Combined use of a pCONus and a Solitaire stent: Report of two cases

Abstract

Objective

The aim of this study was to report our initial experience of the use of the pCONus neck protection device in conjunction with the Solitaire AB stent to assist in the endovascular management of complex intracranial aneurysms with arteries arising from both the neck and the dome of the aneurysm.

Methods

Two patients with unruptured aneurysms underwent elective endovascular management of their aneurysms, one arising from the middle cerebral artery bifurcation and one from the anterior communicating artery. Both aneurysms had vessels arising from the neck and dome of the aneurysm. We present the strategy involved to protect all the arterial branches and coil occlude the aneurysm, the angiographic appearances and clinical status of the patients.

Results

Both cases involved the combined use of a pCONus and Solitaire stent. The parent vessel and efferent branches were all preserved with exclusion of the aneurysm from the circulation. There were no intraoperative complications. One patient developed mild transient symptoms 24 hours post procedure, which had resolved completely on discharge.

Conclusion

The use of the pCONus in conjunction with the Solitaire stent is a useful combination when dealing with complex wide-necked aneurysms with arteries derived from the fundus of the aneurysm.

Introduction

The endovascular management of aneurysms has progressed considerably since the publishing of the International Subarachnoid Aneurysm Trial (ISAT).¹ Technological advancements in catheters, coils and stents have meant that an ever-greater number of aneurysms are amenable to endovascular treatment. Despite these advancements, wide-necked aneurysms remain challenging to the neurointerventionist, and newer devices, such as the pCONus (phenox) have entered the marketplace in order to deal with troublesome anatomy.

The pCONus is a laser-cut stent-like device with a crown of ‘petals’ that is designed to prevent coils protruding into the parent vessel of wide-necked aneurysms. The design of the pCONus also allows for the protection of daughter branches that originate from or close to the neck. Several papers have discussed its use in both elective and acute scenarios.^2–5 However, the use of the pCONus in combination with other devices has not been discussed.

In this report, we present two cases where the combination of a pCONus and Solitaire stent was used to protect the parent vessel in addition to vessels arising from the neck and the fundus of the aneurysm.

Case 1

A patient in their 30s was admitted for embolization of a wide-necked aneurysm arising from the left middle cerebral artery (MCA) bifurcation that was detected incidentally after a computed tomography (CT) scan was performed for recurrent headaches and dizziness. The patient was refused neurosurgical clipping of the aneurysm because of the complex anatomy of the aneurysm and the branch derived from the aneurysm fundus that in combination with the branches at the neck of the aneurysm would result in only a partial clipping. Preoperative angiography and rotational angiography confirmed the complex nature of the aneurysm (Figure 1).

Figure 1.

A wide-necked aneurysm arising from the left middle cerebral artery bifurcation with two M2 branches arising from the neck of the aneurysm and a further branch arising from the fundus of the aneurysm (a; white arrows). The aneurysm measured 10 mm × 8 mm × 11 mm with a 10 mm × 7 mm neck.

After informed consent, the patient was planned for an elective coiling of the aneurysm and loaded with 75 mg of clopidogrel and 150 mg of aspirin for seven days. Under general anaesthesia and after full heparinisation, a 7 Fr Envoy guiding catheter was tracked into the left internal carotid artery. The aneurysm was initially catheterised using a Headway 21 (Microvention) microcatheter through which a pCONus 4-20-12 mm was deployed to protect the neck of the aneurysm. The pCONus was not electrolytically detached at this point. Subsequently, a Prowler Select Plus microcatheter (Cordis) was tracked into the M2 branch originating from the dome of the aneurysm and a 3 mm × 20 mm Solitaire AB stent (Covidien) deployed in both the M2 and M1 segments and through the pCONus device. In order to prevent coils from prolapsing through the Solitaire stent struts, a 4 mm × 7 mm Hyperform (Covidien) balloon was then tracked into the Solitaire stent whilst the Prowler Select Plus microcatheter was repositioned in the aneurysm. After inflating the Hyperform balloon, multiple coils were deployed within the aneurysm (Figure 2). At the end of the coiling procedure, the pCONus device was electrolytically detached.

Figure 2.

