Jailed double-microcatheter technique following horizontal stenting for coil embolization of intracranial wide-necked bifurcation aneurysms: A technical report of two cases

Abstract

The horizontal stenting technique facilitates endovascular treatment of wide-necked bifurcation intracranial aneurysms. Previous literature shows, however, that subsequent coil embolization at initial treatment results in incomplete obliteration in many cases. The authors present two consecutive cases of wide-necked large bifurcation aneurysms to describe an additional coil embolization technique following horizontal stenting. The patients were a 53-year-old female with an unruptured internal carotid artery terminus aneurysm and a 57-year-old female with a recurrent basilar artery tip aneurysm. Both patients underwent endovascular treatment with horizontal stenting followed by coil embolization with jailed double-microcatheters. Immediate complete obliteration was achieved with no complications, and no recanalization was observed at the one-year follow-up in both cases. Coil embolization with jailed double-microcatheter technique following horizontal stenting is a safe and effective strategy for wide-necked bifurcation aneurysms.

Introduction

Wide-necked intracranial aneurysms were originally considered unsuitable for endovascular treatment, but recent advancements in endovascular techniques and devices have enabled coil embolization of such aneurysms.^1,2 However, endovascular treatment of wide-necked bifurcation aneurysms remains technically challenging. Adjunctive techniques, such as stent-assisted coiling (SAC), balloon-assisted coiling, and double-catheter coiling, are often required to facilitate coil embolization of these aneurysms. Various stent configurations have been proposed for SAC of bifurcation aneurysms. The horizontal stenting technique comprises a stent deployment across the neck of bifurcation aneurysms, which optimally reconstructs the aneurysms with a relatively reduced risk of thromboembolic complications.^3–12 However, subsequent coil embolization has resulted in incomplete obliteration in many previous cases, even when the horizontal stent was successfully deployed.^4,8,10 These incomplete results might have been related to coil embolization techniques that were employed following horizontal stenting, although this has not been discussed in detail in the literature.

The authors describe two consecutive cases of wide-necked bifurcation aneurysms that were successfully treated by coil embolization using the jailed double-microcatheter technique following horizontal stenting.

Case 1

A 53-year-old female presented with a 12-mm right internal carotid artery (ICA) terminus aneurysm, which was incidentally detected on cranial magnetic resonance imaging (MRI). The aneurysm had a 6-mm neck encroaching on the right A1 segment. The anterior communicating artery (AComA) was patent with a diameter of 1.4 mm. The patient also had a 4-mm right anterior choroidal artery (AChA) aneurysm.

The patient was put on dual antiplatelet therapy (daily doses of 75 mg clopidogrel and 100 mg aspirin) for seven days prior to the procedure, as well as during and after the procedure. The endovascular treatment consisted of a series of technical steps. First, under general anesthesia, bilateral femoral access was obtained. Second, a 5-French Fubuki guiding sheath (Asahi Intecc, Nagoya, Japan) for stent navigation was placed at the left ICA. Third, a stent delivery microcatheter was navigated; an Excelsior SL-10 microcatheter (Stryker Neurovascular, Fremont, CA, USA) was carefully advanced to the contralateral middle cerebral artery via the AComA, and was exchanged for a Prowler Select Plus microcatheter (Cordis Endovascular, Miami Lakes, FL, USA) using a Transcend exchange microwire (Stryker Neurovascular). Fourth, a 6-French Fubuki guiding sheath for coil delivery was placed at the right ICA. Fifth, double-microcatheters for coil delivery were introduced; an SL-10 microcatheter and an Echelon-10 microcatheter (eV3 Neurovascular, Irvine, CA, USA) were both advanced into the aneurysm sac, one through the anterior side and the other through the posterior side of the Prowler Select Plus microcatheter (Figure 1(a)). Sixth, a self-expandable Enterprise stent (Cordis Endovascular, 4.5 mm × 14 mm) was navigated through the Prowler Select Plus microcatheter and deployed from the right M1 to the right A1 segment. Both coil delivery microcatheters were jailed, one to the anterior wall and the other to the posterior wall of the proximal artery. Each microcatheter tip was located at different positions in the aneurysm (Figure 1(b) and 1(c)). Last, coil packing using the two jailed microcatheters was performed with bare platinum coils. Immediate complete obliteration (CO) was achieved without coil herniation into the parent arteries (Figure 1(d)). The right AChA aneurysm was treated by simple coil embolization. The patient had no neurological complications and no ischemic lesions on postoperative MRI. Follow-up angiography after one year showed no recanalization (Figure 1(e)).

Figure 1.

Intraoperative ((a)–(d)) and follow-up (e) angiography in Case 1 with a right ICA terminus aneurysm.

(a) Right ICA angiography shows the stent delivery microcatheter advanced to the right MCA via AcomA. The two coil delivery microcatheters were inserted into the aneurysm prior to stent placement.

(b) Right ICA angiography shows the stent deployed from the right M1 to the right A1 segment.

