Long-term clinical and angiographic follow-up results of the dual-layer flow diverter device (FRED) for the treatment of intracranial aneurysms in a multicenter study.

PURPOSE: Our aim was to determine the long-term safety and efficacy of the Flow Re-Direction Endoluminal Device (FRED) in this multicenter study with prospective design. MATERIALS-METHOD: This study included 136 consecutive patients with 155 aneurysms treated between March 2013 and June 2016 in 10 centers. Twenty-two (16.2%) patients presented with rupture of the index aneurysm. Large/giant aneurysms comprised 1/3 of the cohort. Adjuvant coil use during the treatment was 15.5%. The effectiveness measure in the study was the percentage of aneurysms with stable occlusion at follow-up. RESULTS: Vascular imaging follow-up was performed at least once in 131/136 (96.3%) patients with 148/155 (95.5%) aneurysms up to 75 months (mean: 37.3 months; median: 36 months according to latest follow-up), and 102/155(65.8%) aneurysms in 90/136 (66.2%) patients had ≥ 24-month control. According to the latest controls, the overall stable occlusion rate was 91.9% (95% CI, 87.5 to 96.3%). Three out of 148 aneurysms with follow-up were retreated (2%, 95% CI 0.0 to 4.3%). Adverse events were noted in 19/136 (14%, 95% CI, 9 to 21%) patients with a morbidity of 1.5% (95% CI, 0.0 to 3.5%). Mortality was 1/136 (0.7%, 95% CI, 0.02 to 2.2%) and was unrelated to aneurysm treatment. In-stent stenosis (ISS) was detected in 10/131 of the patients with follow-up (7.6%, 95% CI; 3.1 to 12.2%), only one being symptomatic. No adverse events have occurred in any of the patients with follow-up after 24 months, except the one resulting from ISS. CONCLUSION: In the treatment of cerebral aneurysms which were candidates for flow diversion technique, this study showed long-term efficacy of FRED with good safety and occlusion rates.

Prasugrel Single Antiplatelet Therapy versus Aspirin and Clopidogrel Dual Antiplatelet Therapy for Flow Diverter Treatment for Cerebral Aneurysms: A Retrospective Multicenter Study.

BACKGROUND AND PURPOSE: The optimal antiplatelet regimen after flow diverter treatment of cerebral aneurysms is still a matter of debate. A single antiplatelet therapy might be advantageous in determined clinical scenarios. This study evaluated the efficacy and safety of prasugrel single antiplatelet therapy versus aspirin and clopidogrel dual antiplatelet therapy. MATERIALS AND METHODS: We performed a post hoc analysis of 4 retrospective multicenter studies including ruptured and unruptured aneurysms treated with flow diversion using either prasugrel single antiplatelet therapy or dual antiplatelet therapy. Primary end points were the occurrence of any kind of procedure- or device-related thromboembolic complications and complete aneurysm occlusion at the latest radiologic follow-up (mean, 18 months). Dichotomized comparisons of outcomes were performed between single antiplatelet therapy and dual antiplatelet therapy. Additionally, the influence of various patient- and aneurysm-related variables on the occurrence of thromboembolic complications was investigated using multivariable backward logistic regression. RESULTS: A total of 222 patients with 251 aneurysms were included, 90 (40.5%) in the single antiplatelet therapy and 132 (59.5%) in the dual antiplatelet therapy group. The primary outcome-procedure- or device-related thromboembolic complications-occurred in 6 patients (6.6%) of the single antiplatelet therapy and in 12 patients (9.0%) of the dual antiplatelet therapy group (P = .62; OR, 0.712; 95% CI, 0.260-1.930). The primary treatment efficacy end point was reached in 82 patients (80.4%) of the single antiplatelet therapy and in 115 patients (78.2%) of the dual antiplatelet therapy group (P = .752; OR, 1.141; 95% CI, 0.599-2.101). Logistic regression showed that non-surface-modified flow diverters (P = .014) and fusiform aneurysm morphology (P = .004) significantly increased the probability of thromboembolic complications. CONCLUSIONS: Prasugrel single antiplatelet therapy after flow diverter treatment may be as safe and effective as dual antiplatelet therapy and could, therefore, be a valid alternative in selected patients. Further prospective comparative studies are required to validate our findings.

