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BackgroundWEB treatment is an endovascular approach for wide-neck bifurcation aneurysms that has demonstrated high safety and good efficacy in mid-term follow-up. While evaluating safety in the long term is important to determine if delayed adverse events occur affecting late morbidity and mortality, the most important point to evaluate is the long-term stability of aneurysm occlusion. The current analysis reports the 3-year clinical and anatomical results of WEB treatment in the combined population of two European trials (WEBCAST (WEB Clinical Assessment of Intrasaccular Aneurysm Therapy) and WEBCAST-2).MethodsAneurysm occlusion was evaluated using a 3-grade scale: complete occlusion, neck remnant, and aneurysm remnant.ResultsThe safety population comprised 79 patients. The efficacy population comprised 61 aneurysms. Aneurysm locations were middle cerebral artery in 32/61 aneurysms (52.5%), anterior communicating artery in 13/61 (21.3%), basilar artery in 9/61 (14.8%), and internal carotid artery terminus in 7/61 (11.5%). No adverse events related to the device or procedure occurred between 2 and 3 years. At 3 years, complete occlusion was observed in 31/61 (50.8%) aneurysms, neck remnant in 20/61 (32.8%), and aneurysm remnant in 10/61 (16.4%). Between 1 year and 3 years, aneurysm occlusion was improved or stable in 53/61 (86.9%) aneurysms and worsened in 8/61 (13.1%). Worsening was mostly from complete occlusion to neck remnant in 6/61 (9.8%) aneurysms. The retreatment rate at 3 years was 11.4%.ConclusionsThis analysis confirms the high safety profile of WEB. Moreover, evidence demonstrates the great stability of aneurysm occlusion with adequate occlusion (complete occlusion or neck remnant) in 83.6% of aneurysms.Clinical trial registrationURL:http://www.clinicaltrials.gov. WEBCAST and WEBCAST-2: Unique identifier:NCT01778322.

BackgroundThe primary goal of the CLARYS study is to assess the protection against rebleeding when treating ruptured bifurcation aneurysms with the Woven EndoBridge (WEB) device.MethodsThe CLARYS study is a prospective, multicenter study conducted in 13 European centers. Patients with ruptured bifurcation aneurysms were consecutively included between February 2016 and September 2017. The primary endpoint was defined as the rebleeding rate of the target aneurysm treated with the WEB within 30 days postprocedure. Secondary endpoints included periprocedural and postprocedural adverse events, total procedure and fluoroscopy times, and modified Rankin Scale score at 1 month and 1 year.ResultsSixty patients with 60 ruptured bifurcation aneurysms to be treated with the WEB were included. A WEB device was successfully implanted in 93.3%. The rebleeding rate at 1 month and 1 year was 0%. The mean fluoroscopy time was 27.0 min. Twenty-three periprocedural complications were observed in 18 patients and resolved without sequelae in 16 patients. Two of these complications were attributed to the procedure and/or the use of the WEB, leading to a procedure/device-related intraoperative complication rate of 3.3%. Overall mortality at 1 month and 1 year was 1.7% and 3.8%, respectively and overall morbidity at 1 month and 1 year was 15% and 9.6%, respectively. WEB-related 1-month and 1-year morbidity and mortality was 0%.ConclusionsThe interim results of CLARYS show that the endovascular treatment of ruptured bifurcation aneurysms with the WEB is safe and effective and, in particular, provides effective protection against rebleeding. It may induce profound change in the endovascular management of ruptured bifurcation aneurysms.

The cost of clinical trials is ever-increasing. In-silico trials rely on virtual populations and interventions simulated using patient-specific models and may offer a solution to lower these costs. We present the flow diverter performance assessment (FD-PASS) in-silico trial, which models the treatment of intracranial aneurysms in 164 virtual patients with 82 distinct anatomies with a flow-diverting stent, using computational fluid dynamics to quantify post-treatment flow reduction. The predicted FD-PASS flow-diversion success rates replicate the values previously reported in three clinical trials. The in-silico approach allows broader investigation of factors associated with insufficient flow reduction than feasible in a conventional trial. Our findings demonstrate that in-silico trials of endovascular medical devices can: (i) replicate findings of conventional clinical trials, and (ii) perform virtual experiments and sub-group analyses that are difficult or impossible in conventional trials to discover new insights on treatment failure, e.g. in the presence of side-branches or hypertension., In-silico trials rely on virtual populations and interventions simulated using patient-specific models and may offer a solution to lower costs. Here, the authors present the flow diverter performance assessment in-silico trial, which models the treatment of intracranial aneurysms with a flow-diverting stent.

Although the cost of clinical trials is ever-increasing, in-silico trials, which rely on virtual populations and interventions simulated using patient-specificc models, may offer a solution to contain these costs. However, in-silico trial endpoints need to be compared to those available from conventional clinical trials to ensure that the predictions of safety or effcacy from the in-silico approach are valid. Here, we present the flow diverter performance assessment (FDPASS) in-silico trial, which modelled the treatment of intracranial aneurysms in 82 virtual patients with a flow-diverting stent, using computational fluid dynamics (CFD) to quantify post-treatment flow reduction in the aneurysm sac. The predicted FD-PASS flow-diversion success rate replicated the values previously reported in three reference clinical trials. The in-silico approach allowed broader investigation of factors associated with insuficient flow reduction and increased stroke risk after flow diversion than would be feasible in a conventional trial. These ndings demonstrate for the rst time that in-silico trials of medical devices can (i) replicate ndings of conventional clinical trials and (ii) incorporate virtual experiments that are impossible in conventional trials.

Introduction: The mechanisms linking obesity to increased mortality in patients with coronavirus-disease 2019 (COVID-19) are unclear. Hypothesis: We hypothesised that obesity would be associated with adverse right ventricular (RV) remodelling and function which might be further exacerbated by COVID-19 associated increases in RV afterload/demand. Methods: We used echocardiography and computed tomography to establish links between RV dimensions and function and bodyweight in patients with severe COVID-19. In obese and non-obese participants without COVID-19, we used cardiovascular magnetic resonance to define the effects of obesity upon RV volumes, energetics, systolic function and stress reserve. Results: In patients with severe COVID-19, increasing bodyweight was associated with disproportionate RV dilatation (n=26, echocardiography, R=0.42, P=0.03, CT n=34, R=0.23, P=0.004) and impairment of RV systolic function (fractional area change (FAC) R=-0.45, P=0.04); obesity (BMI >30kg/m2) was associated with a 32% reduction in RV FAC (P=0.03). Similar associations were seen in a validation cohort (n=91, all P2 ) was associated with RV remodelling, impaired cardiac energetics (PCr/ATP ratio 23% lower, P2 , n=27) had impaired RV diastolic filling rate at rest (P Conclusions: Increasing body weight is associated with both significant alterations in RV volumes, systolic function and stress responses which are mitigated with weight loss and also with disproportionate RV dilatation and dysfunction in severe COVID-19. RV dysfunction is a modifiable mechanism which might link obesity to adverse outcomes in patients with COVID-19 and other disorders stressing the right heart.

