Flow Diversion for Intracranial Aneurysms

Thromboembolic Events After the Coverage of Anterior Cerebral Artery with Flow Diversion: A Single Institution Series and Systematic Review

BACKGROUND

Advances in the use of flow diversion (FD) now extend to bifurcation aneurysms; herein, we compare thromboembolic events in patients with internal carotid artery (ICA) aneurysms treated with and without exclusion of the anterior cerebral artery (ACA).

METHODS

Retrospective analysis of aneurysms in the terminal ICA treated with FD from 2013 to 2023 at a single-center study. Procedures were classified according to the coverage at the origin of the ACA and compared through bivariate-analysis. A review was also carried on PubMed, Web of Science, and EMBASE until April 2024, adhering to the PRISMA reporting guidelines.

RESULTS

Ninety-five patients harboring 113 aneurysms treated in 102 procedures were evaluated. Fifty-eight were treated covering the ACA origin. Dual antiplatelet regimens included aspirin-clopidogrel (50%), aspirin-ticagrelor (44.1%), and aspirin-prasugrel (4.9%). Thromboembolic events occurred in 6 patients (5.9%), all of which presented with large vessel occlusion of the ICA, but without reaching statistical difference in the 2 treated cohorts (P = 0.46). At a median clinical follow-up of 5.95 months, there were no differences in the functional outcomes in the 2 groups (P = 0.22). Contralateral angiographic runs post-treatment after covering the ACA origin demonstrated increase in the A1 (median: 0.45 mm; IQR = 0.4-1.2) and ICA diameter (median: 0.55 mm; IQR = 0.1-1.2). After pooling data from literature and our cohort, complete side branch occlusion after the coverage of ACA was seen in 25% of branches (95%CI = 0.16-0.36), and thromboembolic events were observed after 3% (95%CI = 0.01-0.04) of procedures.

CONCLUSIONS

Thromboembolic events can occur in distal ICA aneurysms treated with FD, but no significant association was seen with covering the ACA origin.

Safety and efficacy of coated flow diverters in the treatment of ruptured intracranial aneurysms: a retrospective multicenter study

BACKGROUND

This multicenter study evaluated the safety and efficacy of coated flow diverters (cFDs) for the treatment of ruptured intracranial aneurysms.

METHODS

Consecutive patients treated with different cFDs for ruptured aneurysms under tirofiban at eight neurovascular centers between 2016 and 2023 were retrospectively analyzed. The majority of patients were loaded with dual antiplatelet therapy after the treatment. Aneurysm occlusion was determined using the O'Kelly-Marotta (OKM) grading scale. Primary outcome measures were major procedural complications and aneurysmal rebleeding during hospitalization.

RESULTS

The study included 60 aneurysms (posterior circulation: 28 (47%)) with a mean size of 5.8±4.7 mm. Aneurysm morphology was saccular in 28 (47%), blister-like in 12 (20%), dissecting in 13 (22%), and fusiform in 7 (12%). Technical success was 100% with a mean of 1.1 cFDs implanted per aneurysm. Adjunctive coiling was performed in 11 (18%) aneurysms. Immediate contrast retention was observed in 45 (75%) aneurysms. There was 1 (2%) major procedural complication (a major stroke, eventually leading to death) and no aneurysmal rebleeding. A good outcome (modified Rankin Scale 0-2) was achieved in 40 (67%) patients. At a mean follow-up of 6 months, 27/34 (79%) aneurysms were completely occluded (OKM D), 3/34 (9%) had an entry remnant (OKM C), and 4/34 (12%) had residual filling (OKM A or B). There was 1 (3%) severe in-stent stenosis during follow-up that was treated with balloon angioplasty.

CONCLUSIONS

Treatment of ruptured aneurysms with cFDs was reasonably safe and efficient and thus represents a valid treatment option, especially for complex cases.

Pipeline embolization device versus Atlas stent assisted coiling for intracranial aneurysm treatment: a retrospective, propensity score matched study with a focus on midterm outcomes and hospital costs

BACKGROUND

Stent assisted coiling (SAC) and flow diverters (FDs) are common endovascular treatments for wide necked cerebral aneurysms, but studies comparing the new generation Atlas SAC and FDs are scarce. We performed a propensity score matched (PSM) cohort study to compare the Atlas SAC and the pipeline embolization device (PED) for proximal internal carotid artery (ICA) aneurysms.

METHODS

Consecutive ICA aneurysms treated at our institution with either the Atlas SAC or PED were studied. PSM was used to control for age, sex, smoking, hypertension, and hyperlipidemia, and the rupture status, maximal diameter, and neck size of the aneurysm (aneurysms >15 mm and non-saccular aneurysms were excluded). Midterm outcomes and hospital costs were compared between these two devices.

RESULTS

A total of 309 patients with 316 ICA aneurysms were included. Following PSM, 178 aneurysms treated with the Atlas SAC and PED were matched (n=89 in each group). Aneurysms treated with the Atlas SAC required a slightly longer procedure time, but had lower hospital costs than those treated with the PED (115.2±24.6 vs 102.4±40.8 min, P=0.012; $27 650.2±$6961.4 vs $34 107.0±$3707.2, P<0.001). Atlas SAC and PED treatments showed equivalent aneurysm occlusion rates (89.9% vs 86.5%, P=0.486), complication rates (5.6% vs 11.2%, P=0.177), and a favorable functional outcome (96.6% vs 97.8%, P=1.0) at follow-up (8.2±3.0 vs 8.4±4.2 months, P=0.652).

CONCLUSION

In this PSM study, midterm outcomes of the PED and Atlas SAC in the treatment of ICA aneurysms were similar. However, SAC required a longer operation time, and the PED may increase the economic cost of inpatients in Beijing, China.

Endoluminal flow diversion as a primary treatment strategy for pediatric traumatic intracranial aneurysms: a case-based review of literature

BACKGROUND

Traumatic intracranial aneurysms (TICAs) constitute a notable portion of pediatric intracranial aneurysms. Their unstable structure dictates a high incidence of rupture or mass effect from enlarging unruptured aneurysms, necessitating prompt diagnosis and treatment. TICAs often lack a true neck or are wide-necked, making them unsuitable for coil embolization and surgical clipping, and their fragile nature poses a risk of rupture during surgical and intrasaccular interventions. Endoluminal flow diverters (FD), deployed without requiring direct access to the aneurysmal sac, have emerged as an appealing sole treatment modality for TICAs. However, the clinical experience with this technique remains limited in the pediatric population.

METHOD

We describe the successful treatment of a paraclinoid TICA in a 4-year-old female using an endoluminal FD alone. Additionally, we conducted a literature review to assess the safety and effectiveness of this treatment modality in pediatric TICAs.

RESULTS

Endoluminal flow diversion led to complete aneurysm obliteration in our case, with no observed complication, at the 9-month follow-up. Our review of the previously reported pediatric TICAs managed by standalone flow diversion highlights this technique as safe, efficient, and promising as a sole treatment modality, particularly in the anterior circulation, with a high rate of persistent total obliteration and a low rate of complications. However, the requirement for long-term antiplatelet therapy with the possibility of frequent dose monitoring and adjustments warrants special attention when using endoluminal FDs. Until guidelines specifically addressing optimal antiplatelet therapy in children with intracranial FDs are formulated, adherence to existing protocols is imperative to avoid in-stent thrombosis.

CONCLUSION

Our literature review and personal experience indicate that endoluminal flow diversion can be a viable treatment approach for pediatric TICAs. However, prospective studies with extensive follow-ups are required to assess the durability of endoluminal FDs in treating pediatric TICAs, considering the long life expectancy of this demographic.

Comparison of a covered stent and pipeline embolization device in intracranial aneurysm: a propensity score matching analysis

BACKGROUND

The Willis covered stent (WCS) and pipeline embolization device (PED) have partly overlapping therapeutic indications. However, the differences of effect between these two treatments remain unclear.

OBJECTIVE

To compare clinical outcome, angiographic outcome, and complications following treatment with a WCS versus PED.

METHODS

Patients with intracranial aneurysms treated by a WCS or PED between January 2015 and December 2020 were included. The primary outcomes were complications, clinical outcome (modified Rankin Scale score >2), and angiographic outcome (incomplete aneurysm occlusion). Propensity score matching was conducted to adjust for potential confounding factors.

RESULTS

A total of 94 aneurysms treated by WCS and 698 aneurysms by PED were included. Compared with the PED group, patients in the WCS group are younger, a greater number have a poor condition at admission, a larger proportion of ruptured, non-saccular, and anterior circulation aneurysms, a smaller aneurysm neck width, and less coiling assistance is required. A total of 42 (44.7%) branches were covered by WCS. After adjustment for age, sex, aneurysm type, rupture status, neck size, aneurysm location, and coiling, 50 WCS and PED pairs were examined for internal carotid artery aneurysms. No significant differences were observed in clinical (10.4% vs 2.1%, P=0.206) and angiographic outcomes (12.8% vs 18.2%, P=0.713). However, 27 branches covered by WCS, including 22 ophthalmic arteries and five posterior communicating arteries. Patients in the WCS group had a higher intraoperative complication rate than those in the PED group (28% vs 6%, P=0.008), especially in the occlusion rate of covered branches (51.9% vs 11.1%, P<0.001).