Evaluation of flow diverters for cerebral aneurysm therapy: recommendations for imaging analyses in clinical studies, endorsed by ESMINT, ESNR, OCIN, SILAN, SNIS, and WFITN.

BACKGROUND: Multiple studies and meta-analyses have described the technical and clinical outcomes in large cohorts of aneurysm patients treated with flow diverters (FDs). Variations in evaluation methodology complicate making comparisons among studies, hinder understanding of the device behavior, and pose an obstacle in the assessment of further advances in FD therapy. METHODS: A multidisciplinary panel of neurointerventionalists, imaging experts, and neuroradiologists convened with the goal of establishing consensus recommendations for the standardization of image analyses in FD studies. RESULTS: A standardized methodology is proposed for evaluating and reporting radiological outcomes of FD treatment of intracranial aneurysms. The recommendations include general imaging considerations for clinical studies and evaluations of longitudinal changes, such as neointimal lining and stenosis. They cover standards for classification of aneurysm location, morphology, measurements, as well as the assessment of aneurysm occlusion, wall apposition, and neck coverage. These reporting standards further define four specific braid deformation patterns: foreshortening, fish-mouthing, braid bump deformation, and braid collapse, collectively termed 'F2B2'. CONCLUSIONS: When widely applied, standardization of methods of measuring and reporting outcomes will help to harmonize the assessment of treatment outcomes in clinical studies, help facilitate communication of results among specialists, and help enable research and development to focus on specific aspects of FD techniques and technology.

Republished: Multiplug flow control technique as a novel transarterial curative approach for the endovascular treatment of cerebrovascular malformations.

Herein, we describe the use of a novel multiplug flow control technique for the curative transarterial embolisation of cerebrovascular malformations using liquid embolic agents (LEAs). The idea behind the use of this technique is to substantially control or arrest flow during LEA injection, with multiple plugs simultaneously formed from microcatheters that are placed within all or multiple feeders, so that the penetration of LEAs is facilitated, with flow control decreasing the washout of a malformation. This technique enables the complete occlusion of a vascular malformation in a shorter injection time than that in other methods because penetration is achieved faster. Details of this technique have been described in the treatment of two cases: one case of unruptured temporal arteriovenous malformation and in the other with a falcotentorial dural arteriovenous fistula, in which the vascular malformations were successfully occluded with transarterial embolisation.

First clinical multicenter experience with the new Pipeline Vantage flow diverter.

BACKGROUND: Flow diversion is an innovative and increasingly used technique for the treatment of intracranial aneurysms. New flow diverters (FDs) are being introduced to improve the safety and efficacy of this treatment. The aim of this study was to assess the safety, feasibility, and efficacy of the new Pipeline Vantage (PV) FD. METHODS: Patients with intracranial aneurysms treated with the PV at 10 international neurovascular centers were retrospectively analyzed. Patient and aneurysm characteristics, procedural parameters, complications, and the grade of occlusion were assessed. RESULTS: 60 patients with 70 aneurysms (5.0% with acute hemorrhage, 90.0% located in the anterior circulation) were included. 82 PVs were implanted in 61 treatment sessions. The PV could be successfully implanted in all treatments. Additional coiling was performed in 18.6%, and in-stent balloon angioplasty (to enhance the vessel wall apposition) in 24.6%. Periprocedural technical complications occurred in 24.6% of the treatments, were predominantly FD deployment problems, and were all asymptomatic. The overall symptomatic complication rate was 8.2% and the neurological symptomatic complication rate was 3.3%. Only one symptomatic complication was device-related (perforator artery infarctions leading to stroke). After a mean follow-up of 7.1 months, the rate of complete aneurysm occlusion was 77.9%. One patient (1.7%) died due to aneurysmal subarachnoid hemorrhage which occurred before treatment, unrelated to the procedure. CONCLUSIONS: The new PV FD is safe and feasible for the treatment of intracranial aneurysms. The short-term occlusion rates are promising but need further assessment in prospective long-term follow-up studies.

