Brain arteriovenous malformation treatment using a combination of Onyx and a new detachable tip microcatheter, SONIC: short-term results

ihtObtura: A novel liquid embolic agent with post-embolization radiopacity loss, in endovascular treatment of brain arteriovenous malformations, dural arteriovenous fistulas, and tumors: CLARIDAD trial

BACKGROUND

Endovascular embolization is frequently used for vascular lesions of the head and neck. Newer agents may help to enhance visualization and improve treatment outcomes.

METHODS

The CLARIDAD clinical trial was a prospective, single center, first-in-man investigation of neurovascular embolization using the novel embolic agent ihtObtura for a broad indication, covering the need for a liquid embolic agent in head and neck procedures. The primary outcomes assessed were therapeutic efficacy to deliver ihtObtura to embolize the catheterized pedicle and associated angiographic vascularity, and subsequent loss of radiopacity. Safety endpoints included procedural adverse events, modified Rankin Scale (mRS) score, morbidity, and mortality. Radiologic and clinical follow-up evaluations were conducted at 30, 90, 180 days, and 1 year post-treatment.

RESULTS

65 consecutive patients (mean age 37.8 years, 50.8% women) were treated over 129 sessions. A total of 42 brain arteriovenous malformations (AVMs; 90% grades III and IV), 8 dural arteriovenous fistulas (DAVFs), and 15 hypervascular tumors were treated with ihtObtura using an average of 3.9 mL per session and 7.7 mL per patient. We achieved therapeutic effectiveness in 99% of catheterizations. Radiopacity loss was complete after 74.3% of the sessions at 30 days, 95.6% at 90 days, and 100% at the 1 year follow-up. Serious adverse events (mRS score >2) occurred in two patients (3.1%) with previously ruptured high grade AVMs leading to one death and one permanent disabling morbidity.

CONCLUSIONS

The study showed that ihtObtura was a novel, safe, and effective liquid embolic agent for the treatment of AVMs, DAVFs, and hypervascular tumors. Its key property of significant radiopacity loss contributes to improve anatomical understanding, particularly in staged procedures, as well as reduction in post-procedural imaging artifact. There may be additional benefits of eliminating tantalum from the embolic mixture in terms of lesion penetration.

Pediatric Cerebral Vascular Malformations : Current and Future Perspectives

Intracranial vascular malformations typically encountered by pediatric neurosurgeons include arteriovenous malformations, vein of Galen malformations and cavernous malformations. While these remain amongst some of the most challenging lesions faced by patients and caregivers, the past decade has produced marked advances in the understanding of the pathophysiology of these conditions, with concomitant innovations in treatment. This article will highlight present and future perspectives relevant to these diseases, with a focus on an emerging approach utilizing disease-specific mutations to develop a novel taxonomy for these conditions.

Primary endovascular embolisation of intracranial arteriovenous malformations (AVM)-UK single centre experience

PURPOSE

Intracranial arteriovenous malformations (AVMs) treated at our institution with modern techniques of endovascular intervention were analysed for the rate of complete occlusion, associated morbidity, and mortality. To our knowledge, this is the first series from the UK evaluating the effectiveness of endovascular embolisation as a primary treatment for selected cases.

METHODS

All newly referred AVMs between January 2017 and June 2022 were reviewed and those treated with primary endovascular intervention were identified. Details of the endovascular procedures were retrospectively reviewed.

RESULTS

In 5½ years, 41.1% of AVMs referred to our institution have been triaged for primary endovascular intervention. Sixty-eight AVMs were embolised and followed-up: 44 ruptured and 24 unruptured. Spetzler-Martin grading varied from I to III, and a single AVM was grade IV. The approach was arterial in 73.5%, solely venous in 7.4%, and combined in 19.1%. The mean follow-up was 18 months for imaging and 26 months for clinical assessment. Complete obliteration was achieved in 95.6%. Ruptured AVM cohort: The rate of functional deterioration was 13.6%. Unruptured AVM cohort: The rate of functional deterioration secondary to complications from embolisation was 4.2%.

CONCLUSIONS

Endovascular embolisation may be a favourable option for primary AVM treatment in carefully selected patients. However, selection criteria need to be better delineated for more specialists to consider this as a primary therapy.

Recurrence of Cerebral Arteriovenous Malformation Following Complete Obliteration Through Endovascular Embolization

Arteriovenous malformation (AVM) recurrence after embolization was rarely reported. This study aimed to explore the potential risk factors of recurrence in angiographically obliterated AVMs treated with endovascular embolization. This study reviewed AVMs treated with embolization only in a prospective multicenter registry from August 2011 to December 2021, and ultimately included 92 AVMs who had achieved angiographic obliteration. Recurrence was assessed by follow-up digital subtraction angiography (DSA) or magnetic resonance imaging (MRI). Hazard ratios (HRs) with 95% confidence intervals were calculated using Cox proportional hazards regression models. Nineteen AVMs exhibited recurrence on follow-up imaging. The recurrence rates after complete obliteration at 6 months, 1 year, and 2 years were 4.35%, 9.78%, and 13.0%, respectively. Multivariate Cox regression analysis identified diffuse nidus (HR 3.208, 95% CI 1.030-9.997, p=0.044) as an independent risk factor for recurrence. Kaplan-Meier analysis confirmed a higher cumulative risk of recurrence with diffuse nidus (log-rank, p=0.016). Further, in the exploratory analysis of the effect of embolization timing after AVM rupture on recurrence after the complete obliteration, embolization within 7 days of the hemorrhage was found as an independent risk factor (HR 4.797, 95% CI 1.379-16.689, p=0.014). Kaplan-Meier analysis confirmed that embolization within 7 days of the hemorrhage was associated with a higher cumulative risk of recurrence in ruptured AVMs (log-rank, p<0.0001). This study highlights the significance of diffuse nidus as an independent risk factor for recurrence after complete embolization of AVMs. In addition, we identified a potential recurrent risk associated with early embolization in ruptured AVMs.

