Prospective Study of Early MRI Appearances following Flow-Diverting Stent Placement for Intracranial Aneurysms

BACKGROUND AND PURPOSE:MR imaging findings of aneurysm enlargement, aneurysm wall enhancement, perianeurysmal edema, and embolic phenomena following deployment of flow-diverting stents may be relevant to those patients who subsequently experience procedure-related intracranial hemorrhage. We sought to document the routine early postoperative MR imaging findings following flow-diverting stent insertion.MATERIALS AND METHODS:Patients requiring flow-diverting stent placement for treatment or retreatment of cerebral aneurysms were prospectively included in the study during a 26-month period. Early postprocedural MR imaging studies were obtained and compared with preoperative imaging. Patient clinical outcome data were also collected.RESULTS:There were 34 stent-placement procedures during the study period. Aneurysm mural enhancement and mild new perianeurysmal edema were present in 50% and 14%, respectively. Any DWI lesion was present in 57% of cases. New or possibly new foci of susceptibility effect were found ipsilateral to the stent and not associated with diffusion restriction in 66% of cases. There were 2 cases (6%) of parenchymal hemorrhage and 2 major clinical complications (6%) causing permanent morbidity.CONCLUSIONS:Asymptomatic aneurysm mural enhancement is frequently seen following flow-diverting stent placement and should not necessarily be interpreted as a sign of impending aneurysm rupture. This finding often persists despite complete aneurysm occlusion. New small brain parenchymal susceptibility foci following stent placement have not previously been reported, to our knowledge, but were common in our series.

Following flow-diverting stent placement to treat intracranial artery aneurysms, complications of delayed aneurysmal and parenchymal hemorrhage, with or without preceding symptomatology, have been described.^1–5 Speculation remains regarding the etiology of both forms of hemorrhage, with an overall hemorrhage risk of 7% in reported series.⁶ Delayed parenchymal hemorrhages typically occur on the side of the treated aneurysm and at an incidence in excess of that expected due to dual antiplatelet medication alone and from that reported in prior non-flow-diverting-stent literature.^7,8 MR imaging case reports have identified perianeurysmal edema, aneurysm expansion, and aneurysm wall enhancement in symptomatic patients before delayed aneurysm rupture.^1,2 It is unknown whether such findings are predictive of subsequent aneurysm rupture. Microembolic change on diffusion imaging is common following angiographic procedures, and hemorrhagic transformation of infarcts is one putative cause of the parenchymal hemorrhages. We sought to document the routine early postprocedural MR imaging findings following flow-diverting stent insertion.     

Middle Cerebral Artery Bifurcation Aneurysms Treated by Extrasaccular Flow Diverters: Midterm Angiographic Evolution and Clinical Outcome

BACKGROUND AND PURPOSE:Flow diverters have been increasingly used lately in off-label, distal intracranial aneurysm treatments. Our aim was to evaluate the effectiveness of flow diverters in the treatment of middle cerebral artery bifurcation aneurysms and to analyze midterm angiographic patterns of regional flow modifications for safety and clinical outcomes.MATERIALS AND METHODS:Consecutive patients treated from January 2010 to December 2014 by the authors by using endovascular flow-diverting stents for MCA bifurcation aneurysms were evaluated retrospectively with prospectively maintained data. All patients had been followed for at least 12 months after treatment, with at least 2 control angiograms; regional flow-related angiographic modifications were registered by using a new angiographic outcome scale for flow diverters. Data were analyzed with emphasis on procedure-related events, angiographic results, and clinical outcome.RESULTS:Fifty-eight patients were included in the study, with 63 MCA bifurcation aneurysms; 13 of these were large and giant. Pretreatment mRS was 0 for 12 patients (20.7%), 1 for 41 (70.7%), and 2 for 5 patients (8.6%). Six-month control revealed mRS 0–2 for 57 (98.3%) patients and 3 for 1 (1.7%) patient. Procedure-related morbidity and mortality were 8.6% (5/58) and 0%, respectively. From 95% of still circulating immediate postprocedure angiographic outcomes, 68% progressed to aneurysm occlusion at 6 months and 95%, to occlusion at 12 months, with a 0% aneurysm rupture rate.CONCLUSIONS:Flow diverters seem to be an effective treatment alternative for complex MCA bifurcation aneurysms, with reasonable complication rates. Longer angiographic follow-ups are needed to assess the morphologic outcome; immediate subtotal occlusions do not seem to be related to rupture.

Flow-diverter (FD) stents have provided a paradigm shift in endovascular cerebral aneurysm treatment. Initially approved for carotid aneurysms, their use has been extended to include distal intracranial localizations such as MCA aneurysms.¹ Covering intracranial arteries with FDs has recently been the subject of debate. While for localizations such as the posterior communicating artery,² side branch coverage does not seem to have clinical consequences for patients, controversy exists regarding MCA branches.The objectives of our study were to evaluate the clinical and midterm angiographic outcomes of FD stent placement for MCA bifurcation aneurysms with emphasis on the regional flow-induced modifications and their impact; the analysis was performed by using an angiographic classification³ that takes into account the hemodynamic evolution of the aneurysm and the regional anatomy with time.     

Visual Outcomes with Flow-Diverter Stents Covering the Ophthalmic Artery for Treatment of Internal Carotid Artery Aneurysms

BACKGROUND AND PURPOSE:Flow-diverting stents can be used to treat intracranial aneurysms that are not amenable to treatment with coils. We analyzed ophthalmic consequences due to coverage of the origin of the ophthalmic artery by flow-diverting stents for the treatment of internal carotid artery aneurysms.MATERIALS AND METHODS:From April 2009 to April 2013, the clinical and angiographic outcomes of all 28 patients treated for aneurysms with flow-diverting stents covering the origin of the ophthalmic artery were prospectively collected. The origin of the ophthalmic artery in relation to the target aneurysm was classified by using a 4-type classification. A complete ophthalmic examination was performed by a single ophthalmologist 48 hours before and 1 week after covering the ophthalmic artery.RESULTS:Ophthalmic artery patency was normal at the end of endovascular treatment in 24/28 cases (85.7%). With extensive ophthalmic examinations, 11 patients (39.3%) showed new ophthalmic complications. Patients with the ophthalmic artery originating from the aneurysm sac were at high risk for retinal emboli (4/5, 80%). Patients with the ophthalmic artery originating from the inner curve of the carotid siphon were at high risk for optic nerve ischemic atrophy (3/4, 75%).CONCLUSIONS:This prospective study shows that covering the ophthalmic artery with a flow-diverting stent is not without potential complications. Ophthalmic complications can occur but are often not diagnosed. The anatomic disposition of the ophthalmic artery in relation to the carotid siphon and aneurysm should be clearly understood because some configurations have a higher risk. When not required, covering of the ophthalmic artery by flow-diverting stents should be avoided.

