Basilar Artery Fenestration Aneurysms: Endovascular Treatment Strategies Based on 3D Morphology

Current research status and future of endovascular treatment for basilar artery aneurysms

Aneurysms occurring along the basilar artery (BA) account for <1% of all intracranial aneurysms. Endovascular treatment (EVT) in particular is recommended for large unruptured BA aneurysms and ruptured BA aneurysms. Given that EVT techniques vary, a detailed review of EVT for BA aneurysms is necessary. In this review, the following issues were discussed: the anatomy and anomalies of the BA, the classification of BA aneurysms, the natural history of BA aneurysms, the status of open surgery, the use of EVT for various types of BA aneurysms and the deployment of new devices. According to the findings of this review and based on our experience in treating BA aneurysms, traditional coiling EVT is still the optimal therapy for most BA aneurysms. However, in some BA aneurysms, flow diverter (FD) deployment can be used. In addition, there are also some new devices, such as intrasaccular flow disruptors and stent-like devices that can be used to treat BA aneurysms. In general, EVT can yield good clinical and angiographic outcomes for patients with BA aneurysms. In addition, recent new devices and techniques, such as new-generation FDs generated via surface modification and virtual reality simulation techniques, show promise for EVT for BA aneurysms. These devices and techniques may further improve EVT outcomes for BA aneurysms.

Endovascular treatment outcomes of vertebrobasilar junction aneurysms: Systematic review and meta-analysis

BACKGROUND

Vertebrobasilar junction (VBJ) aneurysms represent a relatively rare and often anatomically complex subgroup of saccular aneurysms. This systematic review and meta-analysis aimed to assess the safety and efficacy of endovascular treatment (EVT) of VBJ aneurysms.

METHODS

PubMed, Web of Science, Ovid Medline, Ovid Embase, and Scopus were searched from inception to 20 December 2022. We included primary studies assessing the long-term clinical and angiographic outcomes for VBJ aneurysms treated with endovascular techniques. We excluded surgically managed studies. All data were analyzed using R software version 4.2.1. We calculated pooled prevalence rates and their corresponding 95% confidence intervals (CI).

RESULTS

In this meta-analysis, a total of 76 VBJ aneurysms from seven studies were included for quantitative analysis. The results showed that the rate of adequate occlusion (complete + near complete occlusion) was 94.1% (95% CI = 76.71-98.71), and the rate of complete occlusion was 77.7% (95% CI = 63.07-87.65). A modified Rankin Scale (mRS) score of 0-2 was achieved in 93.9% of patients (95% CI = 67.65-99.14). The mortality rate was found to be 5.9% (95% CI = 0.97-28.55), and the retreatment rate was 4.6% (95% CI = 1.50-13.36). The overall ischemic complication rate was 4.7% (95% CI = 0.73-25.4), while the overall hemorrhagic complication rate was 4.6% (95% CI = 1.5-13.36).

CONCLUSIONS

The treatment of VBJ aneurysms with EVT is effective in achieving curative treatment and is associated with good clinical outcomes and low mortality rates. These findings provide important insights into the clinical and angiographic outcomes and the complication rates of EVT for VBJ aneurysms.

Endovascular Coiling of Fenestrated Vertebrobasilar Cerebral Aneurysms

Fenestrated vertebrobasilar junction aneurysms are uncommon vascular lesions. Surgical intervention remains extremely challenging due to the deep location and complex anatomy with adjacent cranial nerves and perforator vessels. Endovascular approach is safer and generally accepted as the primary treatment method. Optimal angiographic projections with three-dimensional reconstructions to guide microcatheter selection remain vital to successfully treating aneurysms with challenging fenestration anatomy. This report details the endovascular methods in two cases of fenestrated vertebrobasilar junction aneurysms with different coiling techniques.

