Initial Experience with Neuroform EZ in the Treatment of Wide-neck Cerebral Aneurysms

Bifurcated Aneurysm Location Predicts In-Stent Stenosis After Neuroform-EZ Stent-Assisted Coiling for Intracranial Aneurysm

Background and Purpose

The Neuroform EZ stent system (Boston Scientific Corporation, Fremont, CA, United States) is a fourth-generation intracranial aneurysm stent designed specifically for the cerebrovasculature to support aneurysm treatment. In this study, we analyzed our consecutive series of patients with aneurysm treated with the Neuroform EZ stent, with special attention to the occurrence of in-stent stenosis (ISS).

Methods

A retrospective review of our center's electronic database was conducted to identify all patients with intracranial aneurysms who underwent aneurysm treatment with the Neuroform EZ stent between January 2016 and October 2018. Patients with at least one digital subtraction angiography (DSA) follow-up in our hospital were enrolled in this study. In-stent stenosis (ISS) was graded as mild (<2–5%), moderate (25–50%), or severe (>50%).

Results

The study included 114 patients (78 women, 68.4%; median age 57.2 ± 9 years) with a total of 116 aneurysms. Of the 116 lesions, 20 were identified with ISS (17.2%) at a mean follow-up of 6.9 ± 1.7 months, and ISS was mild in 30% (6/20), moderate in 50% (10/20), and severe in 20% (4/20). No patients were symptomatic or required further intervention. Patients who developed ISS were younger than those without ISS (52.6 ± 7.8 vs. 57.9 ± 9; p = 0.016). The proportion of aneurysms located at the artery bifurcation was significantly higher in patients with stenosis than located at the sidewall artery (37.9 vs. 10.3%; p = 0.002). In the multivariable analysis, the patients' age (OR = 0.94; 95% CI 0.88–0.998; p = 0.02) and bifurcated aneurysm location (OR = 4.59; 95% CI 1.54–13.67; p = 0.006) were independent predictors of ISS.

Conclusions

In this retrospective study, the incidence of ISS after Neuroform EZ stent placement was 17.2%, and all the ISS cases were asymptomatic. Patients with younger age and bifurcated aneurysm location are more likely to develop ISS. Although Neuroform EZ stent is particularly suitable for bifurcated aneurysms, the ISS for this location should be focused upon.

A Comparison of Safety and Effectiveness Between Wingspan and Neuroform Stents in Patients With Middle Cerebral Artery Stenosis

Background: Percutaneous transluminal angioplasty and stenting with the Wingspan stent has proven safe and effective in patients with middle cerebral artery stenosis (MCAS), but the off-label use of the Neuroform stent might be an alternative treatment. This study aimed to compare the safety and effectiveness of the above two intracranial stents in patients with MCAS. Methods: We retrospectively analyzed consecutive patients with symptomatic MCAS who had been treated with the Neuroform EZ or the Wingspan stent. A propensity score was generated to control for differences in baseline characteristics. The endpoints were the rate of peri-procedural complications within 30 days after stenting, the in-stent restenosis rate, and any target-vessel-related stroke or deaths during follow-up. Results: After matching for propensity score, the peri-procedural complication rate in the Wingspan group was 7.4% compared with 5.6% in the Neuroform group (p = 1.00), while the follow-up in-stent restenosis rates were 23.3 vs. 14.3%, respectively (p = 0.41). In the restenosis group, the patients tended to be younger (p < 0.01) and the degree of artery stenosis before stenting was higher (p < 0.01). Conclusion: This study indicated that in patients with symptomatic MCAS, Neuroform EZ stents are an alternative to Wingspan. Moreover, younger age and higher degree of artery stenosis before stenting might be a risk factor of in-stent restenosis.

