Surgical Revascularization for the Treatment of Complex Anterior Cerebral Artery Aneurysms: Experience and Illustrative Review

Clinical and Technical Outcomes of Intracranial-Intracranial Bypass for Treating Complex Intracranial Aneurysms: An Analysis of 255 Patients

BACKGROUND

Despite the recent increase in publications centered on intracranial-intracranial (IC-IC) bypasses for complex aneurysms, there is no systematic evidence regarding their outcomes. The purpose was to assess the outcomes of patients subjected to IC-IC bypass for aneurysms.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, a systematic review was conducted. Criteria for inclusion entailed studies with a cohort of at least 4 patients having undergone IC-IC bypass for aneurysms, detailing at least one outcome, such as patency, clinical outcomes, complications, and procedure-related mortality. When the study included patients who had undergone extracranial-intracranial (EC-IC) bypass, the authors extracted the patency and clinical data to juxtapose them with the results of IC-IC.

RESULTS

Of the 2509 shortlisted studies, 22 met our inclusion criteria, encompassing 255 patients and 263 IC-IC bypass procedures. The IC-IC bypass procedure exhibited a patency rate of 93% (95% confidence interval [CI]: 89%-95%). The patency rate of IC-IC and EC-IC bypasses did not significantly differ (odds ratio=0.60 [95% CI: 0.18-1.96]). Concerning clinical outcomes, 91% of the IC-IC patients had positive results (95% CI: 85%-97%), with no significant disparity between the IC-IC and EC-IC groups (odds ratio=1.29 [95% CI: 0.43-3.88]). After analysis, the complication rate was 11% (95% CI: 5%-18%). Procedure-related mortality was 1% (95% CI: 0%-4%).

CONCLUSIONS

IC-IC bypass is valuable for the treatment of complex intracranial aneurysms, boasting high patency and positive clinical outcomes. Complications are unusual, and procedure-related mortality is minimal. Comparing IC-IC and EC-IC led to no significant differences.

The application of high-resolution vessel wall imaging in the in situ bypass surgeries for complex anterior cerebral artery aneurysms

OBJECTIVE

Complex anterior cerebral artery (ACA) aneurysms are still technically challenging to treat. Bypass surgery is needed to achieve aneurysm obliteration and ACA territory revascularization. Severe atherosclerosis of aneurysm walls can cause clip slippage, intraoperative rupture, postoperative ischemic events. How to assess the atherosclerotic changes in vascular walls by high-resolution vessel wall magnitude resonance imaging (VWI) is the key question in complex ACA aneurysm surgical management.

METHODS

This retrospective single-center study included eight patients diagnosed with complex anterior cerebral arteries admitted to our hospital for bypass surgery from January 2019 to April 2022. We discussed the application of VWI in aneurysms treated with in situ bypass and reviewed previous experience of revascularization strategies for complex ACA aneurysms.

RESULTS

In this study, we treated 8 cases of complex ACA aneurysms (3 communicating aneurysms/5 postcommunicating aneurysms) over the prior one year. In situ side-to-side anastomosis (1 A2-to-A2/6 A3-to-A3) was performed in seven cases, and trapping combined with excision was performed in another case. Following bypass, complete trapping was performed in 4 cases, and proximal clipping was performed in 3 cases. No surgery-related neurological dysfunctions were observed. The final modified Rankin scale was 0 in seven of the eight cases and 2 in one case.

CONCLUSION

High-resolution VWI, as a favorable preoperative assessment tool, provides insight into patient-specific anatomy and microsurgical options before operations, which can help neurosurgeons develop individualized and valuable surgical plans.

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.

Evolution of Intracranial-Intracranial Bypass Surgery: A Bibliometric Analysis

OBJECTIVE

Modern cerebrovascular bypass surgery uses either extracranial-intracranial (EC-IC) or intracranial-intracranial (IC-IC) approaches. Compared with EC-IC bypasses, IC-IC bypasses allow neurosurgeons to safely address tumors, aneurysms, and other lesions using shorter grafts that are well matched to the size of recipient vessels. Fewer than 100 articles have been published on IC-IC bypasses compared with more than 1000 on EC-IC bypasses. This study examined the increase of interest and innovation in IC-IC bypass.