(c) Contrast-enhanced cone-beam CT shows the two microcatheters jailed to each side of the stent.

(d) Right ICA angiography shows immediate complete obliteration.

(e) Right ICA angiography at the one-year follow-up exam shows no recanalization.

ICA: internal carotid artery; MCA: middle cerebral artery; AcomA: anterior communicating artery; CT: computed tomography.

Case 2

A 57-year-old female, who had undergone simple coil embolization for a ruptured basilar artery (BA) bifurcation aneurysm and an unruptured BA-right superior cerebellar artery aneurysm five years prior, developed a recurrent 10-mm BA tip aneurysm with a 4-mm neck encroaching on the left P1 segment. The right posterior communicating artery (PComA) was patent with a diameter of 1.3 mm.

The treatment strategy in this case was the same as in Case 1. Dual antiplatelet therapy (75 mg clopidogrel and 100 mg aspirin daily) was started seven days prior to the procedure. Under general anesthesia, bilateral femoral access was obtained. A 5-French Fubuki guiding sheath for stent navigation was placed at the right ICA. Through the right PComA, an Excelsior SL-10 microcatheter was advanced to the contralateral posterior cerebral artery, and was exchanged for a Prowler Select Plus microcatheter. A 6-French Fubuki guiding sheath for coil delivery was placed at the left vertebral artery. An SL-10 microcatheter and an Echelon-10 microcatheter were both inserted into the aneurysm sac, one through the anterior side and the other through the posterior side of the Prowler Select Plus microcatheter (Figure 2(a) and 2(b)). A self-expandable Enterprise stent (Cordis Endovascular, 4.5 mm × 22 mm) was navigated through the Prowler Select Plus microcatheter and deployed from the left P1 to the right P1 segment (Figure 2(c)). Both coil delivery microcatheters were jailed, one to the anterior wall and the other to the posterior wall of the proximal artery. Subsequent coil packing was performed using bare platinum coils, resulting in immediate CO without neurological or radiological complications (Figure 2(d) and 2(e)). The postoperative course was satisfactory, and follow-up angiography after one year showed no recanalization (Figure 2(f)).

Figure 2.

Intraoperative ((a)–(e)) and follow-up (f) angiography in Case 2 with a recurrent BA tip aneurysm.

(a) and (b) Anteroposterior (a) and lateral (b) views of left VA angiography show the stent delivery microcatheter advanced into the left PCA via the right PcomA. The two coil delivery microcatheters were inserted into the aneurysm prior to stent placement.

(c) Unsubtracted image shows the stent deployed from the left P1 to the right P1 segment.

(d) and (e) Anteroposterior (d) and lateral (e) views of left VA angiography show immediate complete obliteration.

(f) Left VA angiography at the one-year follow-up exam shows no recanalization.

BA: basilar artery; VA: vertebral artery; PCA: posterior cerebral artery; PcomA: posterior communicating artery.

Discussion

Several studies have demonstrated that SAC induces progressive obliteration of incompletely coiled aneurysms and reduces recanalization rates at follow-up.^1,13 This progressive obliteration is achieved by the hemodynamic and biologic effects of the stent.^14,15 Stents reduce impingement blood flow into aneurysms by causing flow diversion, which leads to stasis and thrombosis in the aneurysm. Delayed stent endothelialization promotes closure of the aneurysm orifice. However, the recanalization rate after SAC remains at 8.1%–17.5%,^13,16–18 and long-term SAC results are still not fully established. Hwang et al. reported that SAC did not significantly improve the rates of progressive occlusion or recanalization at two-year follow-up, compared with non-stenting coil embolization.¹⁷ Ozretić et al. also reported that SAC did not reduce the rate of recurrence and retreatment.¹⁹ Tight coil packing is, therefore, desirable, even when stents are adjunctively placed.

In the case of bifurcation aneurysms, the simple placement of a single stent from the proximal artery to one of the branch vessels often results in insufficient coverage of the aneurysm neck. This causes coil protrusion into the contralateral branch and insufficient coil packing in subsequent coil embolization. Several stent configurations have been proposed for facilitating SAC for wide-necked bifurcation aneurysms, including Y-stenting,²⁰ waffle-cone stenting,^21,22 and horizontal stenting techniques.

