Broad-based Intracranial Aneurysms Research Articles

Development of a bioresorbable self-expanding microstent for interventional applications – an innovative approach for stent-assisted coiling

Objectives Stent-assisted coiling prevents coil migration in broad-based intracranial aneurysms. So far, only permanent metal stents are approved for intracranial use. Bioresorbable stents allow a new therapeutic approach that may prevent the need for lifelong anticoagulation. We developed a neurovascular bioresorbable microstent (NBRS) and compared it in vitro to the commercial Neuroform EZ stent. Materials and Methods The self-expanding NBRS design is oriented on the Neuroform EZ stent. Poly L-lactic acid (PLLA) was used to manufacture semi-finished products in a dipping process. For the compensation of the inferior material properties of PLLA, design adjustments were made. The NBRS were cut by means of femtosecond (fs) laser and were morphologically and mechanically compared in vitro to the Neuroform EZ stent. In vitro implantation of an NBRS was performed using a complex patient-specific 3D-printed aneurysm model. In addition, an in vitro coiling procedure to assess the stent’s ability to support a coil package was conducted. Results The NBRS could be reproducibly manufactured and had high quality regarding surface morphology. The radial force at the indicated vessel diameter of 3.0 mm was slightly higher for the Neuroform EZ stent compared to the NBRS. The self-expansion ability of the NBRS could be proven. The kink behavior of the NBRS was comparable to that of the Neuroform EZ stent, so no vessel lumen size reduction is expected. The stents showed identical deformation under local compression of 25 % based on the initial diameter, resulting in maximum forces of 24 ± 5 mN (Neuroform EZ) and 8 ± 2 mN (NBRS). The implanted NBRS expanded uniformly, and proper vessel wall adaptation was observed. The NBRS has the ability to retain a coil package. Conclusion This study reported a reproducible manufacturing process for the developed NBRS as well as mechanical and morphological in vitro tests. Furthermore, successful NBRS implantation into a complex patient-specific vessel model was presented as proof of concept. The promising results of this study, also considering the commercial Neuroform EZ stent, support the idea of fully biodegradable microstents for intracranial aneurysm treatment. Key Points 

Treatment of broad-based intracranial aneurysms with the LVIS EVO stent: a retrospective observational study at two centers with short- and medium-term follow-up

The use of stents is well established in the treatment of broad-based intracranial aneurysms. The aim of this study is to report on safety, feasibility and midterm follow-up of the new LVIS EVO braided stent for the treatment of cerebral aneurysms. All consecutive patients with intracranial aneurysms who were treated with the LVIS EVO stent in two high volume neurovascular centers were retrospectively enrolled in this observational study. Clinical and technical complications, angiographic outcome and clinical short-term and midterm results were evaluated. The study included 112 patients with 118 aneurysms. 94 patients presented with incidental aneurysms, 13 patients with acute SAH and 2 patients with acute cranial nerve palsy. For 100 aneurysms a jailing technique was used, re-crossing of the stent was performed in 3 cases. For the residual 15 cases the stent was placed as a bail-out or as a second step. Immediate complete occlusion was observed in 85 aneurysms (72%). Midterm follow-up was available for 84 patients with 86 aneurysms (72.9%). One stent showed asymptomatic complete occlusion on follow-up imaging, in all other cases no in-stent stenosis was observed. The rate of complete occlusion was 79.1% at 6 months and 82.2% at 12–18 months. Midterm follow-up data of this retrospective observational cohort of two neurovascular centers corroborates the safety profile of the LVIS EVO device for treatment of ruptured and unruptured intracranial aneurysms.

WEB embolization of very broad-based intracranial aneurysms with a dome-to-neck ratio ≤ 1.1.