Evolution of clinical and translational advances in the management of pediatric arteriovenous malformations

Arteriovenous malformations (AVMs) represent one of the most challenging diagnoses in pediatric neurosurgery. Until recently, the majority of AVMs was only identified after hemorrhage and primarily treated with surgery. However, recent advances in a wide range of fields-imaging, surgery, interventional radiology, radiation therapy, and molecular biology-have profoundly advanced the understanding and therapy of these complex lesions. Here we review the progress made in pediatric AVMs with a specific focus on innovations relevant to clinical care.

Safety and efficacy of dual lumen balloon catheters for the Treatment of cerebral vascular malformations: A systematic review, pooled analysis, and meta-analysis

BACKGROUND

There is little evidence in scientific literature assessing the safety and efficacy of dual-lumen balloon catheters (DLBCs) and their performance compared to single-lumen catheters (SLCs).

METHODS

In this PROSPERO-registered, PRISMA-compliant systematic review, we identified all MEDLINE and EMBASE single-arm (DLBCs) and double-arm (DLBCs vs SLCs) cohorts where DLBCs were used for the treatment of cerebral arteriovenous malformations (AVMs) or dural arteriovenous fistulas (dAVFs). Immediate angiographic outcome, vascular complications, technical failures, reflux episodes and entrapment were the primary outcomes. A meta-analysis of the double-arm studies summarized the primary outcomes of total procedural time and immediate angiographic outcome.

RESULTS

The authors identified 18 studies encompassing 209 treated lesions with reported outcomes. Complete occlusion was achieved in 108/132 treated dAVFs (81.8%, 95% CI: [74-87.8%]) and in 45/77 treated AVMs (58.4%, [46.7-69.4%]). The proportion of completely occluded dAVFs was statistically significantly higher than that of AVMs, p < .001. There were eight reported vascular complications (3.8%, [1.8-7.7%]), five technical failures (2.4%, [0.9-5.8%]), 14 reflux events (6.7%, [3.9-11.2%]), two entrapment events (1%, [0.2-3.8%]) and 0 deaths (mortality rate 0%, [0-2.3%]). In a meta-analysis for the treatment of dAVFs, the total procedural time was significantly less for DLBCs compared to SLCs (64.9 vs 125.7 min, p < .0001). The odds of complete immediate occlusion were significantly higher with DLBCs compared to SLCs (odds ratio (OR) 4.6, [1.5-14.3], p = .008).

CONCLUSION

Dual-lumen balloon catheters are safe and effective for the embolization of cerebral AVMs and dAVFs and can achieve faster and potentially superior results compared to SLCs.

REGISTRATION-URL

https://www.crd.york.ac.uk/prospero/ Unique Identifier: CRD42021269096.

Endovascular Management of Brain Arteriovenous Malformations

Due to the risk of cerebral hemorrhage, and its related morbidity-mortality, brain arteriovenous malformations (bAVMs) are a rare and potentially life-threatening disease. Despite this, there is only one randomized controlled trial on bAVM management, A Randomized trial of Unruptured Brain Arteriovenous malformations (ARUBA). The results of the ARUBA trial favor a noninterventional approach in the case of an unruptured bAVM; however, implementation of these findings is challenging in daily practice. Instead, management of bAVM relies on multidisciplinary discussions that lead to patient-specific strategies based on patient preferences, local expertise, and experience in referral centers. Considering the diverse patterns of presentation and numerous treatment modalities, implementing standardized guidelines in this context proves challenging, notwithstanding the recommendations or expert opinions offered. Endovascular treatment (EVT) of bAVM can be curative, or can serve as an adjunct treatment prior to surgery or radiosurgery ("pre-EVT"). EVT practice is in constant evolution (i.e., venous approach, combination with surgery during the same anesthesia, etc.). Liquid embolic agents such as ethylene vinyl alcohol (EVOH) copolymer and cyanoacrylates (CYA), and their method of injection to increase bAVM occlusion have also benefited from technical evolutions such as the use of adjunctive flow arrest techniques (mini balloons, pressure cooker technique, and multiple catheters). Further research is necessary to evaluate the advantages and disadvantages of EVT for bAVM.

Safety and Effectiveness of First-line Endovascular Management of Low-Grade Brain Arteriovenous Malformations : Single Center Experience in 145 Patients

PURPOSE

Spetzler-Martin grade (SMG) I-II (low-grade) brain arteriovenous malformations (BAVMs) are often considered safe for microsurgical resection; however, the role of endovascular treatment (EVT) remains to be clarified in this indication, especially for unruptured BAVMs. The purpose of our study was to assess the safety and effectiveness of endovascular treatment as the first-line treatment for low-grade BAVMs.

METHODS

From our local database, we retrospectively retrieved patients with low-grade BAVMs, either ruptured or unruptured, treated by embolization as first-line treatment in our department between January 2005 and January 2020. The primary endpoint was the total obliteration rate of BAVMs, and secondary endpoints were hemorrhagic complications and final clinical outcome, assessed through shift of the modified Rankin scale, and mortality rate secondary to BAVM embolization.

RESULTS

A total of 145 patients meeting inclusion criteria and treated by EVT as first-line therapy were included in the study (82 ruptured and 63 unruptured BAVMs). Overall, complete exclusion of BAVMs was achieved in 110 patients (75.9%); 58 patients (70.7%) with ruptured and 52 (82.5%) unruptured BAVMs, including 37.9% BAVMs excluded by EVT alone (35.5% among ruptured and 44.4% among unruptured BAVMs) and 38% by combined treatment (EVT and surgery or EVT and SRS). There was no BAVM volume cut-off predictive for total obliteration by embolization alone. Early minor hemorrhagic complications were reported in 14 patients (9.6%) and early major hemorrhagic complications were reported in 5 patients (3.4%). No late hemorrhagic complications (0%) occurred; mortality rate was 0.7% (1/145 patients). Improved/unchanged mRS was reported in 137 patients (94.5%).

CONCLUSION

Endovascular treatment alone or associated with others exclusion techniques, might be safe and effective for complete exclusion of low-grade brain arteriovenous malformations regardless of the volume.

Microcatheters with extra-long detachable tip: A promising treatment option in dural arteriovenous fistulas

PURPOSE

Treating cerebral dural arteriovenous fistulas (dAVFs) by transarterial embolization is an established endovascular approach but no data exist regarding the utility of using the newly introduced microcatheters with extra-long detachable tip. Aim of our study was to evaluate the value of these microcatheters and, additionally, of combining them with the simplified pressure cooker technique.