Combined deconstructive and reconstructive treatment of a giant vertebrobasilar fenestration aneurysm

Aneurysms associated with a vertebrobasilar fenestration are rare lesions and can grow to a giant size, presenting significant therapeutic challenges. Endovascular treatment of these aneurysms has traditionally been with coiling; however, flow diverter placement within the fenestration arms has recently proven to be a viable treatment strategy. The authors present a case of a giant vertebrobasilar fenestration aneurysm in a patient presenting with a cranial nerve VI palsy. The lesion was treated by using a combination of flow diverter placement and vertebral artery sacrifice. The nuances of flow diversion therapy for these aneurysms and the management of intra- and postoperative complications are discussed. The video can be found here: https://stream.cadmore.media/r10.3171/2022.7.FOCVID2256.

Endovascular treatment of an aneurysm arising from the minor limb of an upper basilar artery fenestration: illustrative case

BACKGROUND

An aneurysm arising in an upper basilar artery (BA) fenestration is extremely rare. The authors reported a case involving successful endovascular treatment of an aneurysm arising from the minor limb of an upper BA fenestration.

OBSERVATIONS

A 65-year-old woman presented with an incidentally detected upper BA aneurysm arising from the minor limb of an upper BA fenestration. The irregularly shaped aneurysm was 6.0 × 2.7 mm in diameter, and the minor limb had several perforators. The aneurysm was nearly completely occluded with a catheter-assisted technique. The authors preserved both limbs of the BA fenestration. The postoperative course was uneventful, and the patient had an excellent clinical course with no neurological deficits or aneurysmal recanalization.

LESSONS

The case is the first report of an unruptured aneurysm arising at the minor limb of an upper BA fenestration. In this case, the authors preserved the minor limb with endovascular treatment. The authors believe catheter-assisted coil embolization to be a feasible endovascular technique in such cases.

Hemodynamic Differences Between Basilar Artery Fenestration and Normal Vertebrobasilar Artery: A Pilot Study

Background: Basilar artery fenestration has been proposed as a contributor to ischemic stroke, as unique flow patterns induced by fenestration may be related to thrombus formation or insufficiency. This study aimed to evaluate the hemodynamics of basilar artery fenestration (BAF) using computational fluid dynamics (CFD).

Methods: Patients with BAF and normal vertebrobasilar system were recruited and separately evaluated using CFD. Specific geometric vascular models were reconstructed based on 3D-rotational angiography (3D-RA). Patients were divided into the BAF group and control group (i.e., patients with the normal vertebrobasilar system). Hemodynamic and geometric variables were calculated and compared between groups using Student's t-test or Wilcoxon rank-sum test.

Results: Overall, 24 patients were included, with 12 patients each in the BAF group and the control group. The BAF group had a significantly smaller basilar artery diameter than the control group (3.1 ± 0.51 vs. 3.76 ± 0.4, p = 0.002). Compared to the control group, the BAF group had higher values of maxOSI (median, 0.3 vs. 0.09, p = 0.028), TAWSSG (median, 983.42 vs. 565.39, p = 0.038) in the flow confluence, higher SAR-TAWSSG in bifurcation (median, 70.22 vs. 27.65, p = 0.002) and higher SAR-TAWSSG in basilar artery (median, 48.75 vs. 16.17, p < 0.001) of the vertebrobasilar artery.

Conclusions: This pilot study suggested that hemodynamic differences between BAF and normal vertebrobasilar artery across multiple shear flow parameters. The disturbed flow in the BAF may increase the risk of thrombus formation, plaque instability, and subsequent ischemic cerebrovascular events. These should be confirmed by future studies.

Reconstructive endovascular treatment of basilar artery fenestration aneurysms: A multi-centre experience and literature review

BACKGROUND

Data on outcome after endovascular treatment of basilar artery fenestration aneurysms (BAFAs) is limited. This study presents our multi-centre experience of BAFAs treated by different reconstructive techniques including coils, stent-assisted coiling (SAC), flow diversion and intra-saccular flow disruption with the Woven Endobridge (WEB).

METHODS

Retrospective analysis of 38 BAFAs treated endovascularly between 2003 and 2020. The primary endpoint was complete aneurysm obliteration defined as Raymond-Roy occlusion classification (RROC) I on immediate and follow-up (FU) angiography. The secondary endpoints were procedure-related complications, rate of re-treatment, and clinical outcome.