Safety and effectiveness of the Woven EndoBridge (WEB) system for the treatment of wide necked bifurcation aneurysms: final 5 year results of the pivotal WEB Intra-saccular Therapy study (WEB-IT).

INTRODUCTION: The US Woven EndoBridge Intra-saccular Therapy (WEB-IT) study is a pivotal, prospective, single arm, investigational device exemption study to evaluate the safety and effectiveness of the WEB device for the treatment of wide neck bifurcation aneurysms (WNBAs). We present complete 5 year data for the cohort of 150 patients. METHODS: 150 patients with WNBAs were enrolled at 21 US and six international centers. Imaging from the index procedure, 6 month, 1 year, 3 year, and 5 year follow-up were reviewed by a core laboratory. Adverse events were reviewed and adjudicated by a clinical events adjudicator. RESULTS: 83 patients had 5 year follow-up imaging and 123 had clinical follow-up. No ruptured (0/9) or unruptured aneurysm (0/141) rebled or bled during follow-up. No new device or procedure related adverse events or serious adverse events were reported after 1 year. At 5 years, using the LOCF method, complete occlusion was observed in 58.1% and adequate occlusion in 87.2% of patients. For patients with both 1 year and 5 year occlusion statuses available, 76.8% (63/82) of aneurysms remained stable or improved with no retreatment. After 1 year, 18 aneurysms were retreated, 11 of which were adequately occluded at 1 year, and 15 of which were retreated in the absence of any deterioration in occlusion grade. CONCLUSIONS: Five year follow-up data from the WEB-IT study demonstrated that the WEB device was safe and effective when used in the treatment of WNBAs. Aneurysm occlusion rates achieved at 1 year follow-up were durable, with rates of progressive thrombosis far exceeding rates of recurrence over time.

Safety and Efficacy of Flow Diverters for Treatment of Unruptured Anterior Communicating Artery Aneurysms: Retrospective Multicenter Study.

BACKGROUND: The anterior communicating artery (AComm) region is the most common site of intracranial aneurysms, with increased rupture risk compared with other locations. Overall, flow diverters present as a safe and efficacious treatment for intracranial aneurysms, but there is paucity of data for their use in the treatment of unruptured AComm aneurysms. We present the largest multicentric analysis evaluating the outcomes of flow diverters in AComm aneurysm treatment. METHODS: Databases from 10 centers were retrospectively reviewed for unruptured AComm aneurysms treated with flow diverters. Demographics, clinical presentation, radiographic characteristics, procedural complications, and outcomes were assessed. RESULTS: A total of 144 patients harboring 147 AComm aneurysms were treated between January 2012 and December 2021. Seventy-four were women (51.4%) and median age was 60 (IQR 50-67) years. All were unruptured AComm aneurysms. Half of the cohort had similar anterior cerebral artery sizes (51.4%). The most common morphology was saccular (94.6%), with a branch involvement in 32.7% of cases. Median vessel diameter was 2.4 mm, and the Pipeline Flex was the most prevalent device (32.7%). Median follow-up time was 17 months, with complete occlusion in 86.4% at the last follow-up. Functional independence (modified Rankin Scale score 0-2) was reported in 95.1%. Intraprocedural complications occurred in 5.6%, and postoperative complications were noted in 9.7% of cases. Combined major complication and mortality rate was 2.1%. CONCLUSIONS: Our study suggests that flow diverters are a useful treatment for AComm aneurysms. Mid-term results indicated favorable aneurysm occlusion with a good safety profile. Additional prospective studies with longer follow-up periods and independent adjudication are warranted to better assess these results.

Braid stability after flow diverter treatment of intracranial aneurysms: a systematic review and meta-analysis.

