Stenting is improving and stabilizing anatomical results of coiled intracranial aneurysms

Predisposing factors for the deformation of parent artery of anterior circulation saccular aneurysm after stent-assisted embolization: A retrospective cohort study

BACKGROUND

It has been previously reported in several studies that deformation of parent artery (DPA) occurs after stent-assisted coil embolization (SACE) for intracranial aneurysms (IAs).

OBJECTIVE

To investigate the predisposing factors of stent-induced DPA, as well as its effect on the follow-up of aneurysm embolization.

METHODS

Clinical and imaging data were collected from 198 patients (201 aneurysms). Angles of the stent-covered parental artery were measured before treatment and during follow-up. Cases in which the angle had changed more than 5 degrees, were defined as DPA. The related factors of DPA were analyzed. The relation between DPA and follow-up results was also studied.

RESULTS

Univariate analysis revealed that sex (p = 0.014), age (p = 0.017), aneurysm location (p < 0.001), stent type (p < 0.001), aneurysm size (p = 0.019), and pretreatment angle (p = 0.002) correlated with DPA. On the other hand, multivariate analysis revealed that aneurysms located in the anterior communicating artery (ACOA) (OR = 4.559, p = 0.013) and middle cerebral artery (MCA) (OR = 9.474, p < 0.001) were independent predisposing factors for DPA after stent implantation, whereas a braided stent (OR = 0.221, p = 0.030), flow diverter (FD) device (OR = 0.100, p = 0.028) were negative factors to develop DPA. The complete occlusion rate in the DPA group was higher (p = 0.035) than in the non-DPA group.

CONCLUSIONS

Aneurysms located in ACOA and MCA are more prone to DPA after SACE than aneurysms at other locations in the anterior circulation, braided stents and FD devices do not predispose to induce vascular deformation. DPA may be beneficial for the long-term cure of IAs after SACE.

Hemodynamic effects of intracranial aneurysms from stent-induced straightening of parent vessels by stent-assisted coiling embolization

BACKGROUND

Straightening of parent vessels happens for stent-assisted coiling embolization (SACE) treatment of intracranial aneurysms. This study aims to investigate aneurysmal hemodynamic modifications caused by stent-induced vessel straightening.

METHODS

Stent and coil deployments of a SACE-treated distal bifurcation aneurysm by finite element method were performed first with the preoperative (not straightened, NS) and postoperative (straightened, S) vessel models respectively. Computational fluid dynamics were then performed for eight models, including (I) NS only model, (II) NS+stent model, (III) NS+coils model, (IV) NS+stent+coils model, (V) S only model, (VI) S+stent model, (VII) S+coils model, and (VIII) S+stent+coils model. Finally, changes in aneurysmal flow velocity, isovelocity surface and wall shear stress (WSS) were analyzed qualitatively and quantitatively.

RESULTS

The flow was less in the S models than that in the corresponding NS models. Coils blocked most of the flow into the aneurysm sac in both NS models and S models and vessel straightening had more profound effect on the high aneurysmal flow volume reduction than coiling, while stenting generated adverse effect on flow reduction. Taking the NS only model as baseline (100%), the sac-averaged velocities of models II to VIII were 112%, 36%, 42%, 45%, 39%, 12%, 13%, and high flow volumes were 119%, 21%, 30%, 10%, 8%, 3%, 3%, while the sac-averaged WSSs were 106%, 37%, 44%, 41%, 35%, 17% and 24%, respectively.

CONCLUSIONS

Stent-induced vessel straightening combined coil embolization has the best performance in hemodynamic modifications and may reduce the recurrence rate, whereas stenting may generate adverse effect on hemodynamic alterations.

Recent advances in stent-assisted coiling of cerebral aneurysms

INTRODUCTION

Stent-assisted coiling (SAC) of intracranial aneurysms paved the way for endovascular coiling of wide-neck and bifurcation aneurysms, improving rates of aneurysm obliteration and recurrence. In this review, we provide a comprehensive review of the most recent advances related to stent-assisted coiling of intracranial aneurysm.

AREAS COVERED

The authors have made an attempt to cover the inception, applications, and limitations of SAC of intracranial aneurysms. Special focus is given to 1) the current and recently introduced SAC techniques, 2) most recent advances in device technology, and 3) outcome data for the discussed techniques and devices. The authors also discuss the potential future direction of SAC.

EXPERT OPINION

technical refinements in the field of SAC should continue to focus on device development and addressing the limitations of SAC, namely aneurysm recurrence and need of antiplatelet agents. Although the recurrence rate of SAC has not been shown to be inferior to flow diverters, the use of intrasaccular and intravascular flow diverters are likely to expand in the future at the expense of SAC.

Double stent assisted coiling of intracranial bifurcation aneurysms in Y and X configurations with the Neuroform ATLAS stent: immediate and mid term angiographic and clinical follow-up

Purpose

Self-expandable stents have broadened the spectrum of endovascular treatment of intracranial aneurysms. However, procedures involving double stenting in Y/X configurations carry a relatively high risk of procedural complications. The Neuroform ATLAS, the evolution of Neuroform EZ, is a nitinol self-expanding hybrid/open cell stent which can be delivered through a low profile 0.017 inch catheter. We present our experience in the treatment of intracranial aneurysms with this stent in Y and X configurations.

Materials and methods

We prospectively maintained a database from consecutive patients who underwent double stent assisted coiling with the Neuroform ATLAS, from July 2015 to February 2019. Clinical and angiographic results were analyzed.

Results

55 patients harboring 55 bifurcation aneurysms were treated with double stenting: 52 ‘Y’ configurations, 3 ‘X’ configurations. Deployment was successful in all cases. Post-treatment control angiography showed complete occlusion in 33 cases (60%), neck remnant in 8 cases (14.5%), and incomplete occlusion in 14 cases (25.4%). The overall symptomatic periprocedural complication rate was 12.7%. 38 aneurysms underwent follow-up (69%, mean duration 16 months): 33 aneurysms (87%) were completely occluded, 3 aneurysms (8%) had a neck remnant, and 2 aneurysms (5%) were incompletely occluded.

Conclusion

The Neuroform ATLAS is an effective device for treatment of bifurcation aneurysms, allowing good conformability, a high level of navigability, and easy mesh crossing to perform Y/X stenting procedures. The rate of procedural complications remains non-negligible, and an indication for a double stenting procedure should be carefully discussed in a multidisciplinary meeting.

Progressive Occlusion of Small Saccular Aneurysms Incompletely Occluded After Stent-Assisted Coil Embolization : Analysis of Related Factors and Long-Term Outcomes

PURPOSE

Incompletely occluded aneurysms after coil embolization are subject to recanalization but occasionally progress to a totally occluded state. Deployed stents may actually promote thrombosis of coiled aneurysms. We evaluated outcomes of small aneurysms (<10 mm) wherein saccular filling with contrast medium was evident after stent-assisted coiling, assessing factors implicated in subsequent progressive occlusion.

METHODS

Between September 2012 and June 2016, a total of 463 intracranial aneurysms were treated by stent-assisted coil embolization. Of these, 132 small saccular aneurysms displayed saccular filling with contrast medium in the immediate aftermath of coiling. Progressive thrombosis was defined as complete aneurysmal occlusion at the 6‑month follow-up point. Rates of progressive occlusion and factors predisposing to this were analyzed via binary logistic regression.

