide the same effective treatment for aneurysms in all directions.

Endovascular Treatment of Anterior Communicating Artery Aneurysms: A Single-Center Experience from a Developing Country

Objective  In recent years, endovascular methods have been developed to treat intracranial aneurysms. To date, results of endovascular treatment (EVT) for anterior communicating aneurysms (ACoAs) have never been investigated in Iran. Thus, we sought to assess the mid-term angiographic and clinical outcomes of patients with ACoAs who underwent EVT in a tertiary center. Materials and Methods  Electronic health documents of patients with ACoAs who underwent EVT from March 2019 to July 2021 were retrospectively reviewed. Demographic and clinical characteristics of patients, procedural and clinical complications along with immediate and 12 months' postprocedural angiographic and clinical results were included in the analysis. Aneurysm occlusion status was classified based on the Raymond-Roy Occlusion Classification (RROC), and clinical outcomes were assessed using the modified Rankin Scale (mRS). Results  Of 38 patients with 38 ACoAs, 32 patients (84.21%) presented with subarachnoid hemorrhage of whom 23 (60.52%) had ruptured ACoAs. EVT included simple coiling in 29 patients (76.32%), balloon-assisted coiling in 6 (15.79%), and stent-assisted coiling in 3 (7.89%). Immediate and 12-month postprocedural angiograms demonstrated complete/near-complete occlusion (RROC I and II) in 32 (84.21%) and 35 patients (97.22%), respectively. Periprocedural complications occurred in five patients (13.15%), and the mortality rate was 5.26%. Thirty-two patients (84.21%) had favorable outcomes (mRS 0-2) at the last follow-up. Conclusion  EVT is a safe and beneficial procedure with favorable mid-term clinical and angiographic outcomes for ACoAs. Our results can lay the foundation for further studies in developing countries and are satisfactory enough for neurointerventionists to put EVT on the therapeutic agenda of ACoAs.

Anatomical variations in the Circle of Willis and the formation and rupture of intracranial aneurysms: A systematic review and meta-analysis

Background

The anterior (AcomA) and posterior communicating arteries (PcomA) are two of the most frequent sites for intracranial aneurysms. Anatomical variations in the Circle of Willis (COW) are frequently observed in patients with AcomA and PcomA aneurysms. Strong evidence is needed to determine the pooled estimate of the effect of COW variations on the formation and rupture of these aneurysms.

Aim

This systematic review and meta-analysis aimed to establish the effect of COW variations on the formation and rupture of AcomA and PcomA aneurysms using available studies.

Summary of review

PubMed, Embase, and Web of Science databases were systematically searched for studies published in English before September 21, 2022. Studies investigating AcomA aneurysms and the hypoplastic/aplastic A1 segment of the anterior cerebral artery and PcomA aneurysms and hypoplastic/aplastic PcomA or fetal-type posterior cerebral artery (FTP) were included. The heterogeneity of the studies was assessed using Cochran Q-test and I² statistic. Pooled estimate was assessed using either a random- or fixed-effects model based on the heterogeneity of the studies. Among the 4,932 studies, 21 were eligible and included in the analysis. The presence of hypoplastic/aplastic A1 was significantly correlated with the formation [OR (95% confidence interval [CI]) = 7.97 (5.58, 11.39), P < 0.001] and rupture [OR (95%CI) = 1.87 (1.29, 2.72), P < 0.001] of AcomA aneurysms. Significant associations between FTP and both the formation [OR (95%CI) = 2.15 (1.41, 3.30), P < 0.001] and rupture [OR (95%CI) = 1.72 (1.26, 2.36), P < 0.001] of PcomA aneurysms were observed.

Conclusions

Significant associations were observed between COW variations and both the formation and rupture of AcomA and PcomA aneurysms. This can help in determining interventions for patients with aneurysms.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=225149, identifier: CRD42021225149.

Flow Diverter Devices in the Treatment of Anterior Communicating Artery Region Aneurysms: Would the Regional Anatomy and the Aneurysm Location Affect the Outcomes?