The initial step in the procedure was to place the pCONus device in the aneurysm to protect the neck and the two M2 branches arising from the base of the aneurysm (a; black arrow pointing to the markers on the distal petals of the pCONus). Subsequently, a Solitaire AB stent was positioned in the M2 branch derived from the fundus of the aneurysm (b; black dashed arrow) through which a Hyperform balloon was tracked (c). This was done in order to prevent coil loops prolapsing through the stent struts. Finally, the aneurysm was coiled (d) following which the pCONus was detached.

Angiography at the end of the procedure demonstrated all vessels to be patent, with no intraoperative complications (Figure 3).

Figure 3.

Angiography at the end of the procedure showed all the M2 branches were patent with no evidence of thromboembolism.

The patient was extubated, and the immediate postoperative neurological status was unchanged from baseline. Approximately 24 hours post procedure, the patient developed transient right-hand paresis and dysphasia. An emergency CT scan was performed, which demonstrated a small infarction within the posterior limb of the internal capsule. There was no evidence of thromboembolism, and the infarction was believed to be due to hypoperfusion. Therefore, the blood pressure of the patient was raised in order to prevent repeat episodes. The patient was discharged on postoperative day 5 with no evidence of neurological deficit. Follow-up angiography at three months showed preservation of all the M2 branches and good exclusion of the aneurysm from the circulation.

Case 2

A patient in their 30s was found to have an incidental aneurysm arising from the anterior communicating artery (AcomA) after a routine magnetic resonance imaging scan for headaches. There was no evidence of previous rupture. Conventional catheter angiography was performed to delineate the anatomy, and this showed a wide-necked aneurysm with the left A2 and Acom arising from the base of the aneurysm with a pericallosal branch arising from the aneurysm fundus (Figure 4(a) and (b), white arrows). The aneurysm dome measured approximately 7 mm in diameter with a 4.5 mm wide neck.

Figure 4.

Rotational angiography demonstrated a complex anterior communicating artery aneurysm with branches arising from both the neck and the dome of the aneurysm (a and b). Initially the pericallosal branch arising from the fundus was catheterised and confirmed on microcatheter angiography. The aneurysm was then catheterised, and a pCONus deployed but not detached (d; black arrow). Subsequently, a microcatheter was tracked distally into the pericallosal branch, after which a Solitaire stent was deployed in the pericallosal branch (d; black dashed arrow). In a second session, the aneurysm was subsequently coiled, and angiography at the end of the procedure revealed good exclusion of the aneurysm from the circulation with all vessels remaining patent (e and f).

After discussion between the neurosurgical team, the neurointerventional team and the patient, it was agreed to attempt endovascular management of the aneurysm. The patient was loaded with 75 mg of clopidogrel and 100 mg of aspirin for seven days, and an adequate response was confirmed using the Multiplate test (Roche).

In the first treatment session under general anaesthesia and using a standard right common femoral approach, a 6 Fr Envoy guide catheter was tracked into the left internal carotid artery after full heparinisation. Initially, the aneurysm was catheterised using a XT27 microcatheter (Stryker), and the pCONus 4-20-8 mm was deployed but not detached. Then the pericallosal branch arising from the aneurysm dome was catheterised and a Prowler Select Plus microcatheter was tracked distally through the petals of the pCONus. Subsequently, a 3 mm × 20 mm Solitaire was deployed into the pericallosal branch and proximally in the left A1 segment (Figure 4(d), black dashed arrowed). In a second treatment session five days later, the aneurysm was then coiled with good exclusion of the aneurysm from the circulation, and all branches were patent with no thromboembolic complications (Figure 4(e) and (f)). The patient was extubated and had baseline neurology on examination. Follow-up angiography is awaited.

Discussion

The endovascular management of wide-necked bifurcation aneurysms represent a unique challenge to the neurointerventionist. The difficulty of achieving aneurysmal occlusion and preservation of the parent vessel is often compounded by the fact that arterial branches may arise from the neck of the aneurysm. This anatomical disposition poses problems not only for neurointerventionists but also neurosurgical colleagues.

