The anterior communicating artery variants: a meta-analysis with a proposed classification system

Morphological and morphometric variants of the anterior communicating artery (AComA) have been described by multiple studies; however, a complete classification system of all possible morphological variants with their prevalence is lacking. The current systematic review with meta-analysis combines data from different databases, concerning the AComA morphological and morphometric variants (length and diameter). Emphasis was given to the related clinical implications to highlight the clinical value of their knowledge. The typical AComA morphology occurs with a pooled prevalence (PP) of 67.3%, while the PP of atypical AComA is 32.7%. The identified AComA morphological variants (artery's hypoplasia, absence, duplication, triplication, differed shape, fenestration, and the persistence of a median artery of the corpus callosum- MACC) were classified in order of frequency. The commonest presented variants were the AComA hypoplasia (8%) and the anterior cerebral artery (ACA) fusion (5.9%), and the rarest ones were the MACC persistence (2.3%), and the AComA triplication (0.7%). The knowledge of those variants is essential, especially for neurosurgeons operating in the area. Given the high prevalence of AComA aneurysms, an adequate and complete classification of those variants is of utmost importance.

Neuropsychological outcomes in patients with ruptured anterior communicating artery aneurysms treated by clipping versus coiling: a systematic review and meta-analysis

Ruptured anterior communicating artery (ACoA) aneurysms are frequently associated with neuropsychological deficits. This review aims to compare neuropsychological outcomes between surgical and endovascular approaches to ACoA. We systematically searched PubMed, Embase, and Web of Science for studies comparing the endovascular and surgical approaches to ruptured ACoA aneurysms. Outcomes of interest were the cognitive function, covered by memory, attention, intelligence, executive, and language domains, as well as motor and visual functions. Nine studies, comprising 524 patients were included. Endovascularly-treated patients showed better memory than those treated surgically (Standardized Mean Difference (SMD) = -2; 95% CI: -3.40 to -0.61; p < 0.01). Surgically clipped patients had poorer motor ability than those with coiling embolization (p = 0.01). Executive function (SMD = -0.20; 95% CI: -0.47 to 0.88; p = 0.55), language (SMD = -0.33; 95% CI: -0.95 to 0.30; p = 0.30), visuospatial function (SMD = -1.12; 95% CI: -2.79 to 0.56; p = 0.19), attention (SMD = -0.94; 95% CI: -2.79to 0.91; p = 0.32), intelligence (SMD = -0.25; 95% CI: -0.73 to 0.22; p = 0.30), and self-reported cognitive status (SMD = -0.51; 95% CI: -1.38 to 0.35; p = 0.25) revealed parity between groups. Patients with ACoA treated endovascularly had superior memory and motor abilities. Other cognitive domains, including executive function, language, visuospatial function, attention, intelligence and self-reported cognitive status revealed no statistically significant differences between the two approaches. Trial Registration PROSPERO (International Prospective Register of Systematic Reviews) CRD42023461283; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=461283.

Clipping of a Ruptured Small Anterior Communicating Artery Aneurysm: Technical Video

In recent years there has been a significant shift in the management of intracranial aneurysms, as most, both ruptured and unruptured, are being treated through an endovascular approach.1-3 However, there are still instances in which open surgical clipping is the best option for definitive management. Both patient factors, such as age and comorbidities, and aneurysm characteristics, such as size, morphology, and location, must be taken into consideration when treating aneurysms. This is especially true for anterior1 communicating artery aneurysms, as these have been treated successfully using multiple different techniques.4,5 There are no absolute guidelines indicating how a particular aneurysm should be treated and, therefore, one must be able to determine how to best manage a patient based on their own skill set, knowledge, and experience. We present a case of a 61-year-old woman who presented with a ruptured anterior communicating artery aneurysm. Initially she was brought to the angiography suite to undergo possible endovascular treatment of the aneurysm, but after reviewing the morphology and size of the aneurysm, we believed that this aneurysm could not be treated safely through an endovascular approach and surgical clipping was the better option. The patient consented to the procedure. In this operative video, we describe the technical aspects of the surgical procedure and the benefits of our approach (Video 1).

Analysis of the impact of intraventricular hemorrhage on the functional outcome of ruptured anterior cerebral artery aneurysm after clipping

Background

Various clinical symptoms and variables have been suggested as potential indicators of outcomes in patients with subarachnoid hemorrhage (SAH) resulting from ruptured intracranial aneurysms. The detailed discussion of the consequences of intraventricular hemorrhage (IVH), frequently reported in cases of anterior communicating artery (ACoA) aneurysms, is still pending. The study aimed to assess the results of aneurysm surgery performed early versus delayed in patients with SAH, specifically focusing on the occurrence of IVH.

Methods

This study involved patients with ACoA aneurysms who experienced SAH and underwent microsurgical clipping of the aneurysm. A retrospective review was conducted on the patients' medical records. The modified Rankin score was compared between two groups of patients based on the presence or absence of IVH.

Results

Ninety-one participants (52 males and 39 females) were included in the study. The initial computed tomography scan showed that 20 patients (with a mean age of 51 ± 13.7 years) had IVH, while 71 patients (with a mean age of 45.8 ± 11.7 years) did not have any signs of IVH. The proportion of patients with poor functional outcomes after six months was 55% in the presence of IVH, compared to 25.4% in patients without IVH, indicating a significant difference in outcome between the two groups (P < 0.016).

Conclusion

Patients with SAH having aneurysms located in the ACoA associated with the intraventricular hemorrhage had a poor functional outcome.

Anatomical Variations and Anomalies of the Anterior Communicating Artery Complex

BACKGROUND

Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all variations and anomalies within the anterior communicating artery complex.

METHODS

PubMed was searched with the terms "Anterior Communicating Artery" AND "Variations" OR "Anomalies." Articles were selected based on their description of variants. Cross-referencing was used to broaden the range of variations. Surgical view during pterional craniotomy and transsylvian approach was used as a baseline for schematic drawings of the variations.

RESULTS

A total of 42 variants were identified, schematically drawn and classified into A1-A2 segment, anterior communicating artery, and the recurrent artery of Heubner.

CONCLUSIONS

The anterior communicating artery complex consists of the anterior cerebral artery, anterior communicating artery and the recurrent artery of Heubner. An overview of these variations may be helpful in distinguishing pathology from anatomical variations, assist neurosurgeons during clipping of cerebral aneurysms, and support interventional radiologists during endovascular treatments. This article summarizes the current knowledge of anatomical variations within the anterior communicating artery complex, their prevalence and clinical relevance. A total of 42 variants were identified and schematically depicted. We encourage all who diagnose, treat, and study the anterior communicating artery complex to use this overview for a uniform and better understanding of its anatomy.

Risk factor analysis of changes in blood flow in the A1 segment of the anterior cerebral artery after flow-diverter coverage of it

Few studies have explored the effect of a flow-diverter device (FD) on blood flow in the A1 segment of the anterior cerebral artery (ACA), after treatment of intracranial aneurysms in the bifurcation region of the internal carotid artery (ICA). The main objective of this article is to investigate the factors that affect A1 blood flow after FD covers the A1 artery. This is a single-center, retrospective study. Data were collected retrospectively from our center, and patients whose FDs were placed for treatment from the terminal of the ICA to the M1 segment were analyzed. A total of 42 patients were included in the study. Immediate post-procedural angiography following device placement revealed decreased blood flow in the A1 of 15 (35.7%) patients and complete occlusion of the A1 segment in 11 (26.2%) patients. During an average follow-up period of 9.8 months, the A1 segment was ultimately occluded in 25 patients (59.5%) and decreased blood flow in 4 patients (9.5%). When using FD to cover the A1 artery for the treatment of intracranial aneurysms, patients with preoperative opening of the anterior communicating artery (AcomA) are more prone to occlusion or decreased blood flow of the A1 artery, compared to patients without opening.

The impact of selection bias in the treatment for ruptured anterior communicating artery aneurysms: different results or different patients?

Background

Anterior communicating artery is one of the most frequent locations for the development of intracranial aneurysm. The availability and advances of different treatments modalities allows for case-specific selection, but potentially impacts our ability to assess equipoise among them.

Objective

Investigate and compare clinical and morphological variables among surgical and endovascular treatment groups with ruptured anterior communicating artery aneurysms.

Methods

Data from patients from a single university hospital treated for ruptured anterior communicating aneurysms after multidisciplinary discussion in a period from January 2009 to January 2020 were retrospectively reviewed. Demographics, clinical status, aneurysm morphologic features and in-hospital complications were registered for each treatment (endovascular coiling vs. microsurgical clipping). Clinical assessment was made from outpatient evaluation at 1-year follow-up.

Results

A total of 119 patients was obtained adding surgical (n = 80) and endovascular (n = 39) treatment groups. No significant changes between groups were detected regarding gender, age of treatment or other risk factors. Global complication rate (p = 0.335, p = 0.225, p = 0.428) and clinical outcome (p = 0.802) was similar among both groups. Univariate and multivariate analysis revealed statistically significant differences between endovascular and surgical treatment groups regarding dome orientation (p = 0.011), aneurysm height (p < 0.001) and maximum diameter (p < 0.001), aspect-ratio (p < 0.001), dome-to-neck ratio (p < 0.001) and dome diameter (p = 0.014).