Purpose: To establish the feasibility of using vessel-encoded pseudocontinuous arterial spin labeling (VEPCASL) for non-invasive vascular territory imaging (VTI) and artery-specific dynamic angiography of a large number of arterial branches above the circle of Willis within a clinically feasible scan time. Methods: 3D time-of-flight angiography was used to select a labeling plane and establish seven pairs of encoding cycles. These were used for VEPCASL VTI and dynamic 2D angiography (8 min and 3 min acquisition times, respectively) in healthy volunteers, allowing the separation of signals arising from 13 arterial branches (including extracranial arteries) in post-processing. To demonstrate the clinical potential of this approach, VEPCASL angiography was also applied in five patients with brain arteriovenous malformation (AVM). Results: In healthy volunteers, the artery-specific filling of the vascular tree and resulting perfusion territories were well depicted. Signal-to-noise ratios were approximately five times higher than those achievable with single-artery selective methods. Blood supply to the AVMs was well visualized in all cases, showing the main feeding arteries and venous drainage. Conclusions: VEPCASL is a highly efficient method for both VTI and dynamic angiography of a large number of arterial branches, providing a comprehensive picture of vascular flow patterns and the effect on downstream tissue perfusion within an acceptable scan time. Automation of labeling plane and vessel-encoding selection would improve robustness and efficiency, and further refinement could allow quantitative blood flow measurements to be obtained. This technique shows promise for visualizing the blood supply to lesions and collateral flow patterns.

BACKGROUND Woven EndoBridge (WEB; Sequent Medical) treatment is an innovative endovascular approach for treatment of wide-neck bifurcation aneurysms. Initial studies have shown high safety with good efficacy at short term confirmed by trials conducted in United States (WEB-Intrasaccular Therapy) and in Europe (WEB Clinical Assessment of Intrasaccular Aneurysm Therapy [WEBCAST], French Observatory, and WEBCAST-2). OBJECTIVE To report the 2-yr clinical and anatomical results of WEB treatment in the combined population of 3 European trials. METHODS In a French Observatory, 2-yr clinical and anatomical data were collected. In WEBCAST and WEBCAST-2, 2-yr follow-up was optional, and data were collected when follow-up was performed. Aneurysm occlusion was evaluated using a 3-grade scale: complete occlusion, neck remnant, and aneurysm remnant. RESULTS The population for safety was 138/168 patients (82.1%), including 89 females (64.5%), with mean age of 55.5 ± 10.2 yr. The population for efficacy was 121/169 aneurysms (71.6%). Aneurysm locations were middle cerebral artery in 65/121 aneurysms (53.7%), anterior-communicating artery in 25/121 (20.7%), basilar artery in 17/121 (14.0%), and internal carotid artery terminus in 14/121 (11.6%). No clinically relevant adverse events occurred between years 1 and 2. At 2 yr, complete occlusion was observed in 62/121 (51.2%) aneurysms, neck remnant in 36/121 (29.8%) aneurysms, and aneurysm remnant in 23/121 (19.0%) aneurysms. The global retreatment rate at 2 yr was 9.3%. CONCLUSION This analysis confirms the high safety profile of WEB treatment at 2 yr. Aneurysm occlusion is generally stable at 2 yr, and the retreatment rate between 1 yr and 2 yr is low (2.0%)., Graphical Abstract Graphical Abstract

Introduction/Purpose Flow Disruption with WEB is an innovative endovascular approach for wide-neck bifurcation aneurysms that has been evaluated in 3 European Good Clinical Practice Studies: WEBCAST (WEB Clinical Assessment of Intrasaccular Aneurysm), French Observatory, and WEBCAST-2. This treatment is associated with a high safety and efficacy at one year.1 Long-term anatomical results have been very few evaluated. The present work is presenting the 2-years safety and efficacy results in the 3 GCP studies. Materials and methods Out of the 168 patients with 169 aneurysms initially included in the 3 GCP studies, 138 patients were clinically evaluated at 2 years and 120 patients with 121 aneurysms were evaluated by vascular imaging. Results There was no bleeding/rebleeding or thromboembolic complication between 1 year and 2 years. Morbidity and mortality at 2 years were 1.4% (2/138) and 5.1% (7/138), respectively. Two deaths (1.4%) were related to the procedure (retroperitoneal hematoma and brainstem compression). The other deaths were unrelated to the disease or the procedure (cancer: 3 patients; pneumonia: 1 patient; cirrhosis: 1 patient). Anatomical results at 2 years were complete occlusion in 62/121 aneurysms (51.2%), neck remnant in 36/121 aneurysms (29.8%), and aneurysm remnant in 23/121 aneurysms (19.0%). Anatomical results were similar in aneurysms treated with WEB DL and WEB SL/SLS. Between 1 and 2 years, aneurysm occlusion was stable or improved in 103/119 aneurysms (86.6%). Aneurysm retreatment was performed in 14 aneurysms (9.3%), 11 between the procedure and 1 year and in 3 between 1 and 2 years. Conclusion The great safety and efficacy of WEB aneurysm treatment is confirmed at 2 years follow-up. No adverse events are observed between 1 year and 2 years. Adequate occlusion is observed in a similar percentage of aneurysms at 1 year (79.1%) and 2 years (81.0%). 1 Pierot L, Soize S, Molyneux A, Byrne J, Spelle. Evaluation of the Safety and Efficacy of Aneurysm Treatment with WEBTM device in the cumulated population of 3 prospective, multicenter series (WEBCAST, French Observatory, WEBCAST-2). J NeuroIntervent Surg. 2018;10:553–559. Disclosures L. Pierot: 2; C; Balt, Medtronic, Microvention, Phenox, Vesalio. X. Barreau: None. I. Szikora: None. D. Herbreteau: None. J. Byrne: None. L. Spelle: None.