METHODS

Twenty-nine patients treated for dAVF with transarterial embolization were enrolled. In a subgroup of fifteen patients the simplified pressure cooker technique was additionally applied. Demographics and characteristics were collected for patients and dAVFs and procedural details reviewed. The association between covariates and binary-coded occlusion status was evaluated.

RESULTS

Microcatheter navigation into the target pedicle as well as application of the simplified pressure cooker technique were successful in all cases. Complete dAVF occlusion was reached in 69.0% at a single stage. In case of complete dAVF occlusion, embolization via only one pedicle was enough. Subgroup analysis revealed a higher occlusion status (80%) if using the simplified pressure cooker technique than if not (57%) but reached not significance level.

CONCLUSION

Using microcatheters with extra-long detachable tip for dAVF embolization seems to offer a safe and effective treatment option with exceptional high occlusion rate at a single stage. The high navigability facilitates catheterization of a single selected target pedicle that is often enough to reach complete dAVF occlusion. Combining these microcatheters with the simplified pressure cooker technique turned out to be safe and easy to handle and might allow an increasing dAVF occlusion rate.

Curative Embolization of Small Brain Arteriovenous Malformations by Ethyl Vinyl Alcohol Copolymer: A Systematic Review and Meta-Analysis

The right choice in treating small (Spetzler-Ponce grade A) brain arteriovenous malformations (AVMs) is a matter of debate with varying views from neurology, neurosurgery, and interventional neuroradiology points of view. The Spetzler-Martin 1 and 2 brain AVMs, especially those in eloquent and deep areas that are difficult to access by micro-neurosurgery, are most suitable for a complete cure by endovascular embolization with ethyl vinyl alcohol (EVOH)-based agents.

A literature search was done with keywords such as endovascular embolization of small brain AVM. Data from 13 articles are included in the study based on predetermined inclusion and exclusion criteria.

Meta-analysis for the complete cure rate was done, publication bias was removed, and regression analysis showed a 76% cure rate with a 95% confidence interval (CI). Major complications were hemorrhage and neurological deficit, which ranged from 0-20% and 0-16% with a mean proportion of 0.11 and 0.09, respectively. Long-term (3-6 months) follow-up data showed 0-4% recurrence at three months, 0-8% recurrence at six months, and 2-10% permanent disability. The mortality rate ranged from 3% to 4%. Three illustrative cases with data from the author’s institute are included in the article. To conclude, endovascular embolization for small brain AVMs is a satisfactory treatment modality, however, prospective registries and randomized controlled trials involving embolization versus neurosurgery and/or stereotactic radiosurgery (SRS) may validate the role of embolization in small brain AVMs as curative treatment.

Proof-of-Principle for AVM Embolization Complications Caused by the Proximal Occlusion Technique Using Onyx: A Theoretical Basis for Ante-Grade Drifting Technique

To analyze the complications of the standard proximal plug technique in arteriovenous malformations (AVMs) embolization by Onyx and promote ante-grade drifting technique for AVM embolization. Seven publications reporting complications of AVM embolization by Onyx were identified and reviewed. Render descriptive statistics regarding causes of ischemic and hemorrhagic complications within 1 month following treatment were provided. A novel Onyx injection technique was proposed to overcome these problems. All reported transarterial Onyx AVM embolizations were conducted by employing the proximal plug technique. Causes of complications elicited by utilizing this strategy may generally be attributed to long-fluoroscopy and long-procedure times, embolisate reflux across a considerable extent of the vessel, catheter entrapment, extravasation of Onyx from the arterial lumen, catheter transgression through the arterial wall, the use of an Onyx volume exceeding, and venous occlusion preceding arterial feeder shutdown. Complications occurring during the course of attempts at embolizing AVMs utilizing Onyx constitute unfortunate causes of patient morbidity resulting from this conventional technique. We suggest that institution of a novel "ante-grade drifting technique" for Onyx injection may avoid these commonly elicited deficits. The proximal plug technique has a series of drawbacks that lead to serious adverse outcomes of AVM embolization. The Onyx embolization technology for AVM could be updated to improve clinical outcomes.

Simplified pressure cooker technique for the treatment of brain AVMs, dAVFs and facial vascular malformations

In 2014, Chapot et al. introduced the pressure cooker technique (PCT), conceived to control undesired reflux of the embolic agent during the treatment of brain arterio-venous malformations (bAVMs). Since then, this technique increased in popularity and it has been extensively used. We present five consecutive cases in which the original PCT was simplified using nylon coils instead of platinum coils and acrylic glue, hence the name of 'Simplified Pressure Cooker Technique' (sPCT). The aim was to obtain a safer, precise and faster creation of the plug to control cohesive embolic agent reflux during the treatment of brain and facial vascular malformations.

Optimal control problem arising in mathematical modeling of cerebral vascular pathology embolization

Arteriovenous malformation (AVM) of the brain is a congenital vascular abnormality, in which the arterial and venous blood pools are intertwined and directly connected. This dangerous disease causes a high risk of intracranial hemorrhage and disrupts brain functioning. The preferred method of AVM treating is embolization, which is the endovascular filling of abnormal AVM vessels with a special embolic agent. Despite the fact that this method is widely used in neurosurgery, in some cases its use is accompanied by perioperative AVM vessels rupture. In this regard, the aim of this work is to study the optimal scenarios for multi-stage AVM embolization from the effectiveness and safety of the procedure point of view. Mathematically, the joint movement of blood and embolic agent in the AVM body is described on the basis of a one-dimensional two-phase filtration model, which takes into account the redistribution of blood to surrounding healthy vessels. For the numerical solution of the resulting integro-differential system of equations, a monotonic modification of the CABARET scheme is used. To find optimal embolization scenarios, the optimal control problem with phase constraints arising from medicine is formulated. A modified particle swarm optimization method is used to solve this problem numerically. This technique is used to obtain optimal embolization scenarios on the basis of real patients clinical data collected during neurosurgical operations.