Conclusions

Despite similar clinical outcomes and rate of complications, morphological differences highlight the presence of a selection bias and high heterogeneity, which hampers inferential analysis when comparing both techniques.

Clipping of Anterior Circulation Aneurysms: Operative Instructions and Safety Rules for Young Cerebrovascular Surgeons

INTRODUCTION

Due to the constant development of the technique, in the last 30 years, the endovascular treatment of the intracranial aneurysms (IAs) has gradually superseded the traditional surgery in the majority of centers. However, clipping still represents the best treatment for some anterior circulation IAs according to their angioarchitectural, topographical, and hemodynamic characteristics. Thus, the identification of residual indications for clipping and the maintenance of training programs in vascular neurosurgery appear nowadays more important than ever.

MATERIALS AND METHODS

We reviewed our last 10-year institutional experience of ruptured and unruptured IAs clipping. We appraised in detail all technical refinements we adopted during this time span and analyzed the difficulties we met in teaching the aneurysm clipping technique to residents and fellows. Then, we described the algorithm of safety rules we used to teach young neurosurgeons how to surgical approach anterior circulation IAs and develop a procedural memory, which may intervene in all emergency situations.

RESULTS

We identified seven pragmatic technical key points for clipping of the most frequent anterior circulation IAs and constructed a didactic approach to teach young cerebrovascular surgeons. In general, they concern craniotomy; cisternostomy; obtaining proximal control; cranial nerve, perforator, and vein preservation; necessity of specific corticectomy; aneurysm neck dissection; and clipping.

CONCLUSION

In the setting of an IA clipping, particularly when ruptured, the young cerebrovascular surgeon needs to respect an algorithm of safety rules, which are essential not only to avoid major complications, but they may intervene during the difficulties helping to manage potentially life-tethering conditions.

Unreported branching pattern of the triplicated anterior cerebral artery associated with multiple bilateral variants of the superior cerebellar artery detected by computed tomography angiography and 3D modeling

A 26-year-old patient underwent a successful ablation of Grade 2 diffuse astrocytoma of the right parietal lobe. The postoperative computed tomography angiography with 3D modeling revealed a residual avascular porencephalic cyst. Otherwise, multiple arterial variants have been encountered. First, the left A1 segment was fenestrated, and three A2 segments arose from the anterior communicating artery. The middle A2 segment was dominant and supplied left callosomarginal and both pericallosal territories. The right A2 segment supplied the right callosomarginal territory, while the left A1 was limited to the left orbitofrontal and frontopolar territories. This configuration represents a triplicated anterior cerebral artery with an unusual branching pattern not included in the classification of Baptista. In addition, on both sides, superior cerebellar artery duplication was present, with one arising from the basilar artery and the other from the P1 segment of the ipsilateral posterior cerebral artery. The left lower superior cerebellar artery was early bifurcated. It is the first time such a cerebrovascular configuration has been reported. Because of the several clinical and surgical applications of the anterior cerebral artery and superior cerebellar artery variants, this case report is of utmost interest to anatomists, radiologists, and neurosurgeons.

Geometric influence of anterior cerebral artery rotation on the formation of anterior communicating artery aneurysm

OBJECTIVE

Several particular morphological factors that contribute to the hemodynamics of the anterior communicating artery (ACoA) have been documented, but no study has investigated the role of the degree of anterior cerebral artery (ACA) rotation on the presence of ACoA aneurysms (ACoAAs).

METHODS

A retrospective study of an institutional aneurysm database was performed; patients with ruptured or nonruptured ACoAAs were selected. Two sex- and age-matched control groups were identified: control Group A (nonaneurysms) and control Group B (middle cerebral artery aneurysms). Measurements of ACA rotation degree were obtained by using a three-dimensional imaging tool.

RESULTS

From 2015 to 2020, 315 patients were identified: 105 in the ACoAA group, 105 in control Group A, and 105 in control Group B. The average age at the time of presentation was 64 years, and 52.4% were female. The ACA rotation degree of the ACoAA group was significantly higher than that of control Group A (p <0.01). The A1 ratio and the A1A2 ratio of the ACoAA group were greater than those of control Group A (p <0.01 and p <0.01, respectively). The ACA rotation degree correlated insignificantly with aneurysm size in ACoAA patients (p=0.78). The ACA rotation degree in the ACoAA group was also insignificantly different from that in control B (p=0.11).

CONCLUSIONS

The degree of ACA rotation was greater in the ACoAA group than in the nonaneurysm group, and it may serve as an imaging marker for ACoAA.

Selective clipping of giant anterior communicating artery aneurysms remains a reliable therapeutic option

BACKGROUND

Giant anterior communicating artery (AcomA) aneurysm represent a significant surgical challenge. Our study aimed to discuss the therapeutic strategy in patients with a giant AcomA aneurysm treated by selective neck clipping through a pterional approach.

METHODS

Among all operated patients from an intracranial aneurysm between January 2015 and January 2022 (n = 726) in our institution, three patients with a giant AcomA aneurysm treated by neck clipping were included. Early (<7days) outcome was noted. Early postoperative CT scan was performed in all patients to detect any complications. Early DSA was also performed to confirm giant AcomA aneurysm exclusion. The mRS score was recorded 3 months after treatment. The mRS≤ 2 was considered as a good functional outcome. Control DSA was performed one year after treatment.

RESULTS

In the three patients, after a large frontopterional approach, a selective exclusion of their giant AcomA aneurysm was obtained after a partial pars orbitalis of the inferior frontal gyrus resection. Ischemic lesion was noted in 1 patient and chronic hydrocephalus in 2 patients with ruptured aneurysm. The mRS score after 3 months was good in 2 patients. Long term complete occlusion of the aneurysm were noted in the three patients.

CONCLUSION

Selective clipping of a giant AcomA aneurysm is a reliable therapeutic option after a careful evaluation of local vascular anatomy. An adequate surgical exposure is frequently obtained through an enlarged pterional approach with an anterior basifrontal lobe resection, especially in an emergency situation and/or in case of high position of anterior communicating artery.

Funnel Shaped Anterior Communicating Artery Fenestration Mistaken for an Aneurysm: A Cautionary Tale

This report portrays a case of a funnel shaped anterior communicating artery (ACoA) fenestration which was mistaken as a small A1 aneurysm in a subarachnoid hemorrhage case. Although tridimensional rotational digital subtraction angiography improves aneurysm diagnosis specially at the ACoA complex, current spatial resolution might leave behind a considerable percentage of ACoA fenestrations. This may lead to diagnostic errors and unnecessary treatments risking iatrogenic complications. Luckily for our patient, a concomitant aneurysm warranted clipping and subsequent surgical exploration of the ACoA complex revealed the pitfall, thus preventing further action. Interestingly, another group of authors who reported similar misdiagnosis with ACoA aneurysms were able to prevent a third error, thanks to the experience acquired with 2 prior cases. Therefore, this clinical image aims to raise wider awareness of the need for very cautious consideration of imaging depicting small and/or atypical aneurysms in the ACoA complex.

Small symptomatic anterior communicating artery aneurysms: report of three cases and literature review

PURPOSE

Given the anatomical relationship between the ACom complex and the optic nerve, small aneurysms of the ACom can present with visual symptoms.

CASE REPORTS

We summarize and illustrate the clinical course of three patients with symptomatic small ACom aneurysms and collect similar other cases reported.

RESULTS

Ten patients with small unruptured visually symptomatic anterior communicating artery aneurysms were found in the literature. Including three patients herein reported, the mean age at presentation was 56. The most common visual symptoms were bitemporal vision loss and/or a decrease in visual acuity.

CONCLUSION

Unruptured aneurysms of the anterior communicating artery can present with visual symptoms due to compression of optic pathways, even at a small size. Prompt recognition and treatment of such a condition are paramount as new onset of visual symptoms can signify impending rupture akin to small PCom aneurysms compressing the third nerve. We discuss a few pitfalls of clipping small ACom aneurysms compressing the optic nerve.

Alternate Simultaneous Bilateral Carotid Angiography in Y-stent-Assisted Coil Embolization for an Anterior Communicating Artery Aneurysm with Triplicate A2 Variant

The triplicate A2 variant is one of several common anomalies of the anterior cerebral artery. An anterior communicating artery aneurysm with triplicate A2 variant in close proximity to the aneurysm neck is challenging to treat due to potential unilateral/bilateral corpus callosum or parietal lobe infarction. Alternate simultaneous bilateral carotid angiography can differentiate triplicate A2 branches through time-difference alternate injection of contrast into the carotid arteries bilaterally, which can enhance anatomic understanding of complex anterior communicating artery aneurysms during complex endovascular treatment. In this case, a complex aneurysm with an associated triplicate A2 variant was treated successfully with Y-stent-assisted coil embolization using alternate simultaneous bilateral carotid angiography.