BACKGROUND

In this study, the authors evaluated the efficacy and the safety of flow diverter devices (FDD) in anterior communicating artery (ACoA) region aneurysms, focusing on anatomical factors that could affect the outcome, such as the location of the aneurysm along the ACoA (centered on ACoA or decentered on the A1-A2 junction) and the anatomy of the ACoA region.

METHODS

Clinical, procedural and follow-up data were analyzed. Aneurysms were classified according to the location along the ACoA (centered or decentered on the A1-A2 junction) and on the basis of the anatomical configuration of the ACoA region. Safety was assessed by recording intraprocedural, periprocedural and delayed complications to determine the morbidity and mortality rates. The functional outcome was evaluated with the modified Rankin scale (mRS) prior to and after the endovascular procedure. To assess the efficacy, midterm and long-term clinical, angiographic and cross-sectional imaging follow-ups were recorded. Subgroup analysis according to the different ACoA regional anatomical configurations and the ACoA aneurysm locations were performed.

RESULTS

33 patients (17 males; 16 females) with ACoA region aneurysms were treated with FDDs. 27 aneurysms were located at the A1-A2 junction (82%) while the remaining six aneurysms were centered on the ACoA. No mortality was recorded. The overall morbidity rate was 6% (2/33 procedures). Major complications occurred in 33% (2/6) of ACoA aneurysms and in the 0% of A1-A2 junction aneurysms. Mid-term and long-term neuroimaging follow-ups showed the occlusion of the aneurysm in 28/33 cases (85%). Complete occlusion rates were 93% in the A1-A2 junction aneurysms and 50% in ACoA aneurysms.

CONCLUSIONS

The FDD is a safe and effective tool that can be used in the treatment of selected cases of ACoA region aneurysms. The location of the aneurysm along the ACoA and the regional anatomy of the ACoA complex could affect the efficacy and safety.

The different recanalization rates of posterior communicating artery aneurysms with a fetal posterior communicating artery and anterior communicating artery aneurysms with a variation of the unilateral A1 segment

BACKGROUND

Posterior communicating artery (PcomA) aneurysms are more likely to recanalize than anterior communicating artery (AcomA) aneurysms. However, it is still unclear whether the recanalization rate of these aneurysms is a result of involvement from the fetal posterior cerebral artery (fPCA) in PcomA aneurysms and variation of the unilateral A1 segment in AcomA aneurysms. The purpose of this study is to retrospectively evaluate the different recanalization rates between PcomA aneurysms with fPCA and AcomA aneurysms with a variation of the unilateral A1 segment.

METHODS

We retrospectively collected information regarding 214 patients, each with communicating segment aneurysms between January 2013 and January 2020. Follow-up documentation on clinical and imaging data was comparatively analyzed between variant types, and recanalization rates of the variant and normal types were analyzed by stratification.

RESULTS

Of the 84 variant-type aneurysms (PcomA with fPCA and AcomA with a variation of the unilateral A1 segment, 41/43), complete recanalization occurred in 23 patients (27.4%), and it was significantly more likely to occur in PcomA aneurysms with fPCA (39.1%) than in AcomA aneurysms with a variation of the unilateral A1 segment (16.3%). Stent-assisted coil embolization (SACE) has been shown to reduce recanalization (OR =0.092, 95% CI: 0.011 to 0.790, P=0.03). Additionally, variant types and the normal type (non-fetal, 106, and bilateral A1 symmetry, 24) have different odds ratios (OR) of recanalization (P=0.04), and the OR of the variant subtypes was significant, unlike the normal type (P=0.49).

CONCLUSIONS

This study suggests that PcomA aneurysms with fPCA are more likely to recanalize than AcomA aneurysms with a variation of the unilateral A1 segment.

Impact of A1 Asymmetry on the Woven EndoBridge Device in Anterior Communicating Artery Aneurysms

BACKGROUND AND PURPOSE

Woven EndoBridge (WEB) devices are increasingly used to treat intracranial aneurysms. A1 asymmetry contributes to anterior communicating artery aneurysm formation and to treatment instability after coiling. We sought to evaluate whether A1 asymmetry had an impact on angiographic outcome in anterior communicating artery aneurysms treated with the WEB.