Flow-diverting stents (FDSs) are commonly used for the endovascular reconstruction of a segmentally diseased parent vessel and treatment of large-neck intracranial aneurysms, which can be difficult to reconstruct with coils, even when used with large-cell stents.^1–6 FDSs aim to maintain normal blood flow through parent and branch vessels while disrupting flow into the aneurysm, causing thrombosis, and eventually sealing the aneurysm ostium through neointimal proliferation across the device struts.^6–8 Good angiographic and clinical results have been achieved in small series.^4–6,9–12One issue concerning intracranial aneurysm treatment by an FDS is the patency of the perforating arteries and side branches covered by the device.¹³ FDSs are designed to provide sufficient coverage across the aneurysm neck to exclude the lesion from circulation but to be porous enough to preserve the patency of any branch vessels covered by the construct through the interstices between the device strands.¹³ The flow into the regional perforators and branch arteries is governed by different factors from those that drive flow into an aneurysm, and the patency of the perforators is maintained by a suction effect due to lower pressure in those branches.¹⁴ This has been studied with histologic evaluation of the Pipeline Embolization Device (PED; Covidien, Irvine, California) in rabbit aorta, demonstrating rounded funnel-like defects into the homogeneous sheet of neoendothelium on the FDS in regard to the orifices of the regional branches.¹⁵This pressure gradient may, however, be less important in vessels that have robust competitive collateral flow.¹⁵ This is most frequently seen when constructs are built over the ophthalmic artery, which occasionally becomes occluded when covered by multiple devices.⁸ In these situations, competitive collateral flow from the external carotid artery may create a “flow equalization point,” resulting in slow flow or proximal occlusion of the ophthalmic artery because of its retrograde supply from the external carotid artery circulation.^15,16 Recently, a study evaluated the patency rate of the ophthalmic artery with standard digital subtraction angiography and any change in angiographic flow in the artery immediately after FDS placement across the arterial inlet for the treatment of 20 proximal ICA aneurysms.¹⁷ This study assessed 21% of ophthalmic artery occlusions and 11% of ophthalmic arteries with slow antegrade flow. In this small, retrospective series, no visual worsening was observed in case of flow change in the ophthalmic artery, but only 5 patients had a detailed ophthalmic examination.¹⁷ Because small visual field amputations due to ischemic lesions can be easily underdiagnosed and they are often asymptomatic, it appears mandatory to explore ophthalmic disorders with a complete examination to identify even small deficits.In this study, we analyzed ophthalmic consequences due to coverage of the ophthalmic artery by the implantation of an FDS covering the origin of the ophthalmic artery for the treatment of terminal ICA aneurysms. This analysis focuses on the anatomy of the origin of the ophthalmic artery in relation to the target aneurysm.     

Flow Diversion with Low-Profile Braided Stents for the Treatment of Very Small or Uncoilable Intracranial Aneurysms at or Distal to the Circle of Willis

BACKGROUND AND PURPOSE:The endovascular treatment of aneurysms located at or distal to the circle of Willis and not amenable to coiling remains a challenge. We report our experience with flow-diversion treatment using low-profile braided stents as a stent monotherapy procedure for treating distally located very small or uncoilable aneurysms.MATERIALS AND METHODS:We retrospectively reviewed our data bases to identify patients with aneurysms located at or distal to the circle of Willis who were treated with stent monotherapy using low-profile braided stents. The immediate and follow-up angiographic findings and clinical status of the patients were assessed.RESULTS:Twenty aneurysms in 19 patients were included in the study. The mean size of the aneurysms was 4.7 ± 2.4 mm. Patients were treated via telescopic implantation of 2 stents for 11 aneurysms; single-stent placement was used for the remaining aneurysms. The technical success rate was 95%. We observed a technical complication in 1 case (5.3%) and a late ischemic event in another (5.3%). The final angiographies during a mean follow-up of 14.7 months showed complete aneurysm occlusion in 73.7%. The complete occlusion rate of the aneurysms treated with telescopic stent placement was 81.8%. The modified Rankin scale scores of all patients at the last follow-up were between 0 and 2.CONCLUSIONS:Flow diversion with low-profile braided stents as a stent monotherapy procedure for very small or uncoilable intracranial aneurysms located at or beyond the circle of Willis is a promising, relatively safe, and durable endovascular procedure.

In the past decade, several self-expandable stents dedicated to intracranial use have been introduced to treat wide-neck and complex aneurysms previously not amenable to coiling.^1–4 Stents create a mechanical scaffold, which prevents coil protrusion into the parent artery. In addition to this mechanical scaffolding effect, the implantation of stents also produces hemodynamic and biologic effects in the parent arteries that promote aneurysm occlusion. Stent deployment across the orifice of an aneurysm redirects the blood flow in the parent artery to decrease hemodynamic stress, which facilitates thrombosis in the aneurysmal sac.⁵ Furthermore, stents induce neointimal proliferation in the parent artery, which eventually leads to healing of the aneurysm neck.⁶ The hemodynamic and biologic effects of stents promote the progressive occlusion of partially coiled aneurysms and impede their recanalization.On the basis of the hemodynamic and biologic effects of stents, flow-diversion treatment as a stent monotherapy procedure using conventional stents has been proposed for the endovascular treatment of intracranial aneurysms not amenable to coiling or alternative open surgical procedures.⁷ Flow diversion as a stent monotherapy procedure consists of the implantation of a self-expandable stent or stents across the neck of an aneurysm, without coiling the aneurysm sac. A limited number of previous case series reported the application of stent monotherapy with balloon-expandable or conventional self-expandable stents and focused on the treatment of aneurysms located proximal to the circle of Willis.^7–10Low-profile braided stents have been recently introduced to treat aneurysms located at small-sized, distal parent arteries. Low-profile intracranial stents can be deployed into arteries with diameters between 1.5 and 3.5 mm, and they can be delivered through microcatheters with an internal diameter of 0.0165 inches, which allows easier navigation in small-sized, delicate vessels.¹¹ In this report, we present our experience with flow-diversion treatment as a stent monotherapy procedure for treating very small or uncoilable intracranial aneurysms located at or beyond the circle of Willis using low-profile braided stents. In this retrospective study, we investigated the feasibility, efficacy, and midterm durability of the stent monotherapy procedure with LEO Baby stents (Balt, Montmorency, France).     

Endovascular Treatment of Middle Cerebral Artery Aneurysms with Flow Modification with the Use of the Pipeline Embolization Device

BACKGROUND AND PURPOSE:The Pipeline Embolization Device was reported to be safe and effective in the treatment of sidewall aneurysms, preserving the patency of the vessels covered by the construct. However, to date, the safety and efficacy of this device in treating bifurcation aneurysms remains unknown. We report our preliminary experience with the use of the Pipeline Embolization Device in the management of MCA aneurysms located at the bifurcations, including mid- and long-term follow-up data.MATERIALS AND METHODS:Wide-neck MCA aneurysms, which give rise to a bifurcating or distal branch in which other endovascular techniques are thought to be unfeasible or more risky, were included. Data including demographics, aneurysm features, antiplatelet therapy, complications, and angiographic follow-up results for up to 30 months were recorded.RESULTS:Twenty-five aneurysms located at the MCA bifurcation (n = 21) or distal (n = 4) were treated. Of these, 22 were small and 3 were large. A single device was used in all but 2. No deaths occurred in the series. All patients had at least 1 control angiographic study, 21 of which were DSA (3–30 months), which showed that 12 of the rising branches were patent whereas 6 were filling in reduced caliber and 3 were occluded asymptomatically. According to the last angiographic follow-up, complete occlusion was revealed in 21 of 25 aneurysms (84%).CONCLUSIONS:The Pipeline Embolization Device provides a safe and effective treatment alternative for wide-neck MCA aneurysms that give rise to a bifurcating or distal branch when other endovascular techniques are thought to be unfeasible or more risky.

Providing diseased parent artery reconstruction in addition to exclusion of the aneurysm from the circulation by means of flow disruption, spontaneous aneurysm thrombosis, and endothelialization mechanisms, flow diversion is a new but widely accepted endovascular treatment technique for intracranial aneurysms. The use of self-expandable neurovascular stents (designed to be used in conjunction with coil embolization) as a monotherapy was previously reported with the implantation of 1 or more stents.^1–5 A few case series with the use of the sole stent placement technique in the treatment of complex fusiform MCA aneurysms also exist in the literature.^6,7 Additionally, Y-stent flow diversion by use of self-expandable stents with a closed-cell design without endosaccular coiling has also been reported to be effective in a small, selected case series, including 5 MCA bifurcation aneurysms with complete occlusion in the follow-up.⁸The introduction of the Pipeline Embolization Device (PED) (Covidien/ev3, Irvine, California) as a dedicated flow diverter added a new dimension to this treatment strategy, with its being porous enough to preserve the patency of the branch vessels covered by the construct.⁹ The previous experience with the PED in the treatment of saccular aneurysms revealed that when a branch was originating directly from the aneurysm sac, this branch was kept patent when there was a flow demand through it.¹⁰ Although, to date, the safety and efficacy of this device in treating bifurcation aneurysms remains unknown. This inspired us to use the PED for treatment of MCA bifurcation or M2 aneurysms in which one of the bifurcating branches or a distal branch originate directly from the aneurysm sac, when other endovascular techniques were deemed unfeasible or more risky. There have been limited numbers of MCA aneurysms reported to be treated with the PED within different case series^11–15; however, none included bifurcation aneurysms. We report, to our knowledge, the first case series focused on the use of the PED in the management of MCA aneurysms, in which a bifurcating or a distal branch emanates directly from the aneurysm sac.     