RESULTS

Endovascular treatment was feasible in 36/38 aneurysms (95%). The most frequent strategy was coiling (21/36, 58%), followed by SAC (7/36, 19%), WEB embolization (6/36, 17%) and flow diversion (2/36, 6%). A successful aneurysm occlusion (defined as RROC 1 and 2) on the final angiogram was achieved in 30/36 (83%) aneurysms including all patients presenting with baseline subarachnoid haemorrhage and 25/36 (69%) were occluded completely. Complete occlusion (RROC 1) was more frequently achieved in ruptured BAFAs (15/25, 60% v. 2/11, 18%; p = 0.031). Procedure-related complications occurred in 3/36 (8%) aneurysms. Re-treatment was executed in 12/36 (33%) aneurysms. After a median angiography FU of 38 months, 30/31 (97%) BAFAs were occluded successfully and 25/31 (81%) showed complete occlusion.

CONCLUSION

Reconstructive endovascular treatment of BAFAs is technically feasible with a good safety profile. Although in some cases re-treatment was necessary, a high rate of final aneurysm occlusion was achieved.

Hemodynamic effects of size and location of basilar artery fenestrations associated to pathological implications

Fenestration is a rare congenital abnormality that refers to a segmental duplication of arteries. It is still not clear about the role of fenestrations in the etiology and pathological evolution of vascular diseases. This study aims to investigate the hemodynamic influence brought by various sizes and locations of fenestration in basilar artery models. A series presumptive fenestration models were established based on a normal basilar artery model with various sizes and locations. Identical boundary conditions were utilized in the computational fluid dynamics simulations and different flow patterns in the fenestration and bifurcation regions were comprehensively analyzed. Wall shear stress (WSS)-related parameters such as oscillatory shear index (OSI) and aneurysm formation index (AFI) were computed and compared. The value of WSS on fenestration increased by the fenestration's tortuosity, and nearly-circular fenestration suffered higher WSS than narrow-strips one. Also, high OSI and low AFI value mainly occurred in the bifurcation region, indicating a high level of turbulence and high risk of aneurysm formation. The location of fenestration mainly changed the impact force of blood flow on the bifurcation and the disorder characteristics of blood flow, while the size of fenestration changed the WSS distribution on the proximal inner wall and bifurcation region of fenestration. In summary, the nearly-circular fenestration should be stratified carefully which may results in a high risk inducing unfavorable vascular wall remodeling.

Endovascular treatment modalities for basilar artery fenestration aneurysms: experience of two centers and literature review

Background/aim

The aim of this study is to present our experience on various endovascular treatment modalities of basilar fenestration aneurysms and reviewing our findings together with literature data.

Materials and methods

A total of 26 basilar artery fenestration (BAF) aneurysms in 24 patients were endovascularly treated in two different neurointerventional radiology clinics. All patients had been evaluated with computed tomography (CT), CT angiography, and digital subtraction angiography before the procedure.

Results

Aneurysms of all patients were successfully occluded (technical success rate 100%). Procedure-related complications were seen in two patients. Our comprehensive literature research revealed that studies related with the topic are composed mostly of case reports. In the literature, a total of 113 BAF aneurysms of 101 patients had been treated endovascularly in 46 studies between 1993 and 2019. Success rate of the treatment was reported as 97%, clinical success rate as 91%, and complication rate as 8.8%, while these rates are 100%, 92%, and 7.6% in our study, respectively.

Conclusion

Although the number of cases is low in our study, to our knowledge, it is the widest series in the literature until today. Our results demonstrate that BAF aneurysms can be treated successfully and safely with different endovascular techniques, with more stent use in recent years.

[Surgical treatment of vertebral artery confluence aneurysms]

BACKGROUND

Aneurysms of vertebral artery confluence and proximal parts of basilar artery are extremely rare. They are usually combined with proximal fenestration of basilar artery. No timely surgical treatment of these aneurysms is associated with high risk of adverse outcomes, and their treatment is a challenge for neurosurgeons.