RESULTS

In 101 (76.5%) of the 132 intracranial aneurysms, complete occlusion was observed in follow-up imaging studies at 6 months. Binary logistic regression analysis indicated that progressive occlusion was linked to smaller neck diameter (odds ratio [OR] = 1.533; p = 0.003), hyperlipidemia (OR = 3.329; p = 0.036) and stent type (p = 0.031). The LVIS stent is especially susceptible to progressive thrombosis, more so than Neuroform (OR = 0.098; p = 0.008) or Enterprise (OR = 0.317; p = 0.098) stents. In 57 instances of progressive thrombosis, followed for ≥12 months (mean 25.0 ± 10.7 months), 56 (98.2%) were stable, with minor recanalization noted once (1.8%) and no major recanalization.

CONCLUSION

Aneurysms associated with smaller diameter necks, hyperlipidemic states and LVIS stent deployment may be inclined to possible thrombosis, if occlusion immediately after stent-assisted coil embolization is incomplete. In such instances, excellent long-term durability is anticipated.

Cerebral aneurysm neck diameter is an independent predictor of progressive occlusion after stent-assisted coiling

BACKGROUND

Some intracranial aneurysms treated by stent-assisted coiling (SAC) with incomplete occlusion undergo progressive occlusion (PO) during follow-up period. We analyzed the predictors for the occurrence of PO.

METHODS

Among 74 cerebral aneurysms treated by SAC using the Enterprise or Neuroform stents from 2010 to 2015, we included 43 aneurysms with occlusion grade of neck remnant (NR, n = 36) or residual aneurysm (RA, n = 7) at the post-procedure. We defined PO as improvement in occlusion grade from RA to NR, or from NR or RA to complete occlusion on angiographic follow-up imaging at 6 months after the procedure. We analyzed the independent predictors for PO using a multivariate logistic regression model and receiver operating characteristic (ROC) curve analysis.

RESULTS

Forty-three aneurysms were analyzed, with mean volume embolization ratio of 30.3 ± 6.7%. Twenty aneurysms (47%) achieved PO. Univariate analysis found that the median neck diameter of the aneurysms was smaller in aneurysms with PO than others. Multivariate logistic regression analysis also found that the odds ratio of neck diameter of the aneurysm for PO was 0.44 (95% CI, 0.19-0.82, p < 0.01). Moreover, ROC curve analysis for PO found that the optimal cut-off value of the neck diameter was 5.5 mm, with a sensitivity of 95%, specificity of 57% (p < 0.01).

CONCLUSIONS

Incompletely occluded aneurysms with a neck diameter of 5.5 mm or less might be more likely to develop PO within 6 months after SAC by using Enterprise or Neuroform stents.

Subarachnoid Hemorrhage: An Update

Subarachnoid hemorrhage (SAH) is a debilitating, although uncommon, type of stroke with high morbidity, mortality, and economic impact. Modern 30-day mortality is as high as 40%, and about 50% of survivors have permanent disability. Care at high-volume centers with dedicated neurointensive care units is recommended. Euvolemia, not hypervolemia, should be targeted, and the aneurysm should be secured early. Neither statin therapy nor magnesium infusions should be initiated for delayed cerebral ischemia. Cerebral vasospasm is just one component of delayed cerebral edema. Hyponatremia is common in subarachnoid hemorrhage and is associated with longer length of stay, but not increased mortality.

Leo stent for endovascular treatment of intracranial aneurysms: very long-term results in 50 patients with 52 aneurysms and literature review

INTRODUCTION

The Leo stent was the first retrievable stent for endovascular treatment of intracranial aneurysms (IAs). We report our experience with this device with emphasis on very long-term follow-up.

METHODS

This study was approved by authors' ethical committee. A retrospective review of our prospectively maintained database identified all patients treated for a saccular IA with this stent in our institution. Technical issues and immediate and long-term outcomes (at least 12 months) were evaluated.

RESULTS

Between 2004 and 2015, 50 patients with 52 IAs were identified. In two patients, the stent could not safely be placed (failure rate = 3.8%). Among 48 treated patients with 50 IAs, there were 44 women and 4 men (mean age, 53 years). Mean aneurysm diameter was 7.2 mm. All IAs but six were wide-necked. There was no immediate morbidity or mortality. Anatomical results included 76% complete occlusions, 22% neck remnants, and 2% incomplete occlusions. Mean follow-up was 50.2 months (range, 12-139 months). Two patients had delayed TIAs but long-term morbidity rate remained = 0%. At follow-up, occlusion was stable in 68% IAs, showed thrombosis in 12%, and recanalization in 20% IAs. Complementary treatment was required in 8% IAs. Final results showed 70% complete occlusions, 24% neck remnants, and 6% incomplete occlusions. Asymptomatic stent occlusion and significant stenosis occurred in one and two cases, respectively.

CONCLUSION

The Leo stent is safe and effective for treatment of wide-necked saccular IAs. Very long-term results show high rates of adequate and stable occlusion. Moreover, the stent is well tolerated.

Application of parallel stent placement in the treatment of unruptured vertebrobasilar fusiform aneurysms

OBJECTIVE

Large vertebrobasilar fusiform aneurysms (VFAs) represent a small subset of intracranial aneurysms and are often among the most difficult to treat. Current surgical and endovascular techniques fail to achieve a complete or acceptable result because of complications, including late-onset basilar artery thrombosis and perforator infarction. The parallel-stent placement technique was established in the authors' department, and this study reports the application of this technique in the treatment of unruptured VFAs.

METHODS

Eight patients with 8 unruptured VFAs who underwent parallel stent placement between April 2011 and August 2012 were included. The diameters of the VFAs ranged from 7.9 to 14.0 mm, and the lengths from 27.5 to 54.4 mm. Of the 8 patients with unruptured VFAs, 3 received double or triple parallel stents and 5 patients received a series-connected stent with another 1 or 2 stents deployed parallel to them. Outcomes for these patients were tabulated, based on the modified Rankin Scale (mRS) score and angiographic results.

RESULTS

All of the 25 stents were successfully placed without any treatment-related complications. During follow-up, 5 patients had decreased mRS scores, 2 were unchanged, and 1 was increased for subarachnoid hemorrhage. Immediate and follow-up clinical outcome was completely or partially recovered in most patients. Follow-up angiograms revealed 2 aneurysms were reduced in size and 6 were unchanged after stent placement. No in-stent stenosis, occlusion of the posterior inferior cerebellar artery, or perforators jailed by the stent occurred in any of the aneurysms.

CONCLUSIONS

These results provide encouraging support for the parallel-stent placement technique, which can be envisaged as an alternative strategy against unruptured VFAs. However, testing in more patients is needed.

