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.

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.

A Novel Risk-Predicted Nomogram for Perioperative Ischemic Complications of Endovascular Treatment Among Ruptured Anterior Communicating Artery Aneurysms

OBJECTIVE

To establish and validate a risk prediction model for perioperative ischemic complication (PIC) of endovascular treatment for ruptured anterior communicating artery aneurysms (ACoAAs).

METHODS

The general clinical and morphologic data, operation schemes, and treatment outcomes of patients with ruptured ACoAAs treated with endovascular treatment in our center from January 2010 to January 2021 were retrospectively analyzed and assigned to primary (359 patients) and validation (67 patients) cohorts. A risk-predicted nomogram for PIC was developed through multivariate logistic regression analysis in the primary cohort. The discrimination ability, calibration accuracy, and clinical usefulness of the established PIC prediction model were evaluated and verified based on the receiver operating characteristic curves, calibration curves, and decision curve analysis in the primary and external validation cohorts, respectively.

RESULTS

A total of 426 patients were included, 47 of whom had PIC. The multivariate logistic regression analysis showed that hypertension, Fisher grade, A1 conformation, use of stent-assisted coiling, and aneurysm orientation were independent risk factors for PIC. Then, we developed a simple and easy-to-use nomogram to predict PIC. This nomogram has a good diagnostic performance (area under the curve, 0.773; 95% confidence interval, 0.685-0.862) and calibration accuracy; we then further validated this nomogram by external validation cohort and showed an excellent diagnostic performance and calibration accuracy. Besides, the decision curve analysis confirmed the clinical usefulness of the nomogram.

CONCLUSIONS

A history of hypertension, high preoperative Fisher grade, complete A1 conformation, use of stent-assisted coiling, and aneurysm orientation (pointing upward) are risk factors for PIC for ruptured ACoAAs. This novel nomogram might serve as a potential early warning sign of PIC for ruptured ACoAAs.

Complete bilateral blindness associated with ruptured anterior communicating artery aneurysm: A literature review and illustrative case

Background

Anterior communicating artery (AcomA) aneurysms are considered one of the most common intracranial aneurysms, contributing to approximately 40% of the subarachnoid hemorrhages related to aneurysmal rupture. Aneurysms of the anterior circulation are commonly present with visual defects varying in their nature according to the aneurysmal site. However, complete bilateral vision loss associated with AcomA aneurysms is a significantly rare finding. We are reporting a case of complete bilateral blindness in a patient with a ruptured AcomA aneurysm with a literature review.

Methods

We conducted a PubMed Medline database search by the following combined formula of subjects' headings: (((Intracranial Aneurysm [MeSH Terms]) AND (AcomA Aneurysm [Title/Abstract])) AND [(Vision loss OR Blindness [Text Word])) AND (case reports [Filter]). Additional articles were searched through the reference lists of the included articles.

Results

Our review yielded a total of five cases. All the present cases revealed unilateral blindness only, and their outcomes after treatment vary from recovery of vision to unchanged complete vision loss - none of the cases found in the literature presented with bilateral blindness.

Conclusion

AcomA aneurysms can be associated with visual loss in some cases. However, usually, the defect is unilateral. Studies of the visual defects, including potential bilateral complete blindness associated with rupture inferiorly, directed AcomA aneurysm, should be highlighted.

Endovascular Treatment for Anterior Communicating Artery Aneurysms

Previously, anterior communicating artery aneurysms were considered unsuitable for endovascular treatment. In recent years, however, endovascular treatment has been increasingly performed due to the fact that it is less likely to cause high dysfunction compared to surgery and the treatment has been improved. The International Subarachnoid Aneurysm Trial reported anterior communicating artery aneurysms comprise 45.4% of cerebral aneurysms on which both endovascular treatment and surgery are suitable. The use of the endovascular treatment for anterior communicating artery aneurysms is expected to increase in the future. In this paper, we present cases from our institution based on the characteristics of anterior and distal communicating artery aneurysms, treatment strategies, and treatment indications.

Risk factors for intraprocedural rupture during emergency endovascular treatment of ruptured anterior communicating artery aneurysms

BACKGROUND

Anterior communicating artery aneurysms are the second most common type of intracranial aneurysm and have a high incidence of rupture. Intraprocedural rupture can lead to a high mortality and morbidity rate, representing a major challenge in emergency endovascular treatment of ruptured anterior communicating artery aneurysms.

METHODS

We performed a retrospective review of 344 consecutive patients with emergency endovascular treatment of ruptured anterior communicating artery aneurysms. Patients were grouped into intraprocedural rupture and non-intraprocedural rupture groups according to whether intraprocedural rupture occurred. Demographic and clinical factors, vessel-related factors and therapy-related factors were compared between the two groups.

RESULTS

Intraprocedural rupture occurred in 11 patients (3.2%). Univariate analysis showed that hypertension, the occurrence of vasospasm, aneurysm size, aneurysm angle and a high aspect ratio value were significantly associated with intraprocedural rupture (P < 0.05). Multivariate analysis showed that hypertension odds ratio (OR, 9.799; P = 0.007), the occurrence of vasospasm (OR, 10.121; P = 0.002) and a high aspect ratio value (OR, 10.571; P = 0.006) were independent risk factors for intraprocedural rupture.