Understanding anterior communicating artery aneurysms: A bibliometric analysis of top 100 most cited articles

Bibliometric analysis is of paramount importance in assessing the research impact wherein studies are ranked on the basis of citations received. It also brings out the excellent contribution of authors and journals in adding evidence for future research. This study aimed at evaluating the top 100 most cited articles on anterior communicating artery (ACoA) Aneurysms. Scopus database was searched using title specific search for the aneurysm of ACoA and top 100 most cited articles along with their authors, author IDs, affiliated institutions, countries and funding bodies were identified. Search yielded 841 articles and top 100 articles were identified to include in this analysis which secured 5615 citations. Citations per year was also calculated to minimize the risk of bias. Maximum citations by any article were 242. The United States was the major contributor to the number of articles while Kessler Institute for Rehabilitation became the highest contributing institution. DeLuca J proved to be a pioneer in this specialized area as he penned 6 studies being first author in 4 of them, making him the most frequent author. National Institutes of Health and the U.S. Department of Health and Human Services were the main funding bodies. Subcategory analysis revealed, 50% studies provided evidence for the treatment and the surgical outcome of the aneurysm. Studies like these can aid in better neurological and neurosurgical management in decision making of ACoA aneurysm.

Wire perforation of the missed tiny aneurysm originating from the fenestrated A1 segment during the endovascular approach

Vascular anomaly and aneurysmal formation of an anterior communicating artery (ACOM) complex has often been reported. Because of such a complicated relationship between the vascular structure and aneurysms, ACOM aneurysm is one of the most difficult aneurysms to treat among other common anterior circulation aneurysms. We herein report a case of wire perforation of a missed tiny aneurysm arising from the fenestrated A1 segment during the endovascular approach to ACOM aneurysm. Although the fenestration of A1 segment is a rare vascular anomaly, it is likely to accompany saccular type aneurysms in the vicinity of the vascular anomaly. Endovascular treatment for ACOM aneurysm requires more detailed evaluations of the accompanying vascular anomaly and hemodynamics around ACOM to avoid complications.

A complex anterior communicating artery aneurysm projecting into the sella turcica

Intrasellar aneurysms are rare vascular lesions that typically present with symptoms of mass effect upon the pituitary gland and optic apparatus. Most arise from the internal carotid artery, while only a handful of case reports describe intrasellar aneurysms originating from the anterior communicating artery. The appropriate recognition and management of these lesions are critical to prevent irreversible neurological deficits and catastrophic hemorrhage. Here, we highlight a patient with an anterior communicating artery aneurysm projecting into the sella turcica, leading to hyponatremia, pituitary dysfunction, and chiasmal compression.

Fast Transition from Open Surgery to Endovascular Treatment of Unruptured Anterior Communicating Artery Aneurysms-A Retrospective Analysis of 128 Patients

OBJECTIVE

Anterior communicating artery aneurysms (ACoAAs) are challenging to treat both surgically and endovascularly. In this study, we evaluate the treatment-related morbidity and clinical outcome of microsurgical clipping and endovascular treatment for a consecutive series of unruptured ACoAAs while the treatment paradigm was in transition from surgical to endovascular first.

METHODS

We retrospectively reviewed clinical and radiologic data of adult patients who underwent microsurgical clipping or endovascular treatment of an unruptured ACoAA at a high-volume academic neurovascular center (Helsinki University Hospital) during 2012-2019. During this period, a transition from microsurgical clipping to endovascular treatment took place. Regarding outcome, we focused on treatment-related complications, discharge-to-home rates, functional performance (modified Rankin Scale score), and obliteration rates.

RESULTS

Of 128 treated ACoAAs, 81 (64%) were treated surgically and 47 (36%) endovascularly. There was no difference in major complications, intracranial hemorrhagic complications or ischemic complications, discharge-to-home rates, or functional performance between the surgically and endovascularly treated patients. With time, a decrease in major complications was observed in the surgical cases (from 29% to 17%), whereas the major complication rate increased in the endovascularly patients (from 0% to 25%). Cerebral ischemia was the most frequent complication in both groups. The risk for permanent neurologic deficit remained low in both groups (9% for endovascular and 5% for surgery).

CONCLUSIONS

We did not find any major differences regarding complications and outcomes after the treatment paradigm shift from clipping to endovascular of unruptured ACoAAs. Prospective studies evaluating durability of treatments are needed to compare overall effectiveness.

Surgical Treatment of Large and Giant Anterior Cerebral Artery Aneurysms in the Endovascular Era: Analysis of Large Clinical Series

OBJECTIVE

Analysis of results of surgical treatment of 112 patients with large and giant anterior cerebral artery (ACA) aneurysms.

METHODS

This is the largest clinical series of large and giant ACA aneurysms ever reported. Retrospective analysis of medical charts, radiographic studies, and intraoperative videos was performed. Univariate and multivariate analysis of relations among 3 types of outcomes (complete aneurysm occlusion, ischemic complications, and clinical outcomes) and predicting factors was performed.

RESULTS

Most aneurysms were communicant (84.8%). Aneurysms of the A1 segment and distal segments (A2-A5) were encountered rarely. Complete aneurysm occlusion (class I) was shown in 95 cases (90.5%). In 4 patients, only exploration and wrapping were performed because of severe atherosclerosis and chronic intraluminal thrombi. Partial occlusion (class III) was shown in 2 patients, and neck residual (class II) in 4 patients. Cerebral ischemia developed in 29 patients postoperatively. Occlusion or injury of the A1 segment and anterior communicating artery perforators and recurrent branch of Heubner were the most common reason for ischemic complications. At follow-up, 97 patients (86.6%) had favorable outcomes. Ten patients (8.9%) had unfavorable outcomes because of postoperative complications.

CONCLUSIONS

Microsurgery provides effective and relatively safe occlusion of complex ACA aneurysms. Direct clipping can be applied in most cases independent of their precise location. In certain cases, alternative methods can be safely used. According to multivariate analysis, giant aneurysm size, aneurysm-related mass effect, involvement of large arterial branches in the aneurysm wall, and intraoperative complications were significant predicting factors for ischemic complications.

CLINICAL CHARACTERISTICS AND MORPHOLOGICAL PARAMETERS ASSOCIATED WITH RUPTURE OF ANTERIOR COMMUNICATING ARTERY ANEURYSMS

We analyzed aneurysm morphology, demographic and clinical characteristics in patients with anterior communicating artery (ACoA) aneurysms to investigate the risk factors contributing to aneurysm rupture. A total of 219 patients with ACoA aneurysms were admitted to our hospital between January 2016 and December 2020, and morphological and clinical characteristics were analyzed retrospectively in 153 patients (112 ruptured and 41 unruptured). Medical records were reviewed to obtain demographic and clinical data on age, gender, presence of hemorrhage, history of hypertension, diabetes, heart disease, and kidney disease. Morphological parameters examined on 3-dimensional digital subtraction angiography included aneurysm size, neck diameter, aspect ratio, size ratio, bottleneck ratio, height/width ratio, aneurysm angle, (in)flow angle, branching angle, number of aneurysms per patient, shape of the aneurysm, aneurysm wall morphology, variation of the A1 segment, and direction of the aneurysm. Male gender, aspect ratio, height/width ratio, non-spherical and irregular shape were associated with higher odds of rupture, whilst controlled hypertension was associated with lower odds of rupture, when tested using univariate logistic regression model. In multivariate model, controlled hypertension, presence of multiple aneurysms, and larger neck diameter reduced the odds of rupture, while irregular wall morphology increased the risk of rupture. Regulated hypertension represented a significant protective factor from ACoA aneurysm rupture. We found that ACoA aneurysms in male patients and those with greater aspect ratios and height/width ratios, larger aneurysm angles, presence of daughter sacs and irregular and non-spherical shapes were at a higher risk of rupture.

Variations of perforating arteries of anterior communicating artery in cases with anterior communicating artery aneurysms: a cadaveric anatomical study

PURPOSE

In terms of postoperative morbidity and mortality, preservation of the perforating arteries branching from the anterior communicating artery (ACoA) during clipping is particularly imperative in patients with ACoA aneurysm. In the present study, we aimed to investigate whether perforating arteries originated from ACoA were pushed away in a different location in patients with ACoA aneurysm. Furthermore, if they did so, we aimed to identify the direction in which they were dislocated and how the perforating arteries could be preserved during clipping.

METHODS

Herein, we categorized 40 brains obtained from cadavers into two groups. The first (n = 26) and second (n = 14) groups included cases without and with ACoA aneurysms, respectively. After completing the preparation procedure, the brains were dissected using surgical microscope and the relevant anatomical region was examined and photographed. Finally, statistical analyses were performed on the data and the results were documented.