BACKGROUND AND PURPOSE: Flow disruption with the Woven EndoBridge (WEB) device is an innovative technique for the endovascular treatment of wide-neck bifurcation aneurysms. The initial version of the device (WEB Double-Layer) was evaluated in the WEB Clinical Assessment of IntraSaccular Aneurysm Therapy (WEBCAST) study, whereas the French Observatory study evaluated both WEB Double-Layer and Single-Layer versions of the device. WEBCAST 2 was designed to evaluate the WEB Single-Layer with Enhanced Visualization. MATERIALS AND METHODS: Patients with wide-neck bifurcation aneurysms for which WEB treatment was possible were included. Clinical data including adverse events and clinical status at 1 month and 1 year were collected and analyzed. A core laboratory evaluated anatomic results at 1 year following the procedure. RESULTS: Ten European neurointerventional centers included 55 patients (38 women; 27–77 years of age; mean, 54.4 ± 10.0 years) with 55 aneurysms. Aneurysm locations were the middle cerebral artery in 25 aneurysms (45.5%), the anterior communicating artery in 16 (29.1%), the basilar artery in 9 (16.4%), and the internal carotid artery terminus in 5 (9.1%). Procedural morbidity and mortality at 1 month were, respectively, 1.8% (1/55 patients) and 0.0% (0/55 patients). Morbidity and mortality at 1 year were, respectively, 3.9% (2/51 patients) and 2.0% (1/51 patients). At 1 year, complete occlusion was observed in 27/50 aneurysms (54.0%); neck remnant, in 13/50 (26.0%); and aneurysm remnant, in 10/50 (20.0%) (adequate occlusion in 40/50, 80.0%). CONCLUSIONS: WEBCAST 2 confirms the high safety and efficacy of WEB aneurysm treatment demonstrated in the WEBCAST and French Observatory studies.

BACKGROUND AND PURPOSE: Accurately and efficiently modeling the transport of angiographic contrast currently offers the best method of verifying computational fluid dynamics simulations and, with it, progress toward the lofty goal of prediction of aneurysm treatment outcome a priori. This study specifically examines the influence of estimated flow rate and contrast properties on such in silico predictions of aneurysm contrast residence and decay. MATERIALS AND METHODS: Four experimental sidewall aneurysms were created in swine, with aneurysm contrast flow patterns and decay rates observed under angiography. A simplified computational fluid dynamics model of the experimental aneurysm was constructed from 3D angiography and contrast residence predicted a priori. The relative influence of a number of estimated model parameters (contrast viscosity, contrast density, and blood flow rate) on contrast residence was then investigated with further simulations. RESULTS: Contrast infiltration and washout pattern were accurately predicted by the a priori computational fluid dynamics model; however, the contrast decay rate was underestimated by ∼25%. This error was attributed to the estimated parent vessel flow rate alone, and the effects of contrast viscosity and density on the decay rate were found to be inconsequential. A linear correlation between the parent vessel flow rate and the corresponding contrast decay rate was observed. CONCLUSIONS: In experimental sidewall aneurysms, contrast fluid properties (viscosity and density) were shown to have a negligible effect on variation in the modeled contrast decay rate. A strong linear correlation was observed between parent vessel flow rate and contrast decay over a physiologically reasonable range of flow rates.

IntroductionThe Woven EndoBridge Intrasaccular Therapy (WEB-IT) Study is a pivotal, prospective, single-arm, investigational device exemption study designed to evaluate the safety and effectiveness of the WEB device for the treatment of wide-neck bifurcation aneurysms.MethodsOne-hundred and fifty patients with wide-neck bifurcation aneurysms were enrolled at 21 US and six international centers. Angiograms from the index procedure, and 6-month and 1-year follow-up visits were all reviewed by a core laboratory. All adverse events were reviewed and adjudicated by a clinical events adjudicator. A data monitoring committee provided oversight during the trial to ensure subject safety.ResultsOne-hundred and forty-eight patients received the WEB implant. One (0.7%) primary safety event occurred during the study—a delayed ipsilateral parenchymal hemorrhage—on postoperative day 22. No primary safety events occurred after 30 days through 1 year. At the 12-month angiographic follow-up, 77/143 patients (53.8%) had complete aneurysm occlusion. Adequate occlusion was achieved in 121/143 (84.6%) subjects.ConclusionsThe prespecified safety and effectiveness endpoints for the aneurysms studied in the WEB-IT trial were met. The results of this trial suggest that the WEB device provides an option for patients with wide-neck bifurcation aneurysms that is as effective as currently available therapies and markedly safer.Trial registration numberNCT02191618

BACKGROUND AND PURPOSE: Although the role of wall shear stress (WSS) in the initiation, growth, and rupture of intracranial aneurysms has been well studied, its influence on aneurysm recurrence after endovascular treatment requires further investigation. We aimed to compare WSS at necks of recurrent and nonrecurrent aneurysms. METHODS: Nine recurrent coil-embolized aneurysms were identified and matched with nine nonrecurrent aneurysms. Patient-specific vessel geometries reconstructed from follow-up 3-D time-of-flight magnetic resonance angiography were analyzed using computational fluid dynamics (CFD) simulations. Absolute WSS and the percentage of abnormally low and high WSS at the aneurysm neck compared to the near artery were measured. RESULTS: The median percentage of abnormal WSS at the aneurysm neck was 49.3% for recurrent and 34.7% for nonrecurrent aneurysms (P = .011). The area under the receiver-operating-characteristic curve for distinguishing these aneurysms according to the percentage of abnormal WSS was .86 (95% CI .62 to .98). The optimal cut-off value of 45.1% resulted in a sensitivity and a specificity of 88.89% (95% CI 51.8% to 99.7%). CONCLUSION: Our findings indicate that necks of recurrent aneurysms are exposed to abnormal WSS to a larger extent. Abnormal WSS may serve as a metric to distinguish them from nonrecurrent aneurysms with CFD simulations a priori.