MATERIALS AND METHODS

Anterior communicating artery aneurysms treated between July 2012 and July 2020 with the WEB from an institutional review board-approved database were reviewed. A1 asymmetry was categorized as the following: absence of the A1 segment on 1 side (unilateral A1) versus bilateral A1. Univariate and multivariable analyses assessed independent predictors of adequate (WEB Occlusion Scale A, B, and C) and complete occlusion (WEB Occlusion Scale A and B).

RESULTS

Forty-eight individual aneurysms (47 patients) were included in the final analysis, of which 16 (33%) were acutely ruptured. The mean size was 6.5 (SD, 2.2) mm. Adequate and complete occlusion was achieved in 33 (69%) and 30 (63%) cases, respectively. Unilateral A1 was associated with significantly higher rates of adequate (92% versus 60% for bilateral A1; P = .03) and complete occlusion (92% versus 50% for bilateral A1; P < .01). Multivariable logistic regression confirmed unilateral A1 as an independent predictor of both adequate (OR = 10.6; 95% CI, 1.6-220.7; P = .04) and complete occlusion (OR = 9.5, 95% CI, 1.5-190.2; P = .04. A sensitivity analysis comparing unilateral "functional" A1 with bilateral "functional" A1 showed similar results. WEB shape modification was not influenced by the unilateral A1 configuration (P = .70).

CONCLUSIONS

Anterior communicating artery aneurysms with a unilateral A1 configuration treated with WEB devices are associated with better angiographic outcome than those with bilateral A1. This finding supports the hypothesis that WEB devices are resistant to unilateral flow in the aneurysm as opposed to coils.

Endovascular Treatment of Ruptured Wide-Necked Anterior Communicating Artery Aneurysms Using a Low-Profile Visualized Intraluminal Support (LVIS) Device

Objective: To evaluate the safety and efficacy of low-profile visualized intraluminal support (LVIS) stent-assisted coiling for the treatment of ruptured wide-necked anterior communicating artery (ACoA) aneurysms.

Methods: The clinical and angiographic data of 31 acutely ruptured wide-necked ACoA aneurysms treated with LVIS stent-assisted coiling between January 2014 and December 2018 were retrospectively reviewed.

Results: All stents were successfully deployed. The immediate angiographic results were modified Raymond-Roy class I in 27 cases, modified Raymond-Roy class II in 2 cases, and modified Raymond-Roy class IIIa in 2 cases. Intraoperative thrombosis and postoperative aneurysmal rebleeding occurred in one case each. Two patients (6.5%) who were admitted due to poor clinical grade conditions died during hospital admission as a result of initial bleeding. Angiographic follow-up (mean: 12.9 months) was performed for 26 patients, the results of which demonstrated that 25 aneurysms were completely occluded and one was class II. The last clinical follow-up (mean: 25.3 months) outcomes demonstrated that 27 patients had favorable clinical outcomes and two had poor clinical outcomes.

Conclusion: LVIS stent-assisted coiling for ruptured wide-necked ACoA aneurysms was safe and effective, with a relatively low rate of perioperative complications and a high rate of complete occlusion at follow-up.

Association between circle of Willis and ischemic stroke: a systematic review and meta-analysis

Background

Circle of Willis is the main structure that provides constant and regular blood flow to the brain, protects the brain from ischemia. Stroke has remained the second leading cause of death globally in the last fifteen years. It is the fifth leading cause of death in the United States. It is also the leading cause of serious adult disability. Interlinked problems related to ischemic stroke are become increasing nowadays. Strong evidence is needed about the pooled measure of association between the circle of Willis (COW) and ischemic stroke. Therefore, this systematic review and meta-analysis were intended to provide compressive and up to date evidence on the association between the variations of COW and ischemic stroke using the available studies.

Methods

PubMed, Google Scholar, Science Direct, and Cochrane Library databases were systematically searched. All essential data were extracted using a standardized data extraction template. The heterogeneity across studies was assessed by using the Cochrane Q test statistic, I² test statistic, and P-values. A fixed-effect model was used to estimate the pooled effect of the measure association between COW and ischemic stroke.