BACKGROUND: The aim of this study was to evaluate the overall rates of braid changes associated with flow diverter (FD) treatment for intracranial aneurysms (IAs). Additionally, we sought to provide an overview of the currently reported definitions related to these complications. METHODS: A systematic search was conducted from the inception of relevant literature up to April 2023, encompassing six databases. The included studies focused on patients with IAs treated with FDs. We considered four main outcome measures as FD braid changes: (1) fish-mouthing, (2) device braid narrowing, (3) device braid collapsing, and (4) device braid deformation. The data from these studies were pooled using a random-effects model. RESULTS: A total of 48 studies involving 3572 patients were included in the analysis. Among them, 14 studies (39%) provided definitions for fish-mouthing. However, none of the included studies offered specific definitions for device braid narrowing, collapsing, or deformation, despite reporting rates for these complications in six, five, and three studies, respectively. The pooled rates for braid changes were as follows: 3% (95% CI 2% to 4%, I2=27%) for fish-mouthing, 7% (95% CI 2% to 20%, I2=85%) for narrowing, 1% (95% CI 0% to 3%, I2=0%) for collapsing, and 1% (95% CI 1% to 4%, I2=0%) for deformation. CONCLUSION: The findings of this study suggest that FD treatment for IAs generally exhibits low rates of fish-mouthing, device braid narrowing, collapsing, and deformation. However, the lack of standardized definitions hinders the ability to compare device outcomes objectively, emphasizing the need for uniform definitions for FD braid changes in future prospective studies on FD.

Delayed thrombosis of a complex fusiform ICA aneurysm treated with flow reversal and partial occlusion: case report and brief review of possible mechanisms.

Immediate complete occlusion of complex cerebral aneurysms associated with perforating or major branch arteries may cause serious ischemic complications due to poor collateral supply. Flow reversal with concomitant proximal occlusion is an important therapeutic strategy in clinical practice and induces gradual thrombosis in the aneurysm within weeks or months, providing a time window for collateral progression. Herein, we report a case of delayed thrombosis of a complex fusiform aneurysm of the ICA following flow reversal with EC-IC bypass and concomitant partial coiling with parent artery occlusion. The effects of hemodynamic alterations on collateral circulation and intra-aneurysmal thrombosis are briefly discussed in the light of the literature.

Multiplug flow control technique as a novel transarterial curative approach for the endovascular treatment of cerebrovascular malformations.

Herein, we describe the use of a novel multiplug flow control technique for the curative transarterial embolisation of cerebrovascular malformations using liquid embolic agents (LEAs). The idea behind the use of this technique is to substantially control or arrest flow during LEA injection, with multiple plugs simultaneously formed from microcatheters that are placed within all or multiple feeders, so that the penetration of LEAs is facilitated, with flow control decreasing the washout of a malformation. This technique enables the complete occlusion of a vascular malformation in a shorter injection time than that in other methods because penetration is achieved faster. Details of this technique have been described in the treatment of two cases: one case of unruptured temporal arteriovenous malformation and in the other with a falcotentorial dural arteriovenous fistula, in which the vascular malformations were successfully occluded with transarterial embolisation.

WingSpan Stent System in the endovascular treatment of intracranial aneurysms: clinical experience with midterm follow-up results.

OBJECT: The WingSpan stent is a new self-expandable neurovascular stent designed for endovascular treatment of intracranial atheromatous lesions. The authors report their experience with the use of this stent for the endovascular treatment of intracranial aneurysms. METHODS: Thirty-seven patients with 40 wide-necked intracranial aneurysms were treated using the WingSpan stent. Twenty-two aneurysms (55%) were small and 18 (45%) were large or giant. In all but 4 aneurysms, embolization was completed by packing the aneurysm sac with platinum coils. In 4 dissecting aneurysms that were fusiform or too small and wide necked to be catheterized, the stent was used alone. In these cases, the stent bridged the aneurysm neck to allow for flow redirection and the potential stent-induced endothelization effect. RESULTS: Follow-up angiograms obtained in 3 of 4 aneurysms, treated with only stent placement, demonstrated aneurysmal thrombosis and parent artery remodeling in 2 patients and moderate decrease in size in 1. Follow-up angiography obtained at 6 months to 1 year in 31 aneurysms after stent-supported coil embolization demonstrated complete occlusion in 23 aneurysms (74.2%) with a progressive thrombosis rate of 66.7% (10 of 15 aneurysms), and a recanalization rate of 16.1%. CONCLUSIONS: In treating wide-necked intracranial aneurysms, the WingSpan Stent System is very flexible, secure, and effective. Its delivery system is very easy and exact in that it exerts higher outward radial force, thus providing an excellent conformability and a strong scaffold to hold the coils in place. It may offer an effective treatment when used alone in some fusiform or very wide-necked, small dissecting aneurysms in which other surgical or endovascular treatment strategies are not deemed feasible.