The Silk flow-diverter stent for endovascular treatment of intracranial aneurysms

Flow diverter (FD) stents represent a new endovascular technique developed for the treatment of complex intracranial aneurysms (wide neck, fusiform, large, and giant aneurysms) that are challenging for classic endovascular techniques such as coiling, balloon-assisted coiling and stent-assisted coiling. Low porosity, high metal coverage, and high pore density are the main properties of FD stents. These properties induce hemodynamic changes redirecting the blood flow away from the aneurysm and into the parent artery leading to gradual thrombosis of the aneurysm. FD stents also provide scaffolding for subsequent neoendothelial proliferation, and vessel wall remodeling. This is considered as a paradigm shift compared to prior endovascular methods, which predominantly aimed at providing treatment inside the aneurysmal sac. This paper describes in detail the first released FD stent, the Silk flow-diverter stent (Balt Extrusion, Montmorency, France), its mechanism of action and deployment technique. It reviews the pertinent literature regarding safety, efficacy and potential risks and complications associated with the use of this stent.

Flow-Diverter Stents for the Treatment of Saccular Middle Cerebral Artery Bifurcation Aneurysms

BACKGROUND AND PURPOSE

The flow-diverter stent has been proved a feasible, safe, and efficient technique, particularly for the treatment of large and broad-neck carotid siphon aneurysms. Wide-neck bifurcation aneurysms remain, in some cases, a challenge for neurointerventionalists. We report the outcomes of the treatment of saccular middle cerebral artery bifurcation aneurysms with flow diversion in our institution.

MATERIALS AND METHODS

From the institution data base, all saccular, nondissecting MCA bifurcation aneurysms, treated with flow-diverter stents, were retrospectively reviewed. Technical issues, immediate posttreatment and follow-up angiographic findings, and clinical outcomes were assessed.

RESULTS

Fourteen patients with 15 aneurysms were included in the study. Ischemic complications, as confirmed by MR imaging, occurred in 6 patients (43%). Procedure-related morbidity and mortality at last follow-up were 21% and 0%, respectively. Angiographic follow-up was available for 13 aneurysms, with a mean follow-up of 16 months. Complete occlusion was obtained for 8 aneurysms (62%).

CONCLUSIONS

Compared with other available therapeutic options, the flow-diverter stent does not appear to be a suitable solution for the treatment of saccular MCA bifurcation aneurysms.

Solitaire AB stent-assisted coiling of wide-necked intracranial aneurysms: mid-term results from the SOLARE Study

BACKGROUND

Endovascular treatment of intracranial aneurysms can be technically difficult when the neck is wide. The Solitaire AB stent (Covidien, Irvine, California), the only fully retrieved stent, assists in the coiling of wide-neck intracranial aneurysms.

OBJECTIVE

To evaluate the mid-term angiographic follow-up of wide-necked aneurysms treated with the Solitaire AB stent.

METHODS

SOLARE (SOLitaire Aneurysm Remodeling) is a consecutive, prospective study conducted in 7 European centers. A core laboratory evaluated the postoperative and mid-term (6 month ± 15 days) angiographic results by using the Raymond classification Scale. Recanalization was defined as worsening, and progressive thrombosis was defined as improvement in the Raymond scale score.

RESULTS

The mean width of the aneurysm sac was 7.5 mm, and the mean diameter of the aneurysm neck was 4.7 mm. Angiographic mid-term follow-up was obtained in 55 of 65 aneurysms (85.9%). Complete occlusion was achieved in 33 aneurysms (60%); a neck remnant was seen in 16 aneurysms (29.1%) and an aneurysm remnant in 6 aneurysms (10.9%). Of 55 aneurysms, recanalization was observed in 8 aneurysms (14.5%), and progressive thrombosis was observed in 17 aneurysms (30.9%). No bleeding or rebleeding was observed during the follow-up period.

CONCLUSION

Stent-assisted coiling of wide-necked intracranial aneurysms was found to be safe and effective with the Solitaire AB stent at 6-month follow-up. Angiographic results improve with time due to progressive thrombosis of the aneurysm.

Comparison between Solitaire™ AB and Enterprise stent-assisted coiling for intracranial aneurysms

The aim of the present study was to analyze the feasibility, rate of procedure-related complications and midterm angiographic follow-up outcomes using the Enterprise (EP) and Solitaire™ AB (ST) stents in the stent-assisted coiling of intracranial aneurysms. In total, 81 patients with 90 aneurysms were included in the study, with the aim to treat 43 aneurysms with the EP stent (47.8%) and 47 aneurysms with the ST stent (52.2%). The 90 aneurysms were successfully stented and subsequently coiled; however, in four patients undergoing treatment with the EP stent, the stent was not navigable; thus, treatment with the ST stent was employed (EP, n=39, 43.3%; ST, n=51, 56.7%). Of the 90 aneurysms, 44 cases were ruptured aneurysms, with 74 located in the anterior circulation and 16 located in the posterior circulation. The stenting success rate of the ST stent was significantly higher compared with the EP stent. However, no statistically significant differences were observed with regard to the packing density, complete occlusion, progressive occlusion, recurrence rate, procedure-related complications, in-stent stenosis and stent migration rates between the two groups. In conclusion, the two common medical devices used for intracranial aneurysms are relatively safe and effective for the treatment of intracranial aneurysms. However, due to the higher stenting success rate of the ST stent, this medical devise was demonstrated to be more flexible and feasible compared with the EP stent.

Long-term angiographic outcome of stent-assisted coiling compared to non-assisted coiling of intracranial saccular aneurysms

AIM

To compare angiographic result at long-term follow-up, and rates of progressive occlusion, recurrence, and retreatment of stent-assisted coiled (SAC) and non-assisted coiled (NAC) intracranial saccular aneurysms.

METHODS

Retrospective evaluation of department records identified 260 patients with 283 saccular intracranial aneurysms who had long-term angiographic follow-up (more than 12 months) and were successfully treated with SAC (89 aneurysms) or NAC (194 aneurysms) at the University Hospital Center Zagreb from June 2005 to July 2012. Initial and control angiographic results in both groups were graded using Roy/Raymond scale, converted to descriptive terms, and the differences between them were evaluated for statistical significance. A multivariate analysis was performed to identify factors related to progression of aneurysm occlusion and recurrence at follow-up, and those related to aneurysm retreatment.

RESULTS

There were more progressively occluded aneurysms in SAC group (38 of 89 aneurysms, 42.7%) than in NAC group (46 of 194, 23.7%) (P=0.002), but there were no significant differences in the rates of recanalization, regrowth, and stable result. Multivariate logistic regression identified the use of stent as the most important factor associated with progressive occlusion (P=0.015, odds ratio 2.22, 95% confidence interval 1.17-4.21), and large aneurysm size and posterior circulation location as most predictive of aneurysm recurrence and retreatment.

CONCLUSION

The use of stent is associated with delayed occlusion of initially incompletely coiled aneurysms during follow-up, but does not reduce the rate of recurrence and retreatment compared to coiling alone. Long-term angiographic follow-up is needed for both SAC and NAC aneurysms.

The Use of Solitaire AB Stents in Coil Embolization of Wide-Necked Cerebral Aneurysms

BACKGROUND

The Solitaire AB stent is one of many assistant stents used for treating wide-necked cerebral aneurysm, and has been used since 2003. However, large sample studies on its safety and effectiveness are lacking. The objective of this study was to evaluate the effectiveness and safety of the Solitaire AB stent in the coil embolization of wide-necked cerebral aneurysms.