The Woven EndoBridge (WEB) is a well-studied intrasaccular device for endovascular treatment of wide-necked bifurcation aneurysms. We evaluated the feasibility, safety and efficacy of the WEB for the treatment of very broad-based aneurysms with a dome-to-neck ratio ≤ 1.1. Thirty-four aneurysms treated at three neurovascular centers were retrospectively identified. The mean aneurysm size was 5.5 ± 1.6 mm with a mean neck width of 4.7 ± 1.5 and a mean dome-to-neck ratio of 1.0 ± 0.1. The primary outcome measures were immediate technical treatment success by WEB only, complete or near-complete occlusion at 6-month follow-up and ischemic stroke. Aneurysm embolization by WEB only was technically feasible in 79.4%. Additional stenting was required in 14.7%. In two aneurysms (5.9%), WEB implantation failed, and the aneurysm was treated by stent- and balloon-assisted coiling, respectively. Thromboembolic events occurred during 5 interventions (14.7%), all of these performed in ruptured aneurysms. One patient (2.9%) remained asymptomatic (follow-up modified Rankin scale [mRS] score: 0), 2 patients (5.9%) had a transient deficit (mRS 0 and 1, respectively), and 2 (5.9%) had a disabling ischemic stroke (mRS 3, respectively). Mid-term angiographic follow-up of 29 patients (4.0 ± 2.6 months, range: 2-9 months) showed complete occlusion (WEB occlusion scale [WOS] A) in 41.4%, near-complete occlusion (WOS B) in 34.5%, a neck remnant (WOS C) in 10.3%, and aneurysm remnants (WOS D) in 13.8%. WEB embolization of very broad-necked aneurysms was technically feasible and could be achieved by WEB only in the majority of cases. Considering the challenging anatomy of very broad-based aneurysms, the WEB procedure was reasonably safe and efficient.

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

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. 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. 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 12months 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). 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.

Stent-assisted coiling of broad-necked intracranial aneurysms with a new braided microstent (Accero): procedural results and long-term follow-up

Intracranial stents have expanded endovascular therapy options for intracranial aneurysms. The braided Accero stent is available for clinical use since May 2015. To date, no clinical reports on the stent are available. Purpose of this study was the evaluation of the safety and efficacy of the Accero stent in stent-assisted coiling. All patients, in whom implantation of the stent was performed, were included. Primary endpoints were good clinical outcome (mRS ≤ 2) and aneurysm occlusion grades 1 and 2 (Raymond Roy Occlusion Classification). Secondary endpoints were procedural and device-related complications with permanent disability or death, complications in the course, and the recanalization rate. Between September 2015 and August 2018, thirty-four aneurysms were treated with stent-assisted coiling using the Accero. Sixteen aneurysms were untreated, four of these were ruptured. Mild neurological complications occurred in 2/34 (5.9%) treatments. Two stent occlusions occurred during follow-up. No patient had a poor procedure- or device-related outcome. After an average of 15 months of follow-up, 28/30 aneurysms were completely or near-completely occluded. The Accero stent proved to be safe and effective in the treatment of broad-based intracranial aneurysms. The complication rate and the rate of successful aneurysm occlusions are similar to those of other stents.

Two-Center Experience in the Endovascular Treatment of Ruptured and Unruptured Intracranial Aneurysms Using the WEB Device: A Retrospective Analysis.

The safety and efficacy of the Woven EndoBridge (WEB) device for the treatment of cerebral aneurysms has been investigated in several studies. Our objective was to report the experience of 2 neurovascular centers with the WEB device in the treatment of broad-based intracranial aneurysms, including the technical feasibility and safety as well as short- and midterm angiographic and clinical follow-up-results. We performed a retrospective analysis of all ruptured and unruptured aneurysms treated with a WEB device (WEB Single-Layer and Single-Layer Sphere) between August 2014 and February 2017. Primary outcome measures included the feasibility of implantation and the angiographic outcome. Secondary outcome measures included the clinical outcome at discharge and procedural complications. One hundred two aneurysms in 101 patients, including 37 (36.3%) ruptured aneurysms, were treated with the WEB device. Implantation was successful in 98 (96.1%) aneurysms. Additional devices (stents/coils) were necessary in 15.3% (15/98) of aneurysms. Procedural complications occurred in 4.9% (5/102). Of these, 4 were thromboembolic events and 1 was an intraprocedural rupture. Angiographic follow-up at 3 and 12 months was available for 79.6% (78/98) and 50.0% (49/98) of all aneurysms to date, respectively, showing a sufficient aneurysm occlusion in 80.7% (63/78) at 3 months and 77.6% (38/49) at 12 months. Delayed aneurysm ruptures have not been observed during the follow-up period to date. The WEB device offers a safe and effective treatment option for broad-based intracranial aneurysms without the need for dual antiplatelet therapy.