Evaluation of the Angiographic Grading Scale in Aneurysms Treated with the WEB Device in 80 Rabbits: Correlation with Histologic Evaluation

BACKGROUND AND PURPOSE:The WEB Occlusion Score has been proposed to assess angiographic outcomes for intracranial aneurysms treated with the Woven EndoBridge (WEB) device. Using a large series of experimental aneurysms treated with the WEB, we had the following objectives: 1) to compare angiographic outcomes as measured by the WEB Occlusion Scale with histologic results, and 2) to assess interobserver and intraobserver agreement of the WEB Occlusion Scale.MATERIALS AND METHODS:Intracranial aneurysms were created in 80 rabbits and treated with WEB devices. Animals were sacrificed at last follow-up for histologic evaluation. DSA was performed just after the deployment of the device and at follow-up. Four investigators independently and retrospectively graded the DSA twice according to the WEB Occlusion Scale. One histopathologist blinded to the angiographic results graded the occlusion according to a 4-point scale patterned on the WEB Occlusion Scale. Intra- and interobserver agreement were evaluated for DSA. Follow-up angiographic grading and histologic reference were compared to determine the WEB Occlusion Scale accuracy for complete (with or without recess filling) versus incomplete occlusion and adequate (complete occlusion or neck remnant) versus inadequate occlusion.RESULTS:Inter- and intraobserver weighted κ for the angiographic WEB Occlusion Scale were, respectively, 0.76 and 0.76, indicating substantial agreement. The sensitivity and specificity of the WEB Occlusion Scale for complete occlusion at follow-up compared with the histologic reference standard were, respectively, 75% and 83.3%, with an overall accuracy of 80%. Similarly, for adequate occlusion at follow-up, sensitivity was 97.7%, specificity was 64.9%, and overall accuracy was 82.5%.CONCLUSIONS:The WEB Occlusion Scale appears to be consistent, reliable, and accurate compared with a histologic reference standard.

The Woven EndoBridge (WEB) device (Sequent Medical, Aliso Viejo, California) is a new and promising tool in the treatment of wide-neck and bifurcation intracranial aneurysms.^1–4 The endosaccular implant conforms to the aneurysm wall and spans the aneurysm neck to essentially function as a flow diverter at the aneurysm neck–parent artery interface. Initial experimental and clinical studies have demonstrated that the WEB is both safe and effective in the treatment of intracranial aneurysms.^1–9Because the mechanism of action of the device differs from that in flow diverters and endosaccular coils, developing tools to assess angiographic occlusion has become a recent priority among many neurointerventionists, and several grading scales have been proposed.^4,7–10 Perhaps the most commonly used scale is the WEB Occlusion Scale (WOS).⁷ However, none of these scales, including the WOS, has previously been validated with histologic studies, to our knowledge. In a large series of elastase-induced aneurysms in rabbits treated with the WEB device, the objectives of this study were the following: 1) to compare angiographic outcomes as measured by the WOS with histologic results, and 2) to assess interobserver and intraobserver agreement of the WOS.     

Posterior Inferior Cerebellar Artery Patency after Flow-Diverting Stent Treatment

BACKGROUND AND PURPOSE:The rate of PICA occlusion after flow-diverting stent placement for vertebral and vertebrobasilar artery aneurysms is not known. The purpose of this study is to determine the medium-term rate of PICA patency and risk factors for occlusion after such aneurysm treatment.MATERIALS AND METHODS:Patients were identified who had vertebral or vertebrobasilar artery aneurysms and who were treated by placing a flow-diverting stent across the PICA ostium. Demographic and procedural factors associated with stent placement were recorded. Patency of the PICA was evaluated immediately after stent placement and on follow-up angiography.RESULTS:Thirteen patients with vertebral or vertebrobasilar artery aneurysms were treated in the study period, of whom 4 presented with subarachnoid hemorrhage. The average number of devices that spanned the PICA ostium was 1.77 (range, 1–3), with no immediate PICA occlusions. There were no postoperative strokes in the treated PICA territory, although there was 1 contralateral PICA-territory stroke of unclear etiology without clinical sequelae. In 11 patients with follow-up angiography at a mean of 10.6 months (range, 0.67–27.9 months), the PICA patency rate remained 100%.CONCLUSIONS:Flow-diverting stent placement across the PICA ostium in the treatment of vertebral and vertebrobasilar artery aneurysms may not result in immediate or midterm PICA occlusion.

The initial studies of safety and efficacy of flow-diverting stents (FDSs), such as the Pipeline Embolization Device (Covidien, Irvine, California), for the treatment of intracranial aneurysms primarily focused on anterior circulation aneurysms.¹ The application of an FDS in posterior circulation aneurysms remains controversial due to an increased risk of thrombotic and hemorrhagic complications.^2–4 The location of some vertebral and vertebrobasilar aneurysms in relation to the PICA often necessitates stent placement across the arterial ostium, theoretically risking PICA occlusion with resultant brain stem infarction. The immediate and midterm rate of branch occlusion of the PICA after FDS placement has not been described.     

Predictors of Incomplete Occlusion following Pipeline Embolization of Intracranial Aneurysms: Is It Less Effective in Older Patients?

BACKGROUND AND PURPOSE:Flow diversion with the Pipeline Embolization Device (PED) for the treatment of intracranial aneurysms is associated with a high rate of aneurysm occlusion. However, clinical and radiographic predictors of incomplete aneurysm occlusion are poorly defined. In this study, predictors of incomplete occlusion at last angiographic follow-up after PED treatment were assessed.MATERIALS AND METHODS:A retrospective analysis of consecutive aneurysms treated with the PED between 2009 and 2016, at 3 academic institutions in the United States, was performed. Cases with angiographic follow-up were selected to evaluate factors predictive of incomplete aneurysm occlusion at last follow-up.RESULTS:We identified 465 aneurysms treated with the PED; 380 (81.7%) aneurysms (329 procedures; median age, 58 years; female/male ratio, 4.8:1) had angiographic follow-up, and were included. Complete occlusion (100%) was achieved in 78.2% of aneurysms. Near-complete (90%–99%) and partial (<90%) occlusion were collectively achieved in 21.8% of aneurysms and defined as incomplete occlusion. Of aneurysms followed for at least 12 months (211 of 380), complete occlusion was achieved in 83.9%. Older age (older than 70 years), nonsmoking status, aneurysm location within the posterior communicating artery or posterior circulation, greater aneurysm maximal diameter (≥21 mm), and shorter follow-up time (<12 months) were significantly associated with incomplete aneurysm occlusion at last angiographic follow-up on univariable analysis. However, on multivariable logistic regression, only age, smoking status, and duration of follow-up were independently associated with occlusion status.CONCLUSIONS:Complete occlusion following PED treatment of intracranial aneurysms can be influenced by several factors related to the patient, aneurysm, and treatment. Of these factors, older age (older than 70 years) and nonsmoking status were independent predictors of incomplete occlusion. While the physiologic explanation for these findings remains unknown, identification of factors predictive of incomplete aneurysm occlusion following PED placement can assist in patient selection and counseling and might provide insight into the biologic factors affecting endothelialization.