RESULTS

In the aneurysms with posterior and superior projections, the perforators appeared to be pushed away inferiorly and were frequently noted at the anteroinferior part of the aneurysm neck. Most of the cases, where one of the A1s was larger at one side, the perforating arteries arose from the larger A1 side.

CONCLUSION

The mortality and morbidity associated with damage to the perforators can be reduced by approaching the patient from the dominant A1 side and pursuing the perforators primarily at the anteroinferior part of the aneurysm neck in the aneurysms with superior and posterior projections.

Trends and Outcomes of Endovascular Embolization and Surgical Clipping for Ruptured Intracranial Aneurysms: A Propensity-Matched Study of 1332 Patients in the United States

OBJECTIVE

To describe recent trends in treatment and outcomes of endovascular coil embolization and microsurgical clipping treatment strategies for ruptured intracranial aneurysms.

METHODS

Using International Classification of Diseases, Tenth Revision, codes, 1332 propensity-matched patients >18 years old who underwent coiling or clipping were identified. Patient demographics, baseline characteristics, comorbidities, and clinical outcomes were evaluated within 1 year postoperatively. Pooled and individual studies of the International Classification of Diseases codes investigated differences in clinical outcomes owing to aneurysm location. Outcomes were mortality, intensive care, surgical complications, hydrocephalus, and vasospasm.

RESULTS

After propensity matching for baseline characteristics and comorbidities, 666 patients were included in the coiling and clipping cohorts. There was no significant difference in 1-year mortality between cohorts. However, incidence of intensive care, surgical/medical complications, and vasospasm was significantly lower in the pooled coiling cohort (P = 0.02, P = 0.03, and P = 0.014) compared with the clipping cohort within 1 year postoperatively. Additionally, individual International Classification of Diseases code analysis revealed that coiling of anterior communicating artery aneurysms was associated with significantly fewer surgical/medical complications and hydrocephalus (P = 0.0008 and P = 0.015) and coiling of posterior communicating artery aneurysms was associated with substantially less vasospasm treatment (P = 0.034) compared with the respective clipping cohorts.

CONCLUSIONS

Analysis revealed no difference in 1-year mortality between coiling and clipping. Clinical outcomes, including intensive care, surgical complications, and vasospasm, favored coiling regardless of aneurysm location. Patients with coiling of anterior communicating artery aneurysms had significantly less hydrocephalus and patients with coiling of posterior communicating artery aneurysms had substantially less vasospasm treatment within 1 year compared with the clipping cohort.

Embryology of the anterior communicating artery complex: implications on possible adult variants

The anterior cerebral artery (ACA) and the anterior communicating artery (AComA) are important arteries of the telencephalon and are prominent location for cerebral aneurysms. Their embryological development is closely linked, and explains the possible variants seen in adults. In this paper, we present details related to the development of these two arteries, focusing on some variants such as the infra-optic course of the ACA, the unpaired ACA, and the persistent primitive olfactory artery.

Multiple cerebral arterial variations incidentally detected by magnetic resonance angiography: a case report

We herein report a case of multiple variations, including (1) anterior communicating artery duplication, (2) accessory anterior cerebral artery (ACA), (3) distal origin right accessory middle cerebral artery (MCA) with bifurcation, (4) proximal origin left accessory MCA with bifurcation, (5) right superior cerebellar artery (SCA) duplication, and (6) left SCA early bifurcation. These variations were found incidentally by magnetic resonance (MR) angiography. Volume-rendering images of MR angiography were more useful than maximum-intensity-projection images for identifying these variations, especially bilateral accessory MCAs, which were superimposed with the A1 segment of the ACAs and the M1 segment of the MCAs.

Greater hemodynamic stresses initiated the anterior communicating artery aneurysm on the vascular bifurcation apex

OBJECTIVE

To investigate hemodynamic stresses associated with the anterior communicating artery (Acom) aneurysm formation using computational fluid dynamics (CFD) analysis.

METHODS

Three-dimensional geometries of the anterior cerebral artery (ACA) bifurcations in 20 patients with Acom aneurysms and 20 control subjects were used for CFD analysis to investigate hemodynamic stresses including the total and dynamic pressure, wall shear stress (WSS), vorticity and strain rate.

RESULTS

At the direct flow impinging center on the bifurcation apex, the total pressure was the maximal but decreased quickly from the impinging center to both daughter branches. The WSS, dynamic pressure, vorticity and strain rate were the minimal at the direct impinging center but increased rapidly and reached the peaks at both daughter branches. The ACA bifurcation angle was significantly (P < 0.001) greater in patients with than without Acom aneurysms (144.2° ± 4.1° vs. 105.1° ± 3.2°). Most aneurysms (70% and 85%, respectively) were deviated to the smaller daughter branch or to the daughter branch forming a smaller angle with the A1 segment of ACA, where the hemodynamic stresses were significantly (P < 0.05) greater than those on the contralateral daughter branch. After aneurysm formation, the hemodynamic stresses on the aneurysm dome were all significantly decreased compared with at the aneurysm initiation site with aneurysm virtual removal (P < 0.001).

CONCLUSION

Formation of the Acom aneurysm is closely associated with and is to decrease the locally abnormally enhanced hemodynamic stresses.

Blister-like aneurysm of the anterior communicating artery treated with only Low-profile Visualized Intraluminal Support Junior stent

Background:

Endovascular treatment is becoming a mainstream treatment for blister-like aneurysms in recent years. Blister-like aneurysms are usually located in the internal carotid artery, whereas that of the anterior communicating artery (AcomA) are very rare. We report the first case of blister-like aneurysm of AcomA that was treated solely with a neck bridging stent that resulted in complete occlusion without complication.

Case Description:

A 50- year- old woman was admitted to our hospital due to a subarachnoid hemorrhage. Digital subtraction angiography showed a very small aneurysm in the dorsal side of the AcomA. We considered it a blister-like aneurysm based on its size and shape. She underwent endovascular treatment under general anesthesia on day 15 after vasospasm period. Dual antiplatelet therapy was administrated 1 week prior. A Low-profile Visualized Intraluminal Support Junior stent was implanted from the left A2 to the right A1, covering the AcomA. The postoperative course was uneventful, and she was discharged with no neurological deficit. The aneurysm remained unchanged on postoperative day 14; however, complete occlusion was achieved 3 months after the treatment.

Conclusion:

Monotherapy with a neck bridging stent is an effective treatment option for blister-like aneurysms. Treatment with a single stent could achieve complete occlusion especially if the aneurysms occur elsewhere than the internal carotid artery. We should consider immediate additional treatment if the aneurysm grows within 1 month after initial treatment.

Comparison between ultra-high-resolution computed tomographic angiography and conventional computed tomographic angiography in the visualization of the subcallosal artery

Background:

The subcallosal artery (ScA) is a single dominant artery arising from the anterior communicating artery. Its injury causes amnesia and cognitive disturbance. The conventional computed tomographic angiography (C-CTA) is a common evaluation method of the intracranial artery. However, to image tinny perforating arteries such as the ScA is technically demanding for C-CTA. The purpose of this study is to investigate whether the ultra-high-resolution CTA (UHR-CTA) could image the ScA better than C-CTA. UHR-CTA became available in clinical practice in 2017. Its novel features are the improvement of the detector system and a small X-ray focus.

Methods:

Between April 2019 and May 2020, 77 and 49 patients who underwent intracranial UHR-CTA and C-CTA, respectively, were enrolled in this study. Two board-certified neurosurgeons participated as observers to identify the ScA based on UHR-CTA and C-CTA images.

Results:

UHR-CTA and C-CTA detected the ScA in 56–58% and 30–40% of the patients, respectively. In visualization of the ScA, UHR-CTA was better than C-CTA (P < 0.05, Fisher’s exact test). Between the two observers, the Cohen’s kappa coefficient was 0.77 for UHR-CTA and 0.78 for C-CTA.

Conclusions:

UHR-CTA is a simple and accessible method to evaluate intracranial vasculature. Visualization of the ScA with UHR-CTA was better than that with C-CTA. The high quality of UHR-CTA could provide useful information in the neurosurgery field.

Geometrical and Hemodynamic Characteristic Changes of Small Anterior Communicating Artery Aneurysms during Follow-ups in a Retrospective Analysis

Background

Small intracranial aneurysms have a low risk of rupture. However, ruptured anterior communicating artery (ACoA) aneurysms are usually smaller in clinical practice. The retrospective study aimed to investigate the geometrical and hemodynamic changes of small unruptured ACoA aneurysms during serial follow-ups.

Materials and Methods

We retrospectively collected patients with small unruptured ACoA aneurysms that were not repaired, who had serial follow-ups from the Electronic Medical Record System in four tertiary hospitals. The geometrical parameters of ACoA aneurysms were measured using a three-dimensional reconstructed model. Intra-aneurysmal hemodynamic parameters were computed using a high-resolution computational fluid dynamics model. Geometrical and hemodynamic changes of the aneurysms were evaluated at each follow-up.