METHODS

Retrospective review of the clinical and image data of 116 patients with wide-necked cerebral aneurysms who had been enrolled at six interventional neuroradiology centers from February 2010 to February 2014 and had been treated by coil embolization; in total, 120 Solitaire AB stents were used. The degree of aneurysm occlusion was examined using digital subtraction angiography (DSA) immediately after the procedure and during follow-up, and was graded using the modified Raymond classification. We also observed complications to evaluate the safety and effectiveness of this therapy.

RESULTS

The 120 Solitaire AB stents (4 mm × 15 mm, four stents; 4 mm × 20 mm, 16 stents; 6 mm × 20 mm, 36 stents; 6 mm × 30 mm, 64 stents) were inserted to treat 120 wide-necked cerebral aneurysms. All stents were inserted successfully. DSA immediately post-surgery revealed 55 cases of complete occlusion, 59 cases of neck remnant, and six cases of aneurysm remnant. Perioperatively, there were four cases of hemorrhage and four cases of stent thrombosis. The follow-up spanned 3-37 months; of 92 patients examined by DSA at the 6-month follow up, 12 had disease recurrence.

CONCLUSIONS

The Solitaire AB stent is effective with a good technical success rate and short-term effect for assisting coil embolization of wide-necked cerebral aneurysms.

Technology developments in endovascular treatment of intracranial aneurysms

Advances in the management and endovascular treatment of intracranial aneurysms are progressing at a tremendous rate. Developments in novel imaging technology may improve diagnosis, risk stratification, treatment planning, intraprocedural assessment, and follow-up evaluation. Evolution of devices, including microwires, microcatheters, balloons, stents, and novel scaffolding devices, has greatly expanded the potential to treat difficult aneurysms. Although developments in technology have greatly improved the efficiency and efficacy of treatment of neurovascular disorders, novel devices do not always improve outcomes and may be associated with unique complications. As such, it is paramount to have an in-depth understanding of new devices and the implications of their introduction into clinical practice. This review provides an update on developments in endovascular treatment of intracranial aneurysms.

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.

Design and biocompatibility of endovascular aneurysm filling devices

The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric-based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.

Flow Re-direction Endoluminal Device in treatment of cerebral aneurysms: initial experience with short-term follow-up results

Object

Flow diverter (FD) stents are relatively new and important devices in the treatment of cerebral aneurysms. The Flow Re-Direction Endoluminal Device has been recently released for clinical use. The authors' aim in this paper is to report their initial single-center FRED experience with short-term results.

Methods

Between February 2012 and May 2013, 33 patients with 37 aneurysms (35 unruptured and 2 previously ruptured aneurysms) were treated with the FRED. Clinical and radiological data of the patients were retrospectively reviewed.

Results

In all patients only 1 device was used without any additional device or material, such as a stent or coil. All procedures were successfully performed. The procedural complication rate was 3% (1 of 33). Thirty patients underwent clinical and radiological follow-up. During the follow-up period, changes in stent morphology, such as “fish mouth” and “foreshortening” phenomena, occurred in 5 patients. The mortality and permanent morbidity rates were 0%. The complete occlusion rates were 32% (6 of 19) at 0–1 month, 67% (8 of 12) at 2–3 months, 80% (4 of 5) at 4–6 months, and 100% (8 of 8) at 7–12 months. The rates for some aneurysms were assessed at more than one time point.

Conclusions

The FRED has an ability to serve neurointerventionalists in the treatment of cerebral aneurysms with its different technical advantages. The occlusion rates with FRED are similar to those with other FD devices. However, these short-term results need to be confirmed with mid- and long-term follow-up results of multicenter large series.

Coil occlusion of wide-neck bifurcation aneurysms assisted by a novel intra- to extra-aneurysmatic neck-bridging device (pCONus): initial experience

BACKGROUND AND PURPOSE

The pCONus is a new stentlike self-expanding nitinol implant with 4 distal petals, which is fully retrievable and electrolytically detachable. The distal end is implanted inside the aneurysm at the neck. The shaft is anchored in the parent vessel. In selected wide-neck bifurcation aneurysms, the pCONus was used to assist coiling. The device was evaluated for its safety and efficacy.

MATERIAL AND METHODS

Twenty-eight patients with 28 wide-neck aneurysms (9 recently ruptured) were treated with pCONus-assisted coiling at the discretion of the operator. Other treatment options were considered but were discarded due to anticipated difficulties. Technical issues, immediate posttreatment angiographic findings, clinical outcome, and follow-up imaging were assessed.

RESULTS

There were 11 MCA, 7 anterior communicating artery, 1 posterior cerebral artery, 1 A2, and 8 basilar artery aneurysms. Insertion and deployment of the pCONus and subsequent coiling were possible in all cases. There were no clinically evident complications associated with the use of the device. Initial anatomic outcome showed 8 complete occlusions, 9 neck remnants, and 11 incomplete occlusions. Neurologic status remained unchanged at follow-up. Angiographic controls were obtained in 22 patients (mean, 7.5 months). Of these, 13 had complete occlusion, 9 showed improvement, and 7 were unchanged. Four died from SAH sequelae or other diseases, and 2 have not yet undergone follow-up. No intimal hyperplasia was observed.

CONCLUSIONS

The pCONus facilitates coil occlusion of unruptured and ruptured wide-neck bifurcation aneurysms. The device can be deployed safely. Coil retention is sufficient to protect the efferent vessels. So far, no intimal hyperplasia in the shaft has been observed.

A Self-expanding Nitinol Stent (Enterprise) for the Treatment of Wide-necked Intracranial Aneurysms: Angiographic and Clinical Results in 40 Aneurysms

Objective

Self-expanding stents are increasingly used for the treatment of complex intracranial aneurysms. The purpose of this study was to evaluate the usefulness and safety of a self-expanding nitinol stent (Enterprise) in the treatment of wide-necked intracranial aneurysms.

Methods

This was a retrospective study of 39 patients with 40 wide-necked intracranial aneurysms who were enrolled in a single-center registry of patients treated with the Enterprise between June 2009 and December 2011. Thirty patients were asymptomatic, four had cerebrovascular accident sequelae, and five had suffered subarachnoid hemorrhage. One aneurysm had reopened after prior coil embolization, while 39 had not been treated. Clinical charts, procedural data, and angiographic results, including both immediate post-procedural angiograms and follow-up imaging, were reviewed.

Results

The mean neck size of the aneurysms was 5.58 mm (range 3-15.1 mm). Embolization was successful in all patients. There were five procedure-related events. There were no fatalities, but one procedure-related morbidity was noted. The immediate angiographic results included eight complete occlusions (20%), six remnant necks (15%), and 26 remnant sacs (65%). At angiographic follow-up (mean: 11.3 months), out of 18 of the aneurysms treated with stent-assisted coiling, there were 13 (72.2%) complete occlusions, four (22.2%) remnant necks, and one recanalization (5.6%).

Conclusion

Stent-assisted coiling using the Enterprise is effective for the treatment of wide-necked intracranial aneurysms. Further angiographic and clinical follow-up investigation will be needed for evaluation of the long-term outcomes.