Two-center experience with Neuroform Atlas stent-assisted coil occlusion of broad-based intracranial aneurysms

PURPOSE

Stent-assisted coiling (SAC) represents an established treatment option for broad-based intracranial aneurysms. Here we report our initial and follow-up experience with the Neuroform Atlas Stent, a hybrid open- and closed-cell low-profile stent in the treatment of broad-based aneurysms.

METHODS

All intracranial aneurysms treated by SAC with the intention to apply the Neuroform Atlas Stent between July 2015 and December 2019 were included. Angiographic and clinical results were analyzed including all follow-up examinations.

RESULTS

A total of 119 aneurysms (8 acutely ruptured) in 112 patients were included. In 19 cases (16.0%) re-catheterization of the aneurysm was performed in a second procedure after failure to re-cross the stent initially. Of all aneurysms, 83.2% (99/119) were completely occluded following the procedure. In 75.6% of all cases (90/119), a single microcatheter was used for both, implantation of the stent and coil occlusion of the aneurysm. At 3-6 and 12 months follow-up, the complete occlusion rates were 75.2 (79/105) and 81.3% (74/91). The thromboembolic (stent thrombosis) and hemorrhagic complication rate was 1.7 (2/119) and 0.8% (1/119), respectively, resulting in a procedure-related morbidity and mortality rate of 0.9 and 0.9% (1/112 patients).

CONCLUSION

SAC using the Neuroform Atlas Stent offers a safe and effective option to treat broad-based intracranial aneurysms with a high angiographic and clinical success rate. In the majority of procedures, the application of two mircocatheters is not required. Prospective comparative studies might help to identify the value of SAC using the Neuroform Atlas Stent among the growing treatment options for broad-based aneurysms.

Simultaneous neck coverage and branch preservation using the proximal portion of a self-expandable open-cell stent for embolization of distal internal carotid artery aneurysms: multi-center, long-term results

PURPOSE

We report the long-term results of a modified stent-assisted coil embolization technique using the far proximal part of a self-expanding open-cell stent. The technique was used to cover the neck of the aneurysm while simultaneously preserving the branches of the distal internal carotid artery in patients with aneurysms of the posterior communicating (Pcom) and anterior choroidal arteries (AchA).

METHODS

We performed a retrospective review of the prospectively maintained databases at two tertiary neurosurgical centers to identify all patients who underwent embolization of Pcom or AchA aneurysms using this technique between January 2014 and July 2019. Postoperative and follow-up clinical and radiological results for initial (n = 16) or re-do (n = 4) embolizations were analyzed.

RESULTS

We identified 19 patients with 20 (16 Pcom and 4 AchA) unruptured (n = 19) or ruptured (n = 1) aneurysms. Eighteen among 20 stents (90.0%) were deployed successfully, and complete occlusions were initially attained in 18 aneurysms (90.0%). At follow-up examinations 8 to 56 months later, 6 of 14 aneurysms (42.8%) showed neck remnants. All of the branches were saved and no thromboembolic event, rupture, or sequelae were noted during or after the procedures.

CONCLUSION

These results suggest that this modified stent-assisted technique is a feasible and reasonable alternative to conventional stent deployment for coil embolization of wide-necked sidewall aneurysms in the distal ICA.

Treatment of acute thrombosis during stent-assisted coil embolization of ruptured proximal posterior inferior cerebellar artery aneurysm

Aneurysms located in the posterior inferior cerebellar artery (PICA) are not a majority of the intracranial aneurysms cases. Many challenges were addressed in the endovascular procedure to treat the disease. The authors have successfully diagnosed and treated a ruptured proximal PICA aneurysm. However, digital subtraction angiography showed acute thrombosis in the vertebral artery in the procedure, which probably could be an acute in-stent thrombosis. The tirofiban hydrochloride injection was subjected through a microcatheter, and then, the second Neuroform EZ stent was planted. In the 6-month follow-up, no recurrence of the aneurysm and complete patency of the right PICA at the site of aneurysm formation were found. We believe that the treatment of PICA aneurysms with Neuroform EZ stents could get a favorable result. Combination of tirofiban hydrochloride and Neuroform EZ stent could be an effective approach in treating acute thrombotic complications.

