A novel technique for stenting in cases of refractory intracranial stenosis

Abstract

Endovascular management of intracranial stenosis is one of the most controversial subjects in neurointervention. Previous level 1 evidence shows superiority of medical management but more recent studies have shown improved outcomes in selective patients. We describe a case demonstrating a new method for stenting of intracranial stenosis using a single system with Coyote angioplasty balloon (Boston Scientific) and the Atlas stent (Stryker).

Introduction

Endovascular management of intracranial stenosis is one of the most controversial topics in neurointerventional surgery. Intracranial atherosclerosis is a common cause of stroke with a high rate of recurrence, up to 30% after two years of follow-up.^1,2 Initially, there was much interest in decreasing this risk with intracranial stenting.³ Published in 2011, a randomized trial named Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) concluded that aggressive medical management was superior to percutaneous transluminal angioplasty and stenting (PTAS) with the Wingspan stent. However, of the 33 strokes in the PTAS group, 25 occurred within one day after stent was deployment and 8 occurred two to six days later. Although the Wingspan stent is FDA approved, its deployment is associated with high procedural morbidity, which may explain its lack of efficacy in the SAMMPRIS trial. One reason for Wingspan's periprocedural morbidity may be the need for intracranial microcatheter exchange between angioplasty and stent delivery. In this case report, we describe an improved delivery mechanism for the Neuroform Atlas stent for the treatment of severe intracranial atheroscleroric stenosis refractory to aggressive medical management. Our technique eliminates the need for intracranial microcatheter exchange by allowing stent deployment through the lumen of a balloon microcatheter.

Case report

A 43-year-old female presented to the emergency department with acute onset of right hemiparesis and aphasia. A computed tomography angiography (CTA) demonstrated complete occlusion of the left internal carotid artery (ICA) at the ophthalmic segment. The patient underwent thrombectomy without complications and intraprocedurally after removing the thrombus, a high-grade stenosis of approximately 80% of the left supraclinoid ICA distal to the ophthalmic artery was identified (Figure 1(a)). Balloon angioplasty using a 2 × 20 mm Coyote ES OTW angioplasty balloon (Boston Scientific) was performed obtaining good recanalization without residual stenosis (Figure 1(b)). The patient did well and was discharged home on Plavix and aspirin without deficit.

Figure 1.

Pre thrombectomy and post angioplasty.

At the three-month follow-up, the patient remained intact but endorsed episodes of transient ischemic attacks and a CTA demonstrated re-stenosis of the supraclinoid left ICA. The risks and benefits of medical management versus angioplasty with stenting to combat rapid restenosis were discussed in detail with the patient. She agreed to proceed with intervention and was scheduled for angioplasty and stenting.

A Benchmark guiding catheter was advanced over a 0.035 glidewire and selectively placed into the cervical segment of the left ICA. Angiography confirmed supraclinoid ICA high-grade stenosis (Figure 2(a)). A 2.5 × 20 millimeter Coyote ES OTW angioplasty balloon was advanced over a 0.014 micro glidewire and selectively placed at the level of the stenosis. We proceeded to perform angioplasty of the origin of the left MCA and supraclinoid ICA and obtained improved caliber with no residual stenosis (Figure 2(b)). The angioplasty micro catheter was left in place and a 4 × 21 mm Atlas stent was advanced through the balloon microcatheter and deployed in a standard technique using the angioplasty balloon as delivery microcatheter between the proximal M1 segment and the distal cavernous ICA just proximal to the ophthalmic artery covering the entire stenotic segment (Figure 2(c)). After deployment, the balloon microcatheter was advanced over the Atlas stent pusher wire into the stent for additional angioplasty if necessary. Final angiographic control after angioplasty showed anterograde flow to the left middle cerebral artery and a known aplastic A1 segment (Figure 2(d)). Patient remained asymptomatic throughout the procedure and was discharged home without deficit. At six-month follow-up the patient had no residual deficits. Follow-up CTA at one year showed no restenosis at the site of the stent (Figure 3).

Figure 2.

(a) Angiography pre angioplasty showing supraclinoid ICA high-grade stenosis and aplastic A1. (b) Balloon angioplasty using Coyote ES OTW, balloon markers (long white arrows), distalend (arrowhead). (c) During deployment of Atlas stent, distal end of stent is deployed (short arrow), proximal stentmarker still constrained within the balloon (short arrow). Balloon markers (long arrows) and distalend of balloon microcatheter (arrowhead). (d) Angiography post angioplasty and stenting showing improved caliber of left ICA.

Figure 3.

CT angiogram demonstrating patency of the left ICA with visible distal radiographic marker of the Atlas stent in the M1 segment.

