Tailoring fenestrated aneurysm clips intraoperatively: Instant solution for a difficult problem.

The anterior communicating artery (AcoA) aneurysms represent the most complex aneurysms of the anterior circulation. For years, surgical challenges including the intricate anatomy and narrow surgical corridor have been overcome using supplementary techniques including extended craniotomies, wide opening of the cisterns, gyrus rectus resection and special clips like fenestrated clips. However, imaginative solutions such as intraoperative clip modification may be inevitable in particular cases for safe clipping. We retrospectively analyzed clinical records of two patients who required clip modification intraoperatively. Case #1 underwent microsurgical clipping of a ruptured, 4-mm AcoA aneurysm. Unfortunately, given the short distance between the two A2s, it was not possible to clip the aneurysm without a compromise to the contralateral A2 with the available shortest 3mm-fenestrated clip. We then used the clip modification technique intraoperatively by shortening the clip tips with mesh-plaque cutter and smoothening the remaining sharp ends using cautery sanding. Eventually, the aneurysm was clipped successfully with the modified-fenestrated clip. Post-clipping imagings confirmed complete occlusion of the aneurysm and patency of parent arteries. Case 2# underwent microsurgical clipping for a ruptured, 1-mm AcoA aneurysm. Like Case 1#, the initial clipping attempt with the available shortest 4mm-fenestrated clip failed given the excessive length of the tips. The patient, thus, required clip modification as described above. The aneurysm was then clipped successfully using the modified-fenestrated clip, protecting bilateral A2s. Post-clipping imagings demonstrated patency of parent arteries with no residual aneurysm filling. Clip modification seems to be an effective option in clipping the AcoA aneurysms when available clips are too long to secure them safely.

Standard Orbitozygomatic Craniotomy versus Mini Orbitozygomatic Craniotomy via an Eyebrow Incision for Microsurgical Treatment of Anterior Communicating Artery Aneurysms.

Background Skull base approaches are utilized to improve microsurgical treatment of cerebral aneurysms. Advantages include early proximal and distal control, increased visualization, and minimal brain retraction. Orbitozygomatic (OZ) craniotomies via pterional incision are commonly used for the treatment of anterior communicating artery (ACoA) aneurysms. A smaller, less invasive OZ craniotomy performed through an eyebrow incision may provide several advantages over a standard OZ approach. Objective We compare surgical outcomes of the standard and eyebrow OZ for the treatment of ACoA aneurysms. Design All patients who underwent microsurgical treatment for ACoA aneurysms by a single surgeon over an 8-year period were included in this retrospective analysis. Patient demographics and clinical data were collected. Participants Thirty-seven consecutive patients were identified, with 15 receiving eyebrow OZ and 22 receiving standard OZ. Main Outcome Measures Data were collected on patient demographics, pathology, intraoperative and perioperative data, and 30-day morbidity. Results A total of 100% of the eyebrow OZ group and 95.5% of the standard OZ group had complete aneurysmal occlusion. Four eyebrow OZ and six standard OZ patients had an intraoperative rupture. All were managed without complication. Two eyebrow OZ and one standard OZ patient died within 30 days of surgery. No patients in either group had aneurysm recurrence, required retreatment, or were limited intraoperatively by exposure. Conclusions The OZ approach via an eyebrow incision has similar outcomes to a standard OZ approach and is a safe option for the treatment of ACoA aneurysms.

Multiple Intracranial Aneurysms Associated With Brain Arteriovenous Malformation: A Case Report and Treatment Strategies.

In the field of cerebrovascular neurosurgery, intracranial aneurysms (IAs) have been occasionally associated with brain arteriovenous malformations (BAVMs), indicating a more aggressive clinical course, and increased rates of hemorrhage and rehemorrhage. Treatment of flow-related IAs in BAVMs remains debatable, with considerations for preventive intervention versus concurrent BAVM treatment. Managing such situations might be challenging, especially in determining which of the IAs or BAVMs should be treated first, and which treatment strategy would be most appropriate for each situation. A precise identification of the rupture site is required, whether it is the AVM nidus or the IA, for choosing the best treatment plans. We present a case of a 29-year-old male patient diagnosed with several intracranial vascular conditions: a ruptured anterior communicating artery (ACoA) aneurysm and an unruptured ophthalmic artery aneurysm, associated with a frontal BAVM. Moreover, we discussed the possible scenarios regarding the association of these conditions, highlighting their manifestations and the most suitable therapeutic approach for each. Thus, our exploration of the challenges and considerations involved in treating these intricate neurovascular conditions underscores the need for a customized approach for each patient's situation.

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.

Kissing Aneurysms of the Anterior Communicating Artery Treated With Surgical Clipping: A Case Report and Literature Review.