In the Y-stenting technique, two stents are deployed in a Y-configuration from the proximal artery to each distal limb of the bifurcation. One stent is delivered through a strut of the other (crossing Y-stent), or both stents are placed in parallel in the proximal artery (kissing Y-stent). This strategy can protect both distal branches from coil herniation. Moreover, the Y-stent configuration has the strongest effect on intra-aneurysmal flow reduction among various stent configurations, which may effectively induce the progressive obliteration and reduce the recanalization rate.¹⁴ The Y-stenting technique, however, poses an increased risk of thromboembolic complications associated with placement of the two stents.^5,8,11 Johnson et al. retrospectively analyzed 486 cases of intracranial aneurysms treated by SAC and reported that Y-stenting was an independent risk factor for permanent disabling complications and for all complications.²

In the waffle-cone technique, a single stent is deployed from the proximal artery to the aneurysm neck, and the distal portion of the stent protrudes into the aneurysm to provide a scaffold for coil placement. This technique uses a single stent, which reduces the risk of thromboembolic complications compared with Y-stenting. However, stent protrusion into the aneurysm might pose a risk for procedural rupture, especially in cases of small aneurysms. Additionally, the stent directs hemodynamic blood flow into the aneurysm, which may increase the risk of postoperative recanalization.^4,22

The horizontal stenting technique necessitates stent delivery through the circle of Willis, and the practicability of horizontal stenting is dependent on accessibility of the stent delivery route, including patency, size, and lack of tortuosity of the communicating arteries.^4,7,10 When stent delivery is achieved, the horizontal stent configuration can remodel wide-necked bifurcation aneurysms, strongly affecting flow reduction into the aneurysm.^12,14 Moreover, this strategy has a theoretically reduced risk of thromboembolic complication compared with the placement of two stents.^{3,5,6,8,9,11,12} Many previous studies have reported on the advantages of horizontal stenting in cases of patients with wide-necked bifurcation aneurysms.^3–11 In the literature, however, subsequent coil embolization has achieved immediate CO only in limited cases, even when the horizontal stent was successfully deployed. Furthermore, regardless of the stent effect, the incomplete angiographic results remained unchanged or even deteriorated at follow-up in some cases.^4,8,10 Immediate CO is preferable for improved endovascular treatment outcome with horizontal stenting.

Tight coil packing by SAC is often difficult, partly because the stent restricts movement of the coil delivery microcatheter during coil placement. This hinders the microcatheter tip, resulting in difficulties with “paint-brushing” or the back-and-forth movement required for uniform distribution of coils in the aneurysm, thereby increasing the risk for compartmentalization and incomplete obliteration of the aneurysm. Additionally, in most previous cases of horizontal stenting, coil placement was performed using the trans-cell technique, in which a horizontal stent was deployed before the aneurysm was catheterized across the stent struts.^3–11 In the trans-cell technique, the coil delivery microcatheter can be easily pushed out of the aneurysm during coil placement, because the microcatheter is not fixed to the vessel walls. Reinsertion of the coil delivery microcatheter is challenging, because the microcatheter can be caught on the stent struts, and axial force to advance the microcatheter through the stent interstices can cause the microcatheter to be thrust into the aneurysm, increasing the risk for aneurysm perforation.²³

To resolve these problems, the authors used jailed double-coil delivery microcatheters for coil embolization following horizontal stenting in two consecutive cases of wide-necked complex bifurcation aneurysm. The two jailed microcatheters passed through each side of the stent, and the microcatheter tips were placed in different positions in the aneurysm. This was helpful in distributing coils entirely throughout the aneurysm to prevent any remaining uncoiled compartments. The microcatheters were jailed using short segments of the stent, because they perpendicularly crossed the stent. This enabled relatively flexible movement of the microcatheter tips, which also contributed to tight coil packing. Immediate CO was achieved without any complications, and recanalization was not observed at the one-year follow-up exam in either case. The jailed double-microcatheter technique achieved effective coil embolization of wide-necked bifurcation aneurysms accompanied by the safety of horizontal stenting. This strategy may broaden the possibility of the endovascular treatment for wide-necked complex bifurcation aneurysms.

The catheterization of the communicating artery by stent delivery microcatheters is sometimes difficult and dangerous, even when the communicating artery is patent and not too tortuous, because the stent delivery microcatheters are typically large and not sufficiently navigable. It may therefore be necessary to catheterize the communicating artery by a suppler and smaller microcatheter first and then exchange it for the stent delivery catheter.¹² This microcatheter exchange enabled easy and safe catheterization of the communicating arteries in the present cases.

This study had some limitations. First, successful implementation of horizontal stenting relies on the accessibility of communicating arteries, and careful case selection is needed for this strategy. Second, the authors have treated only two cases of wide-necked bifurcation aneurysm using this strategy. Third, the use of double-microcatheters could theoretically increase the risk for thromboembolic complications, which may diminish the advantage of horizontal stenting. In the present two cases, the large and elongated morphology of the aneurysms made it difficult to distribute coils throughout the entire aneurysm via a single microcatheter. As both cases had a large-sized parent artery (right ICA in Case 1 and BA in Case 2), locating the two microcatheters in the parent artery entailed a relatively low risk of thromboembolism. Although the present two cases were successfully treated without any complications, further investigation is necessary to confirm the efficacy and safety of coil embolization using the jailed double-microcatheter technique following horizontal stenting for wide-necked bifurcation aneurysms.

Conclusion

The authors report the use of jailed double-microcatheter technique in combination with a horizontal stent as an effective and safe treatment strategy for wide-necked bifurcation aneurysms. This may provide an alternative treatment option for wide-necked complex bifurcation aneurysms.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.