Neuroform EZ Stenting for Symptomatic Intracranial Artery Stenosis: 30 Days Outcomes in a High-Volume Stroke Center

Objective: To test whether Neuroform EZ stent placement combined with the modified techniques in symptomatic severe intracranial stenosis (ICAS) would result in lower rates of peri-procedural complications of intracranial stenting. Methods: We retrospectively reviewed the clinical data from 71 consecutive patients who underwent Neuroform EZ stent placement combined with the modified techniques for symptomatic severe ICAS at our institute between January 2016 and October 2017. The primary outcomes were ipsi-lateral ischemic stroke, intra-cerebral hemorrhage, or death within 30 days after stenting. The secondary outcome was technical success. Results: The technical success rate was 100%. The mean pre and post-stent stenoses were 84.2% ± 9.1% (median 85%, IQR75% to 90%) and 16.9% ± 10.2 % (median 15%, IQR 10% to 25%). The frequency of ipsi-lateral stroke, intra-cerebral hemorrhage, or death within 30 days was 0%. Conclusions: The combined use of Neuroform EZ stent placement and the modified techniques for symptomatic severe ICAS is technically feasible and safe, with very low peri-procedural complications. Further studies are required to assess the long-term results of this approach.

The Interference Phenomenon of Microcatheters in the Jailing Treatment for Internal Carotid Artery Side Wall Aneurysms with an Open Cell Stent System

Objective

Excelsior XT-27 (Stryker Neurovascular, Fremont, CA, USA) or Rebar 27 (eV3 Covidien, Irvine, CA, USA) microcatheters have recently been used to overcome the limitations of the Renegade Hi-Flo microcatheter such as interference between two microcatheters (one for stent delivery and the other for cerebral aneurysm coiling) during the jailing technique. We evaluated differences and influential factors related to the interference phenomenon according to these two microcatheters group.

Materials and Methods

Between June 2011 and September 2013, the jailing technique was applied to 94 internal cerebral artery (ICA) aneurysms. The jailing technique with the Neuroform EZ stent system was performed using Renegade (n = 22), Rebar (n = 35), and XT-27 microcatheters (n = 37). In the Renegade Hi-Flo microcatheter group, the jailing technique was successful in 19/22 patients (86.4%) and interference between the two microcatheters occurred in 6/21 patients (28.6%). In the Rebar and XT-27 microcatheter group, the jailing technique was successful in 71/72 patients (98.6%) and interference between the two microcatheters occurred in 1/72 patients (1.4%).

Results

There was a significant difference in the interference between the two delivered microcatheters group (p-value < 0.000) and the carotid siphon angle (p-value: 0.004) in the univariate analysis. In the multiple logistic regression analysis, the Rebar and XT-27 microcatheter group (odds ratio [OD] [95% confidence interval (CI)]; 31.277 [3.138-311.729], p-value: 0.003) and the carotid siphon angle (OD [95%CI]; 0.959 [0.922-0.997], p-value: 0.035) were found to be influential factors in the interference phenomenon.

Conclusion

The Rebar 27 and XT-27 microcatheters were more successful and exhibited less interference between the two microcatheters than the Renegade Hi-Flo microcatheter.

Use of Triple Microcatheters for Endovascular Treatment of Wide-Necked Intracranial Aneurysms: A Single Center Experience

Objective

The dual microcatheter technique is common practice for coil embolization of a wide-necked aneurysm, due to safety and efficacy. However, technical limitations of some complex configurations may necessitate additional microcatheters to bolster coil stability, compact the coil, or for protection. Described herein is a triple microcatheter technique for endovascular management of wide-necked intracranial aneurysms.

Materials and Methods

Data accruing prospectively between January 2006 and October 2014 on simultaneously executed triple microcatheter coil embolization procedures done in 38 saccular aneurysms were reviewed. Clinical and morphological outcomes were assessed, with emphasis on technical aspects of treatment.