Results

In this meta-analysis, 2,718 participants were involved. The pooled measure of association between COW and ischemic stroke was 1.38 (95% CI 0.87, 2.19). Therefore, this indicated that the presence of any variation in COW was 1.38 times more likely to develop ischemic stroke as compared to the patent COW. The presence of hypoplasia/incompleteness in a posterior communicating artery (PcomA) [Pooled OR: 1.34 (95% CI 0.80, 2.25)] and anterior communicating artery (AcomA) [Pooled OR: 1.32 (95% CI 0.81, 2.19)] were a contributing factor for the development of ischemic stroke. Hypertension was the most common comorbid condition, followed by diabetes mellitus, smoking, coronary artery disease, and hyperlipidemia.

Conclusions

There was a non-significant positive association between COW variation and ischemic stroke in this meta-analysis.

Brain folding shapes the branching pattern of the middle cerebral artery

The folds of the brain offer a particular challenge for the subarachnoid vascular grid. The primitive blood vessels that occupy this space, when the brain is flat, have to adapt to an everchanging geometry while constructing an efficient network. Surprisingly, the result is a non-redundant arterial system easily challenged by acute occlusions. Here, we generalize the optimal network building principles of a flat surface growing into a folded configuration and generate an ideal middle cerebral artery (MCA) configuration that can be directly compared with the normal brain anatomy. We then describe how the Sylvian fissure (the fold in which the MCA is buried) is formed during development and use our findings to account for the differences between the ideal and the actual shaping pattern of the MCA. Our results reveal that folding dynamics condition the development of arterial anastomosis yielding a network without loops and poor response to acute occlusions.

Variations in the Circle of Willis in a large population sample using 3D TOF angiography: The Tromsø Study

The main arteries that supply blood to the brain originate from the Circle of Willis (CoW). The CoW exhibits considerable anatomical variations which may have clinical importance, but the variability is insufficiently characterised in the general population. We assessed the anatomical variability of CoW variants in a community-dwelling sample (N = 1,864, 874 men, mean age = 65.4, range 40–87 years), and independent and conditional frequencies of the CoW’s artery segments. CoW segments were classified as present or missing/hypoplastic (w/1mm diameter threshold) on 3T time-of-flight magnetic resonance angiography images. We also examined whether age and sex were associated with CoW variants. We identified 47 unique CoW variants, of which five variants constituted 68.5% of the sample. The complete variant was found in 11.9% of the subjects, and the most common variant (27.8%) was missing both posterior communicating arteries. Conditional frequencies showed patterns of interdependence across most missing segments in the CoW. CoW variants were associated with mean-split age (P = .0147), and there was a trend showing more missing segments with increasing age. We found no association with sex (P = .0526). Our population study demonstrated age as associated with CoW variants, suggesting reduced collateral capacity with older age.

Is Anatomical Variations a Risk Factor for Cerebral Vasospasm in Anterior Communicating Complex Aneurysms Rupture?

Background and Purpose- One-third of ruptured aneurysms are located on the anterior communicating complex with high prevalence of anatomic variations of this arterial segment. In this study, we hypothesized that anatomic variations of the anterior communicating complex increase the risk of angiographic vasospasm. Methods- Retrospective study of prospectively collected data from a monocentric subarachnoid hemorrhage cohort of patients admitted to neurointensive care between 2002 and 2018. Univariate followed by multivariate logistic regression analysis was used to identify factors associated with angiographic vasospasm. Results- One thousand three hundred seventy-four patients with aneurismal subarachnoid hemorrhage were admitted to our institution; 29.8% (n=410) were related to an anterior communicating complex aneurysm rupture; 9.2% (n=38) of them showed an anterior communicating artery variation. Angiographic vasospasm was diagnosed in 55.6% of this subgroup (vs 28.1%, P=0.003). In the multivariate analysis, external ventricular drain (2.2 [1.32-3.65], P=0.003) and anterior communicating artery variation (2.40 [1.2-4.9], P=0.04) were independently and significantly associated with angiographic vasospasm, while age above 60 years (0.3 [0.2-0.7]; P=0.002) was a protective factor. However, anterior communicating artery variation was not statistically associated with ischemic vasospasm or poor neurological outcome after anterior communicating artery aneurysm rupture. Conclusions- Anatomic variation of anterior communicating artery could be a new biomarker to identify patients at risk to develop angiographic vasospasm post-subarachnoid hemorrhage. External validation cohorts are necessary to confirm these results.