METHODS

PubMed and Web of Science were searched using keywords specific to IC-IC bypass, yielding 717 articles supplemented with 36 reports from other databases and gray literature. The articles were reviewed, and 98 articles were selected for further evaluation. Final articles were categorized as innovations or retrospective studies. Publication metrics were passed through an analytic program to assess statistical measures of growth.

RESULTS

The number of publications describing innovations (n = 52) and retrospective studies (n = 46) in IC-IC surgical techniques increased exponentially (R2 = 0.983 and R2 = 0.993, respectively), with both interest and research in the field increasing. The rate of publications in each group also increased. In recent years, increasing numbers of global institutions have researched and published on IC-IC bypasses.

CONCLUSIONS

As more work is undertaken on IC-IC bypasses, it is critical for knowledge to be shared through research, collaboration, publication, and early teaching within residency training programs. This field has increased exponentially in the past 2 decades and has yet to reach an inflection point, indicating possible additional interest and growth over time.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

A3-A3 Anastomosis in the Management of Complex Anterior Cerebral Artery Aneurysms: Experience With in Situ Bypass and Lessons Learned From Pseudoaneurysm Cases

BACKGROUND

A3-A3 side-to-side bypass is an intracranial-to-intracranial (IC-IC) revascularization option when aneurysm treatment involves occlusion of one anterior cerebral artery (ACA).

OBJECTIVE

To describe applications of A3-A3 side-to-side bypass in the management of ACA true and pseudoaneurysms along with a review of pertinent literature.

METHODS

Six consecutive patients undergoing an A3-A3 bypass as part of their aneurysm management, representing a single-surgeon experience in a 2-yr period, were included in this retrospective review of a prospectively collected database.

RESULTS

Three male and three female patients with a median (range) age of 41.5 (11-69) years representing four ruptured and two unruptured aneurysms were included. Two of the aneurysms were communicating while four were postcommunicating from which three were pseudoaneurysms. Complete aneurysm obliteration was achieved in 5/6 cases. Bypass patency was evaluated in all cases intra- and postoperatively. Good outcomes (modified Rankin Scale score ≤ 2) at follow-up were observed in 4/6 patients. An improvement in mRS scores at the most recent follow-up as compared to preoperative status was achieved in three while scores remained the same in two patients. Ischemic complications related to aneurysm treatment were observed in two patients, both of which achieved good functional recovery upon follow-up. One patient deceased postoperatively due to progression of vasospasm-related infarcts.

CONCLUSION

A3-A3 bypass in the management of true as well as pseudoaneurysms of the ACA can achieve good postoperative outcomes in selected patients. Prompt diagnosis and aggressive surgical treatment needs to be pursued if a vessel injury with pseudoaneurysm formation is suspected.

Giant Serpentine Distal Anterior Cerebral Artery Aneurysm Treated with In Situ Side-to-Side A3-A3 Anastomosis and Aneurysm Resection

BACKGROUND

Giant serpentine aneurysms that occur in the distal anterior cerebral artery are extremely rare and challenging to manage because of their complex structure. In this case, we show an aneurysm resection performed after in situ side-to-side A3-A3 bypass to treat a giant serpentine distal anterior cerebral artery aneurysm.

CASE DESCRIPTION

Here, we present the case of a 55-year-old man with a giant distal anterior cerebral artery serpentine aneurysm who presented with severe headache and progressive unconsciousness. Computed tomography and cerebral angiography revealed a giant serpentine aneurysm in the right A2 segment. Both the right pericallosal and callosal marginal arteries branched from the outflow tract. To relieve the mass effect and preserve distal blood flow, an in situ side-to-side A3-A3 anastomosis and a partial aneurysm resection were performed sequentially. Postoperative cerebral angiography revealed no aneurysm blood filling and good perfusion in both anterior cerebral artery territories.

CONCLUSIONS

Anterior cerebral artery giant serpentine aneurysms are rare and usually present with headache and mass effect. Aneurysm resection and distal flow protection are issues that we must consider. The sequential procedure of anastomosis and aneurysm resection is a feasible and safe option.