BACKGROUND Flow disruption with WEB is an innovative endovascular approach for wide-neck bifurcation aneurysms. Initial series have shown a low complication rate with good efficacy. OBJECTIVE To report clinical and anatomical results of the WEB treatment in the cumulated population of WEBCAST (WEB Clinical Assessment of Intrasaccular Aneurysm) and French Observatory series. METHODS WEBCAST and French Observatory are single-arm, prospective, multicenter, Good Clinical Practice studies dedicated to the evaluation of WEB treatment. Ruptured and unruptured bifurcation aneurysms located in the basilar artery, middle cerebral artery, anterior communicating artery, and internal carotid artery terminus were included in both studies. Clinical data were independently evaluated. Postoperative, 6-month (in WEBCAST), and 1-year aneurysm occlusion was independently evaluated with a 3-grade scale: complete occlusion, neck remnant, and aneurysm remnant. RESULTS The cumulated population was 113 patients (74 female, 65.5%) 33 to 74 years of age with 114 aneurysms with a mean neck size of 5.6 mm. There was no mortality at 1 month, and morbidity was 2.7%. A statistically significant difference in the rate of occurrence of thromboembolic events was observed between the use of any antiplatelet agent and the use of no antiplatelet agent (P < .001). At 1 year, complete aneurysm occlusion was observed in 56.0%, neck remnant in 26.0%, and aneurysm remnant in 18.0%. Worsening of aneurysm occlusion between the procedure and 12 months was observed in 2.0% and between 6 months and 1 year in 7.1%. CONCLUSION The analysis in this large cumulated population of studies confirms favorable safety and efficacy of WEB treatment.

We want to thank the correspondents1 for pointing out an error in our article entitled ‘Aneurysm treatment with WEB in the cumulative population of two prospective, multicenter series: 3- year follow-up’2 and JNIS for giving us the opportunity to respond to their critique. First, we must address the error in the legend to Figure 3 in our article.1 2 This legend should read as follows: ‘Unruptured middle cerebral artery aneurysm. (a) DSA (frontal view) prior to intervention. (b) 1-year follow-up radiograph showing retraction of the WEB. (c) 1-year follow-up DSA showing the resulting aneurysm recurrence. (d) and (e) Post-retreatment images performed using stents and coils.’ We are sorry that the previous legend’s text was ambiguous; the images were chosen to show the cause of failure and the retreatment method. We agree that scientific controversies are a necessary part of scientific progress, and uncorrected untruths are not the right way to build new scientific knowledge. Intrasaccular flow disruption with the Woven EndoBridge (WEB) device (Microvention/Sequent, Aliso Viejo, CA, USA) is an innovative treatment in the sense that the concept and the design of the device is new compared with existing endovascular tools. This treatment modality was introduced in Europe (after CE mark) in 2010 for the treatment of complex aneurysms (wide-neck bifurcation aneurysms (WNBAs)) and clinical evaluation started with the WEBCAST (WEB Clinical Assessment of Intrasaccular Aneurysm Therapy) study (first inclusion in December 2011).3 This evaluation was conducted with the first generation of the device (WEB-DL, dual-layer) and required operators to develop experience during the …

Introduction The intrasaccular flow diversion device WEB is a system used in the treatment of wide necked bifurcation aneurysm. The large number of clinical studies conducted have included mainly unruptured aneurysms. The CLARYS study has been set up to evaluate the efficacy and the safety of the WEB system used to treat bifurcation ruptured aneurysms. Materials and methods The CLARYS study is a prospective, multicenter evaluation conducted in 13 interventional neuroradiological departments in France and Germany. The study design meets the Good Clinical Practice (GCP) standards with data collected in an eDC 100% monitored and endpoints independently evaluated. The primary endpoint is defined as the re-bleeding rate at 1 month post procedure. The secondary endpoints are the rate of adverse events related to the device, the procedure or the disease, the neurological evaluation at 1 month and 1 year based on mRS, the occlusion at 1 year based on the WEB Occlusion Scale (WOS) and the procedure and fluoroscopy time. Results From February 2016 to September 2017, 60 patients (women: 31, 51.7%; mean age: 54.5±1.49 years) with 60 aneurysms were included in the study. The aneurysms locations were at the anterior communicating artery (26/60, 43.3%), the middle cerebral artery bifurcation (23/60, 38.3%), the basilar apex (7/60, 11.7%), the anterior cerebral artery (2/60, 3.3%), the internal carotid artery terminus (1/60, 1.7%) and the posterior communicating artery (1/60, 1.7%). The WEB device was successfully implanted in 56/60 cases (95.0%) The adverse events reported by the sites and adjudicated by the Clinical Event Adjudicator (CEA) were described based on timeline occurrence (per procedure or post procedure), category of events, clinical impact and relationship to device, procedure or disease. The primary endpoint will be presented as well as the morbidity and mortality at 1 month. The 12 months data are under collection so will not be available. Conclusion The study results at 1 month will be presented to address the rate of re bleeding and the safety of the device used in the treatment of ruptured bifurcation aneurysm, following clinical evaluation conducted according to study GCP. Disclosures D. Herbreteau: 2; C; MicroVention. A. Narata: None. R. Bibi: None. L. Ikka: None. C. Mihalea: None. J. Caroff: None. J. Moret: 2; C; MicroVention, Medtronic, Balt. 4; C; Sensome. X. Barreau: None. J. Ferre: None. J. Gauvrit: None. H. Raoult: None. J. Fiehler: 1; C; German Ministry of Science and Education (BMBF), German Ministry of Economy and Innovation (BMWi), German Research Foundation (DFG), European Union (EU), Hamburgische Investitions-und Forderbank (IFB), Medtronic, MicroVention, Philips, Stryker. 2; C; Acandis, Boehringer Ingelheim, Cerenovus, Covidien, Medtronic, Medina, MicroVention, Penumbra, Route 92, Stryker. J. Buhk: 2; C; Sequent, MicroVention. V. Costalat: 2; C; Medtronic, Stryker, Balt, Cerenovus, MicroVention. A. Januel: None. C. Cognard: 2; C; Stryker, MicroVention, Medtronic, Cerenovus. T. Liebig:None. M. Bester: None. H. Desal: None. B. Daumas-Duport: None. R. Bourcier: None. M. Mohlenbruch: None. J. Berkefeld: 2; C; Sequent/MicroVention. R. Du Mesnil de Rochemont: 2; C; Sequent. W. Weber: 2; C; Phenox, MicroVention, Medtronic, Penumbra, Stryker. S. Velasco:None. A. Biondi: None. J. Byrne: 2; C; Oxford Endovascular Ltd. L. Pierot: 2; C; Balt, Cerus Endovascular, MicroVention/Sequent, Phenox, Vesalio, Penumbra.