Onyx HD-500 Liquid Embolic Agent for the Embolization of Broad-Based Saccular Intracranial Aneurysms: A Case Study

Over the years, many different techniques have been used to treat brain aneurysms. Traditionally, open surgery or craniotomy was required for aneurysm clipping, but since the mid 1980s the endovascular treatment of aneurysms has become increasingly popular. The mainstay of endovascular aneurysm treatment has been embolization with platinum coils (a.k.a. “coiling”). However, despite advances in endovascular techniques, such as balloon remodeling and intracranial stent placement, it remains difficult to achieve the complete and permanent occlusion of many broad-based saccular aneurysms. Onyx HD-500 (eV3 Neurovascular, Irvine, CA), a liquid embolic agent, is the latest Food and Drug Association-approved device to be used in attempt to overcome the challenge of occluding broad-based intracranial aneurysms. In this case study, we describe the clinical and procedural issues involved in the treatment of a patient with a large, symptomatic intracranial aneurysm using Onyx HD-500.

Technical feasibility of 2D–3D coregistration for visualization of self-expandable microstents to facilitate coil embolization of broad-based intracranial aneurysms: an in vitro study

The use of self-expandable microstents for treatment of broad-based intracranial aneurysms is widely spread. However, poor fluoroscopic visibility of the stents remains disadvantageous during the coiling procedure. Flat detector angiographic computed tomography (ACT) provides high resolution imaging of microstents even though integration of this imaging modality in the neurointerventional workflow has not been widely reported. An acrylic glass model was used to simulate the situation of a broad-based sidewall aneurysm. After insertion of a self-expandable microstent, ACT was performed. The resulting 3D dataset of the Microstent was subsequently projected into a conventional 2D fluoroscopic roadmap. This 3D visualization of the stent supported the coil embolization procedure of the in vitro aneurysm. In vitro 2D-3D coregistration with integration of 3D ACT data of a self-expandable microstent in a conventional 2D roadmap is feasible. Unsatisfying stent visibility constrains clinical cases with complex parent vessel anatomy and challenging aneurysm geometry; hence, this technique potentially may be useful in such cases. In our opinion, the clinical feasibility and utility of this new technique should be verified in a clinical aneurysm embolization study series using 2D-3D coregistration.

Balloon-assisted coiling of intracranial aneurysms is not associated with a higher complication rate

Within the neurosurgical literature on intracranial aneurysms, balloon-assisted coiling (BAC) remains controversial when compared to conventional coiling (CC). The aim of this study was to compare our results with BAC and CC over a 4-year period. Daily interventional neuroradiology has been available since March 2004 in our institution. Between March 2004 and February 2008, 275 patients with 357 aneurysms were treated by an endovascular approach, including 174 patients/204 aneurysms treated by CC (group I) and 80 patients/92 aneurysms treated by BAC (group II). The remaining patients were treated with other endovascular techniques. Indications of BAC were as follow: aneurysms with an unfavourable neck/sac ratio and/or a branch arising from the neck (90.2%), unstable coiling catheter (6.5%), and anticipated aneurysm rupture (3.3%). The clinical charts, procedural data, and angiographic results of groups I and II were compared. BAC was used in 25.8% (92/357) of all embolized aneurysms and it was successful in 83/92 aneurysms (90%). There was no significant difference in the procedure-related morbidity and mortality rates between group I (2.3% and 1.15%, respectively) and group II (2.5% and 1.25%, respectively). Although retreatment was more frequent in group II (13%) than in group I (11%), the difference was not statistically significant (P = 0.8125). When BAC is used frequently, it is a safe and effective technique that is associated with complication rates comparable to those of CC. Although BAC is not associated with more stable anatomical results, it should be considered as an alternative therapeutic option for the treatment of broad-based intracranial aneurysms.