MATERIAL AND METHODS

We analyzed postoperative outcomes in 17 patients with 21 aneurysms of vertebral artery confluence and proximal parts of basilar artery.

RESULTS

Six patients with 10 aneurysms underwent microsurgical resection, 11 patients with 11 aneurysms - endovascular procedure. Persistent postoperative deterioration was observed in 5 (29.4%) patients: severe neurological symptoms (GOS grade 3) in 1 case (5.9%), minor bulbar disorders in 4 cases (23.53%). There were no lethal outcomes.

CONCLUSION

According to our own and literature data, aneurysms of vertebral artery confluence are extremely rare. The risk of rupture of these aneurysms is extremely high. Endovascular approach is preferred in these patients. Microsurgical procedure is an acceptable alternative if endovascular surgery is impossible.

Endovascular Treatment of Fenestration-related Aneurysms : Morphological Features, Operative Techniques and Therapeutic Outcomes

PURPOSE

Endovascular treatment of fenestration-related aneurysms (FAs) is prone to technical challenges, given the inherent complexities. Herein, we have analyzed FAs in terms of angioarchitectural characteristics and outcomes achieved through endovascular intervention.

METHODS

Data accrued prospectively between January 2002 and July 2020 were productive of 105 FAs in 103 patients, each classifiable by the nature of incorporated vasculature as proximal portion, fenestrated limb, or distal end. Our investigation focused on clinical and morphological outcomes, with emphasis on technical aspects of treatment.

RESULTS

The FAs selected for study originated primarily in anterior communicating artery (AcomA: 88/105, 83.8%), followed by basilar (7/105, 6.7%), anterior cerebral (4/105, 3.8%), and internal carotid (3/105, 2.8%) arteries. In nearly all locations, proximally situated aneurysms (43/105, 41%) were more frequent than aneurysms arising at distal ends (3/105, 2.8%), but the majority of AcomA lesions involved fenestrated segments (58/88, 65.9%); and most fenestrated channels (90/105, 85.7%) were asymmetric in size. Orifices of smaller fenestrated limbs were intentionally compromised during coil embolization in 23 aneurysms (21.9%), achieving complete (n = 19) or incomplete (n = 4) compromise, without resultant symptomatic ischemia. Saccular occlusion proved satisfactory in 77 lesions (73.3%). In follow-up monitoring of 100 patients for a mean period of 35.3 ± 26.5 months, 17 instances of recanalization (17.0%) occurred (minor, 9; major, 8). There was no recanalization of aneurysms with compromised limbs.

CONCLUSION

Coil embolization of FAs is safe and effective, enabling tailored procedures that accommodate aberrant angioanatomic configurations. Compromise of a single limb during coiling also appears safe, conferring long-term protection from recanalization.

Ruptured Bilobed Basilar Artery Fenestration Aneurysm Treated with a WEB Device

Objective

To describe the technique of using a Woven Endo Bridge (WEB) device to treat a ruptured bilobed blister-like aneurysm (BLA) at the basilar artery (BA) fenestration.

Case Presentation

A previously healthy 66-year-old female presented at the emergency room with subarachnoid hemorrhage (SAH), centered around the brainstem. Unenhanced CT and CT angiography showed a BLA of a basilar fenestration limb. The angiogram confirmed the diagnosis. A WEB device was chosen to treat this rare and challenging aneurysm.

Conclusion

In this article, we describe the successful endovascular treatment of a SAH patient with a ruptured BLA at the basilar artery fenestration using a WEB device. And an overview of treatment options is provided.

Endovascular Management of Complex Fenestration-Associated Aneurysms: A Single-Institution Retrospective Study and Review of Existing Techniques

BACKGROUND

Aneurysms associated with fenestrations of intracranial arteries are exceptionally rare findings. Management strategies for these aneurysms are not well-defined, especially regarding endovascular treatment. We sought to investigate the strategies and feasibility of endovascular treatment approaches for various fenestration-associated intracranial aneurysms.

METHODS

We performed a retrospective chart review of 2000 aneurysms treated endovascularly, identifying 8 aneurysms located at arterial fenestrations. The technical details and procedural outcomes were reviewed to identify common management approaches, technical nuances, and treatment outcomes.