The flow-diverting Pipeline Embolization Device (PED; Covidien, Irvine, California) has become a mainstay for the treatment of intracranial aneurysms.¹ The device was approved by the US Food and Drug Administration in 2011 for the treatment of large or giant, wide-neck brain aneurysms along the internal carotid artery in adults.² Numerous studies have since demonstrated the safety and efficacy of the PED in treating aneurysms with varying morphologies in different anatomic locations.^3–8 As the clinical indications for PED placement expand, predictors of radiographic outcomes have become a topic of ongoing investigation. Although 1 study found that fusiform aneurysm morphology and shorter follow-up length were independent predictors of incomplete occlusion, this study was limited by a small sample size and a mean follow-up of 6.1 months.⁹ The expanding use of PEDs for treating intracranial aneurysms necessitates an evaluation of predictors of incomplete occlusion.     

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 stent-assisted coiling technique has broadened the indication for coil embolization, and numerous reports have depicted the value of stents in the treatment of cerebral aneurysms.^1–6We present herein the clinical and angiographic results of a consecutive series of 1815 aneurysms treated over a 9-year period. The aims of this retrospective study were to place the role of stent-assisted coiling into perspective and to determine the factors associated with procedural complications.     

Flow Diversion in Ruptured Intracranial Aneurysms: A Meta-Analysis

BACKGROUND:Flow diversion is now an established technique to treat unruptured intracranial aneurysms not readily amenable to endovascular coil embolization or open microsurgical occlusion. The role of flow-diverting devices in treating ruptured aneurysms is less clear.PURPOSE:To estimate rates of angiographic occlusion and good clinical outcome in patients with ruptured intracranial aneurysms treated with flow-diverting devices.DATA SOURCES:Systematic review of Ovid MEDLINE, PubMed, Cochrane databases, and EMBASE from inception to December 2015 for articles that included ruptured aneurysms treated with flow diversion.STUDY SELECTION:One hundred seventy-two records were screened, of which 20 articles contained sufficient patient and outcome data for inclusion.DATA ANALYSIS:Clinical and radiologic characteristics, procedural details, and outcomes were extracted from these reports. Aggregated occlusion rates and clinical outcomes were analyzed by using the Fisher exact test (statistical significance, α = .05).DATA SYNTHESIS:Complete occlusion of the aneurysm was achieved in 90% of patients, and favorable clinical outcome was attained in 81%. Aneurysm size greater than 7 mm was associated with less favorable clinical outcomes (P = .027). Aneurysm size greater than 2 cm was associated with a greater risk of rerupture after treatment (P < .001).LIMITATIONS:Observational studies and case reports may be affected by reporting bias.CONCLUSIONS:Although not recommended as a first-line treatment, the use of flow diverters to treat ruptured intracranial aneurysms may allow high rates of angiographic occlusion and good clinical outcome in carefully selected patients. Aneurysm size contributes to treatment risk because the rerupture rate following treatment is higher for aneurysms larger than 2 cm.

Endovascular treatment of intracranial aneurysms with detachable coils was first described in 1991¹ and has since become an established method of aneurysm treatment. The International Study of Unruptured Intracranial Aneurysms² and Analysis of Treatment by Endovascular Approach of Nonruptured Aneurysms (ATENA)³ demonstrated the effectiveness and relative safety of endovascular coiling for unruptured aneurysms. Similarly, the International Subarachnoid Aneurysm Trial (ISAT), the Barrow Ruptured Aneurysm Trial, and other trials^4–7 have demonstrated the effectiveness and relative safety of endovascular coiling in ruptured aneurysms.In recent years, flow diverters (FDs) have emerged as a new endovascular treatment option for intracranial aneurysms. FDs are a reconstructive treatment in which altered flow within an aneurysm induces gradual remodeling and eventual thrombosis of the aneurysm. Several studies have demonstrated good safety and efficacy of FDs for the treatment of unruptured intracranial aneurysms,^8–17 though the safe use of these devices requires the use of dual antiplatelet therapy.^18–20Understandably, the need for antiplatelet medications and the delayed nature of aneurysm thrombosis have tempered enthusiasm for using FDs for ruptured aneurysms. Nevertheless, several reports have described the use of FDs to treat recently ruptured aneurysms, particularly those that are difficult to treat by other endovascular or open microsurgical techniques.In this meta-analysis, we review the outcomes associated with the use of FDs for the treatment of ruptured intracranial aneurysms. Specifically, we review aneurysm characteristics and endovascular treatment strategies in relation to the rates of angiographic occlusion and good clinical outcome, with the overall goal of guiding FD use in ruptured aneurysms when other treatment options are not viable.     

Effects of Circle of Willis Anatomic Variations on Angiographic and Clinical Outcomes of Coiled Anterior Communicating Artery Aneurysms

BACKGROUND AND PURPOSE:Anterior communicating artery aneurysms account for one-fourth of all intracranial aneurysms and frequently occur in the context of A1 vessel asymmetry. The purpose of this study was to correlate circle of Willis anatomic variation association to angiographic and clinical outcomes of anterior communicating aneurysm coiling.MATERIALS AND METHODS:The Cerecyte Coil Trial provides a subgroup of 124 cases with anterior communicating artery aneurysms after endovascular coiling. One hundred seventeen of 124 anterior communicating artery aneurysms had complete imaging and follow-up for clinical outcome analysis, stability of aneurysm coil packing, and follow-up imaging between 5 and 7 months after treatment. Clinical outcomes were assessed by the mRS at 6 months.RESULTS:Anterior cerebral artery trunk-dominance was seen in 91 of 124 (73%) anterior communicating artery aneurysms and codominance in 33 of 124 (27%) anterior communicating artery aneurysms. There was no significant difference (P > .5) in treatment success at 5–7 months for anterior communicating artery aneurysms between the anterior cerebral artery trunk-dominant (49 of 86, 57%) and anterior cerebral artery trunk-codominant (19 of 31) groups. Angiographic follow-up demonstrates a statistically significant increase in neck remnants and progressive aneurysm sac filling with the A1 dominant configuration (n = 21, 24% at follow-up versus n = 11, 12% at immediate posttreatment, P = .035). There was no statistically significant difference in clinical outcomes between types of anterior cerebral artery trunk configuration (P > .5).CONCLUSIONS:Anterior communicating artery aneurysms with anterior cerebral artery trunk-dominant circle of Willis configurations show less angiographic stability at follow-up than those with anterior cerebral artery trunk-codominance similar to other “termination” type aneurysms. This supports the hypothesis that anterior cerebral artery trunk-dominant flow contributes to aneurysm formation, growth, and instability after coiling treatment.

The most common site of intracranial aneurysms is the anterior communicating artery (AcomA). AcomA aneurysms account for approximately one-fourth of all intracranial aneurysms.¹ Also very common in the setting of AcomA aneurysms is unilateral anterior cerebral artery trunk (A1) dominance where 1 side supplies both pericallosal artery (A2) arteries, a well-known phenomenon previously shown to be a potent risk factor for AcomA aneurysm formation and rupture.^1–3To what extent vessel dominance influences the long-term result of endovascular packing of these aneurysms with detachable platinum coils and the patients'' clinical outcome is less well known.^4–6 One previous study indicates that vessel dominance is not a major factor in predicting short-term treatment outcome; however, the methodology and definition of vessel dominance as used in this instance was not stated.⁷ Yet, anterior communicating aneurysms are commonly “termination type” with the aneurysm forming with a relatively wide neck at the site of the inferred jet of flowing blood dynamics, with main branches nearly perpendicular to the parent vessel, also commonly seen for basilar tip, internal carotid tip, and middle cerebral bifurcations.⁸The Cerecyte Coil Trial (CCT) was a prospective, randomized, controlled study that entered 500 cases comparing endovascular coiling of ruptured and unruptured cerebral aneurysms with either Cerecyte or bare platinum coils that showed no difference between groups.^9,10 There was an expected large subset of AcomA aneurysms within the CCT cohort (n = 124).⁹ Therefore, data from this trial provided a unique opportunity to obtain a large number of AcomA aneurysm cases for determination of A1 dominance in relation to coiling treatment and angiographic outcomes immediately posttreatment and at follow-up. Our goal was to determine the impact of A1 dominance on treatment success, stability, and clinical outcomes of endovascularly coiled AcomA aneurysms.     