Flow diversion treatment of anterior communicating artery region aneurysms

BACKGROUND AND PURPOSE

Reports on flow diversion treatment of aneurysms beyond the Circle of Willis are limited, with few series dedicated to anterior communicating artery region aneurysms. The purpose of this study is to evaluate the safety and effectiveness of the pipeline embolization device in the treatment of anterior communicating artery region aneurysms.

MATERIALS AND METHODS

The neuro-interventional database of a single institution was retrospectively reviewed for anterior communicating artery aneurysms treated with the pipeline embolization device between November 2016 and December 2018. Data on clinical presentation, aneurysm location, type, vessel size, procedural complications, clinical and imaging follow-up were analyzed.

RESULTS

Ten patients with 11 anterior communicating artery aneurysms were included. Procedural success was achieved in 9/10 patients (90%). Flow diversion with the pipeline embolization device yielded occlusion in 100% of patients at 6.5 months. Symptomatic ischemic complications occurred in 2/10 patients (20%); only one of who had permanent symptoms. Hemorrhagic groin complications were encountered in 2/10 patients (20%). There were no deaths and no cerebral hemorrhagic complications.

CONCLUSIONS

Flow diversion therapy may provide a feasible solution for anterior communicating artery region aneurysms that are not amenable to traditional surgical or endovascular modalities.

Angiographic and clinical results of anterior communicating artery aneurysm endovascular treatment

Introduction

The anterior communicating artery (ACoA) is the most common location of intracranial aneurysms, observed in 35% of cases. Endovascular treatment has become an alternative to surgical clipping and the primary method of choice.

Aim

To assess the treatment results of ruptured and unruptured ACoA aneurysms and to assess the incidence of intraprocedural complications and various factors influencing these aspects.

Material and methods

One hundred and eleven embolizations of ACoA aneurysms (80.7% ruptured and 19.3% unruptured) were retrospectively analysed. The methods of embolization were: coiling, balloon-assisted coiling, stent-assisted coiling. Morphology and dimensions of aneurysms were assessed on 3D digital subtraction angiography (DSA) images. Medical records were analysed for patient’s clinical status at admission, intraprocedural complications, follow-up examination and modified Rankin Scale (mRS) score 1 month after discharge.

Results

Immediately after the procedure 56.9% of patients had Raymond-Roy Occlusion Classification (RROC) class I, 37.6% class II and 5.5% class III. The overall intraprocedural complication rate was 6.6%. There were significantly more cases of bleeding (p = 0.012) and coil prolapse (p = 0.012) during the procedures ending with higher packing density. Twenty-eight (25.7%) patients died during hospital stay, 27 (96.4%) with ruptured aneurysm. In the follow-up of 41 patients, RROC was the same or improved in 73.2% of cases and recanalization occurred in 26.8%. Six patients with aneurysm recanalization underwent repeat embolization.

Conclusions

Endovascular embolization of ACoA aneurysms is an effective and safe treatment method. The most powerful factor influencing the incidence of complications is packing density. Superior orientation of the dome, initial incomplete embolization and poor outcome in mRS scale are factors predisposing to ACoA aneurysm recurrence.

A Median Artery of the Corpus Callosum

The anterior communicating artery is one of the main components of the vascular network that delivers blood to the brain. Therefore, a good understanding of the normal anatomy and its variations is important to neurologists, neurosurgeons, and other health care providers dealing with the central nervous system. Here, we present a case of a median artery of the corpus callosum found in a cadaver, with consideration of cerebral hemodynamics implications.

Clinical relevance of anterior cerebral artery asymmetry in aneurysmal subarachnoid hemorrhage

OBJECTIVE

An asymmetry of the A1 segments (A1SA) of the anterior cerebral arteries (ACAs) is an assumed risk factor for the development of anterior communicating artery aneurysms (ACoAAs). It is unknown whether A1SA is also clinically relevant after aneurysm rupture. The authors of this study investigated the impact of A1SA on the clinical course and outcome of patients with aneurysmal subarachnoid hemorrhage (SAH).