Intrasaccular flow-diversion for treatment of intracranial aneurysms: the Woven EndoBridge

Endovascular approach is now the first option for the treatment of most intracranial aneurysms (IA). However, remaining limitations are the suboptimal stability of aneurysm occlusion and the treatment of complex IA. The use of conventional and flow diverter stents has partially addressed these limitations. Nevertheless, as intraluminal devices, stents require aggressive antiplatelet therapy and are associated with higher thromboembolic (TE) complication rates. Intrasaccular flow disrupters (IFD) are newly developed braided-wire devices designed to achieve flow disruption at the neck without placing material in the parent vessel and without the need of antiplatelet therapy. First clinical series have shown promising anatomical and clinical results. Our purpose is to describe the available IFD and to review the literature about their efficacy, safety, limitations, and developments.

Changes in hemodynamics after placing intracranial stents

Stent-assisted coil embolization has enabled the endovascular treatment of wide-necked cerebral aneurysms. Moreover, recent reports demonstrated that stent-assisted coil embolization was associated with a significant decrease in angiographic recurrences of coiled cerebral aneurysms. One of the possible explanations for this adjunctive effect of stent-assisted coil embolization is changes in the local hemodynamics caused by placing intracranial stents. This study investigated the hemodynamic effect of intracranial stents using computational fluid dynamics (CFD) analysis. The geometry of the intracranial stent, Enterprise(TM) VRD, was acquired by using micro computed tomography and virtually placed across the aneurysm orifice of a saccular aneurysm model (saccular model) and a blister-like aneurysm model (blister-like model) constructed from patient-specific three-dimensional (3D) rotational angiography data. Transient CFD analysis was performed with these models with and without stents. Stent placement induced no significant changes in the 3D streamline in the saccular model and slight changes in the blister-like model. Both saccular and blister-like models with stents had lower wall shear stress (WSS) and flow velocity, and higher oscillatory shear index, WSS gradient, and relative residence time than the equivalent models without stents, indicating the possibility that stent placement induced stagnant and disturbed blood flow. Cross-sectional vector velocity around the stent strut revealed complex blood flow patterns with variable direction and velocity. Although this study was a simulation under limited conditions, similar hemodynamic changes might be induced in the neck remnants treated with stent-assisted coil embolization.

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.

Stent-assisted coiling of unruptured intracranial aneurysms: long-term follow-up in 164 patients with 183 aneurysms

PURPOSE

Stent-assisted coiling (SAC) is increasingly used to treat complex unruptured intracranial aneurysms (UIA) including wide-necked and fusiform IA. However, few data are available over the long-term results of this technique. We report our 9-year-experience of SAC of UIA.

METHODS

A retrospective review of our prospectively maintained database identified all patients treated by SAC for an UIA in 2 institutions. The clinical charts, procedural data and angiographic results were reviewed.

RESULTS

Between 2004 and 2012, we identified 164 patients with 183 UIA. There were 115 women and 49 men with a mean age of 46 years. Embolization was successful in all patients. Procedural morbidity and mortality rates were 2.2% and 0% respectively. Immediate anatomical outcome included 54 complete occlusion (29.5%), 43 neck remnants (23.5%) and 86 incomplete occlusions (47%). Imaging follow-up was available in 137 patients (mean=26 months, range 3 to 99 months) and it showed 104 complete occlusions (75.9%), 23 neck remnants (16.8%) and 10 incomplete occlusions (7.3%). At follow-up, only 3 patients developed a significant intrastent stenosis, one of which was induced by radiosurgery. One of these patients had a symptomatic thrombo-embolic complication 3 years after stent placement.

CONCLUSION

SAC of complex UIA is effective and associated with low complication rates. Even if immediate anatomical results are relatively unsatisfying, mid- and long-term follow-up show a major improvement with a high rate of adequate occlusion that is stable over time. Moreover, the long-term clinical and angiographic tolerance of intracranial stents is excellent.

Indications and practical application of strategies in the endovascular management of intracranial aneurysms

The occlusion of intracranial aneurysms is more successful and stable by properly planning the approach and application of endovascular techniques. The next step is a relentless analysis of the different indications of endovascular treatment, tailoring a strategy suitable for the specific case, and making more rational choices for the management of aneurysms. Indications and strategies according to the analysis of the aneurysmal complex are given, as well as pros and cons of the endovascular technique according to different anatomical locations

Endovascular treatment with flow diverters may fail to occlude experimental bifurcation aneurysms

INTRODUCTION

Animal models may explain how stents and flow diverters (FDs) may succeed or fail to treat bifurcation aneurysms.

METHODS

In vitro studies were designed to anticipate device deformations in bifurcations. Large, wide-necked bifurcation aneurysms were constructed in 21 animals and treated 4-8 weeks later using stents and FDs in various combinations, forming four main groups: parent artery to right branch flow diversion (RBFD, n = 6), parent artery to left branch flow diversion (LBFD, n = 6), Y flow diversion (YFD, n = 4), and compared with high-porosity Y-stenting (YHPS, n = 4). The results include immediate and follow-up angiography at 3 months, followed by grading of the extent of neointimal coverage of devices at pathology.

RESULTS

In vitro, all braided devices showed varying porosities according to characteristic zones. FDs can be compacted to decrease porosities, but a limiting factor is the constant presence of a more porous transition zone. In vivo, 3/6 RBFD, 4/6 LBFD, and 2/4 YFD treated aneurysms had decreased in size by 3 months, while those treated with YHPS increased in size (P = 0.15). There was a significant correlation between device porosities and extent of neointimal coverage (r = 0.639, P = 0.002), and between porosities and angiographic evolution (r = -0.655, P = 0.002), but not between neointima formation and angiographic evolution (r = -0.278, P = 0.235). Failures could be explained in all cases by the presence of leaks or holes in the neointima at the level of the transition zones.

CONCLUSION

FDs did not successfully treat most bifurcation aneurysms, at least in this animal model.

Analysis of complications and recurrences of aneurysm coiling with special emphasis on the stent-assisted technique

BACKGROUND AND PURPOSE

Stent-assisted coiling has expanded the treatment of intracranial aneurysms. With the use of continuously compiled data, we reviewed the role and drawbacks of stent-assisted coiling.

MATERIALS AND METHODS

We compiled data from consecutive patients from 2003-2012 who underwent coiling, with or without stent assistance. Clinical and angiographic results were analyzed retrospectively.

RESULTS

Of 1815 saccular aneurysms in 1505 patients, 323 (17.8%) were treated with stents (299 procedures) and 1492 (82.2%) without stents (1400 procedures). Procedure-related complications occurred in 9.4% with stents versus 5.6% without stents (P = .016, relative risk 1.5; 95% CI, 1.1-2.7). Ischemic complications were more frequent in the stent group than in the no-stent group (7.0% versus 3.5%; P = .005; relative risk, 1.7; 95% CI 1.2-2.5), as were hemorrhagic complications (2.3% versus 1.9%, P = .64). Procedure-induced mortality occurred in 2.7% (8/299) with stents versus 1.1% (15/1400) without stents (P = .029; relative risk, 2.0; 95% CI, 1.1-3.5). Logistic regression analysis identified wide-neck aneurysms as the most significant independent predictor of complications. A total of 64.1% (207/323) of aneurysms treated with stents and 70.3% (1049/1492) treated without stents have been followed, disclosing angiographic recurrence in 15.5% (32/207) versus 35.5% (372/1049), respectively (P < .0001). Logistic regression analysis showed that the presence of a stent was the most important factor for the reduction of angiographic recurrence (P < .0001; relative risk, 2.3; 95% CI, 1.6-3.3).