CONCLUSION

The comparable clinical and angiographic outcomes of WCS or PED demonstrate the therapeutic potential of WCS as a viable alternative for aneurysms. However, the complication of occlusion of covered branches might not be negligible.

Flow diverters in the treatment of intracranial dissecting aneurysms: a systematic review and meta-analysis of safety and efficacy

BACKGROUND

Intracranial dissecting aneurysms present clinical challenges, demanding immediate intervention due to their high bleeding risk. While traditional treatments have limitations, the potential of flow diverters shows promise but remains a subject of ongoing debate for optimal management. The aim of this study was assess the safety and efficacy of flow diverters in the treatment of intracranial dissecting aneurysms.

METHODS

A systematic review and meta-analysis was performed following established guidelines. The search encompassed PubMed, Scopus, Web of Science, and Embase databases up to July 20, 2023. Eligible studies reporting outcomes of interest were included, and relevant data were extracted and analyzed using R software.

RESULTS

The analysis, based on data pooled from 20 included studies involving 329 patients, revealed a favorable functional outcome rate of 89.7% at the last follow-up. The mortality rate during the follow-up period was 2.4%, decreasing to 0.9% when excluding the outlier study. In the final angiographic follow-up, a complete occlusion rate of 71.7% and an adequate occlusion rate of 88.3% were observed. Notably, studies with longer angiographic follow-up times exhibited lower rates of complete (P=0.02) and adequate (P<0.01) occlusion. A minimal aneurysm recurrence/rebleeding rate of 0.1% was noted, while in-stent stenosis/thrombosis occurred at a rate of 1.14%. Additionally, ischemic events/infarctions were seen in 3.3% of cases. The need for retreatment was minimal, with a rate of 0.9%, and the technical success rate was impressively high at 99.1%.

CONCLUSION

This study highlights the safety and efficacy of flow diverters in treating intracranial dissecting aneurysms. Further research, encompassing larger multicenter studies with extended follow-up periods, is crucial for comprehending occlusion dynamics, refining treatment strategies, improving long-term outcomes, and addressing methodological limitations.

Periprocedural management of patients presenting for neurointerventional procedures using flow diverters for complex intracranial aneurysms: An anesthetist's perspective - A narrative review

Complex intracranial aneurysms pose significant challenges in the realm of neurointervention, necessitating meticulous planning and execution. This article highlights the crucial roles played by anesthetists in these procedures, including patient assessment, anesthesia planning, and continuous monitoring and maintaining hemodynamic stability, which are pivotal in optimizing patient safety. Understanding these complex procedures and their complications will aid the anesthetist in delivering optimal care and in foreseeing and managing the potential associated complications. The anesthetist's responsibility extends beyond the procedure itself to postprocedure care, ensuring a smooth transition to the recovery phase. Successful periprocedural anesthetic management in flow diverter interventions for complex intracranial aneurysms hinges on carefully orchestrating these elements. Moreover, effective communication and collaboration with the interventional neuroradiologist and the procedural team are emphasized, as they contribute significantly to procedural success. This article underscores the essential requirement for a multidisciplinary team approach when managing patients undergoing neurointerventions. In this collaborative framework, the expertise of the anesthetist harmoniously complements the skills and knowledge of other team members, contributing to the overall success and safety of these procedures. By providing a high level of care throughout the periprocedural period, anesthetists play a pivotal role in enhancing patient outcomes and minimizing the risks associated with these intricate procedures. In conclusion, the periprocedural anesthetic management of neurointervention using flow diverters for complex intracranial aneurysms is a multifaceted process that requires expertise, communication, and collaboration.

Magnetic resonance perfusion imaging findings following flow diversion in patients with complex middle cerebral artery bifurcation aneurysms: a single-center analysis regarding the jailed cortical branches

BACKGROUND

Flow diverter (FD) devices provide a safe and effective treatment option especially for wide-necked intracranial aneurysms. One of the main concerns in patients treated with FD devices is patency of arterial branches jailed by the stent. However, there are no long-term data from magnetic resonance perfusion (MRP) studies regarding jailed branches. In this study we aimed to reveal the MRP findings in patients with jailed middle cerebral artery (MCA) cortical branches during long-term follow-up after flow diversion.

METHODS

Patients who underwent FD stent treatment for MCA aneurysms with a resulting jailed cortical branch were included. Follow-up clinical, angiographic, and MRP examination findings were recorded. Different MRP parameters were measured in the MCA territory regarding the jailed branches.

RESULTS

Eighteen patients treated endovascularly with flow diversion for a total of 20 MCA aneurysms were included. At angiographic follow-up (median 35 months, range 7-95 months) complete occlusion was observed in 13 (65%) aneurysms and partial occlusion was observed in 6 (30%). The mean transit time (MTT) prolongation, MTT ratio, time-to peak (TTP) prolongation, and TTP ratio were 1.34, 1.20, 1.18, and 1.06 s, respectively, when compared with the contralateral side in the MCA territory. MTT, TTP, and cerebral blood volume values of the patients showed statistically significant differences compared with the contralateral side (P<0.05).

CONCLUSIONS

Flow diversion treatment of complex bifurcation aneurysms can be effective and safe. MRP examination may reveal perfusion changes in the territory vascularized via a jailed branch, and these changes are rarely accompanied by clinical findings.

Mass Effect After Flow Diversion for Unruptured Large and Giant Cavernous or Paraclinoid Internal Carotid Artery Aneurysm

OBJECTIVE

The mass effect associated with large or giant intracranial aneurysms is difficult for traditional endovascular treatment. This study investigated whether flow diverters can relieve the aneurysmal mass effect caused by aneurysmal compression symptoms.

METHODS

Fifty-five patients with unruptured large and giant intracranial aneurysms treated by a flow diverter at our institution from January 2014 to February 2022 were retrospectively evaluated.

RESULTS

In this study, 53 patients were included. Initially, 27 patients (51.9%), including 10 with compressive optic neuropathy, 12 with third nerve palsy, 2 with facial hyperesthesia, and 11 with sixth nerve palsy, were symptomatic. The symptom duration was shorter in the improved group (n = 2.2 ± 4.0 vs. n = 3.1 ± 3.9, P = 0.49). Thrombus formation following the flow diversion procedure was typically observed on magnetic resonance imaging (MRI) performed immediately and was not significantly associated with symptomatic improvement (OR = 0.395; 95% CI (0.058-2.698), P = 0.343). However, symptomatic improvement was seen in most patients when the aneurysm size decreased on MRI. A reduction in the aneurysm size on the MRI at the 3-month follow-up was correlated with symptomatic improvement in the multivariate analysis (OR = 0.08, 95% CI (0.013-0.485), P < 0.05).

CONCLUSIONS

A flow diverter might help alleviate compression symptoms caused by large or giant intracranial aneurysms. Shrinkage of the aneurysm within 3 months postoperatively and a shorter duration of symptoms contribute to the favorable outcomes of mass effect. Ultimately, prompt treatment is crucial for improving symptomatic intracranial artery aneurysms.

Treatment of Ruptured Wide-Necked Aneurysms using a Microcatheter Injectable Biomaterial

Ruptured wide-neck aneurysms (WNAs), especially in a setting of coagulopathy, are associated with significant morbidity and mortality. It is shown that by trapping a sub-millimeter clinical catheter inside the aneurysm sac using a flow diverter stent (FDS), instant hemostasis can be achieved by filling the aneurysm sac using a novel biomaterial, rescuing catastrophic bleeding in large-animal models. Multiple formulations of a biomaterial comprising gelatin, nanoclay (NC), and iohexol are developed, optimized, and extensively tested in vitro to select the lead candidate for further testing in vivo in murine, porcine, and canine models of WNAs, including in a subset with aneurysm rupture. The catheter-injectable and X-ray visible versions of the gel embolic agent (GEA) with the optimized mechanical properties outperform control groups, including a subset that receive a clinically used liquid embolic (Onyx, Medtronic), with and without aneurysm rupture. A combinatorial approach to ruptured WNAs with GEA and FDS may change the standard of medical practice and save lives.

Early Termination versus Standard Regimen Duration of Dual Antiplatelet Therapy in Intracranial Aneurysm Patients Treated With Pipeline Embolization Device Flex With Shield Technology: Preliminary Experience of 3 U.S. Centers

BACKGROUND

Pipeline Flex Embolization Device with Shield Technology (PED-Shield) is a third-generation flow diverter with reduced thromboembolic potential. However, safety profile and dual antiplatelet therapy (DAPT) recommendations with PED-Shield is not well -established. We aim to assess the safety and complication profile with early termination of DAPT with use of PED-Shield.

METHODS

Databases of 3 high-volume cerebrovascular centers were retrospectively reviewed. We identified patients with unruptured and ruptured intracranial aneurysms treated with PED-Shield. Patient demographics, aneurysm characteristics, complications, and angiographic outcomes were extracted. All patients who had early termination of DAPT, defined as <180 days, as well as standard duration were included.