Treatment of wide-necked intracranial aneurysms with a self-expanding stent: mid-term results

Purpose To evaluate mid-term clinical and angiographic results after using a self-expanding neurovascular stent and coils for the management of broad-based intracranial aneurysms. Methods During the period from August 2001 to October 2004 we treated a total of 42 patients with 44 aneurysms using a self-expandable stent. To date we have data on more than 6 months of follow-up in 25 patients with 26 aneurysms. Aneurysm occlusion was divided into the following categories: 100% (complete), 95-99% (subtotal), and Results In 15 aneurysms complete occlusion, in 11 aneurysms subtotal occlusion was initially achieved. Control DSA showed progressive thrombosis in seven aneurysms leading to total occlusion in another 4 aneurysms. Three recanalisations were observed in one large and two giant ICA aneurysms. No vessel occlusion occurred. One vessel stenosis of the stented segment was noted, but it was not clinically relevant. One patient experienced a small embolic infarction after stopping antiplatelet medication. No persistent deterioration of the clinical status occurred. Conclusion Combining a stent with coils seems to be an acceptable treatment option for broad-based intracranial aneurysms. As this special subgroup of treated aneurysms includes only those with an unfavourable geometry, the results are extremely promising.

Treatment of Wide-Necked Intracranial Aneurysms with a Self-Expanding Stent: Mid-Term Results

To evaluate mid-term clinical and angiographic results after using a self-expanding neurovascular stent and coils for the management of broad-based intracranial aneurysms. During the period from August 2001 to October 2004 we treated a total of 42 patients with 44 aneurysms using a self-expandable stent. To date we have data on more than 6 months of follow-up in 25 patients with 26 aneurysms. Aneurysm occlusion was divided into the following categories: 100 % (complete), 95-99 % (subtotal), and < 95 % (incomplete). In 15 aneurysms complete occlusion, in 11 aneurysms subtotal occlusion was initially achieved. Control DSA showed progressive thrombosis in seven aneurysms leading to total occlusion in another 4 aneurysms. Three recanalizations were observed in one large and two giant ICA aneurysms. No vessel occlusion occurred. One vessel stenosis of the stented segment was noted, but it was not clinically relevant. One patient experienced a small embolic infarction after stopping antiplatelet medication. No persistent deterioration of the clinical status occurred. Combining a stent with coils seems to be an acceptable treatment option for broad-based intracranial aneurysms. As this special subgroup of treated aneurysms includes only those with an unfavourable geometry, the results are extremely promising.

Planned Direct Dual-modality Treatment of Complex Broad-necked Intracranial Aneurysms: Four Technical Case Reports

Treatment of complex, broad-based intracranial aneurysms with either microsurgical clipping or endovascular coiling alone is sometimes impossible. In this study, we report the planned combined endovascular and microsurgical treatment of four complex, wide-necked aneurysms in four patients. Three of the four patients presented with subarachnoid hemorrhage. The fourth patient presented with a progressive neurological deficit secondary to an associated arteriovenous malformation. Three of the aneurysms were located in the posterior circulation (two broad-necked basilar apex aneurysms and one bilobed vertebrobasilar junction aneurysm with a wide-necked ventral component). The fourth aneurysm was a broad-based paraclinoid/cavernous-carotid lesion. One of the patients with a basilar apex aneurysm and the patient with the paraclinoid aneurysm underwent surgery intended to create a narrow neck that would be amenable to future coiling. The patient with the bilobed vertebrobasilar junction aneurysm underwent surgery to treat the broad-necked ventral lobe, whereas the dorsal lobe, with the neck partially buried in the brainstem, was treated endovascularly. The second patient with a basilar apex aneurysm was in poor clinical condition after subarachnoid hemorrhage and was therefore treated with coil embolization to reduce the risk of rebleeding. After the patient made a good clinical recovery, the residual aneurysm was surgically clipped. Angiographic follow-up documented the complete obliteration of all four aneurysms. Clinically, all patients had good to excellent outcomes after a follow-up period of 6 to 30 months. Complex, broad-necked aneurysms that may be difficult to treat with a single mode of therapy can be safely and successfully treated with a combination of endovascular and microsurgical techniques. For patients with broad-based aneurysms that are difficult to access surgically without incurring significant morbidity, microsurgical clipping may be used as the initial procedure to create a smaller neck. Alternatively, for patients who are in poor clinical condition after subarachnoid hemorrhage and who harbor a broad-necked aneurysm in a surgically formidable location, partial coiling may be used initially to reduce the short-term risk of rebleeding.