BackgroundFlow disruption with the WEB is an innovative endovascular approach for treatment of wide-neck bifurcation aneurysms. Initial studies have shown a low complication rate with good efficacy.PurposeTo report clinical and anatomical results of the WEB treatment in the cumulative population of three Good Clinical Practice (GCP) studies: WEBCAST (WEB Clinical Assessment of Intrasaccular Aneurysm), French Observatory, and WEBCAST-2.MethodsWEBCAST, French Observatory, and WEBCAST-2 are single-arm, prospective, multicenter, GCP studies dedicated to the evaluation of WEB treatment. Clinical data were independently evaluated. Postoperative and 1-year aneurysm occlusion was independently evaluated using the 3-grade scale: complete occlusion, neck remnant, and aneurysm remnant.ResultsThe cumulative population comprised 168 patients with 169 aneurysms, including 112 female subjects (66.7%). The patients' ages ranged between 27 and 77 years (mean 55.5±10.2 years). Aneurysm locations were middle cerebral artery in 86/169 aneurysms (50.9%), anterior communicating artery in 36/169 (21.3%), basilar artery in 30/169 (17.8%), and internal carotid artery terminus in 17/169 (10.1%). The aneurysm was ruptured in 14/169 (8.3%). There was no mortality at 1 month and procedure/device-related morbidity was 1.2% (2/168). At 1 year, complete aneurysm occlusion was observed in 81/153 aneurysms (52.9%), neck remnant in 40/153 aneurysms (26.1%), and aneurysm remnant in 32/153 aneurysms (20.9%). Re-treatment was carried out in 6.9%.ConclusionsThis series is at the moment the largest prospective, multicenter, GCP series of patients with aneurysms treated with WEB. It shows the high safety and good mid-term efficacy of this treatment.Clinical trial registrationFrench Observatory: Unique identifier (NCT18069); WEBCAST and WEBCAST-2: Unique identifier (NCT01778322).

BACKGROUND AND PURPOSE: Flow disruption with the WEB device is a new technique for the endovascular treatment of wide-neck bifurcation aneurysms. To obtain precise data regarding the safety and efficacy of this treatment with high-quality methodology, the prospective French Observatory study was conducted. Analysis of these data is presented, including 1-year follow-up. MATERIALS AND METHODS: Patients with bifurcation aneurysms for which WEB treatment was indicated were included in this prospective, multicenter Good Clinical Practice study. Clinical data, including adverse events and clinical status at 1 month and 1 year, were collected and independently analyzed by a medical monitor. An independent core laboratory evaluated the anatomic results at 1 year following the procedure. RESULTS: Ten French neurointerventional centers included 62 patients (39 women), 33–74 years of age (mean, 56.6 ± 9.80 years) with 63 aneurysms. Aneurysm locations were the middle cerebral artery in 32 aneurysms (50.8%), anterior communicating artery in 16 (25.4%), basilar artery in 9 (14.3%), and internal carotid artery terminus in 6 (9.5%). Morbidity and mortality at 1 month were, respectively, 3.2% (2/62 patients) and 0.0% (0/62). Morbidity and mortality (unrelated to the treatment) at 1 year were, respectively, 0.0% (0/59) and 3.4% (2/59 patients). At 1 year, complete occlusion was observed in 30/58 aneurysms (51.7%); neck remnant, in 16/58 aneurysms (27.6%); and aneurysm remnant, in 12/58 aneurysms (20.7%). CONCLUSIONS: This prospective French Observatory study showed very good safety of aneurysm treatment with the WEB, with a high rate of adequate aneurysm occlusion at 1 year (79.3%).

Introduction Cerebral vasospasm is the leading cause of morbidity and mortality in patients with aneurysmal subarachnoid haemorrhage (SAH) surviving the initial ictus. Commonly used techniques for vasospasm assessment are digital subtraction angiography and transcranial Doppler sonography. These techniques can reliably identify only the major vessel spasm and fail to estimate its haemodynamic significance. To overcome these issues and to enable comprehensive non-invasive assessment of vasospasm inside the interventional suite, a novel protocol involving measurement of parenchymal blood volume (PBV) using C-arm flat detector computed tomography (FDCT) was implemented. Materials and methods Patients from the neuro-intensive treatment unit (ITU) with suspected vasospasm following aneurysmal SAH were scanned with a biplane C-arm angiography system using an intravenous contrast injection protocol. The PBV maps were generated using prototype software. Contemporaneous clinically indicated MR scan including the diffusion- and perfusion-weighted sequences was performed. C-arm PBV maps were compared against the MR perfusion maps. Results Distribution of haemodynamic impairment on C-arm PBV maps closely matched the pattern of abnormality on MR perfusion maps. On visual comparison between the two techniques, the extent of abnormality indicated PBV to be both cerebral blood flow and cerebral blood volume weighted. Conclusion C-arm FDCT PBV measurements allow an objective assessment of the severity and localisation of cerebral hypoperfusion resulting from vasospasm. The technique has proved feasible and useful in very sick patients after aneurysmal SAH. The promise shown in this early study indicates that it deserves further evaluation both for post-SAH vasospasm and in other relevant clinical settings.

BACKGROUND AND PURPOSE: C-arm flat detector CT parenchymal blood volume imaging allows functional assessment of the brain parenchyma in the neurointerventional suite. This study aimed to determine the optimal C-arm flat detector CT parenchymal blood volume thresholds for demarcating irreversibly infarcted brain parenchyma by using areas of restricted diffusion on MR imaging as a surrogate marker for infarction. MATERIALS AND METHODS: Twenty-six patients with delayed cerebral ischemia following aneurysmal SAH underwent research C-arm CT parenchymal blood volume scans by using a biplane angiography system and contemporaneous MR imaging. Infarct and peri-infarct tissue VOIs and their homologous VOIs in the contralateral uninvolved hemisphere were delineated on the basis of the review of DWI, PWI, and ADC images. Voxel-based receiver operating characteristic curve analysis was performed to estimate the optimal absolute and normalized parenchymal blood volume values for demarcating the infarct voxels. RESULTS: For 12 patients with areas of restricted diffusion (infarct volume, 6.38 ± 7.09 mL; peri-infarct tissue volume, 22.89 ± 21.76 mL) based on the voxel-based receiver operating characteristic curve analysis, optimal absolute and normalized parenchymal blood volume thresholds for infarction were 2.49 mL/100 g (area under curve, 0.76; sensitivity, 0.69; specificity, 0.71) and 0.67 (area under curve, 0.77; sensitivity, 0.69; specificity, 0.72), respectively (P value < .01). For the moderate-to-severely ischemic peri-infarct zone, mean parenchymal blood volume values of the involved hemisphere VOIs were lower compared with the uninvolved hemisphere VOIs (P value < .01). However, for the mild-to-moderately ischemic peri-infarct zone, there was no statistically significant difference between the mean parenchymal blood volume values of the involved and uninvolved hemisphere VOIs (P value > .05). CONCLUSIONS: C-arm flat detector CT parenchymal blood volume maps in conjunction with optimal thresholds are sensitive and specific for the estimation of irreversibly infarcted parenchyma. Parenchymal blood volume maps allow reliable detection of moderate-to-severe ischemia; however, the potential for underestimation of mild-to-moderate ischemia exists.