One-Year Angiographic Follow-Up after WEB-SL Endovascular Treatment of Wide-Neck Bifurcation Intracranial Aneurysms

BACKGROUND AND PURPOSE:Endovascular coiling of wide-neck intracranial aneurysms is associated with low rates of initial angiographic occlusion and high rates of recurrence. The WEB intrasaccular device has been developed specifically for this indication. To date, there has been no report of the long-term follow-up of a series of patients with aneurysms treated with this type of device, to our knowledge. Our aim was to evaluate a 1-year follow-up of angiographic results in a prospective single-center series of patients treated with the WEB-Single-Layer (SL) device.MATERIALS AND METHODS:All patients treated with the WEB-SL device in our center between August 2013 and May 2014 were prospectively included. One-year angiographic outcomes were assessed. Results at follow-up were graded as complete occlusion, neck remnant, or residual aneurysm.RESULTS:Eight patients with 8 unruptured wide-neck aneurysms were enrolled in this study. Average dome width was 7.5 mm (range, 5.4–10.7 mm), and average neck size was 4.9 mm (range, 2.6–6.5 mm). One-year angiographic follow-up obtained in all aneurysms included 1 complete aneurysm occlusion (12.5%), 6 neck remnants (75%), and 1 aneurysm remnant (12.5%). Of 8 aneurysms, worsening of aneurysm occlusion was observed in 2 (25%) by compression of the WEB device. There was no angiographic recurrence of initially totally occluded aneurysms. No bleeding was observed during the follow-up period.CONCLUSIONS:Endovascular therapy of intracranial aneurysms with the WEB-SL device allows treatment of wide-neck aneurysms with a high rate of neck remnant at 1 year, at least partially explained by WEB compression. Initial size selection and technologic improvements could be an option for optimization of aneurysm occlusion in WEB-SL treatment.

The WEB aneurysm embolization system (Sequent Medical, Aliso Viejo, California) is an intrasaccular braided device specifically developed for endovascular treatment of wide-neck intracranial aneurysms with the goal of disrupting flow at the aneurysm neck and promoting aneurysmal thrombosis without the need for reconstruction of the entire parent artery segment with a stent. Several types of WEB devices are currently available¹: the WEB-Dual-Layer (DL), which is made of 2 layers held together and creating 2 compartments, and the WEB-Single-Layer (SL), which is a single-layer device creating only 1 compartment. Only a few studies on the treatment of intracranial aneurysms by using the WEB-DL have been published,^2–5 and to date, only a single published article on aneurysms treated with WEB-SL reported a series including any anatomic follow-up.⁶ We recently published the 6-month clinical and anatomic outcomes of WEB-SL endovascular treatment.⁷The purpose of this study was to evaluate the 1-year angiographic results of patients managed with the WEB-SL device in a prospective single-center series.     

Large Basilar Apex Aneurysms Treated with Flow-Diverter Stents

BACKGROUND AND PURPOSE:The treatment of wide-neck, large basilar apex aneurysms is challenging with either an endovascular or a surgical approach. The aim of the present study was to report our experience treating basilar apex aneurysms with flow-diverter stents and to evaluate their efficacy and safety profile in this specific anatomic condition.MATERIALS AND METHODS:We retrospectively analyzed data from all consecutive patients treated with flow-diverter stents at our institution between January 2011 and January 2015. Patients with large basilar apex aneurysms treated with a flow-diverter stent were included in the study. Clinical presentations, technical details, intra- and perioperative complications, and clinical and angiographic outcomes were recorded, with a midterm follow-up.RESULTS:Of the 175 aneurysms treated with flow-diverter stents at our institution, 5 patients (2 women and 3 men; age range, 44–58 years) received flow-diverter stent for basilar apex aneurysms. The mean follow-up after stent deployment was 21 months (range, 15–24 months). One patient died on day 31 from an early postprocedural midbrain hemorrhage. One patient had a right cerebellar hemispheric ischemic lesion with a transient cerebellar syndrome resolved within 24 hours without neurologic sequelae at the latest follow-up. The mRS was 0 in 4 patients and 6 in 1 patient at last follow-up.CONCLUSIONS:Flow diversion is a feasible technique with an efficacy demonstrated at a midterm follow-up, especially in the case of basilar apex aneurysm recurrences after previous endovascular treatments. Concern about its safety profile still exists.

Wide-neck, large basilar apex aneurysms (BAA) are rare lesions that account for approximately 7%–8% of all intracranial aneurysms.^1,2 Their treatment is challenging when using either endovascular or surgical approaches.^3,4The endovascular approach is considered the “gold standard” for posterior circulation intracranial aneurysms because of a lower rate of procedural complications compared with surgery.⁵ However, long-term angiographic studies of large posterior circulation aneurysms after coiling show high recurrence rates.⁶The advent of flow-diverter stents has allowed for the treatment of wide-neck, large aneurysms with promising clinical and angiographic outcomes.^7–9 Only a few articles have reported the results of the use of flow-diverter stents in posterior circulation aneurysms,^7,10,11 and concerns remain regarding their use.Large BAAs are characterized by specific issues when a flow-diverter stent is the treatment of choice. These issues are mostly related to their anatomic location and include the risk of occlusion of the posterior cerebral (PCA) and superior cerebellar arteries,¹² brain stem ischemic lesions caused by coverage of the perforator arteries,¹³ and delayed rupture of the treated aneurysm.¹⁴The aim of this study was to report midterm follow-up results after the treatment of wide-neck, large BAAs with flow-diverter stents. We describe our experience in terms of the feasibility, safety, and efficacy of the procedure in this specific anatomic condition.     

The FRED Flow-Diverter Stent for Intracranial Aneurysms: Clinical Study to Assess Safety and Efficacy

BACKGROUND AND PURPOSE:Flow-diverter stents are emerging for the endovascular treatment of difficult-to-treat or otherwise untreatable cerebral aneurysms (wide-neck, fusiform, dissecting, blisterlike, or giant). We assessed the clinical safety and efficacy of the Flow-Redirection Endoluminal Device.MATERIALS AND METHODS:This was an institutional review board–approved single-center observational clinical study in 29 patients with 34 aneurysms elected to be treated by endovascular intervention. After providing informed consent, patients were included according to the following criteria: aneurysm fundus-to-neck ratio <2 or neck diameter >4 mm, fusiform, dissecting, or giant aneurysms. The primary end point for clinical safety was the absence of death, absence of major or minor stroke, and absence of transient ischemic attack. The primary end point for treatment efficacy was complete angiographic occlusion according to the O''Kelly Marotta grading scale immediately after the procedure and at follow-up after 3 and 6 months (O''Kelly Marotta D: complete occlusion).RESULTS:The Flow-Redirection Intraluminal Device deployment was technically successful in all cases. In 26/29 (89%) of patients, the primary end point of safety was reached; in the 3 remaining patients, 1 disabling ischemic stroke and 2 minor strokes with complete recovery at follow-up were observed. Angiographic (DSA and MRA) and clinical follow-up were available after 3 months in 29/29 (100%) and after 6 months in 25/29 (86%) patients (after 6 months, only MRA follow-up was performed according to our study protocol and institutional standard). At 3-month follow-up, complete occlusion was reached in 19/34 aneurysms (O''Kelly Marotta D: 19/34; 56%). At 6-month follow-up, aneurysm occlusion was complete in 22/30 aneurysms (O''Kelly Marotta D: 22/30; 73%).CONCLUSIONS:Deployment of the Flow-Redirection Intraluminal Device flow-diverter stent is safe and effective in the treatment of difficult-to-treat or otherwise untreatable intracranial aneurysms.