Glue, Onyx, Squid or PHIL? Liquid Embolic Agents for the Embolization of Cerebral Arteriovenous Malformations and Dural Arteriovenous Fistulas

Background

Endovascular embolization is an effective treatment option for cerebral arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). A variety of liquid embolic agents have been and are currently used for embolization of AVMs and DAVFs. Knowledge of the special properties of the agent which is used is crucial for an effective and safe embolization procedure.

Material and Methods

This article describes the properties and indications of the liquid embolic agents which are currently available: cyanoacrylates (also called glues), and the copolymers Onyx, Squid and PHIL, as well as their respective subtypes.

Results

Cyanoacrylates were the predominantly used agents in the 1980s and 1990s. They are currently still used in specific situations, for example for the occlusion of macro-shunts, for the pressure cooker technique or in cases in which microcatheters are used that are not compatible with dimethyl-sulfoxide. The first broadly used copolymer-based embolic agent Onyx benefits from a large amount of available experience and data, which demonstrated its safety and efficacy in the treatment of cerebral vascular malformations, while its drawbacks include temporary loss of visibility during longer injections and artifacts in cross-sectional imaging. The more recently introduced agents Squid and PHIL aim to overcome these shortcomings and to improve the success rate of endovascular embolization. Novelties of these newer agents with potential advantages include extra-low viscosity versions, more stable visibility, and a lower degree of imaging artifacts.

Conclusion

All the available liquid embolic agents feature specific potential advantages and disadvantages over each other. The choice of the most appropriate embolic agent must be made based on the specific material characteristics of the agent, related to the specific anatomical characteristics of the target pathology.

The 100 most cited articles in the endovascular treatment of brain arteriovenous malformations

BACKGROUND

The literature base for endovascular treatment of brain arteriovenous malformations (BAVMs) has grown exponentially in recent decades. Bibliometric analysis has been used to identify impactful articles in other medical specialties. The aim of this citation analysis was to identify and characterize the top 100 most cited articles in the field of endovascular BAVM treatment.

METHODS

The top-cited papers were identified by searching selected keywords ("endovascular treatment," "interventional treatment," "brain arteriovenous malformation," "emboliz(s)ation") on the Web of Science platform. The top 100 articles were ranked according to their number of citations. Each article was further evaluated to obtain predefined characteristics including citation(s) per year, year of publication, authorship, journal-title and impact factor, article topics, article type, and level of evidence.

RESULTS

The top 100 most cited articles for endovascular BAVM treatment were published between 1960 and 2014. The total number of citations for these articles ranged from 56 to 471 (median 85.5). Most articles (76%) were published between 1990 and 2009 in three journals (56%), originated in the USA (52%) followed by France (16%). The most common topic related to embolization agents and the majority of articles constituted level IV or V evidence.

CONCLUSIONS

This study provides a comprehensive overview of the most cited articles in the field of endovascular BAVM treatment. Our analysis recognizes key contributions from authors and institutions in the field and leads to a better understanding of the evidentiary framework for BAVM treatment.

Safety of the APOLLO Onyx delivery microcatheter for embolization of brain arteriovenous malformations: results from a prospective post-market study

BACKGROUND

Catheter retention and difficulty in retrieval have been observed during embolization of brain arteriovenous malformations (bAVMs) with the Onyx liquid embolic system (Onyx). The Apollo Onyx delivery microcatheter (Apollo) is a single lumen catheter designed for controlled delivery of Onyx into the neurovasculature, with a detachable distal tip to aid catheter retrieval. This study evaluates the safety of the Apollo for delivery of Onyx during embolization of bAVMs.

METHODS

This was a prospective, non-randomized, single-arm, multicenter, post-market study of patients with a bAVM who underwent Onyx embolization with the Apollo between May 2015 and February 2018. The primary endpoint was any catheter-related adverse event (AE) at 30 days, such as unintentional tip detachment or malfunction with clinical sequelae, or retained catheter. Procedure-related AEs (untoward medical occurrence, disease, injury, or clinical signs) and serious AEs (life threatening illness or injury, permanent physiological impairment, hospitalization, or requiring intervention) were also recorded.

RESULTS

A total of 112 patients were enrolled (mean age 44.1±17.6 years, 56.3% men), and 201 Apollo devices were used in 142 embolization procedures. The mean Spetzler-Martin grade was 2.38. The primary endpoint was not observed (0/112, 0%). The catheter tip detached during 83 (58.5%) procedures, of which 2 (2.4%) were unintentional and did not result in clinical sequelae. At 30 days, procedure related AEs occurred in 26 (23.2%) patients, and procedure-related serious AEs in 12 (10.7%). At 12 months, there were 3 (2.7%) mortalities, including 2 (1.8%) neurological deaths, none of which were device-related.

CONCLUSION

This study demonstrates the safety of Apollo for Onyx embolization of bAVMs.

CLINICAL TRIAL REGISTRATION

CNCT02378883.

Flow driven robotic navigation of microengineered endovascular probes

Minimally invasive medical procedures, such as endovascular catheterization, have considerably reduced procedure time and associated complications. However, many regions inside the body, such as in the brain vasculature, still remain inaccessible due to the lack of appropriate guidance technologies. Here, experimentally and through numerical simulations, we show that tethered ultra-flexible endovascular microscopic probes can be transported through tortuous vascular networks with minimal external intervention by harnessing hydrokinetic energy. Dynamic steering at bifurcations is performed by deformation of the probe head using magnetic actuation. We developed an endovascular microrobotic toolkit with a cross-sectional area that is orders of magnitude smaller than the smallest catheter currently available. Our technology has the potential to improve state-of-the-art practices as it enhances the reachability, reduces the risk of iatrogenic damage, significantly increases the speed of robot-assisted interventions, and enables the deployment of multiple leads simultaneously through a standard needle injection and saline perfusion.

The navigation of catheters through blood vessels requires flexible guiding wires that are pushable and tractable at the same time. Pancaldi et al. rely on hydrodynamic forces and magnetic torque in order to access even rather small capillaries with an ultraflexible magnetomechanical probe.