The different results from flat panel detector CT in various pathologies have provoked some discussion. Our aim was to assess the role of flat panel detector CT in brain arteriovenous malformations, which has not yet been assessed. Five patients with brain arteriovenous malformations were studied with flat panel detector CT, DSC-MR imaging, and vessel-encoded pseudocontinuous arterial spin-labeling. In glomerular brain arteriovenous malformations, perfusion was highest next to the brain arteriovenous malformation with decreasing values with increasing distance from the lesion. An inverse tendency was observed in the proliferative brain arteriovenous malformation. Flat panel detector CT, originally thought to measure blood volume, correlated more closely with arterial spin-labeling-CBF and DSC-CBF than with DSC-CBV. We conclude that flat panel detector CT perfusion depends on the time point chosen for data collection, which is triggered too early in these patients (ie, when contrast agent appears in the superior sagittal sinus after rapid shunting through the brain arteriovenous malformation). This finding, in combination with high data variability, makes flat panel detector CT inappropriate for perfusion assessment in brain arteriovenous malformations.

Purpose: WEB Flow disruption is an innovative endovascular treatment for wide-neck bifurcation aneurysms. Safety and efficacy are analyzed in the cumulated population of 3 prospective multicenter GCP (Good Clinical Practice) studies conducted in Europe (WEBCAST, French Observatory, WEBCAST2). Methods: Patients with wide neck bifurcation aneurysms were included in these 3 studies. An independent medical monitor independently analyzed adverse events. An independent expert in Interventional Neuroradiology evaluated anatomical results at 12 months using the 3 grades scale: complete occlusion, neck remnant, and aneurysm remnant. Results: A total of 168 patients with 169 aneurysms including 14 ruptured (8.3%) were included in the 3 studies. Eighty-six out 169 aneurysms were located at middle cerebral artery (50.9%), 36/169 at anterior communicating artery (21.3%), 30/169 at basilar artery (17.8%), and 17/169 at internal carotid artery terminus (10.1%). Placement of the WEB device was feasible in 163/169 aneurysms (96.4%). Morbidity and mortality at one month were reported in 4/168 patients (2.4%) and 0/168 patients (0.0%), respectively. Anatomical results at 12 months were complete aneurysm occlusion in 82/149 aneurysms (55.0%), neck remnant in 38/149 aneurysms (25.5%), and aneurysm remnant in 29/149 aneurysms (19.5%). Conclusion: This analysis in the large cumulated population of 3 GCP studies confirms the high safety of WEB treatment with low morbidity and mortality. At 12 months, adequate occlusion (complete occlusion and neck remnant) was obtained in a high percentage of aneurysms (80.5%).

These lesions comprise arteriovenous fistulas situated in the meninges and supplied partly or wholly by dural arteries. Venous drainage is to dural sinuses and/or leptomeningeal venous channels.

There are few topics in the field of endovascular neurosurgery as challenging as the management of patients with arteriovenous malformations of the brain. In line with other tutorials, which focus on a particular diagnosis, this tutorial describes pathology, clinical findings, diagnosis and treatments in a logical sequence. The emphasis is on optimising treatment for the affected individual. Diagnosis is a crucial part of the process and because of the variety of lesions and the importance of individual phenotype, advice to patients about intervention is now usually generated through multidisciplinary team discussions. The endovascular therapist thus needs to know the latest research findings in addition to being able to perform endovascular embolisation. This tutorial explains the importance of accurate imaging in defining a lesion’s angio-architecture and how this dictates treatment strategy. It also explains the controversies around our understanding of these complex lesions, so that patient advice can be appropriate and based on current guidelines.

The distal venous drainage of the head is through the jugular veins, vertebral veins and the inferior thyroid veins which drain to the brachiocephalic or subclavian veins. These receive the venous drainage of the veins of the face and neck, which for description can be divided into deep and superficial drainage systems or into anterior-to-posterior territories. The following description is a mix, and the reader is invited to use the diagrams to mentally assemble the described pathways into their coherent reality of interconnecting valveless channels. They will be described in groups based on the main veins. These do not fit easily into anatomical areas but collect definable tributaries before reaching the base of the neck. Their relative position will be from proximal to distal in the most consistent direction of blood flow (i.e. towards the heart).

In this tutorial spinal vascular malformations are defined and separated into spinal dural arteriovenous fistula, intradural perimedullary fistula and intramedullary spinal cord arteriovenous malformation. The reader is then taken through a detailed description of the aetiology, pathology, natural history, imaging and endovascular treatment techniques for each type. The clinical features and background literature associated with these lesions is explained, and the trainee is provided with protocols for performing spinal angiography for their diagnosis or exclusion. Other rare vascular lesions of the spine, including metameric syndromes, cavernous malformation and aneurysms are described, to complete a comprehensive review of spinal lesions relevant to the practice of endovascular neurosurgery and interventional neuroradiology.

The radiculospinal arteries supply the spinal cord and its nerve roots. These arteries were termed ‘radicular’, ‘radiculopial’ and ‘radiculomedullary’ by Tanon [1] because they individually provide one of three types of supply to the neural tissue. The radicular artery supplies nerve roots only; the radiculopial artery supplies nerve root and pial plexus (white matter), and the radiculomedullary artery supplies roots, pial plexus and cord medulla (grey matter).

The best available classification of this complex group is the biological description of lesions of infants and children published by Mulliken and Glowacki in 1982 [1]. This exemplifies the best in clinicopathological classifications and can be applied to vascular lesions of the head and neck in all ages. It is based on cellular features and correlated with clinical findings and natural history. It separates two main biologically different lesion types: haemangiomas and vascular malformations (Table 14.1). This chapter will refer extensively to the subtypes it defines. Mulliken and Glowacki classification [1] has stood the test of time and was adopted by the International Society for the Study of Vascular Anomalies in 1996. It is widely used as the basis for describing a group of conditions, often characterised by a ‘birthmark’. A minor modification was proposed in 1988 [2] which additionally divided vascular malformations into low- and high-flow lesions (Table 14.2).