Results

The triple microcatheter technique was successfully applied to all 38 saccular aneurysms, involving the posterior communicating artery (n = 13), the middle cerebral artery (n = 10), the basilar tip (n = 7), the anterior cerebral artery (n = 5), and the internal carotid artery (n = 3). Stent protection was added in four patients and balloon remodeling in one. Dual microcatheters (n = 24) were usually deployed to deliver the coil within sacs of aneurysms, with the additional microcatheter used for protection. Otherwise, triple microcatheters were deployed for coil delivery (n = 11) or coils were delivered via a single microcatheter, with dual microcatheters deployed for protection (n = 3). Successful occlusion of aneurysms was achieved in 89.5% of cases, with no procedure-related morbidity or mortality. Stable occlusion was maintained in 72.2% (26/36) of the aneurysms at the final follow-up (mean interval, 30.2 ± 22.7 months).

Conclusion

The outcomes of this limited study suggest that the triple microcatheter technique may be an effective and safe therapeutic option for wide-necked aneurysms, using technical strategies tailored to complex angio-anatomic configurations.

Modified coil protection for proper coil frame configuration in wide-necked aneurysms

INTRODUCTION

Although various protective techniques for treating wide-necked intracranial aneurysms currently exist and continue to evolve, their utility may be limited in some lesions with complex configurations, small-caliber channels, or inherently tortuous vascular patterns. Described herein is a modified coil protection technique as a novel adjunct for proper coil frame configuration.

METHODS

Initially, a microcatheter is passed into aneurysmal sac, and the first coil is inserted to build a frame. Inevitably, some coils may abut opposite poles of aneurysms and protrude into parent arteries. Should this happen, a second microcatheter may be placed at the site of coil protrusion, so that a separate and smaller coil may be partially deployed for protection. A framing coil may then be configured within aneurysmal sac, under protection of the secondary coil. Once the first coil is entirely in place, the remainder of second coil is carefully inserted, and additional coil may be inserted as needed via dual microcatheters.

RESULTS

This technique was successfully applied to 23 saccular intracranial aneurysms of internal carotid (n = 8), middle cerebral (n = 6), anterior cerebral (n = 6), and superior cerebellar artery (n = 3), combining stent protection in two patients and balloon remodeling in one. Selective endovascular treatment was effective as a result. Excellent outcomes were achieved in all patients, with no morbidity or mortality directly related to the modified procedure.

CONCLUSION

As suggested by outcomes of this small study, our modified coil protection method may be a safe option if traditional coiling strategies are not feasible, enabling stable coil frame configuration in wide-necked aneurysms.

An internet-based method to elicit experts' beliefs for Bayesian priors: a case study in intracranial stent evaluation

RATIONALE

Bayesian methods provide an interesting approach to assessing an implantable medical device (IMD) that has evolved through successive versions because they allow for explicit incorporation of prior knowledge into the analysis. However, the literature is sparse on the feasibility and reliability of elicitation in cases where expert beliefs are used to form priors.

OBJECTIVES

To develop an Internet-based method for eliciting experts' beliefs about the success rate of an intracranial stenting procedure and to assess their impact on the estimated benefit of the latest version.

STUDY DESIGN AND SETTING

The elicitation questionnaire was administered to a group of nineteen experts. Elicited experts' beliefs were used to inform the prior distributions of a Bayesian hierarchical meta-analysis model, allowing for the estimation of the success rate of each version.

RESULTS

Experts believed that the success rate of the latest version was slightly higher than that of the previous one (median: 80.8 percent versus 75.9 percent). When using noninformative priors in the model, the latest version was found to have a lower success rate (median: 83.1 percent versus 86.0 percent), while no difference between the two versions was detected with informative priors (median: 85.3 percent versus 85.6 percent).

