Treatment of Wide-Neck Intracranial Aneurysms with the Woven EndoBridge Device Associated with Stenting: A Single-Center Experience

Technical and Angiographic Outcomes

The WEB and the stent were successfully deployed inside the aneurysm and the artery in all cases, highlighting the feasibility of this technique. Consistent with the literature of WEB devices,^5,10 initial complete/near-complete occlusion immediately after WEB and stent deployment was obtained in 41% of patients, whereas long-term adequate occlusion (RR I/RR II) was 81%. These results appear quite comparable with the angiographic outcome of other endovascular treatment modalities. In a meta-analysis of nearly 1900 aneurysms treated with stent-assisted coiling, the rates of immediate and long-term complete/near-complete occlusion were 54% and 73%, respectively.¹² However, in our study, 3 aneurysms (18%) were incompletely occluded at follow-up and required retreatment with Y-stent-assisted coiling. Although the rate of retreatment was quite high, all of these were large aneurysms located at the basilar tip (On-line Tables 1 and 2). In a recent series of 79 endovascularly treated basilar tip aneurysms, the rate of incomplete occlusion was close to 40%, and large aneurysm size was reported as an independent risk factor for incomplete occlusion.¹³ Similarly, Abecassis et al¹⁴ reported a retreatment rate close to 40% among basilar tip aneurysms treated with endovascular techniques. Accordingly, in our experience, the stent-assisted WEB technique was associated with good angiographic results, except for large aneurysms of the basilar tip, where the bifurcation configuration and the hemodynamic forces may play an important role in the aneurysm recanalization.¹⁵

Among the published series of the WEB, the rate of treatment with the WEB and additional stent placement ranged between 5%⁶ and 18%.^7,16 In general, the stents were implanted due to a suboptimal placement of the WEB inside the sac with a protrusion of the device inside the artery. Kabbasch et al,¹⁶ in a series of 114 intracranial aneurysms treated with the WEB, described 14% of cases requiring additional stent placement, reporting 69% adequate occlusion during follow-up.

In our series, as reported above, the decision to stent the artery was planned before or was made during treatment after deployment of the WEB. In the first situation, during the preoperative planning, the main morphologic factors indicating the need for additional stent placement were the presence of a wide neck and a vessel arising from the aneurysm sac. Thus, the possibility of WEB protrusion into the artery was considered not negligible, and stent placement was planned beforehand. An example is reported in Fig 4, in which a case of nonbranching 5 × 4 mm aneurysm arising from the wall of the angular artery is depicted. The strategy was to exclude the aneurysm with a WEB-SL (6 × 3 mm) and to protect the artery with a Neuroform Atlas (3 × 24 mm). Fig 2 shows another example of planned WEB plus stent placement. The WEB was intentionally undersized to avoid the coverage of the fetal PcomA coming from the aneurysm; accordingly, due to a large basal aneurysm remnant, a PED was deployed from the internal carotid artery to the M1 segment to cause a diversion of the flow from the residual aneurysm. In our opinion, given the undersized device, the risk of WEB compaction and aneurysm recanalization during follow-up was high; consequently, we decided to use a flow-diversion device in the same treatment session.

A third example is reported in Fig 3, depicting a large MCA bifurcation aneurysm recanalized after treatment with a WEB-SL. When we opened the first WEB, an immediate complete aneurysm exclusion was noticed, and no additional devices were used in the first session. However, likely due to the undersized WEB, the aneurysm was recanalized and the WEB was compacted at the midterm follow-up. A second WEB was deployed covering the aneurysm neck, while the M2 branches arising from the sac were protected with a Y-stent placement with 2 LEO baby stents. Complete aneurysm occlusion was achieved during follow-up.

On the other hand, when stent placement was not planned, the decision to stent the artery was because of the WEB protrusion into the bifurcation vessel. Fig 1 shows a wide-neck 6 × 4 mm AcomA aneurysm treated with a WEB-SL (7 × 3 mm). The WEB was protruding into the right A2, leading to a severe stenosis. Accordingly, a laser-cut stent was delivered to restore the caliber of the artery.

In general, larger aneurysms treated endovascularly are associated with lower rates of angiographic occlusion and a higher risk of recurrence.¹⁷ Accordingly, we found a significantly higher mean size among aneurysms incompletely occluded compared with those showing complete occlusion during follow-up (10 versus 5.5 mm, P = .003). This finding is line with a recent series investigating factors related to aneurysm occlusion after the WEB: The authors reported, in the multivariate analysis, that aneurysm size (OR = 1.2; 95% CI, 1.01–1.38; P = .034) was an independent morphologic risk factor for aneurysm remnants.¹⁶

Treatment-Related Complications

A recent large series and meta-analysis of the WEB for the treatment of intracranial aneurysms showed variable rates of treatment-related morbidity (between 2% and 10%).^5,10 In our series, there were no permanent events or major neurologic complications. We describe 2 cases (patients 4 and 7) of intraprocedural complications after stent placement during acute SAH: A mild in-stent thrombosis was reported after stent deployment and was completely resolved after abciximab injection. During follow-up, only 1 patient (patient 13) had an asymptomatic parent vessel occlusion (angular artery) that was discovered during the angiographic long-term follow-up. It is likely that the artery was moderately stenosed by the WEB, and due to the collateral circulation, it became occluded without radiologic (the FLAIR findings were negative) and clinical sequalae (Fig 4).

Treatment with the WEB is, in general, a straightforward strategy, and this is mainly reflected by the brevity of the total fluoroscopic time reported in the literature. Fiorella et al³ in the WEB Intra-saccular Therapy Study (WEB-IT) reported a mean fluoroscopy time of 30 ± 15.7 minutes. Similarly, in a recent series of ruptured aneurysms treated with the WEB, the mean fluoroscopy time was 24 minutes (range, 8–40 minutes).¹⁸ It has been reported that longer intervention time (>120 minutes) is a risk factor associated with ischemic events after endovascular treatment of intracranial aneurysms.¹⁹ In our series, although some aneurysms required more complex treatment such as Y-stent placement plus a WEB, the mean intervention and fluoroscopy times were relatively low (78 and 35 minutes, respectively). Consistent with the literature, among patients reporting intraprocedural ischemic events, the mean fluoroscopy (51.5 versus 33 minutes) and intervention (100 versus 76 minutes) times were higher compared with those without complications.

Limitations of the Study

Our study has limitations intrinsic to single-center series. The number of patients is relatively small, though it is the first larger series investigating WEB-plus-stent placement. The data, though prospectively collected, were analyzed retrospectively. In addition, the imaging outcome was assessed by operators and not independently. There was a lack of standardization of radiologic follow-up.