The future of open vascular neurosurgery: perspectives on cavernous malformations, AVMs, and bypasses for complex aneurysms

Despite the erosion of microsurgical case volume because of advances in endovascular and radiosurgical therapies, indications remain for open resection of pathology and highly technical vascular repairs. Treatment risk, efficacy, and durability make open microsurgery a preferred option for cerebral cavernous malformations, arteriovenous malformations (AVMs), and many aneurysms. In this paper, a 21-year experience with 7348 cases was reviewed to identify trends in microsurgical management. Brainstem cavernous malformations (227 cases), once considered inoperable and managed conservatively, are now resected in increasing numbers through elegant skull base approaches and newly defined safe entry zones, demonstrating that microsurgical techniques can be applied in ways that generate entirely new areas of practice. Despite excellent results with microsurgery for low-grade AVMs, brain AVM management (836 cases) is being challenged by endovascular embolization and radiosurgery, as well as by randomized trials that show superior results with medical management. Reviews of ARUBA-eligible AVM patients treated at high-volume centers have demonstrated that open microsurgery with AVM resection is still better than many new techniques and less invasive approaches that are occlusive or obliterative. Although the volume of open aneurysm surgery is declining (4479 cases), complex aneurysms still require open microsurgery, often with bypass techniques. Intracranial arterial reconstructions with reimplantations, reanastomoses, in situ bypasses, and intracranial interpositional bypasses (third-generation bypasses) augment conventional extracranial-intracranial techniques (first- and second-generation bypasses) and generate innovative bypasses in deep locations, such as for anterior inferior cerebellar artery aneurysms. When conventional combinations of anastomoses and suturing techniques are reshuffled, a fourth generation of bypasses results, with eight new types of bypasses. Type 4A bypasses use in situ suturing techniques within the conventional anastomosis, whereas type 4B bypasses maintain the basic construct of reimplantations or reanastomoses but use an unconventional anastomosis. Bypass surgery (605 cases) demonstrates that open microsurgery will continue to evolve. The best neurosurgeons will be needed to tackle the complex lesions that cannot be managed with other modalities. Becoming an open vascular neurosurgeon will be intensely competitive. The microvascular practice of the future will require subspecialization, collaborative team effort, an academic medical center, regional prominence, and a large catchment population, as well as a health system that funnels patients from hospital networks outside the region. Dexterity and meticulous application of microsurgical technique will remain the fundamental skills of the open vascular neurosurgeon.

Microvascular Revascularization for Recurrent A1 Anterior Cerebral Artery Aneurysm Postendovascular Treatment: A Case Report and Review of the Literature

The recurrence of aneurysms postcoil embolization is a common occurrence. Endovascular coiling has been noted to be more effective for small lesions rather than the giant aneurysms. A postembolization recurrent aneurysm is a difficult condition to manage. We present a case of a recurrent giant aneurysm of the anterior cerebral arteries (ACAs) first segment (A1). It was managed by superficial temporal artery to A3 segment of anterior cerebral artery bypass anastomotic revascularization plus distal A1- segment clipping. A literature review is presented for the management of giant A1 artery aneurysms.

Microvascular anastomosis under 3D exoscope or endoscope magnification: A proof-of-concept study

Background:

Extracranial–intracranial bypass is a challenging procedure that requires special microsurgical skills and an operative microscope. The exoscope is a tool for neurosurgical visualization that provides view on a heads-up display similar to an endoscope, but positioned external to the operating field, like a microscope. The authors carried out a proof-of-concept study evaluating the feasibility and effectiveness of performing microvascular bypass using various new exoscopic tools.

Methods:

We evaluated microsurgical procedures using a three-dimensional (3D) endoscope, hands-free robotic automated positioning two-dimensional (2D) exoscope, and an ocular-free 3D exoscope, including surgical gauze knot tying, surgical glove cutting, placental vessel anastomoses, and rat vessel anastomoses. Image quality, effectiveness, and feasibility of each technique were compared among different visualization tools and to a standard operative microscope.

Results:

3D endoscopy produced relatively unsatisfactory resolution imaging. It was shown to be sufficient for knot tying and anastomosis of a placental artery, but was not suitable for anastomosis in rats. The 2D exoscope provided higher resolution imaging, but was not adequate for all maneuvers because of lack of depth perception. The 3D exoscope was shown to be functional to complete all maneuvers because of its depth perception and higher resolution.

Conclusion:

Depth perception and high resolution at highest magnification are required for microvascular bypass procedures. Execution of standard microanastomosis techniques was unsuccessful using 2D imaging modalities because of depth-perception-related constraints. Microvascular anastomosis is feasible under 3D exoscopic visualization; however, at highest magnification, the depth perception is inferior to that provided by a standard operative microscope, which impedes the procedure.