Intracranial "kissing" aneurysms are rare vascular conditions described as two anatomically adjacent aneurysms originating from either the same or different arteries, with their walls pressed together. Two-dimensional angiography was formerly considered the gold standard for diagnosis, with the three-dimensional rotational type now offering more insightful details about vascular discrepancies. The treatment of anterior communicating artery (AcoA) "kissing" aneurysms poses significant challenges, with surgical clipping proving difficult due to their deep midline location or the bilateral anterograde arterial supply. However, advancements in endovascular coil embolization, such as dual-volume reconstruction, can assist in diagnosis. This study presents the case of a 50-year-old patient who was diagnosed with "kissing" aneurysms of the AcoA. The patient underwent surgical clipping and showed no pathological follow-up findings. The surgical intervention often provides a more direct and effective approach. This case contributes to the body of knowledge surrounding the management of this complex disease.

Successive Development and Rupture of Blister-Like Anterior Communicating Artery Aneurysms at Mirror Locations.

This is the first report of the successive development and rupture of blister-like anterior communicating artery (ACoA) aneurysms at mirror locations with a short interval. A 49-year-old man presented with an angiogram-negative subarachnoid hemorrhage with significant basal frontal interhemispheric blood. Surgical exploration revealed a blister-like aneurysm on the left side of the superior wall of the ACoA, which was treated using a microsuturing technique. On the 18th day after the initial subarachnoid hemorrhage, the second operation due to another angiogram-negative hemorrhage revealed a de novo blister-like aneurysm with a small blood clot on the posterosuperior wall of the ACoA close to the right A1/A2 junction. The rupture point and ACoA on the right side were occluded using an aneurysm clip. Follow-up digital subtraction angiogram (DSA) at 4 years and computed tomography angiogram (CTA) at 14 years after the surgery showed no recurrence or associated abnormality.

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.

Letter to editor : optimizing surgical approaches for anterior communicating artery aneurysms: development and internal validation of a novel surgical scoring system.

The recent publication titled "Optimizing Surgical Approaches for Anterior Communicating Artery Aneurysms: Development and Internal Validation of a Novel Surgical Scoring System" presents a groundbreaking study in neurosurgery. This critique examines both the positive and negative impacts of the research. Positive aspects include the potential to improve patient outcomes through personalized surgical approaches guided by a standardized scoring system. Internal validation enhances the credibility of the scoring system. However, challenges such as the need for external validation and additional surgeon training are acknowledged. Overall, while the study offers promising advancements, further research and validation are essential for widespread implementation in clinical practice.

Influence of circle of Willis modeling on hemodynamic parameters in anterior communicating artery aneurysms and recommendations for model selection.

Computational fluid dynamics (CFD) has been utilized to calculate hemodynamic parameters in anterior communicating artery aneurysm (AComA), which is located at a junction between left and right A1 and A2 segments. However, complete or half circle of Willis (CoW) models are used indiscriminately. This study aims to suggest recommendations for determining suitable CoW model. Five patient-specific CoW models with AComA were used, and each model was divided into complete, left-half, and right-half models. After validating the CFD using a flow experiment, the hemodynamic parameters and flow patterns in five AComAs were compared. In four out of five cases, inflow from one A1 side had a dominant influence on the AComA, while both left and right A1 sides affected the AComA in the remaining case. Also, the average difference in time-averaged wall shear stress between the complete and half models for four cases was 4.6%, but it was 62% in the other case. The differences in the vascular resistances of left and right A1 and A2 segments greatly influenced the flow patterns in the AComA. These results may help to enhance clinicians' understanding of blood flow in the brain, leading to improvements in diagnosis and treatment of cerebral aneurysms.

Flow Diversion as a Definitive Treatment for Recurrently Ruptured A1-A2 Anterior Cerebral Artery Aneurysm Following Clipping and Coiling.

Even after clipping of intracranial aneurysms, patients may experience incomplete occlusion or the future recurrence of their treated aneurysm. This paper presents a distinctive case of a recurrent A1-A2 anterior cerebral artery aneurysm that underwent four interventions over 16 years. The aneurysm was treated with two clippings, subsequent coiling, and flow diversion for definitive treatment. The challenges encountered in managing bifurcation aneurysms are discussed, emphasizing the importance of considering hemodynamic factors, vessel geometry, and recurrence risk factors in treatment decisions. The case highlights the need for closer follow-up of ruptured bifurcation aneurysms due to the higher likelihood of recurrence. The role of flow diverters in reinforcing vessel anatomy and preventing recurrence is also highlighted.

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.

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).

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.

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.

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.