Immediate and midterm follow-up results of using an electrodetachable, fully retrievable SOLO stent system in the endovascular coil occlusion of wide-necked cerebral aneurysms.

OBJECT: Stent-assisted embolization is an alternative endovascular treatment method for wide-necked intracranial aneurysms. Currently available stents have the limitations of poor radial force, difficult delivery systems, and lack of full retrievability. The authors report on their preliminary experience with the use of a new, fully retrievable, self-expanding neurovascular stent, which has a high radial force and easy delivery system, combined with coil or Onyx embolization for the treatment of wide-necked aneurysms, including 6-month follow-up data. METHODS: Fifteen patients with 18 wide-necked intracranial aneurysms were treated using the SOLO stent system and detachable platinum coils. Aneurysms were located at the posterior communicating artery (seven lesions), midbasilar artery (one lesion), internal carotid artery (ICA) bifurcation (one lesion), ICA-ophthalmic artery segment (eight lesions), and posterior cerebral artery (one lesion). Eleven aneurysms were small, six were large, and one was giant. Only one of these aneurysms was in the acute stage of subarachnoid hemorrhage; balloon remodeling alone failed to keep the coils in the aneurysm sac. RESULTS: Only one stent required retrieving and repositioning after it had been fully deployed, and retrieval was easy and successful. No thromboembolic complication, dissection/rupture, or vasospasm occured during stent placement. Follow-up angiograms obtained at 6 months posttreatment in the 18 aneurysms demonstrated that all stents were patent with no evidence of intimal hyperplasia or stenosis. In all cases but one, 100% lesion occlusion was observed at the 6-month control angiography examination. Only one aneurysm had recanalized. CONCLUSIONS: The fully retrievable self-expandible SOLO stent is a feasible, secure, and effective system with a high radial force and ease of delivery in treating wide-necked intracranial aneurysms in combination with coil embolization.

Intrasaccular combination of metallic coils and onyx liquid embolic agent for the endovascular treatment of cerebral aneurysms.

OBJECT: The aim of this study was to report on a novel technique in which metallic embolization coils were combined with the Onyx liquid embolic agent in the aneurysm sac to achieve a more durable result after endovascular treatment. This therapeutic procedure was performed in selected cases in which, based on the authors' experiences, either coil embolization or Onyx alone would likely have failed. The authors report long-term clinical and angiographic follow-up results in 20 consecutive intracranial aneurysms treated using this combination for defined indications. METHODS: Twenty aneurysms in 20 patients were treated with a combination of embolic coils and Onyx. Four aneurysms were giant; 13, large; and three, small. This new technique was used when standard Onyx or coil treatment with balloon assistance was determined to involve a higher possibility of recanalization, because either an adjunctive stent insertion could not be performed or the Onyx technique could not be used due to an unsuccessful seal test or intraaneurysm balloon prolapse. In one case, an adjunctive stent was placed before coil placement and Onyx deposition to control the material in the sac of the aneurysm, which had a fusiform neck. All aneurysms were completely occluded after using this technique. No clinical or technical adverse events occurred in any of the cases. Follow-up angiography was performed in all patients: 3-year studies in six patients, 2-year studies in five, and 1-year studies in nine. None of these studies demonstrated aneurysm regrowth or parent artery occlusion. CONCLUSIONS: The combination of the embolic coils and the Onyx liquid embolic agent provides very durable aneurysm occlusion for defined indications.