Results

Five patients with small unruptured ACoA aneurysms that were not repaired were identified and included in this analysis. Aneurysms rupture occurred in two patients with aneurysm growth. The formation and enlargement of an irregular bleb at the aneurysm neck or dome were observed before the rupture. Ruptured aneurysms showed high wall shear stress (WSS) in the high inflow zone of aneurysm neck while low WSS and high oscillatory shear index (OSI) in the flow-recirculating region of aneurysm dome. Three unruptured aneurysms maintained a stable morphology and a physiological level of WSS.

Conclusions

Aneurysm growth, low WSS, and high OSI at the dome and/or high WSS at the neck potentially contribute to the rupture of small ACoA aneurysms. These aneurysms should be considered for the treatment regardless of the small size.

Anterior Cerebral Artery and Anterior Communicating Artery Variations: Assessment with Magnetic Resonance Angiography

BACKGROUND

Although anterior cerebral artery (ACA) and anterior communicating artery (AcomA) variations have been frequently investigated by contrast-enhanced angiography, the number of studies performed with magnetic resonance angiography is quite low. Our aim in this study is to investigate ACA and AcomA variations with time of flight magnetic resonance angiography (TOF MRA).

METHODS

Source and maximum intensity projection images of 581 adult patients (273 males, 308 females) who were scanned for intracranial arteries with the TOF MRA method were retrospectively analyzed.

RESULTS

We found the typical configuration rate of the ACA and AcomA complex to be 40.6%. The most common structural anatomic variations out of typical configuration were AcomA aplasia (18.9%) and AcomA hypoplasia (17.9%), respectively. The least frequent variation that we found was duplicated AcomA (0.9%). When we examined gender comparatively, unilateral A1 segment aplasia was found to be higher in males and azygos ACA was found to be higher in females (P = 0.001 and P = 0.029, respectively).

CONCLUSIONS

In this study, in which we used the TOF MRA technique, we detected high rates of anatomic variations of ACA and AcomA. This method, which is noninvasive, does not require contrast material and does not contain ionizing radiation, can be preferred especially in the evaluation of patients with kidney disease and contrast allergy.

Posterior Transposition of the Frontal Bridging Veins Together with Sphenoparietal Sinus: A Simple Technique to Widen the Surgical Corridor During Pterional Clipping of the Anterior Communicating Artery

BACKGROUND

High-positioned and/or superoposteriorly directed anterior communicating artery aneurysms can be treated by direct clipping using the pterional (fronto-temporo-sphenoidal) approach. This procedure, however, requires stronger retraction of the frontal lobe. Hence, preservation of the prominent frontal bridging veins (FBVs) draining into the sphenoparietal sinus (SPS) remains a significant challenge in preventing postoperative venous congestion.

METHODS

We developed a technique to release the tension on the FBVs by pulling them together with the SPS epidurally. In 2 patients, who had presented with high-positioned and/or superoposteriorly directed anterior communicating artery aneurysms, we peeled off the arachnoid surrounding the FBVs and detached it from the brain surface. We further released the veins by moving them posteriorly, together with the SPS epidurally.

RESULTS

Using this technique, we established a wide corridor through a more lateral transsylvian trajectory with effective posterior retraction of the frontal lobe and were successful in clipping and obliterating the aneurysms.

CONCLUSIONS

Open clipping of unruptured intracranial aneurysms requires accuracy to preserve higher brain function. Our technique was successful in both patients, and preserving the FBVs could be useful in the treatment of such aneurysms.

An MRI study of typical anatomical variants of the anterior communicating artery complex

PURPOSE

This magnetic resonance imaging study examined the most frequent anatomical variants of the anterior communicating artery (ACoA) complex of the cerebral arterial circle, and aimed to determine whether they were associated with ACoA complex aneurysm.

METHODS

The study enrolled 669 patients. Using three-dimensional time-of-flight magnetic resonance angiography, 617 patients were classified into the following groups based on the anatomical variation in the ACoA complex: no ACoA complex anomaly; ACoA complex aneurysm; and vascular anomaly distant from the cerebral arterial circle.

RESULTS

Of the 617 classified subjects, the classical anatomical description applied to 48.73% in the no ACoA complex anomaly group and 37.5% in the ACoA complex aneurysm group. One variant (left anterior cerebral artery segment A1 hypoplasia) was significantly more frequent in the ACoA complex aneurysm group. There was no sex difference in the prevalence of any variant.

CONCLUSIONS

Anatomical variants of the ACoA complex of the cerebral arterial circle were found in almost half of the subjects. One variant seemed to be associated with a higher likelihood of an aneurysm, but causality could not be inferred.

Analysis of Risk Factors for Anterior Communicating Artery Aneurysm Rupture: A Single-Center Study

BACKGROUND

Congenital hypoplasia or aplasia of the A1 segment of the anterior cerebral artery is associated with an increased incidence of berry aneurysms at the anterior communicating artery (ACoA) complex. We analyzed the factors contributing to ACoA aneurysm rupture.

METHODS

We retrospectively analyzed the data of patients with ACoA aneurysms who had undergone cerebral angiography from July 2008 to January 2020. The risk factors for rupture were identified using univariate and multivariate logistic regression models. We used the imaging data of patients without intracranial aneurysms as the control population.

RESULTS

We confirmed 253 aneurysms in 253 patients, including 137 men (54.2%) and 116 women (45.8%), with a mean age of 54.6 ± 12.7 years. Of the 253 aneurysms, 218 (86.2%) were ruptured and 35 (13.8%) were unruptured, with a mean diameter of 4.56 ± 1.96 mm and 3.24 ± 1.79 mm, respectively. Of the 253 aneurysms, 176 (69.6%) were <5 mm in diameter, 146 (83%) of which were ruptured. Of the 253 patients, 141 (55.7%) exhibited A1 segment hypoplasia or aplasia: 106 (41.9%) on the right side of the circle of Willis and 35 (13.8%) on the left. Multivariate logistic regression analysis identified the aneurysm diameter (odds ratio, 4.11; 95% confidence interval, 1.601-16.07; P = 0.003) and age <65 years (odds ratio, 0.17; 95% confidence interval, 0.062-0.48; P < 0.001) as independent predictors of rupture.

CONCLUSIONS

ACoA aneurysms are small (<5 mm) and have a high risk of rupture. A1 segment hypoplasia or aplasia is a risk factor for ACoA aneurysm formation; however, it was uncorrelated with aneurysm diameter or rupture risk. The strongest independent risk factors for rupture were age <65 years and aneurysm diameter.

The Safety and Efficacy of Endovascular Treatment for Very Small Ruptured Anterior Communicating Artery Aneurysms: A Large Single-Center Experience With 81 Consecutive Cases

OBJECTIVE

This study aimed to investigate the safety and efficacy of endovascular embolization for very small ruptured anterior communicating artery (AcomA) aneurysms.

METHODS

From August 2015 to June 2020, 81 patients with very small (≤3 mm) ruptured AcomA aneurysms treated endovascularly were enrolled in this study. Clinical and radiographic data were analyzed retrospectively, including the aneurysm occlusion rate, complications, and clinical outcome.

RESULTS

Among 81 patients, simple coiling embolization was performed in 52 cases and stent-assisted embolization in 29 cases. Immediate angiography demonstrated complete occlusion in 59 (72.8%) aneurysms, residual neck in 20 (24.7%) aneurysms, and residual lumen in 2 (2.5%). Procedure-related complications rate was 2.5% (2 of 81), all of which were transient thromboembolic events. Angiographic follow-up outcomes of 60 patients (mean: 6.8 ± 3.2 months) revealed complete occlusion in 91.7% (55 of 60), with recurrence in 1 patient. The mean clinical follow-up time was 22.6 ± 11.4 months and good prognosis rates (6-month modified Rankin Scale score: 0-2) reached 90.2% (73 of 81). The differences in aneurysm occlusion and procedure-related complications between the simple coiling group and the stent-assisted coiling group were not statistically significant.

CONCLUSIONS

Coiling with or without stent-assisted technique for the treatment of very small ruptured AcomA aneurysms was safe and effective.

Predictors of Poor-Grade Aneurysmal Subarachnoid Hemorrhage Caused by Anterior Communicating Artery Aneurysm

BACKGROUND

Patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH) are considered to have a poor prognosis. However, the underlying reason for the association between the aneurysmal characteristics and poor-grade aSAH is still unclear. In the present study, we retrospectively evaluated the independent risk factors for patients with anterior communicating artery (ACoA) aneurysms with poor-grade aSAH.

METHODS

From January 2009 to January 2016, 477 consecutive patients with ruptured ACoA aneurysms were included in the present study. Poor-grade aSAH was defined as a World Federation of Neurosurgical Society grade of IV or V, and good-grade aSAH was defined as a grade of I-III. Univariate and multivariable regression analyses were used to investigate the differences in aneurysm morphology and clinical characteristics between the 2 groups.