CONCLUSIONS

We proposed a practical method to elicit experts' beliefs on the success rates of successive IMD versions and to explicitly combine all available evidence in the evaluation of the latest one. Our results suggest that the experts were overoptimistic about this last version. Nevertheless, the proposed method should be simplified and assessed in larger, representative samples.

Analysis of flow changes in side branches jailed by flow diverters in rabbit models

Understanding the flow alteration in side branches during flow diversion treatment of cerebral aneurysms is important to prevent ischemic complications and improve device designs. Flow diverters were placed in the aorta of four rabbits crossing the origin of side arteries. Subject-specific computational models were constructed from 3D angiographies and Doppler ultrasounds (DUSs). Flow simulations were run before and after virtually deploying the flow diverters, assuming distal resistances remained unchanged after treatment. All jailed arteries remained patent angiographically 8 weeks after treatment. The computational models estimated decreases compared to pretreatment in the mean flow rates between 2% and 20% and in peak flow rates between 5% and 36%. The major changes were observed during systole. Flow patterns did not exhibit recirculation zones before treatment. Implantation of the flow diverters altered the flow structure only locally near the device wires. No major recirculation regions were created or destroyed. Flow diverters seem safe with respect to perforator or side branch occlusion. Relatively small changes in flow rates through jailed arteries are expected, even for moderate to large degrees of coverage of their origins. These results seem consistent with previous clinical experiences where no or very few complications related to perforator occlusion have been reported.

Advances in Endovascular Approaches to Cerebral Aneurysms

Recent advancements in all phases of endovascular aneurysm treatment, including medical therapy, diagnostics, devices, and implants, abound. Advancements in endovascular technologies and techniques have enabled treatment of a wide variety of intracranial aneurysms. In this article, technical advances in endovascular treatment of cerebral aneurysms are discussed, with an effort to incorporate a clinically relevant perspective. Advancements in diagnostic tools, medical therapy, and implants are reviewed and discussed.

Neuroform Intracranial Stenting for Aneurysms Using Simple and Multi-stent Technique Is Associated With Low Risk of Magnetic Resonance Diffusion-Weighted Imaging Lesions

BACKGROUND:

Detection of procedural thromboembolism by diffusion-weighted magnetic resonance imaging (MR-DWI+) can help identify and mitigate endovascular risk factors. Data remain scant on procedural MR-DWI+ following the use of the Neuroform open-cell design stent in aneurysm embolization.

OBJECTIVE:

We sought to evaluate the incidence of MR-DWI+ in Neuroform simple and multi-stent construct stenting for intracranial aneurysms in an attempt to delineate baseline risk and identify possible associated procedural factors.

METHODS:

Seventy-six patients receiving 97 Neuroform stents in the treatment of intracranial aneurysm were identified from a prospective database and eligible for inclusion in the study. Diffusion-weighted magnetic resonance imaging (MR-DWI) was obtained in all patients within 48 hours of the procedure and reviewed for the presence of MR-DWI+ with patient records reviewed for analysis of factors predisposing to these lesions.

RESULTS:

Patients were treated with single-stent Neuroform constructs in 57 cases (73%) and multi-stent Neuroform constructs in 21 cases (27%). Y-stent technique was used in 16 cases. MR-DWI+ was identified in 7 of 78 cases (9.0%), with MR-DWI+ in 0 of 10 subarachnoid hemorrhage cases. No MR-DWI lesions led to a permanent neurological deficit at discharge. There was no MR-DWI+ in patients treated with Y-stenting or multi-stent Neuroform constructs. The only factor associated with ipsilateral MR-DWI+ was target aneurysm location on an arterial sidewall over bifurcation (P = .01).

CONCLUSION:

The Neuroform stent carries a very low risk of MR-DWI+ compared with its closed-cell design counterpart. Subarachnoid hemorrhage and deployment of multiple stents in the same anatomical region in configurations such as the Y-stent construct did not increase the risk of acute procedural thromboembolism.