CONCLUSIONS

The stent-assisted coiling technique is associated with a significant decrease in recurrences but a significant increase in complications. The treatment of wide-neck aneurysms remains hazardous.

The safety and efficacy of stenting in the treatment of complex posterior cerebral artery aneurysms: a seven-case report and literature review

OBJECTIVE

To investigate the safety and efficacy of stenting with coil in the endovascular treatment of complex posterior cerebral artery (PCA) aneurysms.

METHODS

The data on PCA aneurysms treated with stents were retrospectively reviewed from a prospectively collected intervention database. The literature was reviewed concerning the use of stents for PCA aneurysms.

RESULTS

Seven cases with complex PCA aneurysms (male: female = 6:1; ruptured: unruptured = 4:3) were retrieved from our database. Three aneurysms were localized at the junction of P1 and P2 segments (P1-2), two at P1, and two at P2A. Four were wide-necked saccular aneurysms, while the other three were dissecting ones. A total of nine stents (one Neuroform and eight Enterprise stents) were successfully deployed. Two aneurysms were totally eliminated, three were with neck residues and two were partially occluded. No procedure-related complications occurred. All patients recovered well. Angiographic follow-ups (FU) showed that three aneurysms achieved total obliterations, one got improved, two remained stable, and one recurred. The recurred aneurysm caused no symptom and was treated with two stents. Clinical FU demonstrated no neurological deterioration or bleeding. In literature review, the procedure-related mortality is 5.3 % (2/38). The incidence of permanent neurologic deficit is 2.6 % (1/38). Three (3/23) aneurysms recurred, of which one caused rebleeding. Four (4/23) in-stent stenoses were all asymptomatic. No other hemorrhagic or ischemic event occurred in clinical FU.

CONCLUSION

Stent offers a therapeutic alternative for complex PCA aneurysms especially when PVO cannot be tolerated. Long-term therapeutic efficacy requires further observations in clinical series with larger case numbers.

Use of stent-assisted coil embolization for the treatment of wide-necked aneurysms: A systematic review

Background:

The use of stent-assisted coiling (SAC) has been shown to be a treatment option for complex aneurysms. We reviewed systematically the immediate and mid-term angiographic results following treatment of wide-necked aneurysms with self-expanding stents and coils, as well as the peri- and postprocedural rate of complications.

Methods:

A computerized database search was conducted from 01/2000 to 04/2011 using appropriate indexed terms on Pubmed. Inclusion criteria were: (1) homogeneous populations of ≥10 patients with wide-necked aneurysms; (2) use of a self-expandable neurovascular stent and coils for aneurysm treatment; (3) immediate and follow-up angiographic results; and (4) periprocedural and delayed thrombotic complications.

Results:

Seventeen studies were included, containing retrospectively collected data on 656 patients/702 aneurysms. The target aneurysm was located on the anterior circulation in 78.4% of patients. The immediate rate of complete occlusion was 46.3%, (19.3-98.1%). The intra- and postprocedural rate of intrastent thrombosis or thromboembolic event was 4.6% and 4.3%, respectively. Complete occlusion was documented in 71.9% at last angiographic follow-up. The rate of recanalization was 13.2% of aneurysms (0-28.8%). Delayed in-stent stenosis occurred in 5.3% cases (0-20.6%).

Conclusion:

SAC has been considered a treatment option for selected wide-necked aneurysms in some institutions. The use of intracranial stents should take into consideration the risk of ischemic complications, recanalization, delayed in-stent stenosis; and the currently unknown lifetime risks for stenosis, vascular injury, device failure, and aneurysm recurrence related to intracranial stenting. There is an evident need for a prospective multicenter registry for all treated patients with SAC.

Stent-assisted coil embolization of intracranial aneurysms using the Solitaire™ AB Neurovascular Remodeling Device: initial and midterm follow-up results

INTRODUCTION

The purpose of this retrospective review was to present our experience in using the Solitaire™ AB Neurovascular Remodeling Device in the stent-assisted treatment of intracranial aneurysms, focusing on midterm results. To date, this is the largest series using the Solitaire™ AB Neurovascular Remodeling Device.

METHODS

From February 2008 to December 2010, 102 patients harboring 104 wide-necked or complex intracranial aneurysms were consecutively enrolled. Forty-five patients presented with an acute subarachnoid hemorrhage. Stent implantation was combined with a standard coiling procedure in 100 patients; in 13 of them, by bailout stenting. On average, at least one clinical and angiographic follow-up was available in 63 patients after 6.3 months. Forty-nine patients were followed for up to 13.6 months.

RESULTS

Of the stents, 98.4 % could be deployed successfully. A Raymond class 1 occlusion was obtained in 51 % of the aneurysms, a Raymond class 2 occlusion in 44 %, and in the remaining 5 % a Raymond class 3 occlusion was obtained. Procedure-related morbidity was 3.9 % (n = 4) and procedure-related mortality was 2.9 % (n = 3). During the follow-up period, 39.2 % of the aneurysms showed further thrombosis, 45.1 % remained unchanged, and 15.7 % recanalized. In the follow-up clinical examination according to the modified Rankin Scale, 16.3 % of all patients presented with clinical improvement, 73.5 % were unchanged, and 10.2 % of patients deteriorated.

CONCLUSION

Considering that stent-assisted coiling is indicated in unfavorable aneurysms, which are not amenable to standard coiling procedures, the Solitaire AB stent proved to be an efficient and safe device in midterm angiographic and clinical follow-up results.

Review of 2 decades of aneurysm-recurrence literature, part 1: reducing recurrence after endovascular coiling

SUMMARY

Angiographic recurrence following endovascular therapy is an indirect measure of the potential for hemorrhage. Because patients and physicians consider recurrence to be a suboptimal outcome with some chance of future hemorrhage, much effort has been expended to reduce the incidence of recurrence. The literature regarding aneurysm recurrence following endovascular therapy, spanning 2 decades, is extensive. We will review and summarize the effort to reduce recurrence following endovascular treatment of cerebral aneurysms.

Safety and efficacy of neuroform for treatment of intracranial aneurysms: a prospective, consecutive, French multicentric study

BACKGROUND AND PURPOSE

Endovascular embolization of wide-neck intracranial aneurysms can be technically challenging, especially when the anatomy is complex. Stent reconstruction of the parent artery is commonly used to treat wide-neck and bifurcated aneurysms. The main objective of this study was to investigate the periprocedural and midterm morbidity and mortality results of this procedure.

MATERIALS AND METHODS

SENAT is a consecutive, prospective, multicentric study. Patients with unruptured cerebral aneurysms who underwent endovascular treatment with the Neuroform stent system were recruited and recorded. Technical outcomes and complications were also assessed. The midterm anatomic results were re-evaluated at 12-18 months.

RESULTS

A total of 113 stents were used to treat the 107 aneurysms in 107 patients. The mean width of the aneurysm sac was 6.2 mm, and the mean diameter of aneurysm neck was 4.5 mm. The complete occlusion rate postprocedure was 66.4%. The rate of progressive occlusion at 12-18 months was 14%, and the rate of recurrence was 9.7%. The rate of subsequent treatment was 4%. The thromboembolic rate in the periprocedural period was 3.7%, and the rate of delayed TE events was 3%. Overall, the mortality rate at 12-18 months was 1%, and the permanent morbidity rate was 1%.