RESULTS

A total of 37 patients, totaling 37 aneurysms, had early termination of DAPT and 24 patients with 24 aneurysms received standard duration (>180 days) of DAPT. There was no difference in pre-procedural DAPT regimens between the groups (P = 0.503). Following DAPT termination, o1ne major thromboembolic complication was observed in the early termination group while no major or minor thromboembolic or hemorrhagic complication was noted in the standard duration group. Time of angiographic follow-up was not statistically different (P = 0.063) between the early termination (343 days, interquartile range [IQR] 114-371 days) and the standard duration (175 days, IQR 111-224.5 days) groups. There were no statistically significant differences in complete aneurysm occlusion (P = 0.857), residual neck (P = 0.582), and aneurysm remnant (P = 0.352) rates between the groups on angiography.

CONCLUSIONS

Early termination of DAPT proves safe after PED-Shield treatment of intracranial aneurysms with comparable complete occlusion rates.

Device use trends in neuroendovascular procedures in the United States from 2015 to 2020

BACKGROUND

Neuroendovascular therapies involve an everchanging landscape of new technologies. Understanding the real-world timeframe of adaptation of such technologies can provide further guidance on mechanisms that could be employed to shorten the duration necessary for the widespread use of proven therapies. In this study, we aim to investigate the trends in the use of neuroendovascular technologies, utilizing the sales of neuroendovascular devices, as a proxy for procedural volume.

METHODS

Utilizing a device sales data registry from the Decision Resources Group, a healthcare research and consulting company, we examined trends in the sales of devices utilized in cerebrovascular thrombectomy, cerebral aneurysm treatment, and carotid stenting from the same 407 reporting hospitals in the United States between January 1, 2015, and January 1, 2020. Device sales per year were plotted as both the total number of devices sold per year as well as the percent of total device sales when compared against at least one other device. The Cochran-Armitage test for trend was performed when comparing at least two devices to each other. Analyses were performed using RStudio Version 1.1.456 (https://rstudio.com).

RESULTS

Between 2015 and 2020, there was a significant increase in the use of flow-diverting stents as well as nondiverting stents utilized for coil assistance. However, the total number of coils utilized over the years has declined. In terms of stroke therapy, between 2015 and 2020, there was a trend of increased use of both aspiration catheters as well as stent retrievers, which plateaued in 2020. The number of stents used for carotid procedures has also been gradually increasing over time.

CONCLUSION

Our study demonstrates an increase in the use of flow-diverting stents, nondiverting stents, carotid stents, and reperfusion devices for acute ischemic stroke intervention between 2015 and 2020. Coil use for aneurysmal treatment has declined.

Endovascular and microsurgical management of blister aneurysms: a multi-centre review

Blister aneurysms (BA) are high-risk cerebrovascular lesions accounting for 1% of intracranial aneurysms. The defective vessel wall and broad-based neck make this clinical entity difficult to treat, with high rates of re-rupture and mortality in patients presenting with acute subarachnoid haemorrhage. Blister aneurysms pose substantial challenges for both endovascular and microsurgical management. The objective of this study is to evaluate endovascular and microsurgical outcomes in intracranial blister aneurysm management across two tertiary hospitals. A review of two tertiary hospitals with a systematic imaging database search for term of "blister" in modalities from January 2010 to October 2022 was conducted. Operation reports were screened for the 5-year period since cerebral angiogram reports transitioned to surgical database. Identified reports were screened and reviewed for confirmed diagnosis by consultant neuroradiologist. A total of 21 cases of blister aneurysms managed at respective facilities were included. Sixteen cases (76%) were managed endovascularly. Four cases (19%) were managed surgically-2 with primary clipping, and 2 wrap and clipping. One case was managed conservatively (5%). Clinical outcomes were discharge disposition, aneurysm exclusion and post-operative complications. BAs have challenging considerations with high mortality and morbidity. Endovascular treatment offers a less invasive modality with lower rates of intraoperative rupture and morbidity. Mortality rates and patients discharged home were comparable. Commencement of dual anti-platelet therapy was safe in patients with flow diversion stents despite sub-arachnoid blood volume. Management of blister aneurysms is complex. Endovascular treatment shows promise for acute management but careful collaborative consideration of antithrombotic regime and requirement for further surgery should be considered.

Evaluation of Intra-Aneurysmal Residual Blood Flow with the iMSDE T1-Black Blood Imaging after Flow Diverter Treatment

Objective

We aimed to evaluate the efficacy of the "improved motion-sensitized driven-equilibrium (iMSDE)"-prepared T1-weighted black blood (T1-BB) MRI for monitoring treatment effect with a flow diverter (FD) for cerebral aneurysms.

Methods

Following the exclusion of concomitant coiling and retreatment cases from 60 consecutive cases of cerebral aneurysms treated with FDs at our institution, 32 with imaging data were included in the analysis. Detectability of residual blood flow within the aneurysms was validated as follows: 1) comparison of MRI sequences (iMSDE-prepared T1-BB images, T1-weighted images [ T1WI], and time-of-flight [ TOF]-MRA) in cases of incompletely occluded aneurysms and 2) comparison of angiography and MRI sequences in the same period.

Results

1) The probability of diagnosing intra-aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB (iMSDE-prepared T1-BB vs. T1WI, p <0.001; iMSDE-prepared T1-BB vs. TOF-MRA, p <0.001). 2) The diagnostic accuracy of residual aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB than that with T1WI (p = 0.032). Furthermore, in cases of incomplete occlusion, the probability of detecting intra-aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB (iMSDE-prepared T1-BB vs. T1WI, p <0.001; iMSDE-prepared T1-BB vs. TOF-MRA, p = 0.023).

Conclusion

Our results demonstrated that iMSDE-prepared T1-BB could help distinguish between blood flow and thrombus within the aneurysms after FD treatment, especially in the early stages of FD treatment.

Supraorbital keyhole approach for paraclinoid aneurysms clipping: A case series with literature review

Background

Paraclinoid aneurysms (PcAs) are challenging aneurysms due to the complexity of their relation to the surrounding bony and neurovascular structures. Although over the past decade, their management strategy has shifted from transcranial to endovascular approaches; here, we try to revolve around a subcategory to which minimal invasive supraorbital keyhole (SOK) surgery is feasible depending on specific radiological criteria with a literature review.

Methods

A group of unruptured PcAs was managed surgically, with a subset that was clipped through the SOK approach. They were selected by preoperative simulation images using 3D computed tomography (CT) angiography (CTA). We also conducted an extensive literature review based on a database available on PubMed and Google Scholar, the yielded cases from the literature review plus our cases were analyzed according to six parameters including their size, location, dome direction, need for clinoidectomy and proximal cervical control, and surgical outcome.

Results

From February 2009 to August 2022, 49 cases of unruptured PcAs were managed by clipping, and of these, four cases were clipped by the SOK approach, in addition, four cases were yielded through the literature review. The sizes of the PcAs ranged from 3 to 8 mm. Their location fluctuated from anterior to the superomedial wall and their domes pointed superiorly except for one which points posteriorly. Six of eight cases required anterior clinoidectomy, the outcome was uneventful.

Conclusion

A subset of unruptured PcAs are amenable to SOK with criteria such as unruptured small aneurysm (<10 mm) and projected superiorly. These characteristics can be determined preoperatively using CTA.

Machine learning and reduced order modelling for the simulation of braided stent deployment

Endoluminal reconstruction using flow diverters represents a novel paradigm for the minimally invasive treatment of intracranial aneurysms. The configuration assumed by these very dense braided stents once deployed within the parent vessel is not easily predictable and medical volumetric images alone may be insufficient to plan the treatment satisfactorily. Therefore, here we propose a fast and accurate machine learning and reduced order modelling framework, based on finite element simulations, to assist practitioners in the planning and interventional stages. It consists of a first classification step to determine a priori whether a simulation will be successful (good conformity between stent and vessel) or not from a clinical perspective, followed by a regression step that provides an approximated solution of the deployed stent configuration. The latter is achieved using a non-intrusive reduced order modelling scheme that combines the proper orthogonal decomposition algorithm and Gaussian process regression. The workflow was validated on an idealized intracranial artery with a saccular aneurysm and the effect of six geometrical and surgical parameters on the outcome of stent deployment was studied. We trained six machine learning models on a dataset of varying size and obtained classifiers with up to 95% accuracy in predicting the deployment outcome. The support vector machine model outperformed the others when considering a small dataset of 50 training cases, with an accuracy of 93% and a specificity of 97%. On the other hand, real-time predictions of the stent deployed configuration were achieved with an average validation error between predicted and high-fidelity results never greater than the spatial resolution of 3D rotational angiography, the imaging technique with the best spatial resolution (0.15 mm). Such accurate predictions can be reached even with a small database of 47 simulations: by increasing the training simulations to 147, the average prediction error is reduced to 0.07 mm. These results are promising as they demonstrate the ability of these techniques to achieve simulations within a few milliseconds while retaining the mechanical realism and predictability of the stent deployed configuration.