RESULTS

There were 3 (37.5%) aneurysms associated with fenestrations of the basilar artery or vertebrobasilar junction. All 3 were successfully treated with a previously undescribed coil-assisted flow-diversion technique, resulting in complete obliteration. Three (37.5%) aneurysms were associated with fenestrations of the anterior communicating artery. Of those, 2 were successfully treated with stent-assisted coil embolization and 1 with coil embolization alone. One (12.5%) aneurysm was associated with a fenestration of the paraclinoid internal carotid artery and 1 (12.5%) aneurysm found was at the takeoff of the posterior inferior cerebellar artery at a fenestration of the vertebral artery. Both were successfully treated with coil-assisted flow diversion. There were no permanent procedural complications. Major considerations for endovascular management of these aneurysms were the dominance of fenestration trunks, aneurysms arising from the fenestration apex or a fenestration limb, amenability to flow diversion, and anticipation of vascular remodeling.

CONCLUSIONS

Fenestration-associated aneurysms are very rare. We have identified common factors to help guide decision-making for endovascular approaches and demonstrate successful aneurysm treatment using these methods.

A case of multiple Vertebrobasilar artery fenestration misdiagnosed as vertebral artery dissection

Background

Fenestration of vertebra-basilar artery is an uncommon congenital vascular anomaly, which is identified by incidental findings on imaging in patients presented without related symptoms or in patients with intracerebral hemorrhage secondary to concomitant artery aneurysm or arteriovenous malformations. Yet, cases of fenestration being misdiagnosed as cerebral artery dissection have never been reported.

Case presentation

We present a patient of 66-year-old female with acute onset of dizziness after chiropractic manipulation of the neck. Neck computed tomography angiography (CTA) showed ‘double lumen’ sign and ‘intimal flap’ of the V1 segment of the vertebral artery, which led to the initial diagnosis of vertebral artery dissection (VAD). However, vertebral artery fenestration at V1 segment was eventually identified by multi-directional digital subtraction angiography (DSA). Interestingly, concomitant vertebral fenestration at V3 segment, basilar fenestration and basilar artery tip aneurysm was also revealed by DSA.

Conclusion

The triple fenestration at vertebrobasilar artery with basilar tip artery aneurysm is extremely rare, and the fenestration at the V1 segment of vertebral artery was easily misdiagnosed as VAD due to the similar imaging morphology.

Fenestration deformity of the basilar artery trunk with an aneurysm: A case report

RATIONALE

Fenestration of the basilar artery is most common in the proximal portion near the vertebrobasilar artery junction. Conversely, fenestration of the middle and distal portions of the basilar artery is not common, and fenestration of the basilar artery with an aneurysm is even less common.

PATIENT CONCERNS

This study reports the case of a 37-year-old woman with basilar artery fenestration malformation and an aneurysm at the mid-distal junction; her symptoms included sudden headaches with nausea and vomiting.

DIAGNOSES

Head digital subtraction angiography showed fenestration at the junction of the middle and upper portions of the basilar artery associated with an aneurysm, and spontaneous pseudoaneurysm formation could not be excluded.

INTERVENTIONS

The patient underwent stent-assisted fenestration and channel occlusion.

OUTCOMES

Five months later, no abnormalities were found by head magnetic resonance imaging. The stents were well positioned, and no occluded branches or aneurysms were present.

LESSONS

For mid-distal basilar artery fenestration malformation with an aneurysm, occlusion of the lesion channel is relatively safe when there are no perforating vessels in the fenestration channel and the lesion channel is a nondominant channel. Overall, more attention should be paid to the possibility of pseudoaneurysm formation in the diagnosis and treatment of this type of aneurysm.