RESULTS

On univariate analysis, older patients (P = 0.038), larger aneurysm size (P = 0.013), larger size ratio (P = 0.007), larger aspect ratio (P = 0.009), positive history of stroke (P = 0.001), and posterior projection aneurysms (P = 0.001) were associated with poor-grade aSAH. Multivariate analyses revealed that older patients (odds ratio [OR], 1.654; 95% confidence interval [CI], 1.004-2.728; P = 0.048), larger size ratio (OR, 1.280; 95% CI, 1.111-1.475; P = 0.001), positive history of stroke (OR, 6.051; 95% CI, 1.712-21.381; P = 0.005), and posterior projection aneurysms (OR, 2.718; 95% CI, 1.607-4.598; P < 0.001) were independently associated with poor-grade aSAH.

CONCLUSIONS

Poor-grade aSAH was independently associated with older patients, a larger size ratio, a positive history of stroke, and posterior projection aneurysms in patients with a ruptured ACoA aneurysm. These parameters could contribute to screening for patients with the potential for poor-grade aSAH.

Vascular Geometry Associated with Anterior Communicating Artery Aneurysm Formation

OBJECTIVE

To identify clinical and morphologic risk factors correlated with anterior communicating artery (ACoA) aneurysm formation.

METHODS

Three-dimensional morphologic parameters obtained from computed tomography angiography or digital subtraction angiography from 504 patients with ACoA aneurysms and 201 patients with aneurysms in other locations that were diagnosed at Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016 were evaluated. The presence of hypoplastic and aplastic A1 segments and diameters and angles of surrounding parent and daughter vessels were examined. Univariable and multivariable statistical analyses were performed to determine statistical significance. Sensitivity analyses for small (≤3 mm) aneurysms only were also performed.

RESULTS

Aplastic and hypoplastic A1 segments were more common in the ACoA group (38.9% vs. 6.5% hypoplastic and 22.2% vs. 0.5% aplastic). In multivariable analysis, the presence of a hypoplastic A1 segment was associated with ACoA aneurysms. An A2-ACoA (daughter-daughter) angle was also significantly associated with ACoA aneurysms in multivariable analysis; however, as Pearson's correlation test between aneurysm width and daughter-daughter angle was significant, the daughter-daughter angle was most likely not independently associated with aneurysm presence, but rather might have been a result of the presence of an aneurysm. Subgroup analyses of small aneurysms (≤3 mm) and of unruptured aneurysms showed similar results.

CONCLUSIONS

Our results demonstrate that of all the morphologic parameters, the presence of a hypoplastic A1 segment was the only parameter independently associated with the presence of ACoA aneurysms that was not correlated with aneurysm size and could aid as a simple screening parameter.

A Cadaveric Anatomical Study on Anterior Communicating Artery Aneurysm Surgery by Extended Endoscopic Endonasal Approach

Background:

The use of minimally invasive approaches in the management of cerebral aneurysms continues to evolve and a purely endoscopic endonasal approach (EEA) for cerebral aneurysm has its own advantages. The purpose of the present study is to perform a detailed anatomical dissection study to test the usefulness of the extended EEAs for selected anterior communicating artery (ACoA) aneurysm.

Materials and Methods:

Nine human cadaveric heads were used for this study, and all dissections were performed through the endonasal corridor. Endoscopic endonasal surgical dissections were carried out, and surgery was simulated in all specimens to reach the ACoA region. The ACoA complex, its neural and osseous relations, degree of vascular exposure, and the ability to perform clip placement were observed and analyzed.

Results:

The transplanum and transtuberculum approaches exposed the A1 and A2 segments of the anterior cerebral artery and the ACoA in all specimens. This route allowed clip ligation of the distal A1 branches, ACoA and proximal A2 branches to the level of the pericallosal segment. Proximal and distal control was most readily achievable at the level of the ACoA complex.

Conclusion:

The present cadaveric study on nine specimens with bilateral dissection has demonstrated that the endonasal transplanum transtuberculum approach to the ACoA region provides excellent visualization of the vasculature. When selected prudently, such lesions may be favorable targets for an extended endoscopic endonasal (EEA) in comparison to transcranial approaches that may provide a suboptimal exposure.

Proximal Branches of the Anterior Cerebral Artery: Anatomic Study and Applications to Endoscopic Endonasal Surgery

BACKGROUND

The endoscopic endonasal approach is a surgical alternative for midline anterior skull base tumors. A detailed understanding of the proximal anterior cerebral artery (ACA) branches' anatomy from an endonasal perspective is essential for avoiding vascular complications.

OBJECTIVE

To evaluate, from an endonasal perspective, the anatomic variations of the ACA and its proximal branches, specifically the recurrent artery of Heubner (RAH), and the fronto-orbital (FOA) and frontopolar (FPA) arteries.

METHODS

We study the origin, course, branching pattern, diameter, and relationship between the proximal ACA branches and the optic apparatus and olfactory tract in 25 head specimens.

RESULTS

The RAH was present in all hemispheres and originated within 3 ± 1.5 mm of the AcomA, with a 0.4 ± 0.1 mm diameter. Based on its relationship with the A1 segment, we observed three RAH courses: anterior (40%), superior (22%), and posterior (38%). The FOA was present in all cases, a mean of 6 ± 4 mm from the AcomA, with a 0.7 ± 0.4 mm diameter. The FOA arose mainly from the A2 (70%), with three courses in relation to the olfactory tract: crossing its proximal third (54%), crossing its middle third (31%), and running parallel to it along the gyrus rectus (15%). The FPA was present in 92% of the hemispheres, a mean of 10 ± 5 mm from the AcomA, always arising from the A2 and coursing anteriorly within the interhemispheric fissure towards the frontal pole.

CONCLUSION

The RAH, FOA, and FPA can be differentiated by origin, course, and destination using the A1 segment, olfactory tract, and interhemispheric fissure, respectively, as surgical landmarks.

Anatomical variants of anterior communicating artery complex. A study by Computerized Tomographic Angiography

Advances in imaging techniques have led to the identification of normal variations and abnormalities of cerebral arteries. Although the anterior communicating artery complex (ACAC) variations are usually asymptomatic, their description is essential in the radiologic report, since they can have clinical relevance. The aim of this study is to describe arterial anomalies of the ACAC and their prevalence. A retrospective observational descriptive analysis of ACAC variations in Computerized Tomographic Angiography (CTA) was performed. All CTA (426 studies) obtained in our center from 2015 to 2017 were included. Presence of aneurysm was recorded and its relationship with arterial variants was analyzed with a Chi-square test. The most common variants found in our study are linked to the A1 segment (42.3%) of the anterior cerebral artery (ACA): absence: 10.6%, hypoplasia: 31.2%, fenestration: 0.5%. A2 segment variants were present in 15.3% (absence: 0.2%; hypoplasia 8.5%; Azygos artery: 1.4%; triple ACA: 5.2%). Anterior Communicanting Artery was typical in 92.5%, absent in 4.7%, double/fenestrated in 0.9%, triple in 0.2%, X-shape in 1.2% and Y-shape in 0.2%. Aneurysms were present in 10.7%. Anterior circulation aneurysm involved the 50% of patients with aneurysm. Although the 60.9% of them showed artery variants, they did not reach statistical significance (p = 0.6). In conclusion, the Anterior Communicating Artery Complex presents variations in its anatomy. The most common anterior circulation vascular variants are the hypoplasia and the absence of the A1 segment. There does not appear to be a clear association between intracranial aneurysms and anatomical variations.

Morphological risk model assessing anterior communicating artery aneurysm rupture: Development and validation

OBJECTIVE

Prediction of the rupture risk in anterior communicating artery (ACoA) aneurysms remains challenging. We aimed to investigate the association of detailed morphologies with ACoA aneurysm rupture.

PATIENT AND METHODS

759 consecutive patients with ACoA aneurysms were identified from December 2007 to January 2016. An independent cohort was collected for validation from March 2017 to October 2019. Morphological parameters of the aneurysms were measured using CT angiography. Univariable and multivariable analyses were used to investigate the association of morphological characteristics with aneurysm rupture. Area under receiver operating characteristic curves (AUC) were used to assess the performance of the model.

RESULTS

A total of 650 patients with 650 ACoA aneurysms were included for the derivation, and 41 patients with 41 ACoA aneurysms were included for the validation. Aneurysm size, neck size, aspect ratio, size ratio, vessel angle, anterior projection, dominant A1 segment, irregular shape, the presence of a daughter dome, vessel size, and aneurysm angle were risk factors for rupture. The multivariable analysis showed that a larger aneurysm, anterior projection of aneurysms, dominant A1 segment, and irregular aneurysms were associated with aneurysm rupture, whereas larger vessel size was inversely associated with rupture. The morphological risk score showed good discrimination of ruptured and unruptured aneurysms with an AUC of 0.73 in the derivation and an AUC of 0.80 in the validation, and good calibration in both cohorts, signifying a good fit.

CONCLUSION

The morphological risk model may contribute to evaluating the risk of rupture of ACoA aneurysms.