Utility of flow diverters in treatment of acutely ruptured uncoilable aneurysms of the posterior circulation of the brain

PURPOSE

Aim of this study is to evaluate safety and efficacy of flow diverters (FDs) in treatment of acutely ruptured posterior circulation aneurysms MATERIALS AND METHODS: Databases of three participating institutions were retrospectively scanned for patients in whom FD placement was attempted for treatment of acutely ruptured vertebrobasilar aneurysms. An interval of 14 days or fewer between the latest ictus and treatment was used as inclusion criterion. Patients with dolichoectasia of vertebrobasilar arteries were excluded. If necessary, adjunctive techniques including coiling or stenting were utilized. Clinical outcomes were graded using mWFNS (modified World Federation of Neurosurgical Societies Scale) and mRS (modified Rankin Scale). Aneurysmal occlusion was defined as Raymond-Roy Class 1. Spearman's (ρ) test was used to assess the correlation between variables. Univariate and multivariate logistic regression were used to assess outcomes.

RESULTS

31 patients (25 women, mean age: 52.7 ± 15.2) harboring 32 aneurysms (16 non-saccular, mean size: 11.4 ± 7 mm) were included. Mean number of FDs used was 1.22 ± 0.42. In six cases, adjunctive coiling and in five cases, apposing stent placement were used. Overall mortality rate and procedure-related mortality rates were 22.5% (7/31) and 9.6% (3/31), respectively. At a mean imaging follow-up of 17.2 ± 12.6 months, total occlusion was achieved in 22 aneurysms (91.6%). Univariate analysis showed that mortality was positively correlated with vasospasm (ρ = 0.600, p < 0.05), higher mWFNS Scale (ρ = 0.685, p < 0.05), higher modified Fischer Score (ρ = 0.609, p < 0.05), higher mRS (ρ = 0.594, p < 0.05) on admission and negatively correlated with saccular morphology (ρ = -0.529, p < 0.05). Multivariate logistic regression identified mWFNS on admission as a significant predictor. (OR: 7.148, 95% CI 1.777-28.758, p: 0.01). Adjunctive coiling positively correlated with aneurysm occlusion. (ρ = 0.522, p < 0.05).

CONCLUSION

The procedure-related morbidity and mortality is not negligible. However, the risks and efficacy associated with FDs are acceptable, especially when adjunctive coiling is possible, given the lack of treatment alternatives.

Ticagrelor versus clopidogrel dual antiplatelet therapy for unruptured intracranial aneurysms treated with flowdiverter

BACKGROUND AND PURPOSE

Antiplatelet therapy (APT) is a key element limiting the risk of thromboembolic events (TEE) in neuroendovascular procedures, including aneurysm treatment with flowdiverter. Clopidogrel combined with aspirin is the mostly reported dual APT (DAPT). However, resistance phenomenon and intraindividual efficacy fluctuation are identified limitations. In recent years, ticagrelor has been increasingly used in this indication. We compared these two DAPT regimens for intracranial aneurysm treated with flowdiverter.

METHODS

We conducted a multicentric retrospective study from prospectively maintained databases in two high volume centers extracting consecutive patients presenting unruptured intracranial aneurysm treated with flowdiverter and receiving DAPT (May 2015 to December 2019).  Two groups were compared according to their DAPT regimen: "ticagrelor+aspirin" and "clopidogrel+aspirin". Clopidogrel group was systematically checked with platelet test inhibition before endovascular procedure. The primary endpoint was composite, defined as any thrombo-embolic event (TEE) or major hemorrhagic event occurring the first 6 months during and after embolization RESULTS: 260 patients met our inclusion criteria. Baseline patients and aneurysms characteristics were comparable between groups, except for aneurysm location, median size and pre-treatment modified Rankin scale. No significant difference was observed regarding the primary composite outcome: 11.5% (12/104) in the ticagrelor group versus 10.9% (17/156) in the clopidogrel group (p = 1.000). There was also no significant difference in secondary outcomes including TEE (10.5 vs 9.0%; p = 0.673), major hemorrhage (0.9 vs 1.2%; p = 0.651) and clinical outcome (at least 1-point mRS worsening during follow up: 6.7% vs 8.3%; p = 0.813).

CONCLUSION

First-line DAPT with ticagrelor+aspirin seems as safe and effective as clopidogrel+aspirin regimen.

A review of technological innovations leading to modern endovascular brain aneurysm treatment

Tools and techniques utilized in endovascular brain aneurysm treatment have undergone rapid evolution in recent decades. These technique and device-level innovations have allowed for treatment of highly complex intracranial aneurysms and improved patient outcomes. We review the major innovations within neurointervention that have led to the current state of brain aneurysm treatment.

Treatment results of anterior choroidal artery aneurysms treated mostly with coil embolization: A single-center experience

BACKGROUND

Anterior choroidal artery (AchA) aneurysms are usually small in diameter because of the size of the involved artery and are often wide-necked. Coil embolization of AchA aneurysm is thus challenging because of serious risks, such as thromboembolic occlusion of artery and perforation of aneurysm dome. Therefore, aneurysmal neck clipping remains widely performed despite a recent increase in the use of coil embolization for aneurysm treatment. We report the treatment results of AchA aneurysms mostly (92.3%) treated with coil embolization at our institute.

METHODS

The database and medical records of patients who underwent coil embolization for AchA aneurysms were retrospectively analyzed. The clinical and imaging results and procedure-related complications were investigated after coil embolization performed between January 2006 and March 2022 at our institute.

RESULTS

In total, 96 AchA aneurysms comprising 65 unruptured and 31 ruptured aneurysms, including only 1 ruptured aneurysm (1.0%) re-embolized at postoperative day 192 because of coil compaction, were evaluated. After the initial coil embolization, complete occlusion was attained in 41, residual neck in 45, and residual aneurysm in 10 patients. Follow-up radiological studies after 6-174 months were performed for 80 aneurysms. Complete occlusion was noted in 57 patients, residual neck in 22, and residual aneurysm in 1. The dysarthria experienced by one (1.0%) patient was the only symptomatic procedure-related complication. After coil embolization, neither delayed new rupture nor re-rupture was observed.

CONCLUSIONS

The results of this study demonstrate that coil embolization is a safe and effective treatment option for patients with AchA aneurysms.

Choroidal and retinal anatomical response following treatment of carotid-ophthalmic aneurysms with flow diverter stents

BACKGROUND

Flow diverter stents(FDSs) are recent additions to the endovascular armament for treating ophthalmic segment aneurysms(OSA). In our study we evaluated the long-term effect of FDS placement on multiple Optical Coherence Tomography(OCT) findings, best corrected visual acuity(BCVA) and intra-ocular pressure(IOP).

METHODS

A prospective cohort study was conducted in 35 patients treated with a single FDS placement for OSA, between 2013 and 2018. Spectral-domain OCT was used to measure retinal nerve fiber layer thickness, ganglion cell complex thickness, subfoveal choroidal thickness(SFCT), and other stereometric parameters. Choroidal Vascularity Index(CVI) in a 1.5 mm wide subfoveal choroidal area was calculated. BCVA and IOP were also assessed. These measurements, at final follow up, were compared to the untreated fellow eye to evaluate the long-term effect of FDS placement.

RESULTS

This study included 70 eyes from 35 patients (100% female) with a mean age of 54.9 ± 9.8 years and mean follow-up period of 37.3 ± 18.9 months. No ophthalmic artery occlusion was encountered. The mean CVI was significantly higher in the stented side compared to the fellow normal eye (66.90±1.95 vs 65.05±1.93, p=.001) while mean SFCT was significantly reduced (251.23±68.54 vs 288.78±78.95, p=.037). Differences in the remaining studied parameters did not reach statistical significance. The difference in BCVA between stented and fellow normal eyes was also not significant (0.057±0.213 vs 0.060±0.214, p=.977 in logMAR).

CONCLUSION

Treatment with FDSs did not cause permanent visual damage. This study is the first to report a decrease in SFCT with a compensatory increase in CVI following FDS placement for OSA.

Intracranial aneurysms in pediatric population treated with flow diverters: A single-center experience

Background:

Pediatric intracranial aneurysms (PIAs) are uncommon. Flow diverters (FDs) have shown to be effective on treatment of selected aneurysms.

Methods:

We describe 10 cases of PIAs treated with FDs at one medical center in Mexico, from April 2015 to April 2020.

Results:

Out of 230 patients treated with FDs, 10 (4.3%) were pediatric. Average age was 9.4 years old (R: 6–15). Two patients (20%) had subarachnoid hemorrhage, 3 had epilepsy (30%), 3 (30%) had clinical signs of cranial nerve compression, and 4 (40%) had only headache. Two patients were in 1a grade of Hunt and Kosnik scale. Out of the nonruptured aneurysms, 7 (70%) were in 15 points of Glasgow Coma Scale and 1 patient (10%) was in 13 points. Treatment was performed without complications; nevertheless, appropriate distal deployment was not achieved in one case. At discharge, nine patients had 5 points of Glasgow Outcome Scale. All patients underwent computed tomography angiography or digital subtraction angiography at 1, 3, 6, and 12 months, 2 patients (20%) had a 2-year follow-up, and 3 patients (30%) had a 3-year follow-up. According to Kamran grading scale, 9 patients (90%) were classified as Grade 4 and 1 patient (10%) as Grade 3.