Endovascular treatment as the main approach for Spetzler-Martin grade III brain arteriovenous malformations

BACKGROUND

Because Spetzler-Martin (SM) grade III brain arteriovenous malformations (bAVMs) constitute a heterogeneous group of lesions with various combination of sizes, eloquence, and venous drainage patterns, their management is usually challenging. The aim of this study is to evaluate the clinical/imaging outcomes and the procedural safety of endovascular approach as the main treatment for the cure of SM grade III bAVMs.

METHODS

In this retrospective study, prospectively collected data of SM grade III bAVMs treated by endovascular techniques between 2010 and 2018 at our hospital were reviewed. Patients older than 16 years with angiographic follow-up of at least 6 months after endovascular treatment were entered in the study. The patients had a mean follow-up of 12 months. The data were assessed for clinical outcome (modified Rankin Scale), permanent neurological deficit, post-operative complications, and optimal imaging outcome, defined by complete exclusion of AVM. The independent predictive variables of poor outcome or hemorrhagic complication were assessed using binary logistic regression.

RESULTS

Sixty-five patients with 65 AVMs were included in the study. Mean age of the patients was 40.0±14.4. Most common presentation was hemorrhage (61.5%). The patients underwent one to eight endovascular procedures (median=2). Mean nidus diameter was 30.2±13.0. A complete obliteration of AVM was achieved in 57 patients (87.7%). Post-procedure significant hemorrhagic and ischemic complications were seen in 13 (20%) and five (7.7%) patients respectively, leading to five (7.7%) transient and four (6.2%) permanent neurological deficits. Eight patients (12.3%) experienced worsening of mRS after embolization. Ten patients (15.4%) had poor outcome (mRS 3-5) at follow-up and two (3%) died.

CONCLUSIONS

Endovascular treatment can achieve a high rate of complete exclusion of grade III AVM but may be associated (as in other treatment modalities) with significant important complications.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02879071.

The transvenous retrograde pressure cooker technique for the curative embolization of high-grade brain arteriovenous malformations

BACKGROUND

Transvenous embolization of brain arteriovenous malformations (AVMs) can be curative. We aimed to evaluate the cure rate and safety of the transvenous retrograde pressure cooker technique (RPCT) using coils and n-butyl-2-cyanoacrylate as a venous plug.

METHODS

All AVM patients treated via transvenous embolization between December 2004 and February 2017 in a single center were extracted from our database. Inclusion criteria were: inability to achieve transarterial cure alone; AVM < 3 cm; and single main draining vein. Outcome measures were immediate and 90 days' angiographic AVM occlusion rate, and morbidity and mortality at 30 days and 12 months, according to the modified Rankin Scale (mRS) score.

RESULTS

Fifty-one patients (20 women; median age 47 years) were included. A majority (71%) were high grade (3 to 5 in the Spetzler-Martin classification). AVMs were deeply seated in 30 (59%) and cortical in 21 patients (41%). Thirty-three patients were previously embolized transarterially (65%). All patients but one were cured within a single session with the RPCT (96%). Cure was confirmed on follow-up digital subtraction angiography at 3 months in 82% of patients. Three patients experienced intracranial hemorrhage (6%), one requiring surgical evacuation. There were no deaths. One treatment-related major permanent deficit was observed (2.0%). Mean mRS before treatment, at 30 days, and 12 months after RPCT was 1.5, 1.5, and 1.3, respectively.

CONCLUSIONS

The retrograde pressure cooker technique can be curative in carefully selected high-grade AVMs. Long-term follow-up and prospective studies are needed to confirm our results.

Modelling of the arteriovenous malformation embolization optimal scenario

Cerebral arteriovenous malformation (AVM) is a congenital brain vessels pathology, in which the arterial and venous blood channels are connected by tangles of abnormal blood vessels. It is a dangerous disease that affects brain functioning causing the high risk of intracerebral haemorrhage. One of AVM treatment methods is embolization-the endovascular filling of the AVM vessel bundle with a special embolic agent. This method is widely used, but still in some cases is accompanied by intraoperative AVM vessels rupture. In this paper, the optimal scenario of AVM embolization is studied from the safety and effectiveness of the procedure point of view. The co-movement of blood and embolic agent in the AVM body is modelled on the basis of a one-dimensional two-phase filtration model. Optimal control problem with phase constraints arising from medicine is formulated and numerically solved. In numerical analysis, the monotone modification of the CABARET scheme is used. Optimal embolization model is constructed on the basis of real patients' clinical data collected during neurosurgical operations. For the special case of embolic agent, input admissible and optimal embolization scenarios were calculated.

Embolic Agents and Microcatheters for Endovascular Treatment of Cerebral Arteriovenous Malformations

Endovascular embolization of cerebral arteriovenous malformations (AVMs) originally entailed delivery of N-butyl cyanoacrylate glue to the nidus via a flow-directed microcatheter. Within the past decade, several new liquid embolic agents and novel microcatheter technologies have become available that have improved the ease of use and efficacy of endovascular therapies for AVMs. Nonadhesive copolymers, such as Onyx and Precipitating Hydrophobic Injectable Liquid, have largely replaced N-butyl cyanoacrylate given a lower risk of catheter entrapment. The emergence of balloon microcatheters has allowed for improved protection of the normal cerebral vasculature and has improved the penetration of liquid embolics into large AVMs, ultimately reducing procedure times and radiation exposure. Finally, several detachable tip microcatheters have been developed to facilitate removal of the catheter from hardened liquid embolic cast, preventing the morbidity associated with distal catheter entrapment. This article reviews the embolic agents and microcatheters currently available for the treatment of cerebral AVMs in the United States as well as the data demonstrating the safety and efficacy of these devices.