CONCLUSIONS

Stent-assisted coiling with the Neuroform stent system provides a high level of occlusion with low rates of subsequent treatment despite a predominant population of patients with wide-neck aneurysms. Morbidity and thromboembolic rates were comparable to studies investigating stand-alone coiling.

Safety and cost of stent-assisted coiling of unruptured intracranial aneurysms compared with coiling or clipping

OBJECTIVE

Stent-assisted coiling (SAC) of unruptured intracranial aneurysms is a treatment alternative to clipping or coiling, although high complication and procedure-related mortality rates have been reported.

METHODS

A retrospective study was conducted of patients undergoing SAC, coiling or clipping of unruptured intracranial aneurysms between 2003 and 2010. Rates of residual aneurysm, recanalization, complications, cost (adjusted to 2010), length of stay (LOS) and outcome were compared between groups.

RESULTS

Of 116 subjects, 47 underwent SAC, 33 coiling and 36 clipping. The groups were similar in age, gender and aneurysm location, although the SAC group had significantly larger aneurysms with wider necks (p=0.001). Patients who underwent SAC had more residual aneurysm after initial treatment than those treated with coiling or clipping (75%, 52% and 19%, respectively, p<0.0001), but this difference was smaller at follow-up angiography (50%, 50% and 17% residual, respectively) and was not significant after adjusting for baseline aneurysm and neck size. SAC was not associated with increased recanalization, requirement for additional treatment, mortality or complications after adjusting for aneurysm and neck size. Patients who underwent SAC and those who underwent coiling were more likely to have a good discharge disposition than patients treated with clipping (100% vs 91%, p=0.042). LOS was significantly shorter for patients who underwent SAC or coiling compared with those treated with clipping (p<0.0001). The overall direct cost was higher for patients who underwent SAC than for those treated with coiling or clipping (median $22 544 vs $12 933 vs $14 656, p=0.001), even after adjusting for aneurysm and neck size, LOS and retreatment.

CONCLUSIONS

SAC is a safe alternative to coiling or clipping of unruptured aneurysms but it is currently more expensive.

Unruptured non-branching site aneurysms located on the anterior (dorsal) wall of the supraclinoid internal carotid artery: aneurysmal characteristics and outcomes following endovascular treatment

BACKGROUND

This study was undertaken to evaluate the aneurysmal characteristics and clinico-radiological outcomes of unruptured non-branching site aneurysms located on the anterior (dorsal) wall of the supraclinoid internal carotid artery (ICA).

METHODS

The data of 34 patients that underwent endovascular treatment for 36 unruptured ICA anterior wall aneurysms were reviewed. ICA anterior wall aneurysms were defined as aneurysms that projected superiorly from the anterior wall of the ICA ophthalmic (n = 35) or communicating (n = 1) segment on lateral angiograms, without any branch vessel relationship. In addition, aneurysmal characteristics and treatment outcomes were compared with those of 60 unruptured aneurysms originating from the posterior (ventral) wall of the ICA ophthalmic segment.

RESULTS

Patients with an ICA anterior wall aneurysm frequently had a mirror aneurysm on the contralateral side (14.7 % versus 3.3 %) or another ICA aneurysm (35.3 % versus 15 %). Two of the 36 ICA anterior wall aneurysms exhibited ICA narrowing suggestive of dissection, and another five had dysplastic ICA dilatation around the neck. Stent-assisted embolization was more frequently performed for ICA anterior wall aneurysms (66.7 % versus 36.7 %) because of unfavorable dome/neck (mean, 1.21) and aspect (mean, 1.15) ratios, and because of microcatheter instability associated with superior aneurysmal projections against the abrupt curvature of the carotid siphon. Procedure-related thromboembolic complications occurred in three patients in the anterior aneurysm group, but no patient deteriorated clinically. Immediate radiological outcomes were more unfavorable for ICA anterior wall aneurysms (residual sac, 36.1 % versus 16.7 %). Nevertheless, rates of recanalization (2.9 % versus 5.2 %) and progressive occlusion (24.7 % versus 8.1 %) during follow-up slightly favored ICA anterior wall aneurysms. Two stent-treated ICA anterior wall aneurysms developed asymptomatic ICA steno-occlusion (8.3 %).

CONCLUSIONS

Stent-assisted embolization is safe and effective for the treatment of unruptured ICA anterior wall aneurysms exhibiting unfavorable aneurysmal geometries and projections for coil embolization.

[Anterior cerebral artery aneurism presenting as a third ventricular mass and hydrocephalus. Case report]

Aneurysms which appear as third ventricular masses are uncommon; most are giant aneurysms arising from the basilar apex. We present the case of a 67-year-old male who was admitted to hospital with a 4-week history of gait instability, urinary incontinence and progressive visual loss. A cranial computed tomography scan revealed a hyperdense mass in the third ventricle with triventricular dilatation. Cerebral magnetic resonance imaging, magnetic resonance-angiography and conventional angiography identified this lesion as a partially thrombosed aneurysm of the anterior cerebral artery. To our knowledge, this is the first report of an anterior cerebral artery aneurysm with these clinical and radiological features.

Stent-assisted coiling of bifurcation aneurysms may improve endovascular treatment: a critical evaluation in an experimental model

BACKGROUND AND PURPOSE

Endovascular treatment of wide-neck bifurcation aneurysms often results in incomplete occlusion or aneurysm recurrence. The goals of this study were to compare results of coil embolization with or without the assistance of self-expandable stents and to examine how stents may influence neointima formation.

MATERIALS AND METHODS

Wide-neck bifurcation aneurysms were constructed in 24 animals and, after 4-6 weeks, were randomly allocated to 1 of 5 groups: 1) coil embolization using the assistance of 1 braided stent (n = 5); 2) coil embolization using the assistance of 2 braided stents in a Y configuration (n = 5); 3) coil embolization without stent assistance (n = 6); 4) Y-stenting alone (n = 4); and 5) untreated controls (n = 4). Angiographic results were compared at baseline and at 12 weeks, by using an ordinal scale. Neointima formation at the neck at 12 weeks was compared among groups by using a semiquantitative grading scale. Bench studies were performed to assess stent porosities.

RESULTS

Initial angiographic results were improved with single stent-assisted coiling compared with simple coiling (P = .013). Angiographic results at 12 weeks were improved with any stent assistance (P = .014). Neointimal closure of the aneurysm neck was similar with or without stent assistance (P = .908), with neointima covering coil loops but rarely stent struts. Y-stent placement alone had no therapeutic effect. Bench studies showed that porosities can be decreased with stent compaction, but a relatively stable porous transition zone was a limiting factor.

CONCLUSIONS

Stent-assisted coiling may improve results of embolization by allowing more complete initial coiling, but these high-porosity stents did not provide a scaffold for more complete neointimal closure of aneurysms.

Endovascular treatment of proximal superior middle cerebral artery aneurysms

INTRODUCTION

Aneurysms superiorly located on the proximal segment of the middle cerebral artery (PMCAA) are rare and challenging to treat. No information is available regarding their management by endovascular approach. The aim of this study was to report our experience with endovascular treatment (EVT) of PMCAA.