Conclusion:

Even though it is a small series, as this is an uncommon disease, we may suggest that FDs are useful to treat properly selected PIAs. Our study has consecutive imaging assessment at least a year of follow-up in which aneurysm stable occlusion was observed in 90% of patients.

North American multicenter experience with the Flow Redirection Endoluminal Device in the treatment of intracranial aneurysms

OBJECTIVE

Flow diverters have revolutionized the endovascular treatment of intracranial aneurysms. Here, the authors present the first large-scale North American multicenter experience using the Flow Redirection Endoluminal Device (FRED) in the treatment of cerebral aneurysms.

METHODS

Consecutive cerebral aneurysms treated with FRED at 7 North American centers between June 2020 and November 2021 were included. Data collected included patient demographic characteristics, aneurysm characteristics, periprocedural and long-term complications, modified Rankin Scale (mRS) scores, and radiological follow-up.

RESULTS

In total, 133 aneurysms in 116 patients were treated with 123 FRED deployment procedures and included in this study. One hundred twenty-six aneurysms (94.7%) were unruptured, 117 (88.0%) saccular, and 123 (92.5%) located in anterior circulation. The mean (range) aneurysm maximal width and neck width sizes were 7.2 (1.5-42.5) mm and 4.1 (1.0-15.1) mm, respectively. Successful FRED deployment was achieved in 122 procedures (99.2%). Adjunctive coiling was used in 4 procedures (3.3%). Radiological follow-up was available for 101 aneurysms at a median duration of 7.0 months. At last follow-up, complete occlusion was observed in 55.4% of patients, residual neck in 8.9%, and filling aneurysm in 35.6%; among cases with radiological follow-up duration > 10 months, these values were 21/43 (48.8%), 3/43 (7.0%), and 19/43 (44.2%), respectively. On multivariate regression analysis, age (OR 0.93, p = 0.001) and aneurysm neck size (OR 0.83, p = 0.048) were negatively correlated with odds of complete occlusion at latest follow-up. The retreatment rate was 6/124 (4.8%). The overall complication rate was 31/116 (26.7%). Parent vessel occlusion, covered branch occlusion, and in-stent stenosis were detected in 9/99 (9.1%), 6/63 (9.5%), and 15/99 (15.2%) cases, respectively. The FRED-related, symptomatic, thromboembolic, and hemorrhagic complication rates were 22.4%, 12.9%, 6.9%, and 0.9% respectively. The morbidity rate was 10/116 patients (8.6%). There was 1 death due to massive periprocedural internal carotid artery stroke, and 3.6% of the patients had an mRS score > 2 at the last follow-up (vs 0.9% at baseline).

CONCLUSIONS

As the first large-scale North American multicenter FRED experience, this study confirmed the ease of successful FRED deployment but suggested lower efficacy and a higher rate of complications than reported by previous European and South American studies on FRED and other flow-diverting devices. The authors recommend judicious use of this device until future studies can better elucidate the long-term outcomes of FRED treatment.

Progressive volume reduction and long-term aneurysmal collapse following flow diversion treatment of giant and symptomatic cerebral aneurysms

Background

The primary goal of conventional endovascular and microvascular approaches is the clinical and radiological resolution of the symptomatic aneurysm-induced mass effect. This study assessed the volume changes and mass effect reduction due to sac shrinkage after treatment with flow diverter stents (FD) for unruptured cerebral aneurysms.

Methods

We analyzed retrospectively 36 symptomatic aneurysms that were larger or equal to 25 mm in diameter in patients treated at our center from January 2016 to April 2022. Radiological and clinical outcomes were analyzed, including aneurysmal volume changes and resolution of aneurysm-related symptoms.

Results

At 6 months, 25 aneurysms decreased in size, 2 remained unchanged, and 9 aneurysms demonstrated a post-treatment dimensional increase. At 12 months, 30 aneurysms showed a progressive radiological volume reduction. Either no change or negligible shrinkage was observed in the remaining six aneurysms. At 24 months, 32 aneurysms showed aneurysmal shrinkage by a mean 47% volume loss with respect to baseline. At the last follow-up, all 13 patients who had presented with third cranial nerve palsy showed improvements. Complete reversal of the pretreatment edematous changes was confirmed in all cases. The overall post-treatment complication rate was 8.3%, as 3 patients experienced non-fatal delayed rupture of their aneurysm. There was no mortality in this study.

Conclusion

Flow diversion could effectively induce progressive aneurysmal shrinkage and resolution of the mass effect associated with giant symptomatic cerebral aneurysms.

Feasibility and Safety of Flow Diversion in the Treatment of Intracranial Aneurysms via Transradial Approach: A Single-Arm Meta Analysis

Background

While studies have confirmed that flow diversion (FD) can treat intracranial aneurysms via transradial approach (TRA), it remains unclear whether their treatment ultimately impacts safety and feasibility. We aim to conduct a systematic review and meta-analysis assessing the safety and feasibility after FD treatment of intracranial aneurysms via TRA.

Methods

PubMed, EMBASE, and Web of Science were systematically reviewed. The primary outcomes were the success rate and the access-related complications of deploying FD via TRA. Meta-analysis was performed using a random or fixed effect model based on heterogeneity. And the publication bias was evaluated using a funnel plot. This study was registered with PROSPERO, number CRD42021244448.

Results

Data from 8 studies met inclusion criteria (250 non-duplicated patients). The success rate was 93% (95% confidence interval [CI] 0.86–0.98; I² = 61.05%; p = 0.01). The access-related complications rate was 1% (95% CI 0–0.03; I² = 0.00%; p < 0.01). The mainly access-related complications included radial artery spasm (85.7%) and radial artery occlusion (14.3%). The TRA convert to transfemoral approach (TFA) was 7% (95% CI 0.02–0.14; I² = 61.05%; p = 0.01).

Conclusions

Although TFA is still the main access for FD in the treatment of intracranial aneurysms, the TRA also has a higher success rate and lower access-related complications rate. With the improvement of future experience and equipment, the TRA may become the main access for FD which has more advantages. Future studies should design prospective, multicenter randomized controlled studies for long-term follow-up.

Intrasaccular neck-bridging: A technical note on Nautilus-assisted coiling of wide-necked cerebral aneurysms. Feasibility study, immediate and early angiographic results

PURPOSE

Various adjunctive devices have been reported to be helpful during the endovascular coiling of complex, wide-necked cerebral aneurysms. This study aimed to describe the utilization of a recently introduced intrasaccular neck-bridging implant specifically designed to facilitate coil embolization.

METHODS

We retrospectively reviewed eight consecutive patients who underwent treatment for intracranial aneurysms with the Nautilus intrasaccular bridging system between February 2022 to May 2022. We evaluated the angiographic appearances of treated aneurysms at the end of the procedure and early follow-up, the clinical status and complications.

RESULTS

Eight patients with eight cerebral aneurysms (3 men and 5 women, mean age 52.8 years (range 39-66) were analyzed. Five of the treated aneurysms were managed in an acute case scenario. There were no technical difficulties while executing the technique. No other procedural adverse events were documented. Immediate complete occlusion of the aneurysm was seen in 6 patients, neck remnant in 1 and stable aneurysm reperfusion in one case. Early radiological follow-up was available in five patients, and the observed occlusion rates were - RR class I in all radiologically screened aneurysms.

CONCLUSION

Nautilus-assisted coil embolization represents a rapid and safe solution for complex cerebral aneurysms. In our opinion this device symbolizes a significant step forward in treating intracranial aneurysms. We believe that the technique's actual value consists of the fact that the device is fully compatible with the modern low-profile microcatheter technology and does not involve the need for antiplatelet medications.

Use of a p64 MW Flow Diverter with Hydrophilic Polymer Coating (HPC) and Prasugrel Single Antiplatelet Therapy for the Treatment of Unruptured Anterior Circulation Aneurysms: Safety Data and Short-term Occlusion Rates

Purpose

To assess the safety and short-term occlusion rates in procedures using the p64 MW hydrophilic polymer-coated (HPC) flow diverter (FD) with prasugrel single antiplatelet therapy (SAPT) for the treatment of anterior circulation saccular aneurysms.

Methods

We retrospectively identified patients who underwent treatment of one or more intracranial anterior circulation saccular aneurysms between March 2020 and December 2021 with a p64 MW HPC FD and prasugrel SAPT with verified P2Y12 platelet receptor inhibition. Patients diagnosed with fusiform, dissecting, or recently ruptured aneurysms were excluded. Periprocedural and postprocedural complications, clinical outcomes, and angiographic follow-up results were evaluated.

Results

One hundred and two patients with 132 intracranial aneurysms met the inclusion criteria. Previous or concomitant treatments (e.g., coil occlusion) had been performed on 18 of these aneurysms. The technical success rate (i.e., implantation of the intended FD) was 100% with an average of 1.1 devices implanted per patient. Periprocedural and postprocedural complications occurred in 13.6% and 6.8% of these patients, respectively. No mortality or permanent clinical deterioration (i.e., modified Rankin scale score ≥ 3) were reported. Early follow-up digital subtraction angiography revealed aneurysmal occlusion rates of 72.6% and 83.8% at four and nine months, respectively.