Multimodality treatment of intracranial arteriovenous malformations in South Island, New Zealand

Treatment of intracranial arteriovenous malformations is complex and multidisciplinary. This article presents the treatment model utilized in Christchurch, New Zealand which provides cerebrovascular surgery and interventional neuroradiology to the entire south island (approximate population of 1.1 million). A total of 40 patients treated over a 10 year period (2004-2014) are analysed here. Nine patients were managed surgically and complete resection was achieved in 100% of cases. Permanent mortality was 0% and permanent morbidity was 22% however median mRS improved from 3.0 preoperatively to 1.0 at follow up. Embolisation was utilized in 31 patients (mean age 40), of which 45% presented with haemorrhage, 39% with seizures, 10% with a headache only, and 6% with a deficit. None were found incidentally. The Spetzler-Martin grade 1 cases accounted for 10% of the cohort, 23% were grade II, 42% grade III, 23% grade IV and 3% grade V. A single aneurysm was present in 42% of cases, and multiple in 13%. The nidus was obliterated in 9.6% of cases with a morbidity rate of 6.5% and mortality rate of 3%. Modified Rankin scale improved marginally from 0.9 at diagnosis to 0.88 at final follow up (mean 22 months). There were no cases of recanalization. The total nidus obliteration rate using our algorithm of surgery alone for small accessible lesions, then staged embolization for larger lesions with adjuvant radiosurgery reserved for cases with residual nidus, was 50%.

Embolization of brain arteriovenous malformations with intent to cure: a systematic review

OBJECTIVE

Endovascular embolization has been established as an adjuvant treatment strategy for brain arteriovenous malformations (AVMs). A growing body of literature has discussed curative embolization for select lesions. The transition of endovascular embolization from an adjunctive to a definitive treatment modality remains controversial. Here, the authors reviewed the literature to assess the lesional characteristics, technical factors, and angiographic and clinical outcomes of endovascular embolization of AVMs with intent to cure.

METHODS

Electronic databases-Ovid MEDLINE, Ovid Embase, and PubMed-were searched for studies in which there was evidence of AVMs treated using endovascular embolization with intent to cure. The primary outcomes of interest were angiographic obliteration immediately postembolization and at follow-up. The secondary outcomes of interest were complication rates. Descriptive statistics were used to calculate rates and means.

RESULTS

Fifteen studies with 597 patients and 598 AVMs treated with intent-to-cure embolization were included in this analysis. Thirty-four percent of AVMs were Spetzler-Martin grade III. Complete obliteration immediately postembolization was reported in 58.3% of AVMs that had complete treatment and in 45.8% of AVMs in the entire patient cohort. The overall clinical complication rate was 24.1%. The most common complication was hemorrhage, occurring in 9.7% of patients. Procedure-related mortality was 1.5%.

CONCLUSIONS

While endovascular embolization with intent to cure can be an option for select AVMs, the reported complication rates appear to be increased compared with those in studies in which adjunctive embolization was the goal. Given the high complication rate related to a primary embolization approach, the risks and benefits of such a treatment strategy should be discussed among a multidisciplinary team. Curative embolization of AVMs should be considered an unanticipated benefit of such therapy rather than a goal.

Embolizing intracranial arteriovenous malformations with Onyx: experience at a single center with 250 patients

Objective The aim of this study is to evaluate the embolization techniques, as well as the effects and complications, using the non-adhesive liquid embolic material Onyx in intracranial arteriovenous malformations (AVMs). Methods The study comprises a retrospective analysis of 250 patients with intracranial AVMs treated with Onyx in Guangdong General Hospital from Jan 2010 to Dec 2017. The therapeutic strategies, as well as embolization effects and complications, of Onyx are summarized. Results Of 250 cases, 170 were male and 80 were female. Following the Spetzler-Martin (S-M) grading system, there were 35 cases of grade I, 77 of grade II, 72 of grade III, 39 of grade IV, and 27 of grade V. All cases were treated with Onyx. In addition, 69 cases were treated with Glubran glue. The injected volume of Onyx per patient ranged from 1 mL to 10 mL. The largest volume of Onyx injected in one procedure was 10 mL. The cure rate was 67.9% (76/112) of grade I-II patients, 15.0% (11/72) of grade III patients, 7.7% (3/39) of grade IV patients, and 0% (0/27) of grade V patients. The total cure rate was 36.0% (90/250). The average number of targeted vascular branches per patient was 2.28. The microcatheter broke off in two cases. There were two patients who suffered an intracranial hemorrhage during the embolic procedure; in one of these two patients, the microcatheter also broke off. There were two patients who suffered an intracranial hemorrhage after the embolic procedure; one of them died. Seven cases suffered new-onset neurological deficits or their original symptoms deteriorated. Six of them improved or recovered within 3-6 months. The total complication rate was 5.2% (13/250). Conclusion The application of Onyx in intracranial AVMs is flexible, effective and safe, and may also reduce the complications.

Endovascular treatment of intracranial arteriovenous malformations using detachable-tip microcatheters and Onyx 18®

PURPOSE

To evaluate clinical and imaging features before embolization, data of embolization procedure and outcome in patients with ruptured or unruptured intracranial arteriovenous malformation (AVM) who were treated by endovascular embolization using detachable-tip microcatheters and Onyx 18^®.

MATERIAL AND METHODS

Forty-three patients treated with endovascular embolization using a detachable-tip microcatheter and Onyx18^® between January 2008 and April 2016 were evaluated. There were 27 men and 16 women with a mean age of 35.9±14.1years (range: 10-68years). Clinical and imaging features, embolization details and post-treatment findings were analyzed. Patients were divided into ruptured AVM and unruptured AVM groups. Death, complications and total embolization rates of each group were assessed.

RESULTS

Fifty-one embolization sessions were performed in 43 patients. Total embolization rate was 40% (17/43). There were significant relationships between AVM diameter and total embolization success and AVM diameter and complication rates. The degree of embolization was partial in all patients who had complications. Catheter retention and iatrogenic rupture were not observed in any procedure. No major neurologic deficit was seen in patients who had unruptured AVM and complications after treatment.

CONCLUSIONS

Our results show the efficacy of endovascular embolization of AVM using detachable-tip microcatheters and Onyx 18^®. A new AVM classification system based on AVM diameter for this embolization technique may be more predictive in terms of total embolization success and complication development.

Use of the Apollo detachable-tip microcatheter for endovascular embolization of arteriovenous malformations and arteriovenous fistulas

OBJECTIVE

Liquid embolic agents have revolutionized endovascular management of arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs). Nonetheless, since 2005, the US FDA has received more than 100 reports of microcatheter breakage or entrapment related to Onyx embolization, including 9 deaths. In 2014, the Apollo detachable-tip microcatheter became the first of its kind available in the US. Since then, few reports on its safety have been published.