Endovascular treatment of intracranial aneurysms by coiling has become an accepted alternative to surgical clipping, with increasing evidence for lower morbidity and mortality rates, especially in clinical equipoise.^1–3 However, especially in wide-neck, fusiform, dissecting, and giant aneurysms, incomplete coiling and reperfusion are still a major limitation preventing stable long-term occlusion. Aneurysm recanalization and/or neck remnants may be observed despite further refinement in coil technology such as coated platinum coils⁴ and/or procedural modification such as the balloon-remodeling technique⁵ or stent-assisted coil embolization.⁶The development of flow-diverter (FD) stents has offered the potential of aneurysm occlusion through thrombosis triggered by the disruption of flow into the aneurysm sac.^7–16 As a key element of construction, these stents have a braided mesh with a densely covered surface. Once the FD is expanded to cover the aneurysm neck, thrombosis is induced by stasis of flow within the aneurysmal sac. The porosity of the FD mesh and the pressure gradient between parent and smaller adjacent branch vessels preserve flow and patency of the latter even if covered. The Flow-Redirection Endoluminal Device (FRED; MicroVention, Tustin, California) is a new generation of FDs for reconstruction of the parent artery and aneurysm occlusion. Its unique dual-layer design composed of a low-porosity inner mesh and a high-porosity outer stent may provide potential advantages over other available FDs in safe deliverability and effective occlusion of the target lesion. We report our analysis of the clinical safety and efficacy of the FRED in 29 patients with 34 aneurysms.     

Dual Stenting Using Low-Profile LEO Baby Stents for the Endovascular Management of Challenging Intracranial Aneurysms

BACKGROUND AND PURPOSE:Endovascular treatment of wide-neck, complex, and distally located cerebral aneurysms is a challenging issue. This study evaluated the safety and efficacy of dual stent placement by using a low-profile stent system (LEO Baby) for the treatment of challenging distal intracranial aneurysms.MATERIALS AND METHODS:We retrospectively reviewed patients in whom at least 1 LEO Baby stent was used in the context of dual stent placement for the treatment of intracranial aneurysms. Patients who were treated with dual stent-assisted coil embolization and telescopic implantation of LEO Baby stents were included in the study. Clinical and angiographic findings, procedural data, and follow-up are reported.RESULTS:Twelve patients were included in this study. Three patients presented with subarachnoid hemorrhage in the subacute-chronic phase, and the remaining patients had unruptured aneurysms. Nine patients were treated by using the dual stent-assisted coiling method. X- (nonintersecting), Y- (intersecting and reversible), T-, and parallel-stent configurations were performed for the dual stent-assisted coiling procedures. Three patients were treated by using telescopic stent placement for a flow diverter–like effect. The procedures were successful in all cases. Technical complications without a significant clinical adverse event developed in 2 patients. The 3- and 6-month control MRAs and DSAs demonstrated complete occlusion of the aneurysms in all patients except 1. All patients had good clinical outcomes on follow-up (mRS ≤1).CONCLUSIONS:The results of this small study showed the feasibility of dual stent placement by using low-profile LEO Baby stents to treat distally located complex intracranial aneurysms.

Coiling of intracranial aneurysms is safe and effective, but endovascular treatment of wide-neck and anatomically complex aneurysms remains challenging.¹ Self-expandable intracranial stents have been used in the past decade to achieve successful and durable coil embolizations of these aneurysms.^2–4 The placement of a stent bridging the ostium of a wide-neck aneurysm creates a scaffold, which prevents the protrusion or herniation of coils into the parent artery and results in denser coil packing. In addition to the mechanical effect, intracranial stents have hemodynamic and biologic effects.^5–8 Stent deployment across the orifice of an aneurysm is thought to redirect blood flow from the sac of the aneurysm toward the distal parent artery and decrease the hemodynamic stress that contributes to thrombosis of the aneurysmal sac.⁹ Furthermore, stent-induced neointimal overgrowth leads to the healing of the neck of the aneurysm.¹⁰ On the basis of these effects, stent monotherapy has been proposed as an alternative strategy for the endovascular treatment of uncoilable and complex intracranial aneurysms.^9–11 The telescopic placement of self-expandable intracranial stents can adequately divert the blood flow, especially for the treatment of blisterlike aneurysms.¹²Recently, low-profile, self-expandable, braided intracranial stents (LEO Baby [Balt, Montmorency, France] and LVIS Jr. [MicroVention, Tustin, California]) have been available for the endovascular treatment of complex and/or distal aneurysms.^13,14 These low-profile intracranial stents can be deployed into arteries with diameters of <3.5 mm and delivered through microcatheters with an internal diameter of 0.0165 inches, which allows easier navigation in small-sized, delicate vessels.A single stent may not suffice for the endovascular treatment of wide-neck and geometrically complex bifurcation aneurysms with involvement of 1 or both side branches. Endovascular treatment of these complex aneurysms often necessitates the implantation of 2 stents (ie, dual stent placement) in various configurations, such as Y-, X-, or parallel configurations.^14–16This retrospective study evaluated the safety and efficacy of dual stent placement by using a low-profile stent system (LEO Baby) for the treatment of challenging intracranial aneurysms.     

Stent-Assisted Coiling versus Coiling Alone in Unruptured Intracranial Aneurysms in the Matrix and Platinum Science Trial: Safety,Efficacy, and Mid-Term Outcomes

BACKGROUND AND PURPOSE:Stent-assisted coiling may result in less aneurysm recanalization but more complications than coiling alone. We evaluated outcomes of coiling with and without stents in the multicenter Matrix and Platinum Science Trial.MATERIALS AND METHODS:All patients in the Matrix and Platinum Science Trial with unruptured intracranial aneurysms treated per protocol were included. Baseline patient and aneurysm characteristics, procedural details, neurologic outcomes, angiographic outcomes, and safety data were analyzed.RESULTS:Overall, 137 of 361 (38%) patients were treated with a stent. Stent-coiled aneurysms had wider necks (≥4 mm in 62% with stents versus 33% without, P < .0001) and lower dome-to-neck ratios (1.3 versus 1.8, P < .0001). Periprocedural serious adverse events occurred infrequently in those treated with and without stents (6.6% versus 4.5%, P = .39). At 1 year, total significant adverse events, mortality, and worsening of mRS were similar in treatment groups, but ischemic strokes were more common in stent-coiled patients than in coiled patients (8.8% versus 2.2%, P = .005). However, multivariate analysis confirmed that at 2 years after treatment, prior cerebrovascular accident (OR, 4.7; P = .0089) and aneurysm neck width ≥4 mm (OR, 4.5; P = .02) were the only independent predictors of ischemic stroke. Stent use was not an independent predictor of ischemic stroke at 2 years (OR, 1.1; P = .94). Stent use did not predict target aneurysm recurrence at 2 years, but aneurysm dome size ≥10 mm (OR, 9.94; P < .0001) did predict target aneurysm recurrence.CONCLUSIONS:Stent-coiling had similar outcomes as coiling despite stented aneurysms having more difficult morphology than coiled aneurysms. Increased ischemic events in stent-coiled aneurysms were attributable to baseline risk factors and aneurysm morphology.