Unilateral absence of the internal carotid artery associated with anterior communicating artery aneurysms: Systematic review and a proposed management algorithm

Background:

Absence or hypoplasia of the internal carotid artery (ICA) is a rare congenital anomaly that is mostly unilateral and highly associated with other intracranial vascular anomalies, of which saccular aneurysm is the most common. Blood flow to the circulation of the affected side is maintained by collateral pathways, some of which include the anterior communicating artery (Acom) as part of their anatomy. Therefore, temporary clipping during microsurgery on Acom aneurysms in patients with unilateral ICA anomalies could jeopardize these collaterals and place the patient at risk of ischemic damage. In this paper, we review the literature on cases with a unilaterally absent ICA associated with Acom aneurysms and provide an illustrative case.

Methods:

We combined our experience of one case of a unilaterally absent ICA associated with an Acom aneurysm with the 33 existing publications on the same subject in the literature, for a total of 40 cases. We provide a detailed systematic literature review of this association of vascular anomalies, exploring different aspects regarding the collateral pathways and how they impact management strategies and propose a management algorithm to deal with such association.

Results:

The mean age was 48.2 ± 16.5 years. The aneurysmal rupture was the most common presentation (75%). Agenesis was observed in 70% of patients, followed by hypoplasia (20%) and, finally, aplasia (10%). Lie Type A was the most common pattern of collaterals (50%), with Types B and D being of almost equal proportions. Most aneurysms were located at the A1-Acom junction contralateral to the anomalous side (Fisher’s Exact test; P = 0.03). One case of temporary clipping was reported in the literature.

Conclusion:

Acom aneurysms in patients with unilateral ICA anomalies, given they are more commonly present contralaterally, could be of acquired etiology, warranting periodic screening in asymptomatic patients. Temporary clipping might be safe in patients with Type D collateral pattern, while those with Types A or B may require intraoperative rupture risk assessment and a tailored management plan to avoid disrupting collateral flow and causing ischemia.

Recurrence and retreatment of anterior communicating artery aneurysms after endovascular treatment: a retrospective study

Background

Surgical treatment of anterior communicating artery (Acom) aneurysm is challenging due to anatomic complexity. We aimed to describe our experiences with endovascular treatment (EVT) of Acom aneurysms, and to evaluate the incidence and risk factors of recurrence and retreatment.

Methods

The study comprised 260 patients who were treated at a single center between January 2010 and December 2018. Patients who had EVT, including stent-assisted coiling of Acom aneurysms, were included. All medical records were retrospectively reviewed. The incidence and risk factors of recurrence and retreatment were evaluated. Univariate and multivariate analysis were conducted.

Results

Recurrence of Acom aneurysms occurred in 38 (14.6%) patients. Mean follow-up duration was 27 months (range 1–110). Multivariate logistic regression indicated that ruptured aneurysm (odds ratio [OR] 3.55, P = 0.001), dome direction (anterior) (OR 3.86, P = 0.002), maximal diameter (OR 1.19, P = 0.02), and mean age (OR 0.96, P = 0.02) were independent risk factors for aneurysm recurrence. Of 38 cases of recurrence, 10 (3.8%) patients underwent retreatment. Ruptured aneurysm (OR 14.7, P = 0.004), maximal diameter (OR 1.56, P = 0.02), inflow angle (OR 1.04, P = 0.03), and Raymond-Roy classes II and III (OR 6.19, P = 0.03) showed significant relation to retreatment in multivariate logistic regression analysis.

Conclusions

In our study, recurrence rate of Acom aneurysms after EVT was 14.6%. Rupture, anterior dome direction, maximal diameter, and mean age were significantly associated with recurrence. Retreatment rate of recurrent Acom aneurysms after EVT was 3.8%. Patients with Acom aneurysms with large inflow, rupture, large size, or incomplete occlusion may be at a high risk of retreatment of recurring aneurysm.

Post-traumatic aneurysmal rupture involving the circle of Willis affected by fibromuscular dysplasia. A case report and systematic review

The fatal rupture of a saccular aneurysm at the junction between the left anterior cerebral artery and anterior communicating artery affected by fibromuscular dysplasia (FMD) is a rare condition. Here is reported the case of a subject involved in a road traffic accident a few minutes before the death, which opened the debate on the real cause of death in a forensic setting. By autopsy, the examination of the brain revealed subarachnoid haemorrhage with flooding of the ventricles due to the breached saccular aneurysm of the junction between the left anterior cerebral artery and anterior communicating artery, in FMD mainly affecting the circle of Willis arteries. A spontaneous aneurysmal rupture was excluded on the basis of probabilistic analysis, in the presence of alternative hypotheses that could explain the facts. The passenger's delayed loss of consciousness may be explained as much by a hypertension-linked rupture of the aneurysm triggered by the emotional stress experienced, as by the traumatic shaking/impact of the aneurysm against the bony skull structures, in a subject predisposed to aneurysm frailty due to FMD. Overall, the concausal role of both the road traffic accident, typified by high kinetic energy, and the presence of a pre-existing aneurysmatic weakness due to FMD is fully recognized. The identification of anatomical variants, jointly with uncommon diseases at the examination of the brain base arteries in any case of isolated basal subarachnoid haemorrhage, may avoid wrong legal consequences even when the cause of death seems to be obviously of simple traumatic origin.

Comparative Analysis of Pterional, Supraorbital, Extended Supraorbital, and Transtubercular-Transplanum Approaches for Exposing the Anterior Communicating Artery Complex: A Cadaveric Study

OBJECTIVE

We aimed to quantify and compare surgical exposure and freedom at the anterior communicating artery (ACoA) complex using pterional (PT), supraorbital (SO), extended supraorbital withorbital osteotomy (SOO), and endonasal endoscopic transtubercular-transplanum (EEATT) approaches.

METHODS

Right-sided PT, SO, SOO, and EEATT approaches were performed using 10 cadaveric heads. Surgical exposure and freedom (horizontal and vertical attack angle) at the ACoA complex were measured. The farthest clipping distance from ACoA to A1 (precommunicating segment of the anterior cerebral artery)/A2 (postcommunicating segment of the anterior cerebral artery) was also quantified.

RESULTS

There was a significantly greater exposure length of right A1 in the PT approach (12.20 ± 2.48 mm) compared with the EEATT approach (9.52 ± 2.09 mm; P = 0.029). Among the 4 approaches, EEATT provided the shortest clipping distance for right A1 (6.56 ± 1.33 mm; P = 0.001) and the longest clipping distance for right A2 (3.36 ± 1.24 mm; P = 0.003). SO, SOO, and PT approaches (2.9 ± 0.9) had more observations on perforators from ACoA than did the EEATT approach (2.0 ± 0.66; P = 0.029). The EEATT approach (50.90 ± 17.45 mm²) provided better exposure of the superior part of the ACoA complex compared with the SO approach (29.37 ± 17.27 mm²; P = 0.05). PT and SOO approaches provided the greatest horizontal (36.88° ± 5.85°) and vertical (19.37° ± 4.70°) attack angle, respectively.

CONCLUSIONS

The SO, SOO, and PT approaches provided a better hemilateral view of the ACoA complex and similar surgical exposure, whereas the EEATT approach offered greater exposure in the upper part of the ACoA complex, with relatively limited exposure of perforators from ACoA and surgical freedom. The EEATT approach can play a role in exposure of lesion involving the ACoA complex.

Association of Anterior Communicating Artery Aneurysms with Triplicate A2 Segment of the Anterior Cerebral Artery

OBJECTIVE

Triplicate A2 segment of the anterior cerebral artery is a rare anatomical variant (1%-3% prevalence) that which is thought to result mainly from persistence of the embryonic median artery of the corpus callosum. We sought to determine whether the triple-A2 variant is specifically associated with anterior communicating artery (ACoA) aneurysm.

METHODS

We reviewed 2-dimensional digital-subtraction angiography (2D-DSA) as well as 3-dimensional rotational angiography (3D-RA) images of 55 patients with ACoA aneurysms who presented for evaluation and treatment between 2009 and 2014 at our institution. The criteria for definitively obtaining an accurate accounting of all A2 segments was presence of adequate cross-filling across the ACoA on 2D-DSA or 3D-RA imaging, or ability to fuse left and right 3D-RA images. Patients whose imaging did not meet these criteria were excluded from further analysis.

RESULTS

We obtained a definitive count of all A2 segments in 36 patients. Among these, 19 patients (5 with the triple-A2 variant) were treated surgically, and 17 patients (2 with the triple-A2 variant) were treated endovascularly. The triple-A2 variant was seen in 7 patients. The prevalence of triple-A2 variant among patients with ACoA aneurysm was 19.4%. Patients with ACoA aneurysms had a significantly higher prevalence of the triple-A2 variant compared with the general population (P < 0.00001).

CONCLUSIONS

Compared with the normal population, patients with ACoA aneurysms deemed to require treatment have a significantly higher likelihood of having triplicate A2 segment. Knowledge of this anatomical variation is of critical importance in planning and executing endovascular and microsurgical treatment of ACoA aneurysms.