Epistaxis is common. At least 60% of us will have episodes of nose bleeding at some time [2]. These occur with peak incidences in children ( 50 years). Only 6% of episodes require medical treatment, and these are usually in the older age group. Bleeding can arise from veins, arteries or arterialised veins (e.g. associated with a vascular malformation or an arteriovenous shunt). Most episodes are idiopathic, though epistaxis in adults is frequently associated with systemic hypertension and other medical comorbidities.

A carotid cavernous fistula (CCF) consists of an abnormal connection between the cavernous segment of the internal carotid artery (ICA) and the cavernous sinus. The resulting high-flow shunt raises pressure in the drainage pathways of the cavernous sinuses and causes symptoms due to venous hypertension in the orbit, cortical or deep cerebral veins and venous stenosis due to secondary hyperplasia. It is the most frequent location of direct intracranial arteriovenous fistulas and the majority are caused by trauma. Spontaneous fistulas are caused by rupture of an aneurysm of the cavernous ICA or other arterial diseases that weakens the wall. The connection is usually a single hole or less frequently a small number of individual holes. The point of rupture in the arterial wall is often large (1–10 mm) and spontaneous cure is therefore rare. Including this condition in a classification of angiographic patterns in dural arteriovenous malformations of the cavernous sinus region [1] is confusing the two conditions and adds little to their understanding or management.

Infants and children presenting with the vein of Galen malformation is a situation that an endovascular neurosurgeon is likely to encounter in their practice but not sufficiently often to develop the specialist skills for comprehensive management. This tutorial is tailored to give the reader an overview of management and specifically the knowledge needed for diagnosis, preliminary discussions with parents and follow-up support. In the UK this is sufficient for most practitioners since generally patients are referred on to specialist centres for interventions. In many other countries, referral to a special paediatric centre may not be an option so the principles of clinical assessment, timing of intervention and embolisation techniques are described. The background literature and classification of angiographic types are covered and the tutorial includes a discussion of non-Galenic arteriovenous fistulas because of similarities in their endovascular management with the vein of Galen malformation.

In this tutorial embolisation of tumours is first considered in general terms and then how it is applied to specific tumour types. A generic description guides the reader though the process of selection and pre-procedure assessments needed to achieve successful tumour devascularisation. The therapeutic aims dictated by histology and tumour locations are discussed and how they determine the assessment of risks and benefits prior to embolisation explained. Procedure techniques, precautions and post-procedure patient care are covered. The tutorial then takes the reader through the application of these principles to the commonly treated pathologies of the head and neck region, namely, meningioma, juvenile nasopharyngeal angiofibroma and paraganglioma. Other cranial and spinal tumours likely to be referred for embolisation are described in less detail but maintaining the same emphasis on the need to plan endovascular treatments and set achievable outcome goals for all interventions.

Context Despite the major risk of regrowth of clinically nonfunctioning pituitary adenomas (CNFAs) after primary treatment, systematic data on the probability of further tumor progression and the effectiveness of management approaches are lacking. Objective To assess the probability of further regrowth(s), predictive factors, and outcomes of management approaches in patients with CNFA diagnosed with adenoma regrowth after primary treatment. Patients, design, and setting Retrospective cohort study of 237 patients with regrown CNFA managed in two UK centers. Results Median follow-up was 5.9 years (range, 0.4 to 37.7 years). The 5-year second regrowth rate was 35.3% (36.2% after surgery; 12.5% after radiotherapy; 12.7% after surgery combined with radiotherapy; 63.4% with monitoring). Of those managed with monitoring, 34.8% eventually were offered intervention. Type of management and sex were risk factors for second regrowth. Among those with second adenoma regrowth, the 5-year third regrowth rate was 26.4% (24.4% after surgery; 0% after radiotherapy; 0% after surgery combined with radiotherapy; 48.3% with monitoring). Overall, patients with a CNFA regrowth had a 4.4% probability of a third regrowth at 5 years and a 10.0% probability at 10 years; type of management of the first regrowth was the only risk factor. Malignant transformation was diagnosed in two patients. Conclusions Patients with regrown CNFA after primary treatment continue to carry considerable risk of tumor progression, necessitating long-term follow-up. Management approach to the regrowth was the major factor determining this risk; monitoring had >60% risk of progression at 5 years, and a substantial number of patients ultimately required intervention.

Introduction: This study assessed volume changes of unruptured large and giant aneurysms (greatest diameter >20 mm) after treatment with flow diverter (FD) stents. Methods: Clinical audit of the cases treated in a single institution, over a 5-year period. Demographic and clinical data were retrospectively collected from the hospital records. Aneurysm volumes were measured by manual outlining at sequential slices using computerised tomography (CT) or magnetic resonance (MR) angiography data. Results: The audit included eight patients (seven females) with eight aneurysms. Four aneurysms involved the cavernous segment of the internal carotid artery (ICA), three the supraclinoid ICA and one the basilar artery. Seven patients presented with signs and symptoms of mass effect and one with seizures. All but one aneurysm was treated with a single FD stent; six aneurysms were also coiled (either before or simultaneously with FD placement). Minimum follow-up time was 6 months (mean 20 months). At follow-up, three aneurysms decreased in size, three were unchanged and two increased. Both aneurysms that increased in size showed persistent endosaccular flow at follow-up MR; in one case, failure was attributed to suboptimal position of the stent; in the other case, it was attributed to persistence of a side branch originating from the aneurysm (similar to the endoleak phenomenon of aortic aneurysms). At follow-up, five aneurysms were completely occluded; none of these increased in volume. Conclusion: Complete occlusion of the aneurysms leads, in most cases, to its shrinkage. In cases of late aneurysm growth or regrowth, consideration should be given to possible endoleak as the cause. © 2013 Springer-Verlag Berlin Heidelberg.