As intracranial aneurysm treatment has shifted in the past 30 years from exclusively surgical to predominantly endovascular, aneurysm morphologies once considered untreatable endovascularly are now treatable with coils, stents, and flow diverters.^1–3 Particularly for saccular aneurysms with broad necks and short domes, stent-assisted coiling has become a common technique.^4–8 Prior studies have reported that stent-coiling may result in less aneurysm recanalization over time but more complications—both intraprocedurally and in a delayed fashion—than coiling alone.^9–13 A recent large, single-institution, retrospective series described higher morbidity and mortality rates associated with the stent-coiling technique as compared with coiling either with or without balloon assistance.¹⁴Given that prospective data on stent-coiling are limited, we analyzed data from the prospective, randomized, multicenter Matrix and Platinum Science (MAPS) Trial ({"type":"clinical-trial","attrs":{"text":"NCT00396981","term_id":"NCT00396981"}}NCT00396981, www.clinicaltrials.gov). The MAPS Trial was primarily designed to determine whether polymer-modified coils or platinum bare metal coils result in lower aneurysm recanalization, lower aneurysm rupture or rerupture, or lower aneurysm retreatment. Although patients were randomly assigned to platinum bare metal coil or polymer-modified coil implantation, adjunctive devices (including balloons and stents) could be used in any case at the discretion of the operating physician.We compared baseline patient and aneurysm characteristics, procedural details, safety data, neurologic outcomes, and angiographic outcomes in MAPS patients with unruptured intracranial aneurysms who were treated with stent-coiling or coiling without stent placement. Additionally, we analyzed results for the subset of patients with wide-neck aneurysms.     

HydroCoils Are Associated with Lower Angiographic Recurrence Rates Than Are Bare Platinum Coils in Treatment of “Difficult-to-Treat” Aneurysms: A Post Hoc Subgroup Analysis of the HELPS Trial

BACKGROUND AND PURPOSE:The HydroCoil Endovascular Aneurysm Occlusion and Packing Study was a randomized controlled trial that compared HydroCoils to bare platinum coils. Using data from this trial, we performed a subgroup analysis of angiographic and clinical outcomes of patients with “difficult-to-treat” aneurysms, defined as irregularly shaped and/or having a dome-to-neck ratio of <1.5.MATERIALS AND METHODS:Separate subgroup analyses comparing outcomes of treatment with HydroCoils to that of bare platinum coils were performed for the following: 1) irregularly shaped aneurysms, 2) regularly shaped aneurysms, 3) aneurysms with a dome-to-neck ratio of <1.5, and 4) aneurysms with a dome-to-neck ratio of ≥1.5. For each subgroup analysis, the following outcomes were studied at the last follow-up (3–18 months): 1) any recurrence, 2) major recurrence, 3) re-treatment, and 4) an mRS score of ≤2. Multivariate logistic regression analysis was performed to determine if the HydroCoil was independently associated with improved outcomes in these subgroups.RESULTS:Among the patients with an irregularly shaped aneurysm, the HydroCoil was associated with lower major recurrence rates than the bare platinum coils (17 of 66 [26%] vs 30 of 69 [44%], respectively; P = .046). Among the patients with an aneurysm with a small dome-to-neck ratio, the HydroCoil was associated with lower major recurrence rates than the bare platinum coils (18 of 73 [24.7%] vs 32 of 76 [42.1%], respectively; P = .02). No difference in major recurrence was seen between HydroCoils and bare platinum coils for regularly shaped aneurysms (42 of 152 [27.6%] vs 52 of 162 [32.1%], respectively; P = .39) or aneurysms with a large dome-to-neck ratio (41 of 145 [28.3%] vs 50 of 155 [32.3%], respectively; P = .53).CONCLUSIONS:This unplanned post hoc subgroup analysis found that HydroCoils are associated with improved angiographic outcomes in the treatment of irregularly shaped aneurysms and aneurysms with a dome-to-neck ratio of <1.5. Because this was a post hoc analysis, these results are not reliable and absolutely should not alter clinical practice but, rather, may inform the design of future randomized controlled trials.

The HydroCoil Endovascular Aneurysm Occlusion and Packing Study (HELPS) was a randomized controlled trial that compared the rate of clinical and angiographic outcomes in patients treated with the HydroCoil Embolic System (MicroVention, Tustin, California) and those treated with bare platinum coils.¹ This study found a statistically significant lower rate of major recurrence among aneurysms treated with the HydroCoil (a secondary trial outcome) but found no difference in the rates of trial primary composite outcome, which was a composite measure of adverse outcomes including major aneurysm recurrence at 18 months after treatment and procedure-related deaths and morbidity that resulted in the patients not having follow-up angiography.Hydrogel coils are manufactured with an expansile hydrogel that has been shown to result in improved aneurysm filling when compared with bare platinum coils.² Experimental models have suggested that hydrogel-coated coils are more effective in filling areas of potential aneurysm growth, such as aneurysm rupture points, lobulations, and daughter sacs, and along the aneurysm neck.^3–5 Aneurysms with a small dome-to-neck ratio (D/N) (<1.5) and lobulated/irregularly shaped aneurysms have been identified as difficult to coil and at high risk of recanalization after coil embolization with bare platinum coils.⁶ On the basis of findings from experimental models, we hypothesized that HydroCoils would result in a significantly lower rate of aneurysm recurrence than would bare platinum coils in “difficult-to-treat” aneurysms, defined as irregularly shaped aneurysms and aneurysms with a D/N of <1.5. We evaluated this hypothesis by using data from the HELPS trial and performing the following subgroup analyses: 1) analysis of angiographic and clinical outcomes in treatment groups of patients with an irregularly or regularly shaped aneurysm treated with the HydroCoil versus those treated with a bare platinum coil and 2) analysis of angiographic and clinical outcomes of patients with a small D/N (<1.5) aneurysm or large D/N (≥1.5) aneurysm treated with the HydroCoil versus those treated with a bare platinum coil. Because this was not a prespecified subgroup analysis, it is important to mention that the results of this study should not be used to alter clinical management but, rather, to inform the design of future clinical trials.     

Preliminary results of the luna aneurysm embolization system in a rabbit model: a new intrasaccular aneurysm occlusion device

BACKGROUND AND PURPOSE:Recent advances in endovascular devices have been aimed at providing high density, mesh-like metallic materials across the aneurysm neck, in place of coil technology. Therefore our aim was to report the in vivo preclinical performance of a self-expanding intrasaccular embolization device.MATERIALS AND METHODS:Elastase-induced aneurysms were created in 12 rabbits. Each aneurysm was embolized with a Luna AES. DSA was performed preimplantation; 5, 10, and 30 minutes postimplantation; and at 1 month in 12 rabbits and at 3 months in 8 rabbits. Early postimplantation intra-aneurysmal flow was graded as unchanged, moderately diminished, or completely absent. One- and 3-month DSAs were graded by using a 3-point scale (complete, near-complete, or incomplete occlusion). Aneurysms were harvested for gross and microscopic histologic evaluation at 1 month (n = 4) and at 3 months (n = 8). Tissues within the aneurysm dome and across the aneurysm neck were assessed by using HE staining.RESULTS:Ten (83%) of 12 aneurysms demonstrated complete cessation of flow within 30 minutes of device implantation. At 1-month follow-up, 10 (83%) of 12 aneurysms were completely occluded. At 3 months, 7 of 8 (88%) aneurysms remained completely occluded. One-month gross examination in 4 rabbits demonstrated that membranous tissue completely covered the device in 3 subjects (75%). Microscopic examination showed that 3 aneurysms had loose connective tissue filling the aneurysm cavity. Three-month gross and microscopic examinations demonstrated membranous tissue completely covering the device, loose connective tissue filling the aneurysm cavity, and neointima formation crossing the aneurysm neck in 8 of 8 (100.0%) subjects.CONCLUSIONS:The Luna AES achieved high rates of complete angiographic occlusion and showed promising histologic findings in the rabbit aneurysm model.