Conclusions

The implantation of a p64 MW HPC FD with prasugrel SAPT is safe and results in rapid, reliable and effective aneurysmal occlusion.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-022-03153-8.

A comparative propensity-adjusted analysis of microsurgical versus endovascular treatment of unruptured ophthalmic artery aneurysms

OBJECTIVE

Ophthalmic artery (OA) aneurysms are surgically challenging lesions that are now mostly treated using endovascular procedures. However, in specialized tertiary care centers with experienced neurosurgeons, controversy remains regarding the optimal treatment of these lesions. This study used propensity adjustment to compare microsurgical and endovascular treatment of unruptured OA aneurysms in experienced tertiary and quaternary settings.

METHODS

The authors retrospectively reviewed the medical records of all patients who underwent microsurgical treatment of an unruptured OA aneurysm at the University of California, San Francisco, from 1997 to 2017 and either microsurgical or endovascular treatment at Barrow Neurological Institute from 2011 to 2019. Patients were categorized into two cohorts for comparison: those who underwent open microsurgical clipping, and those who underwent endovascular flow diversion or coil embolization. Outcomes included neurological or visual outcomes, residual or recurrent aneurysms, retreatment, and severe complications.

RESULTS

A total of 345 procedures were analyzed: 247 open microsurgical clipping procedures (72%) and 98 endovascular procedures (28%). Of the 98 endovascular procedures, 16 (16%) were treated with primary coil embolization and 82 (84%) with flow diversion. After propensity adjustment, microsurgical treatment was associated with higher odds of a visual deficit (OR 8.5, 95% CI 1.1-64.9, p = 0.04) but lower odds of residual aneurysm (OR 0.06, 95% CI 0.01-0.28, p < 0.001) or retreatment (OR 0.12, 95% CI 0.02-0.58, p = 0.008) than endovascular therapy. No difference was found between the two cohorts with regard to worse modified Rankin Scale score, modified Rankin Scale score greater than 2, or severe complications.

CONCLUSIONS

Compared with endovascular therapy, microsurgical clipping of unruptured OA aneurysms is associated with a higher rate of visual deficits but a lower rate of residual and recurrent aneurysms. In centers experienced with both open microsurgical and endovascular treatment of these lesions, the treatment choice should be based on patient preference and aneurysm morphology.

Rupture of an adjacent cerebral aneurysm following the deployment of a Pipeline embolization device: illustrative case

BACKGROUND

Although the Pipeline embolization device (PED) is effective for intracranial aneurysm treatment, its impact on the surrounding vascular structure is unknown.

OBSERVATIONS

A 71-year-old woman was incidentally found to have a simultaneous large posterior communicating artery aneurysm and an ipsilateral small anterior choroidal artery aneurysm. She underwent flow diversion therapy for both aneurysms with a PED, but the distal shortening of the PED after deployment led to the exposure of the anterior choroidal artery aneurysm. Follow-up angiography revealed complete obliteration of the posterior communicating artery aneurysm, but the anterior choroidal artery aneurysm remained. Three years after the endovascular surgery, the patient experienced a subarachnoid hemorrhage due to the rupture of the anterior choroidal artery aneurysm. Retrospective analysis of angiographic images revealed a change in the vascular geometry surrounding the ruptured aneurysm after PED deployment; this was further accompanied by an increase in the flow velocity inside the aneurysm.

LESSONS

Because PED use might induce the adverse effects on the adjacent uncovered aneurysm by changing the vascular geometry and hemodynamic stress, a cautious therapeutic strategy, such as proper placement of the stent and using a longer and appropriate-sized PED, should be chosen when deploying the PED.

Effect of flow diverter stent malposition on intracranial aneurysm hemodynamics—An experimental framework using stereoscopic particle image velocimetry

Background

Flow-diverting stents are increasingly used for the minimally-invasive treatment of intracranial aneurysms. However, a correct positioning of such devices can be challenging due to varying vessel diameters as well as the complex anatomy of the neurovasculature. As a consequence, unsuccessful treatment outcomes are increasingly reported requiring an improvement of the understanding of stent-induced flow modification.

Methods

To evaluate the effect of different degrees of flow diverter stent malposition on intra-aneurysmal hemodynamic changes, a controlled hemodynamic configuration was created using an idealized intracranial aneurysms model. Afterwards, four different treatment scenarios were reproduced comprising of 1) the ideal treatment, 2) an insufficient wall apposition in the region of the ostium, 3) a distorted device migrating into the aneurysm sac and 4) an inaccurately deployed stent due to wrong release location. For the assessment of the individual flow modifications, high-resolution stereoscopic particle image velocimetry (PIV) measurements were carried out.

Results

The analysis of the precise in-vitro PIV measurements reveals that in all cases a considerable reduction of the cycle-averaged and peak-systolic velocity was obtained. Compared to the untreated aneurysm configuration, the flow reduction ranged from 63% (scenario 4) up to 89% (scenario 3). The ideal treatment reached a reduction of 78%, which is known to be sufficient for a successful therapy. However, inaccurate device positioning leads to increased oscillating flow towards the lateral directions reducing the chances of sufficient thrombus formation.

Conclusions

High-resolution in-vitro PIV measurements enable an accurate quantification of the treatment efficacy for flow-diverting devices. Furthermore, insufficient treatment outcomes can be reproduces allowing for an assessment of intra-aneurysmal hemodynamic changes.

Comaneci plus Balloon-assisted Embolization of Ruptured Wide-necked Cerebral Aneurysms

BACKGROUND AND PURPOSE

Recently, avant-garde combinations of ancillary devices as an adjunct to coil embolization for acutely ruptured and wide-necked cerebral aneurysms have emerged. This study sought to investigate the feasibility, safety and durability of the simultaneous combination of temporary neck-bridging devices plus balloon-assisted coiling (BAC) to treat acutely ruptured and wide-necked cerebral aneurysms.

METHODS

A retrospective review was performed of patients with ruptured and wide-necked intracranial bifurcation aneurysms treated with temporary stent plus balloon-assisted coiling. Anatomical features, technical details, intraprocedural complications, clinical and angiographic results were reviewed. Preprocedural and follow-up clinical statuses were evaluated using the modified Rankin scale (mRS).

RESULTS

A total of 21 patients (mean age 54.5 years, range 37-72 years) were identified. The immediate postprocedural angiography revealed complete aneurysm occlusion in 85.7% (18/21) of the cases. A periprocedural complication developed in 9.5% of the cases. There was no mortality in this study. The permanent morbidity rate was 4.7%. Long-term follow-up angiography was performed in 18 of 21 patients (85.7%) (the mean follow-up period was 21 months). The rate of complete aneurysm occlusion at final follow-up was 89.4%.

CONCLUSION

The results of this study confirmed that temporary stent plus balloon-assisted coiling is a durable and relatively safe endovascular technique for the treatment of ruptured wide-necked bifurcation aneurysms located in both the posterior and anterior cerebral circulation.

Efficacy of the Flow Re-direction Endoluminal Device for cerebral aneurysms and causes of failed deployment

Purpose

The Flow Re-direction Endoluminal Device (FRED) has recently become available for flow diversion in Japan. We have encountered cases that failed to deploy the FRED. In this study, we report our initial experience with the FRED for cerebral aneurysms and clarify the causes of failed FRED deployment.

Methods

A retrospective data analysis was performed to identify patients treated with the FRED between June 2020 and March 2021. Follow-up digital subtraction angiography was performed at 3 and 6 months and assessed using the O’Kelly-Marotta (OKM) grading scale.

Results

Thirty-nine aneurysms in 36 patients (average age: 54.4 years) were treated with the FRED. The average sizes of the dome and neck were 9.9 mm and 5.2 mm, respectively. In nine patients, additional coiling was performed. In one patient (2.6%), proximal vessel injury caused direct carotid-cavernous fistula during deployment. Ischaemic complications were encountered in one patient (2.6%) with transient symptoms. Angiographic follow-up at 6 months revealed OKM grade C or D in 86.6% of patients. FRED deployment was successful in 35 (92.1%) procedures. In the failure group, the differences between the FRED and the minimum vessel diameter (P = 0.04) and the rate of the parent vessel having an S-shaped curve (P = 0.04) were greater than those in the success group.

Conclusions

Flow diversion using the FRED is effective and safe for treating cerebral aneurysms. The use of the FRED for patients with an S-shaped curve in the parent vessel and oversizing of more than 2 mm should be considered carefully.

Evaluation of a novel flow diverter, the DiVeRt system, in an animal model

BACKGROUND

Using a surgical aneurysm model, this study assessed the performance of a new flow diverter (FD), the DiVeRt, and evaluated the angiographic and histologic features at different periods after stent deployment.