METHODS

The authors conducted a retrospective review of endovascular cases by searching the patient databases at 2 tertiary cerebrovascular centers (Barrow Neurological Institute and University of Pittsburgh Medical Center). Patients who underwent endovascular embolization of an AVM or AVF using the Apollo microcatheter were identified. Patient demographics and lesion characteristics were collected. The authors analyzed Apollo-specific endovascular variables, such as number of microcatheterizations, sessions, and pedicles embolized; microcatheter tip detachment status; obliteration rate; and endovascular- and microcatheter-related morbidity and mortality.

RESULTS

From July 2014 to October 2016, a total of 177 embolizations using the Apollo microcatheter were performed in 61 patients (mean age 40.3 years). The most frequent presentation was hemorrhage (22/61, 36.1%). Most lesions were AVMs (51/61, 83.6%; mean diameter 30.6 mm). The mean Spetzler-Martin grade was 2.4. Thirty-nine (76.5%) of 51 patients with AVMs underwent resection. Microcatheterization was successful in 172 pedicles. Most patients (50/61, 82%) underwent a single embolization session. The mean number of pedicles per session was 2.5 (range 1-7). Onyx-18 was used in 103 (59.9%), N-butyl cyanoacrylate (NBCA) in 44 (25.6%), and Onyx-34 in 25 (14.5%) of the 172 embolizations. In 45.9% (28/61) of the patients, lesion obliteration of 75% or greater was achieved. Tip detachment occurred in 19.2% (33/172) of microcatheters. Fifty-three (86.9%) of the 61 patients who underwent embolization with the Apollo microcatheter had good functional outcomes (modified Rankin Scale score 0-2). No unintended microcatheter fractures or related morbidity was observed. One patient died of intraprocedural complications unrelated to microcatheter selection. In the univariate analysis, microcatheter tip detachment (p = 0.12), single embolized pedicles (p = 0.12), and smaller AVM nidus diameter (p = 0.17) correlated positively with high obliteration rates (> 90%). In the multivariate analysis, microcatheter tip detachment was the only independent variable associated with high obliteration rates (OR 9.5; p = 0.03).

CONCLUSIONS

The use of the Apollo detachable-tip microcatheter for embolization of AVMs and AVFs is associated with high rates of successful catheterization and obliteration and low rates of morbidity and mortality. The microcatheter was retrieved in all cases, even after prolonged injections in distal branch pedicles, often with significant reflux. This study represents the largest case series on the application of the Apollo microcatheter for neurointerventional procedures.

Endovascular Treatment for Low-Grade (Spetzler-Martin I-II) Brain Arteriovenous Malformations

BACKGROUND AND PURPOSE

Surgical resection is usually considered as the first-line curative strategy for low-grade (Spetzler-Martin grade I-II) brain arteriovenous malformations because it has a high cure rate and low complications. The role of endovascular treatment remains to be clarified in this indication, especially after A Randomized Trial of Unruptured Brain Arteriovenous Malformations. Our objective was to assess the safety and efficacy of first-line endovascular treatment in low-grade brain arteriovenous malformation management at our institution.

MATERIALS AND METHODS

Patients with low-grade brain arteriovenous malformations treated primarily with embolization in our department between January 2005 and December 2015 were retrieved from our prospectively collected registry. The primary outcome was the brain arteriovenous malformation obliteration rate, and secondary outcomes were disability or death secondary to brain arteriovenous malformation embolization assessed through modification of the modified Rankin Scale.

RESULTS

Two hundred twenty-four patients completed endovascular treatment during the study period and represent our study population. Complete exclusion of brain arteriovenous malformations was achieved in 205 patients (92%), including 62.1% of brain arteriovenous malformation exclusions after a single endovascular treatment session. One patient died of a hemorrhagic complication after endovascular treatment, leading to a mortality rate of 0.4%. Twelve patients (5%) kept a permanent neurologic deficit secondary to a complication of the endovascular treatment. An overall good outcome (mRS 0-2) was reported in 179 patients (80%).

CONCLUSIONS

Endovascular treatment might be a suitable alternative to surgical resection for complete exclusion of selected low-grade brain arteriovenous malformations.

Combined treatment approach to cerebral arteriovenous malformation in pediatric patients: stereotactic radiosurgery to partially Onyx-embolized AVM

PURPOSE

Treatment of cerebral arteriovenous malformations (AVM)-the most common cause of stroke in the pediatric population-can be challenging due to the complexity of size, morphology, and location. There is a significant risk in comparison to AVM treatment among adults. Thus, AVM treatment in the pediatric population imposes unique challenges. Recent improvements include optimized catheter techniques and better embolization materials, such as Onyx, a non-adhesive liquid embolic agent used in the adult population. These improvements have increased the success rate of total and near-total obliteration of cerebral AVM. However, the use of Onyx causes significant distortion of the MR and CT images, which must be accounted for in any radiation treatment planning predicated on CT and MRI. These image distortions impact on the actual delivered dose to the nidus and behoove heterogeneity correction. Our group has previously shared a solution for heterogeneity correction in the adult population. The purpose of this study is to show our experience in this unique group of pediatric patients.

METHODS

This is a retrospective review of pediatric patients, who were undergoing combined endovascular embolization followed by SRS. The cohort consists of 14 patients undergoing SRS treatment in our institute between November 2006 and December 2012 with a mean follow-up of 49.9 months. Within this cohort, we retrospectively reviewed 12 consecutive pediatric patients who underwent a combined endovascular and SRS approach with a mean follow-up of 52.1 months and two patients receiving SRS-only treatment were excluded.