Plaque Distribution of Basilar Artery Fenestration by 3D High-Resolution MR Vessel Wall Imaging

The association between fenestrations and neurovascular pathology is not well defined. The morphology of vessel wall plays an important role in the development of neurovascular pathology. We sought to explore the plaque distribution around basilar artery fenestration (BAF) by three-dimensional high-resolution MR vessel wall imaging (3D HRMRI). Patients with BAF on 3D HRMRI images were enrolled. All cross-sectional slices of basilar arteries were assessed and categorized based on the location of fenestration as proximal segment, in-bifurcation segment, and distal segment. Furthermore, plaques in the in-bifurcation segment were classified according to their orientation being centered on the lateral, interior, dorsal, or ventral wall of the vessel. In all, 12 cases with BAF involving 661 cross-sectional image slices in entire basilar arteries were included. Plaques were found in 190 image slices, with the distribution of 41 slices in the proximal segment, 144 slices in the in-bifurcation segment and 67 slices in the distal segment. Plaques were found more frequently in the proximal and in-bifurcation segments than in the distal segment (P < 0.001), but there was no statistical difference between the proximal and in-bifurcation segment (P = 0.11). In the in-bifurcation segment, plaques were more frequently located at the lateral (50.0%) than other interior (16.0%), dorsal (21.0%), and ventral (13.0%) wall (P < 0.001).Plaques of BAF tend to locate in the proximal and in-bifurcation segments, especially at the lateral wall of the in-bifurcation segment.

Flanking the fenestration: circumferential limb-to-limb stent-assisted coiling of a basilar artery fenestration aneurysm

A man aged 61 years with a history of a ruptured basilar fenestration aneurysm underwent unassisted coiling in 1997 and repeat intervention for a recurrence at the aneurysm mouth in 2011. At repeat intervention, the decision was made to intentionally leave some filling at the base to preserve the parent vessels. Stent-assisted coil embolization, although technically feasible, was not pursued given the relative risks of the procedure. In 2017, the patient returned for repeat surveillance and further coil compaction was found at the aneurysm base. With the advent of more compliant woven stents deliverable through 0.017 microcatheters, stent-assisted coiling was possible. This case demonstrates hereto unseen agility afforded by novel low-profile stents allowing a circumferential approach to a basilar artery fenestration aneurysm and resultant limb-to-limb stent-assisted coiling. Techniques described here may be extended to more common anatomic variants that require stent-assisted coiling.

Flanking the fenestration: circumferential limb-to-limb stent-assisted coiling of a basilar artery fenestration aneurysm

A man aged 61 years with a history of a ruptured basilar fenestration aneurysm underwent unassisted coiling in 1997 and repeat intervention for a recurrence at the aneurysm mouth in 2011. At repeat intervention, the decision was made to intentionally leave some filling at the base to preserve the parent vessels. Stent-assisted coil embolization, although technically feasible, was not pursued given the relative risks of the procedure. In 2017, the patient returned for repeat surveillance and further coil compaction was found at the aneurysm base. With the advent of more compliant woven stents deliverable through 0.017 microcatheters, stent-assisted coiling was possible. This case demonstrates hereto unseen agility afforded by novel low-profile stents allowing a circumferential approach to a basilar artery fenestration aneurysm and resultant limb-to-limb stent-assisted coiling. Techniques described here may be extended to more common anatomic variants that require stent-assisted coiling.

Endovascular Treatment of Large Unruptured Fusiform Fenestrated Vertebrobasilar Junction Aneurysm

Fenestrated vertebrobasilar junction aneurysms are rare vascular lesions. Microsurgical intervention is extremely difficult due to the complex anatomy in the vicinity of these aneurysms. Endovascular neurosurgery appears to be safe and should be considered as the first modality of treatment. This case study details the treatment of an unruptured fusiform fenestrated vertebrobasilar junction aneurysm with endovascular occlusion with stent-assisted coiling. The optimal angiographic exposure and selective microcatheterization of the aneurysm were challenging due to the patient’s body habitus, and the aneurysm was large with one dominant fenestrated limb.