The goals of endovascular procedures for the treatment of cerebral aneurysms are to exclude the aneurysm sac from the cerebral arterial circulation and preserve parent vessel patency. There are 2 main categories of endovascular aneurysm treatment, intrasaccular and endoluminal procedures.The safety and efficacy of intrasaccular detachable coil embolization is well documented^1–3 but has limitations. Even with evolving procedural techniques and technology, the rate of aneurysmal total occlusion remains suboptimal.^4,5 The prevalence of coil compaction, which results in posttreatment recanalization and recurrence, is frequent.^4,6,7Conceptually, endoluminal flow diverters direct blood flow away from the aneurysm cavity primarily by placing a stent-like device across the aneurysm neck. However, flow diverters have had limited clinical utility, though they have shown excellent occlusion rates, even in large and giant aneurysms.^8–12 These devices may remain problematic in ruptured aneurysms, not only because they require concomitant use of dual antiplatelet therapy but also because immediate aneurysm occlusion usually does not occur. Furthermore, there are drawbacks when placing these devices in bifurcation aneurysms due to the inherent design limitations.In the present study, we describe the in vivo performance of a new type of embolization device. This new device, the Luna AES (NFocus Neuromedical, Palo Alto, California) is a self-expanding ovoid braided implant that when placed into an aneurysm cavity, provides an attenuated mesh of metal across the neck. The purpose of this study was to evaluate the safety, performance, and efficacy of the Luna AES in the rabbit elastase-induced aneurysm model.     

Intrasaccular Flow Disruption in Acutely Ruptured Aneurysms: A Multicenter Retrospective Review of the Use of the WEB

BACKGROUND AND PURPOSE:Use of the WEB intra-aneurysmal flow-disruption device in unruptured wide-neck bifurcation aneurysms has proven safety and efficacy. However, ruptured aneurysms are underrepresented in existing studies. This retrospective multicenter study describes the use of the WEB in patients with a ruptured intracranial aneurysm.MATERIALS AND METHODS:Ten centers contributed to this study. Clinical and procedural data of 47 patients with 52 aneurysms were analyzed retrospectively together with follow-up angiographies.RESULTS:There were 37 anterior and 15 posterior circulation aneurysms with a neck size of ≥4 mm in 49 of 52 (94%) aneurysms; 45 (87%) aneurysms were <10 mm, and 2 were partially thrombosed. Successful placement of the WEB was possible in every case. Adjunctive devices were used in 8 of 52 (15%) aneurysms. Thromboembolic events were observed in 4 of 52 (8%) patients. Adverse events occurred in 15 patients with 16 aneurysms, 9 of which were potentially related to the WEB procedure (3 thromboembolic events, 5 protrusions, and 1 perforations; 2 perforations were caused by the wire or catheter), but none had a clinical impact. Four patients were retreated. Short-term follow-up in 25 of 39 patients revealed complete occlusion in 15 of 25 (60%), 5 of 25 (20%) with residual neck, and 5 of 25 (20%) with residual aneurysm filling. Short- to midterm imaging in 9 of 25 patients revealed complete occlusion in 5 (55.6%), residual neck in 2 (22%), and residual aneurysm filling in 2 (22%). Of 47 patients, 23 (49%) had an mRS score of 0, 1, or 2; 13 (28%) had an mRS score of 3 or 4; and none had an mRS score of 5 at discharge.CONCLUSIONS:This retrospective series showed good procedural safety, feasibility, and stability of midterm occlusion in ruptured wide-neck bifurcation aneurysms.

The prevalence of intracranial aneurysms in the general population ranges from 0.2% to 9.0%.^1,2 Aneurysmal subarachnoid hemorrhage occurs at an annual incidence of 7–13 per 100,000 person-years in most Western countries. It is associated with a high mortality rate of up to 50% and a high morbidity rate for patients admitted to the hospital.^3,4 The risk of rupture increases with aneurysm size and location.^5–9 The primary purpose of treating a ruptured aneurysm is to prevent recurrent hemorrhage in the acute and subacute phases.¹⁰ The preferred treatment in patients with SAH, endovascular coil occlusion may be limited by aneurysm geometry, particularly in wide-neck or broad-based aneurysms that typically necessitate the use of a stent for proper reconstruction of the neck and sufficient occlusion of the aneurysm sac. This treatment usually requires the use of antiplatelet medication, which may impose an increased risk in the presence of a recently ruptured aneurysm.¹¹The WEB aneurysm embolization system (WEB; Sequent Medical, Aliso Viejo, California) is a self-expanding microbraid mesh implant delivered through a microcatheter and sized to fit and occlude an aneurysm in a single step. Two versions are available: a dual-layer type (WEB-DL), which is composed of 2 concentric cages, and a single-layer type (WEB-SL or SLS). The available sizes range from 4 to 11 mm in diameter and 3 to 9 mm in height. The mesh is designed to disrupt the flow at the neck of the aneurysm and to ultimately exclude it from the blood flow while preserving the flow in the parent artery (Fig 1). It seems to be especially suitable for broad-based bifurcation aneurysms and may eliminate the need for other reconstructive measures inside the parent artery, such as placing a stent.¹² Numerous publications have described the successful use of the WEB in the treatment of unruptured wide-neck bifurcation aneurysms.^12–14 Just recently, a single-center experience with the WEB in 6 ruptured aneurysms was reported, and the results were promising.¹⁵ In this retrospective multicenter case series, we describe use of the WEB in 52 aneurysms in 47 patients who presented with subarachnoid hemorrhage secondary to a ruptured intracranial aneurysm.Open in a separate windowFig 1.A, WEB-DL, a double-layer microbraid, used in 37 of the 52 aneurysms in this series. B, WEB-SL, a single-layer implant, used in 15 of the 52 aneurysms in this series.     

Delayed ipsilateral parenchymal hemorrhage following flow diversion for the treatment of anterior circulation aneurysms

BACKGROUND AND PURPOSE:The PED is a flow-diverting stent designed for the treatment of cerebral aneurysms. We report 4 cases of delayed ipsilateral IPH following the technically successful treatment of anterior circulation aneurysms with the PED.MATERIALS AND METHODS:Clinical and imaging data from all patients undergoing aneurysm treatment with the PED at 2 institutions were analyzed to assess the incidence of delayed IPH after treatment with the PED.RESULTS:A total of 66 patients (47 anterior circulation) with cerebral aneurysms underwent treatment with a PED between January 2008 and November 2010. Four patients experienced delayed periprocedural IPH, all after the treatment of anterior circulation aneurysms (8.5%, 4/47). The aneurysm size ranged from 5 to 21 mm. All IPHs occurred within the cerebral hemisphere, ipsilateral to the treated aneurysm, and were anatomically remote from the treated aneurysms. All procedures were uncomplicated, and patients emerged from general anesthesia at neurologic baseline. The hemorrhages became clinically evident between 1 and 6 days after the procedure. Two patients had unfavorable outcomes (mRS scores, 4 and 6).CONCLUSIONS:Delayed IPH may occur after the treatment of anterior circulation aneurysms with flow diverters. This complication does not seem to be restricted to a specific aneurysm subtype and does not seem to be related to an intraprocedural complication or solely attributable to DAT.

Flow diverters have recently received full European Conformity Mark approval for commercialization within the European Union and FDA approval for their use within the United States. To date, the reported periprocedural and midterm follow-up results have been extremely impressive,^1–5 with very high rates of complete aneurysm occlusion and relatively low rates of postoperative morbidity and mortality. However, as more experience is accrued, their potential limitations and optimal applications are becoming increasingly evident.^6–12We report 4 cases of delayed ipsilateral IPH following the treatment of anterior circulation aneurysms with the PED.