Objective The frequency and the degree of recovery of anterior pituitary hormone deficits in patients with macroprolactinoma responsive to cabergoline are not clear. Our aim was to evaluate pituitary function in these patients with particular reference to an assessment of the possible restoration of pituitary deficits. Subjects and Methods The records of all subjects prospectively presenting to our Department with macroprolactinomas treated with cabergoline over a 2-year period were reviewed. Pituitary function was assessed at diagnosis and, if abnormal, for three consecutive years for the GH, FSH/LH and ACTH axes, and at 3 years for the TSH axis. Results Twelve patients were included. Severe GH deficiency was found in 83% at diagnosis and did not resolve in any patient at last assessment. Gonadotrophin deficiency was found in 90% at diagnosis and in 50% at last evaluation (showing reversal in 44% of deficient patients, all achieved within 1 year). ACTH deficiency was found in 17% at diagnosis and it did not reverse in any patient at last assessment. TSH deficiency was found in 36% at diagnosis and in 27% at last assessment (reversal in 25% of deficient patients). Conclusions In our study, in a group of patients with macroprolactinoma systematically assessed at intervals, pituitary dysfunction in response to cabergoline was found to be mostly irreversible, except for the gonadotroph axis which showed restoration in a subset of subjects following achievement of normoprolactinaemia. It would appear that the reversibility of pituitary axes may be less common than previously thought. © 2012 John Wiley and Sons Ltd.

Background: Aneurysmal subarachnoid hemorrhage (SAH) and surgical clipping of intracranial aneurysms are associated with substantial morbidity and mortality. Objective: To compare cognitive outcome and structural damage in patients with aneurysmal SAH treated with surgical clipping or endovascular coiling. Methods: Forty case-matched pairs of patients with aneurysmal SAH treated by surgical clipping or endovascular coiling were prospectively assessed by use of a battery of cognitive tests. Twenty-three case-matched pairs underwent MRI 1 year after the procedure. Matching was based on grade of SAH on admission, location of aneurysm, age, and premorbid IQ. Results: Both groups were impaired in all cognitive domains when compared with age-matched healthy control subjects. Comparison of cognitive outcome between the two groups indicated an overall trend toward a poorer cognitive outcome in the surgical group, which achieved significance in four tests. MRI showed focal encephalomalacia exclusively in the surgical group. This group also had a significantly higher incidence of single or multiple small infarcts within the vascular territory of the aneurysm, but both groups had similar incidence of large infarcts and global ischemic damage. Conclusion: Endovascular treatment may cause less structural brain damage than surgery and have a more favorable cognitive outcome. However, cognitive outcome appears to be dictated primarily by the complications of SAH.

BACKGROUND AND PURPOSE: TDAVFs are uncommon causes of spontaneous intracranial hemorrhage. A retrospective review of their management was performed after repeatedly observing a previously under-recognized medial dural-tentorial branch of the SCA. MATERIALS AND METHODS: Thirteen patients were diagnosed with TDAVFs by CT/MR imaging and DSA during a 5.8-year period. Seven patients presented after intracranial hemorrhage. Twelve patients were treated endovascularly, and one, surgically. RESULTS: Eleven TDAVFs were located in the midline (7 at the falx cerebelli and 4 at the torcular), and 2 were petrotentorial. All torcular TDAVFs were associated with sinus thrombosis and showed bidirectional drainage relative to the tentorium. No sinus thrombosis was seen in the falx cerebelli subtype, which drained infratentorially only, except in 1 patient who had had unrelated surgery previously. Venous drainage was directly to cortical veins except for 1 petrotentorial and 2 torcular TDAVFs. A branch of the SCA, the medial dural-tentorial artery, was observed in 5 midline TDAVFs. Its anatomy was defined with selective angiography. Endovascular therapy resulted in a cure in 5 and subtotal occlusion in 6, and staged treatment is ongoing in 1 patient. One patient was cured after surgery. CONCLUSIONS: TDAVFs frequently cause intracranial hemorrhage and therefore warrant treatment. Endovascular therapy proved effective in this series, and arteriography was essential for understanding the various fistula subtypes and for treatment planning. We emphasize the importance of recognizing the medial dural-tentorial artery of the SCA with its characteristic course along the tentorium on angiography. This artery should be included in future anatomic descriptions of the cranial blood supply.

INTRODUCTION: Thrombotic events are a common and severe complication of endovascular aneurysm treatment with significant impact on patients' outcome. This study evaluates risk factors for thrombus formation and assesses the efficacy and safety of abciximab for clot dissolution. MATERIALS AND METHODS: All patients treated with abciximab during (41 patients) or shortly after (22 patients) intracranial aneurysm coil embolisation were retrieved from the institutional database (2000 to 2007, 1,250 patients). Sixty-three patients (mean age, 55.3 years, +/- 12.8) had received either intra-arterial or intravenous abciximab. Risk factors for clot formation were assessed and the angiographic and clinical outcome evaluated. RESULTS: No aneurysm rupture occurred during or after abciximab application. The intra-procedural rate of total recanalisation was 68.3%. Thromboembolic complications were frequently found in aneurysms of the Acom complex and of the basilar artery, whilst internal carotid artery aneurysms were underrepresented. Two patients died of treatment-related intracranial haemorrhages into preexisting cerebral infarcts. Two patients developed a symptomatic groin haematoma. CONCLUSIONS: Abciximab is efficacious and safe for thrombolysis during and after endovascular intracranial aneurysm treatment in the absence of preexisting ischaemic stroke.

PURPOSE OF REVIEW: This brief review highlights some factors affecting the short-term and long-term outcomes after endovascular treatment (EVT) of patients with intracranial aneurysms. RECENT FINDINGS: The principal procedural risks associated with EVT are symptomatic thromboembolic events affecting 2.4-5.2% of treatments, and aneurysm perforation which occurs in 0.5-2.4% of the patients with unruptured aneurysms and 2.3-6.5% of patients with subarachnoid haemorrhage. The risk of subsequent aneurysm recurrence requiring retreatment is about 10% and does not negate the morbidity advantage (relative to surgical clipping) of the initial EVT. This risk is about three-fold greater in aneurysms with a neck width more than 4 mm and sac maximum diameter greater than 10 mm. The incidence of rebleeding after EVT is 0.11-0.32% per annum and is probably lower if EVT achieves complete occlusion. SUMMARY: EVT dramatically reduces the risk of rebleeding in patients with subarachnoid haemorrhage. Treatment risks and rates of incomplete occlusions are increased in ruptured in comparison with unruptured aneurysms. Large aneurysms have higher risk of procedural thromboembolism, incomplete treatment and rate of recurrences with strong interdependence between these variables. The low risk of rebleeding in patients with subarachnoid haemorrhage is probably increased in incompletely treated aneurysms and in patients revealing aneurysm growth over time.