Treatment of internal carotid artery aneurysms with a covered stent: experience in 24 patients with mid-term follow-up results.

BACKGROUND AND PURPOSE: We present our preliminary experience, including mid-term angiographic and clinical follow-up results, with an alternative technique for the endovascular treatment of intracranial aneurysms in a series of patients. This new method, previously described in anecdotal case reports, consists of endovascular deployment of an artificial vessel graft (stent graft or covered stent) in the parent vessel to exclude the intracranial aneurysm sac from circulation. METHODS: Twenty-five internal carotid artery (ICA) aneurysms in 24 patients were successfully treated by using a Jostent coronary stent graft deployed in the parent artery across the aneurysm neck. All except four aneurysms were extradural, located in the petrous or cavernous portion of the ICA. The four intradural aneurysms were located in the carotico-ophthalmic region. Seventeen aneurysms in 16 patients occurred posttraumatically, secondary to motor vehicle accidents or surgical injury. RESULTS: Twenty-three aneurysms were immediately excluded from circulation after stent graft placement. In two aneurysms, a slow contrast material filling (endoleak) into the aneurysm cavity was observed immediately after treatment. One was thrombosed, as shown by late control angiography; in the other one, a second larger bare stent was used to appose the stent graft's distal end to the ICA wall, thus sealing the endoleak into the distal graft. No technical adverse event, including vessel dissection, vessel perforation, or thromboembolism, occurred with or without clinical consequence. No mortality or morbidity developed during or after the procedure, including the follow-up period. Two-year control angiography in one patient, 1.5-year control angiography in two patients, 1-year control angiography in six patients, and 6-month control angiography in 12 patients were performed, revealing reconstruction of the ICA with no aneurysm recanalization. All symptoms resolved after treatment in the patients who had initially presented with mass effect. CONCLUSION: Initial anatomic, clinical and mid-term follow-up results in this small series of patients are encouraging. This technique has been proved to have potential in the reconstructive treatment of intracranial aneurysms. Further research and development are needed to optimize the stent graft technology for the cerebrovascular system.

CT and MR imaging findings and their implications in the follow-up of patients with intracranial aneurysms treated with endosaccular occlusion with onyx.

BACKGROUND AND PURPOSE: Our purpose was to describe the CT and MR features of intracranial aneurysms occluded with the liquid polymer Onyx. METHODS: At two centers, 35 aneurysms in 33 patients and 11 in nine patients were treated with the polymer. In 17 patients, adjunctive stents were placed at the aneurysm neck. All but three aneurysms originated from the internal carotid artery (ICA). Eighteen were giant; 15, large; and 13, small. Patients underwent pre- and postprocedural CT and/or MR imaging; MR angiograms (MRAs) were available in 22. In 35 patients (38 aneurysms), 3-month and/or 1-year follow-up angiograms were obtained for correlation with sectional images. RESULTS: Except in two small aneurysms, polymer filling created beam hardening artifacts on CT scans. In 10 aneurysms, the polymer did not fill the aneurysm sac entirely; five showed recanalization at follow-up. On MR images (all sequences), the polymer appeared hypointense, probably because of its tantalum content; it did not create artifacts. MRAs falsely suggested reduced or absent ICA flow in 11 of 22 patients, nine of whom with stents. In the rest, MRA provided results comparable to those of selective angiography. In 12 patients, postprocedural imaging revealed new lesions. CONCLUSION: Onyx appears hypointense on MR images, with no artifact, and it does not interfere with MRA except in patients with stents. MR imaging may reveal new parenchymal lesions, even in asymptomatic patients. In the immediate control and follow-up of polymer-treated aneurysms, MR imaging and MRA may be preferred. CT may show the degree of filling in the aneurysmal sac, but Onyx creates artifacts that hinder CT evaluation.

HyperForm balloon remodeling in the endovascular treatment of anterior cerebral, middle cerebral, and anterior communicating artery aneurysms: clinical and angiographic follow-up results in 800 consecutive patients.