METHODS

Fifteen New Zealand White rabbits were treated 3 days prior to intervention and until euthanization with dual antiplatelets. DiVeRt was implanted in bilateral carotid aneurysms (n=30) as well as in the aorta (n=15). The rate of technical success, assessment of aneurysm occlusion (measured by the O'Kelly-Marotta grading (OKM) scale), and stent patency were examined using angiography and histologic examinations in three groups at 1, 3, and 6 months follow-up (FU). In each FU group one control animal was included and treated with the XCalibur stent (n=3).

RESULTS

Overall, DiVeRt placement was successful and without apparent intraprocedural complications. In total, four stents in the carotid artery were occluded and in-stent stenosis was registered in two carotid (7%) and one aortic (6%) vessels. Complete or near complete aneurysm occlusion (OKM scale D1 and C3) was seen in 100% in the 1-month FU group, 70% in the 2-month FU group, and 100% in the 3-month FU group. Histology showed loose, organizing fibrous tissue matrix within the sac and adequate neck endothelialization in all vessels. All branches covered by the DiVeRt remained patent.

CONCLUSIONS

The DiVeRt system appears to be feasible and effective for the treatment of aneurysms with high rates of complete aneurysm occlusion, excellent vessel patency, and evidence of high biocompatibility. Occurrences of parent artery occlusion at follow-up did not result in clinical consequences.

The evolution of intracranial aneurysm treatment techniques and future directions

Treatment techniques and management guidelines for intracranial aneurysms (IAs) have been continually developing and this rapid development has altered treatment decision-making for clinicians. IAs are treated in one of two ways: surgical treatments such as microsurgical clipping with or without bypass techniques, and endovascular methods such as coiling, balloon- or stent-assisted coiling, or intravascular flow diversion and intrasaccular flow disruption. In certain cases, a single approach may be inadequate in completely resolving the IA and successful treatment requires a combination of microsurgical and endovascular techniques, such as in complex aneurysms. The treatment option should be considered based on factors such as age; past medical history; comorbidities; patient preference; aneurysm characteristics such as location, morphology, and size; and finally the operator’s experience. The purpose of this review is to provide practicing neurosurgeons with a summary of the techniques available, and to aid decision-making by highlighting ideal or less ideal cases for a given technique. Next, we illustrate the evolution of techniques to overcome the shortfalls of preceding techniques. At the outset, we emphasize that this decision-making process is dynamic and will be directed by current best scientific evidence, and future technological advances.

Long-term follow-up of the Derivo® Embolization Device (DED®) for intracranial aneurysms: the Italian Multicentric Registry

BACKGROUND

The flow-diverter devices (FDDs) safety and effectiveness have been demonstrated by large series and meta-analyses. Due to the high occlusion rates and the acceptable morbidity rates of FDDs, the indications for their use are continuously expanding. We presented our Italian multicentric experience using the second generation of DERIVO® Embolization Device (DED^®; Acandis, Pforzheim, Germany) to cure cerebral aneurysms, evaluating both middle and long-term safety and efficacy of this device.

METHODS

Between July 2016 and September 2017 we collected 109 consecutive aneurysms in 108 patients treated using DED^® during 109 endovascular procedures in 34 Italian centers (100/109 aneurysms were unruptured, 9/109 were ruptured). The collected data included patient demographics, aneurysm location and characteristics, baseline angiography, adverse event and serious adverse event information, morbidity and mortality rates, and pre- and post-treatment modified Rankin Scale scores. Midterm and long-term clinical, angiographic and cross-sectional CT/MR follow-up were recorded and collected until December 2018.

RESULTS

In 2/109 cases, DED^® placement was classified as technical failures. The overall mortality and morbidity rates were respectively 6.5% and 5.5%. Overall DERIVO® related mortality and morbidity rates were respectively 0% and 4.6% (5 out of 108 patients). Midterm neuroimaging follow-up showed the complete or nearly complete occlusion of the aneurysm in 90% cases, which became 93% at long-term follow-up. Aneurysmal sac shrinking was observed in 65% of assessable aneurysms.

CONCLUSIONS

Our multicentric experience using DED^® for endovascular treatment of unruptured and ruptured aneurysms showed a high safety and efficacy profile, substantially equivalent or better compared to the other FDDs.

Microsurgical Clipping Techniques and Outcomes for Paraclinoid Internal Carotid Artery Aneurysms

BACKGROUND

Microsurgical clipping of paraclinoid aneurysms presents unique technical challenges because of the anatomical complexity of the paraclinoid region.

OBJECTIVE

To analyze microsurgical clipping techniques, complications, and outcomes associated with paraclinoid aneurysms, with a focus on clip selection and clipping technique according to aneurysm location.

METHODS

From 1997 to 2016, 231 unruptured paraclinoid aneurysms from 216 patients were treated using microsurgical clipping. We retrospectively reviewed patient records to analyze clinical outcomes.

RESULTS

A total of 80 aneurysms (34.6%) were treated with simple clipping. Among them, fenestrated clips were used with superior hypophyseal artery (SHA) aneurysms, but curved clips were used with most other aneurysms. A total of 151 aneurysms (65.6%) were treated using multiple clips, including tandem clipping for ophthalmic artery (OphA) aneurysms, tandem angled-fenestrated clipping for SHA and ventral carotid aneurysms, stacked clipping for dorsal carotid aneurysms, and various techniques for clinoidal segment/carotid cave aneurysms. Postoperative angiography was performed in 214 aneurysms (92.6%), and complete obliteration was confirmed in 195 aneurysms (91.1%). Using the modified Rankin Scale (mRS), overall functional outcome was good (mRS 0-2) in 99.6% of patients, although 30 cases (13.0%) showed new postoperative visual deficits.

CONCLUSION

Surgical clipping of paraclinoid aneurysms is an excellent treatment modality with good clinical outcomes and acceptable complication rates, particularly in centers with large experience in the microsurgical management of cerebrovascular disorders. Appropriate clip selection and clipping techniques are required to perform complete and safe clipping.

Whether Intracranial Aneurysm Could Be Well Treated by Flow Diversion: A Comprehensive Meta-Analysis of Large-Sample Studies including Anterior and Posterior Circulation

BACKGROUND

Flow diversion (FD) has become a widely adopted treatment method for intracranial aneurysms in the clinic, but a comprehensive meta-analysis of large-sample studies including anterior and posterior circulation is still lacking.

METHODS

The PubMed, Embase, Web of Science, and Cochrane databases were searched between January 1, 2008, and December 1, 2019. A random-effect model was used to calculate the efficacy and safety data as well as 95% confidence intervals (CIs).

RESULTS

The pooled sample size of all included studies was 6695 patients; the mean age was 55.5 years old, with a total of 7406 aneurysms. For efficacy, the complete occlusion rate in angiographic follow-up (AFU) at 6 months was 78% (95% CI, 0.77, 0.80), and the AFU rate at 6-12 months was 90% (95% CI, 0.88, 0.92). For safety, the hemorrhagic event rate was 2%, the ischemic event rate was 5%, and the mortality rate was 3%.

CONCLUSION

FD is an effective and safe treatment for intracranial aneurysm with high complete occlusion rate and acceptable complication rate.

Healthy and diseased in vitro models of vascular systems

Irregular hemodynamics affects the progression of various vascular diseases, such atherosclerosis or aneurysms. Despite the extensive hemodynamics studies on animal models, the inter-species differences between humans and animals hamper the translation of such findings. Recent advances in vascular tissue engineering and the suitability of in vitro models for interim analysis have increased the use of in vitro human vascular tissue models. Although the effect of flow on endothelial cell (EC) pathophysiology and EC-flow interactions have been vastly studied in two-dimensional systems, they cannot be used to understand the effect of other micro- and macro-environmental parameters associated with vessel wall diseases. To generate an ideal in vitro model of the vascular system, essential criteria should be included: 1) the presence of smooth muscle cells or perivascular cells underneath an EC monolayer, 2) an elastic mechanical response of tissue to pulsatile flow pressure, 3) flow conditions that accurately mimic the hemodynamics of diseases, and 4) geometrical features required for pathophysiological flow. In this paper, we review currently available in vitro models that include flow dynamics and discuss studies that have tried to address the criteria mentioned above. Finally, we critically review in vitro fluidic models of atherosclerosis, aneurysm, and thrombosis.

CD31 Mimetic Coating Enhances Flow Diverting Stent Integration into the Arterial Wall Promoting Aneurysm Healing

BACKGROUND AND PURPOSE

Beyond aneurysmal occlusion, metallic flow diverters (FDs) can induce an adverse endovascular reaction due to the foreignness of metal devices, hampering FD endothelialization across the aneurysm neck, and arterial healing of intracranial aneurysms. Here, we evaluated the potential benefits of an FD coating mimicking CD31, a coreceptor critically involved in endothelial function and endovascular homeostasis, on the endothelialization of FDs implanted in vivo.

METHODS

Nitinol FD (Silk Vista Baby) and flat disks were dip-coated with a CD31-mimetic peptide via an intermediate layer of polydopamine. Disks were used to assess the reaction of endothelial cells and blood elements in vitro. An aneurysm rabbit model was used to compare in vivo effects on the arterial wall of CD31-mimetic-coated (CD31-mimetic, n=6), polydopamine-coated (polydopamine, n=6), and uncoated FDs (bare, n=5) at 4 weeks post-FD implantation. In addition, long-term safety was assessed at 12 weeks.