Unveiling rupture risk and clinical outcomes in midline aneurysms: A matched cohort analysis investigating the impact of localization within the anterior or posterior circulation.

Intracranial aneurysms (IAs) located in the anterior and posterior circulations of the Circle of Willis present differential rupture risks. This study aimed to compare the rupture risk and clinical outcomes of anterior communicating artery aneurysms (AcomA) and basilar tip aneurysms (BAs); two IA types located along the midline within the Circle of Willis. We retrospectively collected data from 1026 patients presenting with saccular IAs. Only AcomA and BAs with a 3D angiography were included. Out of 186 included IAs, a cohort of 32 BAs was matched with AcomA based on the patients' pre-existing conditions and morphological parameters of IAs. Clinical outcomes, including rupture risk, hydrocephalus development, vasospasm incidence, and patients' outcome, were compared. The analysis revealed no significant difference in rupture risk, development of hydrocephalus, need for ventricular drainage, or vasospasm incidence between the matched AcomA and BA cohorts. Furthermore, the clinical outcomes post-rupture did not significantly differ between the two groups, except for a higher Fisher Grade associated with BAs. Once accounting for morphological and patient factors, the rupture risk between AcomA and BAs is comparable. These findings underscore the importance of tailored management strategies for specific IA types and suggest that further investigations should focus on the role of individual patient and aneurysm characteristics in IA rupture risk and clinical outcomes.

Retrospective Application of Risk Scores to Unruptured Anterior Communicating Artery Aneurysms.

BACKGROUND: Treatment decisions for unruptured intracranial aneurysms (UIAs) pose a challenge for neurosurgeons, prompting the development of clinical scales assessing hemorrhage risk to provide management guidance. This study compares recommendations from the PHASES and UIA treatment scores (UIATS) applied to anterior communicating artery (AComA) UIAs against real-world management. METHODS: While UIATS recommends management, for PHASES, an aneurysm with score of 10 or more was considered "high-risk". Analysis involved assessing the concordance in each group alongside comparison to real-word management. RESULTS: Among 129 patients, 46.5% were observed and 53.5% were treated. PHASES scores were significantly higher in the treatment group (p = 0.00002), and UIATS recommendations correlated with real-world decisions (p < 0.001). We observed no difference in the frequencies of UIATS recommendations between high- and low-risk groups. When comparing the UIATS and PHASES, 33% of high-risk aneurysms received a UIATS conservative management recommendation. In 39% of high-risk aneurysms, the UIATS recommendation was not definitive. Conversely, 27% of low-risk aneurysms obtained a UIATS UIA repair recommendation. Overall, concordance between PHASES and UIATS was 32%. CONCLUSIONS: Significant discordance in therapeutic suggestions underscores the predominant influence of center experience and individual assessments. Future studies should refine and validate decision-making strategies, potentially exploring alternative applications or developing tailored scales.

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.

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.

Dominant A1 Direction as an Additional Factor for Deciding Surgical Approach for A1 Bifurcation Aneurysms.

BACKGROUND AND OBJECTIVE: Clipping of aneurysms located in the anterior communicating artery (AcomA) is considered a critical surgical procedure for neurosurgeons worldwide because of the complexity of the surgical area. The present study was conducted to discuss the importance of the geometric curvatures and the direction of the dominant A1 artery and their impact on aneurysmal growth direction and choice of side selection of the pterional surgical approach side. METHODS: The present study enrolled 183 patients with ruptured AcomA-located aneurysms. The aneurysms were all treated surgically through a pterional approach. Because of multiple dominant A1 directions, we divided the artery into 2 segments, and based on the second segment direction, we categorized the patients into ascending A1, descending A1, and horizontal A1 groups. The ascending group includes the superiorly projecting aneurysms, whereas the horizontal and descending groups include the anteriorly and inferiorly projecting aneurysms, respectively. A contralateral pterional approach to the dominant A1 was chosen for aneurysms with an ascending artery. However, the ipsilateral pterional approach was conducted in the horizontal and descending A1 dominant groups. RESULTS: The aneurysmal growth projection axis always follows the direction of the second dominant A1 segment. Full neck control with satisfactory inspection of perforators was achieved through the contralateral approach in most cases of an ascending A1, especially if ipsilateral A2 was posterior to the neck. The A1 segment can be satisfactorily seen from the contralateral exposure before the aneurysmal neck is exposed in ascending A1 geometries. CONCLUSIONS: A1 direction is an important additional factor that is to be considered for side selection when deciding pterional exposure of A1 bifurcation aneurysms. Accessing the contralateral dominant ascending A1 has better visualization of the neck than entering from an ipsilateral approach, especially if the ipsilateral A2 was posterior to the neck.