METHODS

The authors retrospectively analyzed data on consecutive SAH patients treated at their institution between January 2005 and December 2012. The occurrence and severity of cerebral infarctions in the ACA territories were evaluated on follow-up CT scans up to 6 weeks after SAH. Moreover, the risk for an unfavorable outcome (defined as > 3 points on the modified Rankin Scale) at 6 months after SAH was assessed.

RESULTS

A total of 594 patients were included in the final analysis. An A1SA was identified on digital subtraction angiography studies from 127 patients (21.4%) and was strongly associated with ACoAA (p < 0.0001, OR 13.7). An A1SA independently correlated with the occurrence of ACA infarction in patients with ACoAA (p = 0.047) and in those without an ACoAA (p = 0.015). Among patients undergoing ACoAA coiling, A1SA was independently associated with the severity of ACA infarction (p = 0.023) and unfavorable functional outcome (p = 0.045, OR = 2.4).

CONCLUSIONS

An A1SA is a common anatomical variation in SAH patients and is strongly associated with ACoAA. Moreover, the presence of A1SA independently increases the likelihood of ACA infarction. In SAH patients undergoing ACoAA coiling, A1SA carries the risk for severe ACA infarction and thus an unfavorable outcome.

Clinical trial registration no.: DRKS00005486 (http://www.drks.de/)

Treatment of complex anterior cerebral artery aneurysms with Pipeline flow diversion: mid-term results

BACKGROUND

The off-label use of flow diverters in the treatment of distal aneurysms continues to be debated.

OBJECTIVE

To report our multicenter experience in the treatment of complex anterior cerebral artery aneurysms with the Pipeline embolization device (PED).

METHODS

The neurointerventional databases of the four participating institutions were retrospectively reviewed for aneurysms treated with PED between October 2011 and January of 2016. All patients treated for anterior cerebral artery aneurysms were included in the analysis. Clinical presentation, location, type, vessel size, procedural complications, clinical and imaging follow-up were included in the analysis.

RESULTS

Twenty patients (13 female) with 20 aneurysms met the inclusion criteria in our study. Fifteen aneurysms were classified as saccular and five as fusiform (mean size 7.3 mm). Thirteen aneurysms were located in the anterior communicating region (ACOM or A1/2 junction), six were A2-pericallosal, and one was located in the A1 segment. Six patients had presented previously with subarachnoid hemorrhage and had their aneurysms initially clipped or coiled. There was one minor event (a small caudate infarct) and one major event (intraparenchymal hemorrhage). Sixteen of the 20 patients had angiographic follow-up (mean 10 months). Eleven aneurysms were completely occluded, one had residual neck, and four had residual aneurysm filling.

CONCLUSIONS

The treatment of complex anterior cerebral artery aneurysms with the PED as an alternative for patients who are not good candidates for conventional methods is technically feasible and safe. Mid-term results are promising but larger series with long-term follow-up are required to assess its effectiveness.

Anatomic variations in the anterior circulation of the circle of Willis in cadaveric human brains

OBJECTIVE

The Cycle of Willis unites the internal carotid and vertebrobasilar system and maintains the stability of blood supply to the brain. This present study aims to analyze the anatomic variations in the anterior part of the Cycle of Willis.

METHODS

Forty five formalin-preserved human brains (90 cerebral hemispheres) with intact dura mater from Chinese adults were dissected under the surgical microscope. The anterior components of the Circle of Willis were observed and measured. Anatomic variations of this segment were observed and photographed. The data collected in this investigation was statistically analyzed.

RESULTS

In approximately 13.3% (6/45) of all cerebral samples, a caliber difference of ≥ 0.5 mm was noted between the left A1 and the right segments. The A2 segments of left and right hemispheres were derived from the contralateral A1 segment in 6.7% (3/45) of the brain specimens. Simple anterior communicating artery (ACoA) was observed in 37.8% (17/45) whereas complex ACoA was noted in 60% (27/45) of cerebral samples.

CONCLUSION

As it demonstrates the anatomic variations of ACAC, all surgical approaches should be performed after angiographic demonstrations. Understanding of these anatomic variations plays a pivotal role in neurovascular procedures.