METHODS

A retrospective review of our prospectively maintained database identified all PMCAA treated in our institution. The clinical charts, procedural data, and angiographic results were reviewed.

RESULTS

From April 2004 to December 2011, 17 patients were identified including six who presented with subarachnoid hemorrhage (SAH) and 11 with an unruptured PMCAA. All aneurysms were small (<6 mm) and had a branch arising from the neck or the sac, and 15/17 were wide-necked. All patients were successfully treated by balloon-assisted coiling (n = 10), stent-assisted coiling (n = 5), and coiling (n = 2). No technical or clinical complication occurred. Fifteen patients showed an excellent clinical outcome, and two kept a slight or a significant deficit that were both SAH-related. Immediate anatomical outcome includes nine complete occlusions and eight neck remnants. Imaging follow-up in 11 patients (mean = 21, range, 6 to 60 months) showed stable or improved results in all cases.

CONCLUSION

Our study is the first reported series of patients with PMCAA treated by selective embolization. It suggests that EVT is a safe and effective alternative to surgery for the management of PMCAA. Balloon- or stent-assisted coiling are needed in most cases because of PMCAA morphological characteristics.

Pipeline flow-diverter stent for endovascular treatment of intracranial aneurysms: preliminary experience in 20 patients with 27 aneurysms

OBJECTIVE

To report our preliminary experience with the Pipeline flow-diverter stent for the endovascular treatment (EVT) of intracranial aneurysms.

METHODS

Between September 2009 and October 2010, 20 patients with 27 fusiform or wide-necked unruptured aneurysms were included and treated by Pipeline stent placement alone. Technical issues, immediate findings, delayed complications, and clinical and imaging follow-up at three and six months were assessed.

RESULTS

EVT was successfully performed in all patients. Clinical outcome was excellent in all but one patient who died. This latter patient developed a massive infarct due to a delayed stent thrombosis. Other complications without permanent deficit included one perimesencephalic subarachnoid hemorrhage and one retroperitoneal hematoma. Minor technical issues without clinical consequence were encountered in nine patients and included stent migration, stent misplacement, unanticipated stent shortening, and the impossibility to recapture the distal coil tip of the supporting device. Angiographic follow-up in 19 patients with 25 aneurysms showed 21 complete occlusions, one neck remnant, and three incomplete occlusions. No significant parent artery stenosis was seen.

CONCLUSION

This study shows that the Pipeline stent is useful for EVT of fusiform and wide-necked intracranial aneurysms. Moreover, the stent is well tolerated with a low rate of intra-stent stenosis at short-term follow-up. However, technical improvements are needed to ensure safe and precise use of the device.

Estimation of aneurysm wall stresses created by treatment with a shape memory polymer foam device

In this study, compliant latex thin-walled aneurysm models are fabricated to investigate the effects of expansion of shape memory polymer foam. A simplified cylindrical model is selected for the in-vitro aneurysm, which is a simplification of a real, saccular aneurysm. The studies are performed by crimping shape memory polymer foams, originally 6 and 8 mm in diameter, and monitoring the resulting deformation when deployed into 4-mm-diameter thin-walled latex tubes. The deformations of the latex tubes are used as inputs to physical, analytical, and computational models to estimate the circumferential stresses. Using the results of the stress analysis in the latex aneurysm model, a computational model of the human aneurysm is developed by changing the geometry and material properties. The model is then used to predict the stresses that would develop in a human aneurysm. The experimental, simulation, and analytical results suggest that shape memory polymer foams have potential of being a safe treatment for intracranial saccular aneurysms. In particular, this work suggests oversized shape memory foams may be used to better fill the entire aneurysm cavity while generating stresses below the aneurysm wall breaking stresses.

Intracranial aneurysms: review of current treatment options and outcomes

Intracranial aneurysms are present in roughly 5% of the population, yet most are often asymptomatic and never detected. Development of an aneurysm typically occurs during adulthood, while formation and growth are associated with risk factors such as age, hypertension, pre-existing familial conditions, and smoking. Subarachnoid hemorrhage, the most common presentation due to aneurysm rupture, represents a serious medical condition often leading to severe neurological deficit or death. Recent technological advances in imaging modalities, along with increased understanding of natural history and prevalence of aneurysms, have increased detection of asymptomatic unruptured intracranial aneurysms (UIA). Studies reporting on the risk of rupture and outcomes have provided much insight, but the debate remains of how and when unruptured aneurysms should be managed. Treatment methods include two major intervention options: clipping of the aneurysm and endovascular methods such as coiling, stent-assisted coiling, and flow diversion stents. The studies reviewed here support the generalized notion that endovascular treatment of UIA provides a safe and effective alternative to surgical treatment. The risks associated with endovascular repair are lower and incur shorter hospital stays for appropriately selected patients. The endovascular treatment option should be considered based on factors such as aneurysm size, location, patient medical history, and operator experience.

Stent-assisted embolization as "bailout" option in aortic aneurysm

The authors report two cases of stent-assisted embolization (SAE) in the aorta. In one case, SAE was performed for treatment of a pseudoaneurysm; the procedure consisted of stent placement and embolization with an AMPLATZER Vascular Plug and detachable coils through the stent struts. In the second case, SAE was performed to stop acute bleeding from an aortoureteral fistula. Before SAE in this case, the aortic bifurcation was reconstructed with self-expandable and balloon-expandable stents. SAE was technically successful in both cases. SAE for aortic pathologic processes may be useful in selected cases as an alternative to surgery or endovascular stent-graft therapy.

Endovascular Treatment of Posterior Circulation Fusiform Aneurysms: Single-Center Experience in 31 Patients

BACKGROUND:

Posterior circulation fusiform aneurysms are rare but difficult to treat.

OBJECTIVE:

To report our experience with endovascular treatment of posterior circulation fusiform aneurysms.

METHODS:

A retrospective review of our prospectively maintained database identified all posterior circulation fusiform aneurysms treated by endovascular approach over a 6-year period. Clinical charts, procedural data, and angiographic results were reviewed.

RESULTS:

From March 2004 to March 2010, 31 patients were identified: 11 asymptomatic patients, 9 who presented with a subarachnoid hemorrhage, 6 with a stroke, and 5 with a mass effect. All but 1 patient (97%), who died before being treated, were successfully treated by parent artery occlusion (n = 10), stenting plus coiling (n = 10), or stenting alone with conventional or flow-diverting stents (n = 10). Twenty-two patients showed a good or an excellent outcome (73%); 3 had a fair or a poor outcome (10%); and 5 patients died (17%). These 8 patients initially presented with severe subarachnoid hemorrhage or mass effect. Procedure-related morbidity includes only one patient who kept a worsening of cranial nerve palsies. There was no definitive procedure-related morbidity or mortality. Immediate aneurysm occlusion was incomplete in 20 cases (67%) and complete in 10 cases (33%). Mean follow-up of 20 months in 23 patients showed 12 further thromboses, 9 stable results, and 2 flow reductions. Final results included 19 complete occlusions (83%) and 4 incomplete occlusions (17%).

CONCLUSION:

Posterior circulation fusiform aneurysms may be treated by different endovascular approaches with satisfying clinical and anatomical results in most cases. However, patients who present with severe subarachnoid hemorrhage or mass effect still have a poor prognosis.