CONCLUSIONS

A history of hypertension, the occurrence of vasospasm and a high aspect ratio value are independent risk factors for intraprocedural rupture among patients with ruptured anterior communicating artery aneurysms.

Tailored Communicating Bypass for the Management of Complex Anterior Communicating Artery Aneurysms: "Flow-Counteraction" In Situ Bypass and Interposition Bypass Using Contralateral A2 Orifice as Donor Site

BACKGROUND

The use of bypass surgery for anterior communicating artery (ACOM) aneurysms is technically challenging. Communicating bypass (COMB), such as pericallosal artery side-to-side anastomosis, is the most frequently used and anatomically directed reconstruction option. However, in many complex cases, this technique may not afford a sufficient blood supply or necessitate sacrificing the ACOM and the eloquent perforators arising from it.

OBJECTIVE

To evaluate tailored COMB and propose a practical algorithm for the management of complex ACOM aneurysms.

METHODS

For 1 patient with an aneurysm incorporating the entire ACOM, conventional in Situ A3-A3 bypass was performed as the sole treatment in order to create competing flow for aneurysm obliteration, sparing the sacrifice of eloquent perforators. In situations in which A2s were asymmetric in the other case, the contralateral A2 orifice was selected as the donor site to provide adequate blood flow by employing a short segment of the interposition graft.

RESULTS

The aneurysm was not visualized in patients with in Situ A3-A3 bypass because of the "flow-counteraction" strategy. The second patient, who underwent implementation of the contralateral A2 orifice for ipsilateral A3 interposition bypass, demonstrated sufficient bypass patency and complete obliteration of the aneurysm.

CONCLUSION

The feasibility of conventional COMB combined with complete trapping may only be constrained to selected ideal cases for the treatment of complex ACOM aneurysms. Innovative modifications should be designed in order to create individualized strategies for each patient because of the complexity of hemodynamics and the vascular architecture. Flow-counteraction in Situ bypass and interposition bypass using the contralateral A2 orifice as the donor site are 2 novel modalities for optimizing the advantages and broadening the applications of COMB for the treatment of complex ACOM aneurysms.

Minimally invasive medial supraorbital, combined subfrontal-interhemispheric approach to the anterior communicating artery complex-a cadaveric study

INTRODUCTION

In selected cases, microsurgical clipping remains a valuable treatment alternative to endovascular occlusion of anterior communicating artery (AComA) aneurysms. Their clipping is challenging and carries a risk of postsurgical cognitive impairment. We evaluate the microsurgical anatomy of a new, minimally invasive combined interhemispheric-subfrontal approach to the AComA complex via a medial supraorbital craniotomy.

METHODS

In this descriptive anatomic study, four alcohol-embedded, silicon-injected human cadaver heads were used. In each of the two cadavers, the AComA complex was approached from either the right or left side. An operating microscope and standard microsurgical instruments were used.

RESULTS

After a medial eyebrow incision, a medial supraorbital minicraniotomy was performed. The frontal sinus was opened and cranialized. Following the dural opening, a subfrontal arachnoid dissection was performed to identify the optico-carotid complex. By following the A1 segment, a low-lying AComA complex could be visualized. Shifting the corridor towards the midline enabled an interhemispheric dissection. This dissection resulted in a wide superior-inferior corridor. Higher-lying AComA complexes could also be visualized. The achieved exposure of the AComA complex would allow safe dissection and clipping of low- and high-lying AComA aneurysms, with minimal retraction and preservation of the surrounding anatomical structures, in particular the perforators.

CONCLUSIONS

We demonstrate the anatomy of a novel approach for surgical clipping of AComA aneurysms. Our study suggests that this approach provides good exposure without concomitant structural and vascular injury and thus might reduce the risk of procedure-related morbidity.

Proposed Parent Vessel Geometry Based Classification of Anterior Communicating Artery-Located Aneurysms

BACKGROUND AND OBJECTIVES

The present study is focused on correlation of parent vessels and neck diameters with anterior communicating artery (AComA) aneurysmal depth and growth direction. The study principally aims to suggest a new classification of AComA-located aneurysms based on the physical characteristics of parent vessels.

METHODS

A retrospective analysis was performed of 155 patients with ruptured AComA-located aneurysms. The percentage of difference between both A1 arteries was measured on computed tomography angiography images and neck locations were determined. Accordingly, AComA-located aneurysms were classified into 2 groups. In both groups, A1 and A2 arteries and neck size diameters were measured and their relation with aneurysmal depth was studied. The aspect ratio was calculated.

RESULTS

Eleven patients in which the aneurysm neck originates from the AComA proper with almost equal A1s were classified as the true AComA aneurysm group whereas 144 patients in whom the aneurysm neck originates at the dominant A1 bifurcation into the AComA and A2 with the average difference between both A1s of about 84.44% were classified as the dominant A1-bifurcation group. There is significant correlation between aneurysmal depth and neck diameter in both groups (P ≤ 0.05, P < 0.001). The aspect ratio was calculated as equal to 1.166.

CONCLUSIONS

The dominant A1 bifurcation type is the most common type of AComA-located aneurysm. The present classification provides clinical value in understanding how AComA aneurysms grow and behave. It helps to understand the geometry of multilobulated aneurysms such as ruptured blebs locations during treatment procedures respecting the direction of the dominant A1 axis in group II. Multiple anatomic variations of this complex AComA area can clarify future subtypes of these 2 groups. Thus, further investigation of more patients is needed.