Dual flow diversion stents for aneurysm treatment in a partial unfused basilar artery

Unfused basilar arteries, frequently but erroneously referred to as 'fenestrations', are not uncommonly associated with aneurysms. The difficulty in treating these aneurysms lie in the fact that they are often wide necked and frequently incorporate both channels of the unfused segment, with varying calibres of the channels, necessitating technically challenging treatment strategies. It is important to preserve both channels because of the potential presence of perforating arteries originating from these segments. There are numerous case reports of such aneurysms being treated by coils alone, coiling with balloon assistance and stent-assisted coiling in configurations such as 'X', 'double barrel' or waffle cone. We present an exemplary case, in which an aneurysm on a partial unfused basilar segment was treated with parallel flow diverters with an excellent result on follow-up imaging.

Double Stent Assist Coiling of Ruptured Large Saccular Aneurysm in Proximal Basilar Artery Fenestration

Basilar artery fenestration is infrequent and even rarer in association with a large aneurysm. With proximity to brain stem and vital perforators, endovascular coiling can be considered first. If the large ruptured aneurysm with a wide neck originated from fenestra of the proximal basilar artery and the fenestration loop has branches of posterior circulation, therapeutic consideration should be thorough and fractionized. We report endovascular therapeutic details for a case of a ruptured large saccular aneurysm in proximal basilar artery fenestration.

Fenestra Obscura: Flow Diverter Reconstruction of a Complex Vertebrobasilar Aneurysm Through an Obscured Fenestration Limb: Technical Case Report

BACKGROUND AND IMPORTANCE

Basilar fenestration aneurysms are rare, challenging intracranial vascular lesions with atypical anatomy. The posterior circulation represents a difficult therapeutic dilemma because of the close proximity of crucial life-sustaining brainstem structures. The use of flow diverter technology has been very limited in posterior circulation vessels.

CLINICAL PRESENTATION

We present the case of a 49-year-old female patient, who was diagnosed with a symptomatic large vertebrobasilar junction aneurysm, which was initially thought to be a proximal basilar dilatation. The aneurysm was later verified to arise from the proximal end of a basilar fenestration, distended by the aneurysm fundus. The small-caliber fenestration limbs were the only connection to the distal basilar artery, but were stretched laterally and concealed by the aneurysm fundus. This complex lesion was successfully treated by flow diverter deployment through one of the fenestration limbs, followed by coiling of the aneurysm fundus, and sacrificing the contralateral vertebral artery. A 6-month follow-up angiogram showed remodeling of the basilar artery and complete occlusion of the aneurysm with good clinical outcome. Careful diagnostic workup, multidisciplinary discussions, and the innovative use of versatile endovascular technology were crucial to achieve an optimal result in this case.

CONCLUSION

This is the first report of a successful basilar artery reconstruction for the treatment of a large atypical vertebrobasilar junction fenestration aneurysm by deployment of a flow diverter device directly in a small, obscured fenestration limb.

Vertebro-basilar junction aneurysms: a single centre experience and meta-analysis of endovascular treatments

Vascular lesions of the vertebrobasilar junction (VBJ) are challenging in neurosurgical practice, and their gold-standard therapy is still under debate. We describe the operative strategies currently in use for the management of these complex vascular lesions and discuss their rationale in a literature meta-analysis and single centre blinded retrospective study. The single centre study included a review of initial presentation, angiographic features and clinical outcome (with modified Rankin Scale [mRS] scores) over a long-term follow-up. In our series, small aneurysms were effectively treated by endosaccular coil embolization, whereas a strategy including flow-diverter devices combined with endosaccular coil embolization was the option of choice in large and giant aneurysms, leading to satisfactory outcomes in most cases. Our Medline review showed that endovascular treatment was chosen in most VBJ cases, whereas the microsurgical option was assigned to only a few cases. Among the endovascular treatments, the most common techniques used for the treatment of VBJ aneurysms were: coiling, stent-assisted coiling and flow diversion. Our study highlights that aneurysm morphology, location and patient-specific angio-architecture are key factors to be considered in the management of VBJ aneurysms. Most case series, including our own, show that parent artery reconstruction using a flow-diverter device is a feasible and successful technique in some cases of giant and complex aneurysms (especially those involving the lower third of the basilar artery) while a "sit back, wait and see" approach may represent the safest and most reasonable option.