OBJECT: The purpose of this paper was to present the safety, efficacy, and clinical/angiographic follow-up results of HyperForm balloon-assisted endosaccular coil occlusion of distal anterior circulation bifurcation aneurysms. METHODS: Over a 7-year period, the authors treated 864 middle cerebral artery, distal anterior cerebral artery bifurcation, and anterior communicating artery aneurysms by means of coil embolization with HyperForm balloon assistance in 800 patients. In 37 aneurysms, 2 HyperForm balloons were used simultaneously for remodeling. RESULTS: The overall mortality rate was 7.1%, including 1.4% procedural mortality. Various neurological deficits were present at discharge in 8.9% of the patients, and 4.4% had permanent disabling morbidity 6 months posttreatment (modified Rankin Scale score ≥ 2). Thromboembolic complications developed during the treatment of 15 aneurysms (1.7%) causing morbidity or mortality in 10 cases (1.3%). There were 14 intraoperative perforations (1.6%). In all 14 cases, the HyperForm balloon saved patients from severe bleeding. The perforation led to morbidity or mortality in 3 cases (0.4%); there were no negative consequences in 11. There were 726 patients with 757 aneurysms (87.6%) available for follow-up. Control angiograms were obtained at 6 months in 386 patients, at 1 year in 267, and at 2 years in 104, revealing an 82% complete obliteration rate according to the most recent follow-up angiograms. CONCLUSIONS: The satisfactory results obtained in this experience demonstrate that HyperForm balloon remodeling provides strong benefits for the endovascular management of middle cerebral, anterior cerebral, and anterior communicating artery aneurysms without increasing the risk of treatment. Not only does this technique allow for the safe treatment of these aneurysms, but it also expands the indications of endovascular treatment to include aneurysms that otherwise cannot be treated with simple coil embolization.

Endovascular treatment of brain arteriovenous malformations with prolonged intranidal Onyx injection technique: long-term results in 350 consecutive patients with completed endovascular treatment course.

OBJECT: The purpose of this study was to present the authors' clinical experience and long-term angiographic and clinical follow-up results in 350 patients with brain arteriovenous malformations (AVMs) treated using prolonged intranidal Onyx injection with a very slow "staged" reflux technique described by the authors. METHODS: Three hundred and fifty consecutive patients with brain AVMs treated using Onyx between 1999 and 2008 and in whom definitive status for endovascular treatment was reached are presented. There were 206 (59%) male and 144 (41%) female patients, with a mean age of 34 years. There were 607 endovascular sessions performed. Onyx was the only agent used for intranidal injections in all patients, but in 42 patients high-concentration N-butyl cyanoacrylate glue was used adjunctively to close high-flow direct arteriovenous intra- or perinidal fistulas, or when a feeding vessel or nidus perforation and/or dissection occurred. RESULTS: Angiographically confirmed obliteration was achieved in 179 patients (51%) with only endovascular treatment; 1 patient died due to intracranial hemorrhage after the treatment. Twenty-two patients underwent resection, and 136 patients were sent to radiosurgery after endovascular treatment. In 4 patients embolization therapy was discontinued, and 5 additional patients refused the suggested complementary surgery. In all 178 surviving patients who had angiographically confirmed AVM obliteration by embolization alone, 1-8 years of control angiography (mean 47 months) confirmed stable obliteration, except for 2 patients in whom a very small recruitment was noted in the 1st year on control angiography studies, despite initial apparent total obliteration (recanalization rate 1.1%). In the entire series, 5 patients died; the mortality rate was 1.4%. The permanent morbidity rate was 7.1%. CONCLUSIONS: With the prolonged intranidal injection technique described herein, Onyx allows the practitioner to achieve higher rates of anatomical cures compared with the cure rates obtained previously with other embolic agents. More importantly, due to this technique's much more effective intranidal penetration, it allows high-grade AVMs to be made radiosurgically treatable in a group of patients for whom there has been no treatment alternative.