A variety of endovascular techniques have been developed over the years to deal with this scenario. In acutely ruptured aneurysms, many prefer to avoid the use of stents and the concomitant administration of antiplatelet agents, and hence opt for balloon-assisted coiling. This can be performed using a variety of different techniques with regards to wide-necked bifurcation aneurysms, including the use of a super compliant balloon in a single branch that is inflated and bulges across the aneurysm neck; two balloons inflated together and placed into two different branches of the bifurcation (kissing balloon technique); and the use of a double lumen balloon through which the aneurysm is coiled. These balloon remodelling techniques have been shown to be safe and with good anatomical outcomes.^6–8

Stents have also been used to assist the coiling of wide-necked bifurcation aneurysm. The type of stenting procedure required is dependent upon the anatomical configuration of the parent vessel and the branches. In some instances, a single stent may suffice. However, in other cases, more complex Y-stenting or T-stenting procedures have been developed. Several authors have evaluated the efficacy of Y-stenting with high rates of aneurysm occlusion and acceptable rates of peri-procedural morbidity and mortality.^9–11 The difficulty with both the Y- and T-stenting techniques rests in the need to catheterise each branch selectively, which can often prove technically challenging. In order to negate catheterising each branch, the ‘waffle cone’ technique was developed with the pCONus, representing the next evolutionary step in this technique (Figure 5).

Figure 5.

In wide-necked bifurcation aneurysms where branches originate from the neck (a), the pCONus device (black arrow) can be placed with its distal end in the aneurysm neck and provide protection for both the neck and the branches (b).

The available published literature on the pCONus device has shown it to have a good safety profile and aneurysm occlusion rate.^2–5 In certain anatomical dispositions, the use of a pCONus alone may not suffice in protecting various arterial branches. In these situations, the combined use of a pCONus to provide neck protection with the concomitant use of a stent in the arterial branch can provide protection for both the neck as well as the arterial branch (Figure 6).

Figure 6.

In certain anatomical situations, an arterial branch may arise from the aneurysm fundus (a). The placement of a pCONus to protect the true neck of the aneurysm will not protect the branch derived from the fundus. Therefore, a further stent is required to protect this branch (b), whilst the placement of the pCONus will protect the branches at the neck. In case 1, a balloon was placed inside the Solitaire stent in order to protect the lumen of the solitaire (c). In case 2, a balloon was not used inside the stent. Following the placement of the pCONus and the Solitaire stent, the aneurysm was coiled (d).

This strategy can provide an elegant solution to an otherwise difficult anatomical problem. In addition, one may be able alter haemodynamically important parameters using this technique. It has previously been shown in bifurcation aneurysms of the AcomA and MCA that larger angles between the parent and daughter vessels are associated with ruptured aneurysms.¹² Furthermore, it has also been shown that stents can cause a remodelling effect on this angle and that the longitudinal stiffness of the stents plays an important part in this remodelling effect.¹³ Whilst in our cases we opted to use Solitaire stents, there is no reason that other stents with other properties such as the Enterprise stent (Cordis) or Leo (Balt) could not be used. This combination approach would then offer several advantages, including robust neck protection allowing high coil packing density as well as protection of daughter arteries and a remodelling effect that over time may reduce intra-aneurysmal flow and wall shear stress.¹⁴ This technique could be expanded with the placement of a flow-diverting stent within the branch derived from the aneurysm fundus. This would need to be very carefully located and would likely require the flow diverter to be implanted within another stent using a stent-in-stent technique. This would then redirect flow away from the aneurysm in a similar fashion to that performed in fusiform aneurysms.^15,16

We believe that it is likely that the stent placed within the arterial branch will not endothelialise or that this process will occur very slowly. Therefore, the antiplatelet regime needs to be carefully considered, with life-long dual antiplatelet medication likely to be necessary.

Conclusion

We present two cases using a combination of a pCONus and Solitaire stent to provide neck protection as well as protection for branches derived from the aneurysmal fundus. We believe that this combination can provide an elegant solution in anatomically challenging situations.

Declaration of conflicting interests

The authors declared the following potential conflicts of interest with respect to the research, authorship and/or publication of this article: HH is co-founder and shareholder in phenox. PB, MAP and RMM are consultants for phenox with moderate compensation.

Funding

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