Discussion

The Neuroform Atlas stent (NAS) is a self-expanding intracranial stent developed to assist in endovascular treatment of wide neck aneurysms. It is designed to be delivered through a 0.0165″ or 0.017″ ID microcatheter. The Coyote ES OTW PTA balloon dilatation catheter (Boston Scientific) is designed for below the knee angioplasty and has a very low lesion entry profile of 0.017″ with great trackability over a 0.014 microguidewire. The recommended guidewire is 0.014″ (<0.39 mm) and no information about the inner diameter (ID) is available. It is available in balloon diameters ranging from 1.5 to 4.0 mm and in shaft lengths from 142 to 146 cm depending on the length of the balloon. The Coyote OTW version has longer shafts however; the balloon lengths are very long and not suitable for intracranial use.

After our experience using the Coyote ES OTW for intracranial balloon angioplasty and having shown better trackability and lesion crossability in our experience than the Gateway balloon (Stryker), we decided to test its ability to deliver the new NAS. Because no information about the ID is available, we table tested the balloon with a 0.016 microguidewire and after being able to smoothly advance the guidewire through the length of the PTA balloon we tested a 4.5 mm Neuroform atlas stent, the largest diameter available. The Neuroform Atlas stent was successfully and smoothly delivered through the Coyote ES OTW PTA angioplasty catheter. We have noted that the minimum balloon diameter to deliver the stent is the 2.0 mm balloon. The NAS will not advance through the 1.5 mm diameter PTA microcatheter. Delivering the NAS using the Coyote ES OTW as a delivery microcatheter has the advantage of avoiding the exchange maneuver, reduce time of procedure and has the ability of potentially recrossing the stent immediately over the pusher wire for post stent placement angioplasty if necessary. The total length of the balloon catheter should also be taken into consideration when choosing a support system as all current balloon catheters (longest shaft is around 145–150 mm) may not be long enough to come out of a distal access catheter (DAC) or aspiration catheter. It is our standard practice when performing angioplasty to undersize the balloon based on the normal diameter of the target vessel, for example if a normal segment of the ICA not affected by the stenosis is 3 mm, we utilize the next size down for the balloon, in this case 2.5 mm. The balloon should be inflated slowly to nominal pressure to avoid snowplowing atherosclerotic plaque causing occlusion of perforators (∼1 atmosphere every 5–10 s), the balloon should be deflated the same way to avoid or minimize the chance of intimal dissection. The stent is then sized up to the next size up from the normal target vessel, in this case a 4 mm Atlas stent, to provide extra radial force. We have to note a few features to be aware while delivering the NAS, the Coyote balloon as its Gateway counterpart, do not have a radiopaque distal marker, it has two radiopaque markers for the balloon and the tip of the microcatheter is 5 mm from the distal end of the distal marker. For this reason, is important to remember that the distal marker of the balloon is not the distal point of stent implantation, we usually position the distal marker of the balloon at the distal end of the diseased segment, which gives us at least a 5 mm distal landing zone for the NAS. Once deployed, the NAS is not resheathable. Another potential problem in tortuous anatomy is the ovalization of the balloon microcatheter, when this happens is necessary to release the forward tension of the balloon while advancing the NAS, straightening the balloon microcatheter as much as possible allows to smoothly advance the stent. Tortuous anatomy may also prevent recrossing the stent with the pusher wire in which case, a 0.014 guidewire may be re-advanced to have more support and be able to recross the stent. Additionally, around curves and in tortuous cases we recommend using a shorter length balloon to prevent straightening of parent vessels that can tear perforators.

In the aftermath of SAMMPRIS, the most common indication for intracranial stenting remains intracranial stenosis refractory to medical management. The WEAVE trail as well as other non-randomized trials in the interim tried new combinations of stenting and angioplasty with greatly improved outcomes (risk of stroke or death 2–4%).^4–6 The Neuroform Atlas stent appears to be an example of a modern endovascular technology that improves upon its older counterpart, although its radial force is low and long-term results are necessary to assess for stability when used in atherosclerotic disease. In our experience, its deployment is much simpler with shorter procedure times and lower complication rate. To our knowledge, this is the first description of this deployment protocol for NAS in the literature.

Conclusion

The Neuroform Atlas stent is able to deploy directly through a Coyote angioplasty balloon. This technique appears useful in case of refractory intracranial stenosis. Further study is needed to evaluate if this simplified intracranial stenting technique provides superiority to medical management alone.

Authors’ note

This work represents the combined efforts of the individual authors.

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.

ORCID iD

Hugo Cuellar https://orcid.org/0000-0002-8348-4535