RESULTS

In vitro, CD31-mimetic coated disks displayed reduced adhesion of blood elements while favoring endothelial cell attachment and confluence, compared to bare and polydopamine disks. Strikingly, in vivo, the neoarterial wall formed over the CD31-mimetic-FD struts at the aneurysm neck was characteristic of an arterial tunica media, with continuous differentiated endothelium covering a significantly thicker layer of collagen and smooth muscle cells as compared to the controls. The rates of angiographic complete occlusion and covered branch arterial patency were similar in all 3 groups.

CONCLUSIONS

CD31-mimetic coating favors the colonization of metallic endovascular devices with endothelial cells displaying a physiological phenotype while preventing the adhesion of platelets and leukocytes. These biological properties lead to a rapid and improved endothelialization of the neoarterial wall at the aneurysm neck. CD31-mimetic coating could therefore represent a valuable strategy for FD biocompatibility improvement and aneurysm healing.

Design of Personalized Devices—The Tradeoff between Individual Value and Personalization Workload

Personalized medical devices adapted to the anatomy of the individual promise greater treatment success for patients, thus increasing the individual value of the product. In order to cater to individual adaptations, however, medical device companies need to be able to handle a wide range of internal processes and components. These are here referred to collectively as the personalization workload. Consequently, support is required in order to evaluate how best to target product personalization. Since the approaches presented in the literature are not able to sufficiently meet this demand, this paper introduces a new method that can be used to define an appropriate variety level for a product family taking into account standardized, variant, and personalized attributes. The new method enables the identification and evaluation of personalizable attributes within an existing product family. The method is based on established steps and tools from the field of variant-oriented product design, and is applied using a flow diverter—an implant for the treatment of aneurysm diseases—as an example product. The personalization relevance and adaptation workload for the product characteristics that constitute the differentiating product properties were analyzed and compared in order to determine a tradeoff between customer value and personalization workload. This will consequently help companies to employ targeted, deliberate personalization when designing their product families by enabling them to factor variety-induced complexity and customer value into their thinking at an early stage, thus allowing them to critically evaluate a personalization project.

In vitro investigation of an intracranial flow diverter with a fibrin-based, hemostasis mimicking, nanocoating

Flow diversion aims at treatment of intracranial aneurysms via vessel remodeling mechanisms, avoiding the implantation of foreign materials into the aneurysm sack. However, complex implantation procedure, high metal surface and hemodynamic disturbance still pose a risk for thromboembolic complications in the clinical praxis. A novel fibrin and heparin based nano coating considered as a hemocompatible scaffold for neointimal formation was investigated regarding thrombogenicity and endothelialization. The fibrin-heparin coating was compared to a bare metal as well as fibrin- or heparin-coated flow diverters. The implants were tested separately in regard to inflammation and coagulation markers in two different in vitro hemocompatibility models conducted with human whole blood (n = 5). Endothelialization was investigated through a novel dynamic in vitro cell seeding model containing primary human cells with subsequent viability assay. It was demonstrated that platelet loss and platelet activation triggered by presence of a bare metal stent could be significantly reduced by applying the fibrin-heparin, fibrin and heparin coating. Viability of endothelial cells after proliferation was similar in fibrin-heparin compared to bare metal implants, with a slight, non-significant improvement observed in the fibrin-heparin group. The results suggest that the presented nanocoating has the potential to reduce thromboembolic complications in a clinical setting. Though the new model allowed for endothelial cell proliferation under flow conditions, a higher number of samples is required to assess a possible effect of the coating.

Comaneci device-assisted embolization of wide-necked carotid aneurysms with an unfavorable ratio

Background

Endovascular treatment is the technique of choice for most intracranial aneurysms. However, the treatment of morphologically complex wide-necked aneurysms with an unfavorable anatomy is still a therapeutic challenge.

The purpose of the study is to describe the initial experience with the Comaneci embolization assist device for the treatment of wide-necked aneurysms with an unfavorable ratio for direct embolization.

Methods

We report a retrospective single-center analysis taken from a prospective database of consecutive aneurysms of the anterior circulation treated using the Comaneci device in the period from March 2017 to March 2019.

Results

Eighteen aneurysms were collected from 16 patients (9 women and 7 men) treated using the Comaneci device. The mean age was 48.4 years (range 36–81). Twelve patients had SAH, three were incidental aneurysms and one had compressive symptoms. A complete asymptomatic occlusion rate of 88.8% was obtained. The major complication rate was 5.55%.

Conclusion

The Comaneci embolization assist device is a safe, effective option for endovascular treatment of complex aneurysms with an unfavorable ratio.

Predictors of Extended Length of Stay Following Treatment of Unruptured Adult Cerebral Aneurysms: A Study of The National Inpatient Sample

BACKGROUND

In an unprecedented era of soaring healthcare costs, payers and providers alike have started to place increased importance on measuring the quality of surgical procedures as a surrogate for operative success. One metric used is the length of hospital stay (LOS) during index admission. For the treatment of unruptured cerebral aneurysms, the determinants of extended length of stay are relatively unknown. The aim of this study was to identify the patient- and hospital-level factors associated with extended LOS following treatment for unruptured cerebral aneurysms.

METHODS

The National Inpatient Sample years 2010 - 2014 was queried. Adults (≥18 years) with unruptured aneurysms undergoing either clipping or coiling were selected using the International Classification of Diseases, Ninth Revision, Clinical Modification coding system. Extended LOS was defined as greater than 75^th percentile for the entire cohort (>5 days). Weighted patient demographics, comorbidities, complications, LOS, disposition and total cost were recorded. Multivariate logistic regression was used to determine the odds ratio for risk-adjusted extended LOS. The primary outcome was the degree which patient comorbidities or postoperative complications correlated with extended LOS.

RESULTS

A total of 46,880 patients were identified for which 9,774 (20.8%) patients had extended LOS (Normal LOS: 37,106; Extended LOS: 9,774). Patients in the extended LOS cohort presented with a greater number of comorbidities compared to the normal LOS cohort. A greater proportion of the normal LOS cohort was coiled (Normal LOS: 63.0% vs. Extended LOS: 33.5%, P<0.001), while more patients in the extended LOS cohort were clipped (Normal LOS: 37.0% vs. Extended LOS: 66.5%, P<0.001). The overall complication rate was higher in the extended LOS cohort (Normal LOS: 7.3% vs. Extended LOS: 43.8%, P<0.001). On average, the extended LOS cohort incurred a total cost nearly twice as large (Normal LOS: $26,050 ± 13,430 vs. Extended LOS: $52,195 ± 37,252, P<0.001) and had more patients encounter non-routine discharges (Normal LOS: 8.5% vs. Extended LOS: 52.5%, P<0.001) compared to the normal LOS cohort. On weighted multivariate logistic regression, multiple patient-specific factors were associated with extended LOS. These included demographics, preadmission comorbidities, choice of procedure, and inpatient complications. The odds ratio for extended LOS was 5.14 (95% CI, 4.30 - 6.14) for patients with 1 complication and 19.58 (95% CI, 15.75 - 24.34) for patients with > 1 complication.

CONCLUSIONS

Our study demonstrates that extended LOS after treatment of unruptured aneurysms is influenced by a number of patient-level factors including demographics, preadmission comorbidities, type of aneurysm treatment (open surgical versus endovascular), and, importantly, inpatient complications. A better understanding of these independent predictors of prolonged length of hospital stay may help to improve patient outcomes and decrease overall healthcare costs.

Comparative Analysis of the Pipeline and the Derivo Flow Diverters for the Treatment of Unruptured Intracranial Aneurysms-A Multicentric Study

OBJECTIVE

Flow diversion represents a safe and efficient technique for the endovascular treatment of complex intracranial aneurysms. This study compares 2 competing flow diverters, the Pipeline embolization device (PED) and the Derivo Embolization Device (DED) regarding technical aspects, clinical outcome, and angiographic results.

METHODS

A total of 111 patients with unruptured aneurysms were treated with the PED (n = 62) or the DED (n = 49) between 2011 and 2019. Procedural specifics, complication rates, functional outcome, and aneurysm occlusion were evaluated retrospectively.

RESULTS

Flow-diverter implantation was technically successful in all patients. There were no significant differences regarding baseline characteristics, adjunctive coiling, and fluoroscopy time. Multiple devices were more often used in the PED group (35.6%) than in the DED group (4.1%, P < 0.001). Procedural adverse events occurred in 4 cases of each group (PED: 5.5%, DED: 8.2%, P = 0.713), including 3 thromboembolic events and 1 hemorrhagic event per group. Morbidity rates were similar between the 2 groups (PED: 2.7%, DED: 4.1%, P = 1.0). There was no procedural mortality. At 6-month follow-up, complete or near-complete occlusion (O'Kelly-Marotta scale C+D) was achieved in 79.0% (49/62) after PED implantation and 80.0% (32/40) after DED implantation (P = 0.354).

CONCLUSIONS

In regard to complication rates, functional outcome, and aneurysm occlusion, no significant differences were found between the PED and DED collective.