Intraoperative Shortening of Aneurysm Clips: Revisiting an Old Technique in a New Era

BACKGROUND

It can sometimes be challenging to find a suitable clip to treat an unusual aneurysm, or when the surrounding anatomy is unusual, especially in resource-limited environments. We describe a method to modify aneurysm clips based on the method originated by Sugita et al in 1985. Herein clip modification (Clip-Mod) is used to treat anatomically difficult anterior communicating artery aneurysms.

METHODS

The Department of Neurological Surgery database was reviewed to find aneurysm patients treated using modified aneurysm clips. Clip-Mod was performed during surgery by shortening the tines of titanium aneurysm clips by abrasion applied from the side of a standard 3-mm surgical diamond drill bit under constant irrigation. Note that the thickness of the tines and the clip spring were not modified or contacted by the drill.

RESULTS

Four cases used modified aneurysm clips, from 648 total clip-treated aneurysms (0.6%) by 2 surgeons over a 14-year period. Three patients presented with subarachnoid hemorrhages that were determined to be due to anterior communicating artery aneurysms. One patient presented with an incidental unruptured anterior communicating artery aneurysm. All 4 patients were treated with 3-mm titanium clips shortened intraoperatively to 1- to 2-mm lengths, to achieve aneurysm obliteration without stenosing parent or perforating vessels.

CONCLUSIONS

All 4 patients have done well clinically with no reoccurrences after 2-6 years' follow-up, which included angiographic evaluation. The use of this "Clip-Mod" technique thus appears useful for anterior communicating artery aneurysms. Clip-Mod could also be considered for treating other aneurysms when the "perfect" length clip is not available.

Anterior communicating artery duplication associated with a triplication of anterior cerebral artery - A rare anatomical variation

Background:

The anterior communicating artery complex may presente several anatomical variations, and many abnormalities have been reported in radiologiacal and cadaveric studies.

Case Description:

The authors present a case of a 44-year-old Caucasian female, with a prior history of smoking and arterial systemic hypertension, admitted in the emergency department complaining of a sudden headache, nausea, and vomiting followed by tonic-clonic seizures. Computerized tomography (CT) and angiography (angio- CT) were carried out and showed Fisher Grade IV subarachnoid hemorrhage. Angio-CT revealed an anterior communicating artery (AComA) aneurysm. Minimally invasive craniotomy and microsurgical clipping were performed uneventfully. An unusual anatomical variation of the AComA complex characterized by duplication of the AComA associated with a triplication of anterior cerebral artery (ACA) was observed. The patient was discharged with no neurological deficits.

Concluision:

This unique anatomical variation of the AComA-ACA complex constitute risck factors for development and rupture of aneurysms.

Factors determining the side of approach for clipping ruptured anterior communicating artery aneurysm via supraorbital eyebrow keyhole approach

PURPOSE

The purpose of this study was to review the microsurgical anatomy and clipping of ruptured anterior communicating artery (AComA) aneurysms and to plan and avoid complications before operation.

METHODS

A total of 523 cases of cerebral aneurysms admitted to the neurosurgery department of the Third Affiliated Hospital of Sun Yat-Sen University from September 2010 to October 2018 were analyzed retrospectively. Among them, 85 patients had ruptured AComA aneurysms. This study was limited to 85 of these cases, whose satisfactory preoperative angiographic diagnostic films can be retrieved from the hospital database system because of the need for detailed review.

RESULTS

We performed supraorbital eyebrow keyhole approach (SOEK) craniotomy in 85 patients to clip 85 AComA aneurysms, in the setting of subarachnoid hemorrhage (SAH). Patients' mean age was (52.69 ± 9.94) years (range, 28-78 years). The proportions of small, medium and large aneurysms were 83.5%, 15.3%, and 1.2%, respectively. The average size of the aneurysms was (5.07 ± 2.36) mm. There were 77.8% of patients with inferior aneurysms and 81.3% of patients with superior aneurysms achieved good results. There was a significant correlation between A1 dominance and operation method (p < 0.001). There was no significant relationship between surgical approach and aneurysm projection or A2 plane (p = 0.157 &p = 0.318).

CONCLUSION

Regardless of whether the A2 plane is open or closed, the A1 dominant side is still a better choice for accessing AComA aneurysms to avoid dangerous premature bleeding.

Quantitative measurement of the surgical freedom for anterior communicating artery complex-a comparative study between the frontotemporal pterional and supraorbital craniotomy; a laboratory study

OBJECTIVE

To quantitatively measure surgical degree of freedom (SDF) to the anterior communicating artery (AComA) complex via removal of the orbital rim. Comparisons of SDF quadrants were made between a supraorbital and standard frontotemporal pterional craniotomy according to the surgeons' geometric microscope compass-based views.

METHODS

Eleven latex-injected formalin-fixed cadaveric heads; 14 sides (eight unilateral and three bilateral) were dissected. Standard frontotemporal pterional and subsequent supraorbital craniotomy approaches were conducted in each specimen. Point "0" was allocated as a point 1 cm distal to the ipsilateral A1 and A2 junction of AComA. The tip of a 10-cm long pointer was used to locate point 0. The base of the pointer stick was maneuvered outside the craniotomy in eight compass directions, with the most peripheral points expressed as target points 1-8. The center of this octagon was attributed point C. A pyramid was established by connecting the points 0, C, and 2 neighboring target points. A frameless stereotaxic instrument was used as a three-dimensional digitizer to measure pyramid volume. Each neighboring two pyramids form a hexagonal cone and was expressed as a surgical freedom quadrant (cm³). The quadrants are depicted counterclockwise (surgeons view) as orbital-nasal, vertex-nasal, vertex-temporal, and orbital-temporal.

RESULTS

Total SDF obtained via supraorbital and pterional approaches were 122.8 ± 109.66 and 159.94 ± 93.65, respectively (mean ± SD cm³; supraorbital < pterional by 30.2%). Supraorbital to pterional, in the orbital-nasal quadrant was 21.9 ± 35.5 and 13.04 ± 8.7, vertex-nasal 31.3 ± 28.5 and 16.7 ± 13.7, vertex-temporal 39.5 ± 42.14 and 60.4 ± 4.7, and orbital-temporal 30.14 ± 42.14 and 70.01 ± 42.14, respectively (mean ± SD cm³). In the vertex-nasal quadrant, the supraorbital approach provides a 47.3% increase in SDF compared to the standard frontotemporal pterional craniotomy approach.

CONCLUSION

Given that the AComA complex is located more nasally and the surgeon's view is more vertex, we propose that a supraorbital craniotomy allows a more contralateral portion of the AComA complex to be visualized during dissection.

The effect of anterior communicating artery flow on neurovascular injury and neurobehavioral outcomes in mice with recurrent stroke

BACKGROUND

Previous studies have estimated that the risk of recurrent stroke was nearly 20% shortly after a transient ischemic attack (TIA) or minor stroke. A missing or hypoplastic (<0.5 mm) anterior communicating artery can have deleterious effects on the brain. Our study aimed to investigate the effect of anterior communicating artery flow on neurovascular injury and neurobehavioral outcomes in mice with recurrent stroke and to identify its underlying mechanisms.

METHODS

A recurrent stroke model was established by an initial cortical infarction followed by a corticostriatal infarction 3 days later. The vascular structure was visualized using synchrotron radiation angiography & magnetic resonance angiography in vivo and transparent endovascular perfusion imaging in vitro. Microvessel perfusion was assessed via fluorescein isothiocyanate perfusion. The infarct volume was measured by magnetic resonance imaging.

RESULTS

The finding that anterior communicating artery flow facilitates pial artery patency in the ipsilateral hemisphere in mice with recurrent stroke suggests that compensatory collateral patency contributes to increased regional cerebral blood flow, enhanced microcirculatory perfusion, improved neurological function and reduced infarct volume.

CONCLUSIONS

The results of this study demonstrate that anterior communicating artery flow alleviates recurrent stroke-induced neurovascular injury and improves neurobehavioral outcomes by promoting the establishment of collateral circulation.

Infundibulum of Accessory Anterior Cerebral Artery: Rare, Likely Benign Malformation of Anterior Communicating Artery Complex to Keep in Mind

BACKGROUND

Infundibular dilations (IDs) are funnel-shaped enlargements located at the origin of cerebral arteries. Neuroradiologists and neurosurgeons are familiar with IDs of the posterior communicating artery, which are relatively common. Other locations, being unexpected sites of IDs, can pose diagnostic and therapeutic challenges.

CASE DESCRIPTION

In this paper, we describe a case of infundibulum of the accessory anterior cerebral artery, diagnosed with 3-dimensional reconstructions of computed tomography angiography, which is to our knowledge the first report of an ID of this anatomic variant.

CONCLUSIONS

Anterior communicating artery represents a rare location for infundibular dilations. Differential diagnosis between them and true aneurysms can be sometimes challenging, especially when associated with anatomic variants; thus neurosurgeons and radiologists must be aware of these pathologic entities.