RESULTS

In our cohort of 14 patients, 7 (50%) were male, with a mean age of 17.3 years (12.0-22.9) at the time of radiosurgery treatment. Mean age of beginning the combined modality treatment was 15.3 years (8.4-20). The median time from diagnosis to SRS was 24.3 months (11.1-64.4 months) in the complete cohort and 25.6 months (11.1-64.4) in the multimodality group. The overall median follow-up period was 49.9 months (range 12.8-118.8 months) in the complete cohort and 52.1 months (range 12.8-118.8 months) in the multimodality group. Eleven (78.6%) patients had at least one episode of hemorrhage prior to treatment. Spezler-Martin grades at baseline ranged from 2 to 5 (mean 3.2). Fifty percent had grade IV and V. Patients underwent a median of 2 (range 1-5) embolization procedures. The radiosurgical treatment dose to the margin of the angiography-based nidus: median prescription dose of 21.49 Gy (14.39-27.51) with a median max dose of 27.77 Gy (18.93-32.52). The median treatment volume was 0.6 cm³ (0.1-7.3 cm³). The Onyx embolization reduced the nidus target volume by a median of 66.7% (12.0-92.7%). We confirmed 10/14 (71%) complete closures. In 2/14 (14.2%) additional patients, a significant flow reduction was noted. In 1/14 (7.1%) patients, no significant change was noted during the observation period and two (14.2%) patients were without follow-up information. In two patients, post-treatment edema was noted; however, none was clinically significant and resolved without additional intervention or treatment.

CONCLUSIONS

This cohort comprises the largest combined Onyx-SRS pediatric experience in the literature. In conjunction with our adult group study, we show that the use of Onyx reduces the SRS treatment target volume significantly. Importantly, we implemented the heterogeneity correction to avoid increased radiation exposure to normal surrounding brain tissue. The combined approach appears to be safe provided that the above-mentioned corrections are implemented.

Transvenous embolization of arteriovenous malformations

Embolization of arteriovenous malformations is characteristically used as part of a multimodal treatment approach, pre-operatively to facilitate microsurgical resection or as a preradiosurgical adjunct. The concept of AVM cure via embolization alone has gained popularity in recent years. Embolization of AVMs has been most commonly performed transarterially, with the transvenous route traditionally eschewed given concern over precipitating premature venous occlusion and consequent hemorrhage. However, the transvenous approach in treating AVMs offers several distinct advantages compared to the transarterial route and can be used in instances when the latter is not feasible, with several series having proven its efficacy and safety. Conceptually, AVM embolization performed via the transvenous route achieves complete obliteration by directly and facilely targeting the nidus. Nidal embolisate penetration is facilitated by control of arterial inflow via systemic or local hypotension. Innovation in endovascular strategies has led to significantly improved obliteration rates. The experience with transvenous AVM embolization is reviewed and discussed.

Novel Use of Pipeline Stent Device After Inadvertent Microcatheter Rupture During Arteriovenous Fistula Embolization

BACKGROUND

Onyx, a liquid embolic agent, is the mainstay of embolization treatment of arteriovenous malformation or arteriovenous fistula. Microcatheter retention in an embolic cast is a well-known complication. Rupture of catheter with spillage of onyx is a rare phenomenon but can lead to potential occlusion of the parent vessel.

METHODS

We describe a case in which a patient with ruptured arteriovenous fistula experienced rupture of a microcatheter at the proximal part and spillage of onyx on embolization. A Pipeline embolization device (PED) was successfully deployed, and onyx was jailed between the catheter and vessel wall at the third segment of the vertebral artery (V3 segment). A balloon angioplasty helped to complete the opening of the stent.

RESULTS

The procedure was uneventful, and the patient recovered well. Follow-up angiogram revealed patency of posterior circulation. The 6-month follow-up angiogram revealed a patent stent.

CONCLUSIONS

Microcatheter rupture and spillage of onyx during embolization of arteriovenous malformation/arteriovenous fistula is a potential complication, and management should be individualized. The unique close cell design of the PED was successfully used to avoid a potentially life-threatening occlusion of the vertebrobasilar system. To the best of our knowledge, we report for the first time this novel use of PED.

Quantification of tantalum sedimentation rates in liquid embolic agents

Background Endovascular treatment (EVT) of brain arteriovenous malformations has evolved from cyanoacrylate derivatives such as N-butyl cyanoacrylate, an adhesive glue, to ethylene vinyl copolymer-based liquid embolics such as Onyx® and SQUID® dissolved in dimethyl sulfoxide. Although these agents offer several advantages, their rapidly decreasing radiopacity, as a result of the sedimentation of tantalum powder, compromises visual control during EVT. This study aims to quantify and compare tantalum sedimentation rates of several liquid embolic agents, and determine their effects on radiopacity. Methods The rate of sedimentation of liquid embolics Onyx 18®, SQUID 12®, and SQUID 18® was measured after preparation by single x-ray exposures for a period of 30 minutes. The signal-to-noise ratios (SNRs) of the suspension of each liquid embolic was calculated at various time points as tantalum settled out of the suspension. Precipitating Hydrophobic Injectable Liquid (PHIL®) was imaged as a control. Results Onyx 18® demonstrated the fastest sedimentation rate of the liquid embolics analyzed and demonstrated a threefold faster drop in SNR compared to SQUID 18® over 30 minutes. Onyx 18® demonstrated a one and a half times faster drop in SNR compared to SQUID 12®. Although PHIL 25® maintained constant SNR over the same time, it was lower at baseline immediately after preparation compared to tantalum-based liquids. Conclusion Caution during long injections using tantalum-based agents is advised. Onyx 18® has a significantly faster drop in radiopacity compared to SQUID 12® and SQUID 18®. Covalently bonded iodine-based embolics like PHIL® demonstrate constant radiopacity over time.

Assessment of periprocedural hemodynamic changes in arteriovenous malformation vessels by endovascular dual-sensor guidewire

Endovascular embolization is an important modality in the treatment of brain AVMs. Nowadays staged embolization is the method of choice for the prevention of perioperative hemorrhagic complications. Current theory suggests that simultaneous occlusion of more than 60% of AVM volume induces significant redistribution local blood flow. That, in turn, may lead to hemorrhage due to AVM rupture. Aside from angiographic findings, there is still no method that predicts the degree of safe partial embolization. Intraluminal measurement of flow velocity and pressure in the vicinity of the AVM nidus might allow detecting the changes in local hemodynamics. That can provide a valuable data and shed the light on the origin of vascular catastrophes. Ten patients underwent 12 embolization sessions with intraluminal flow velocity and pressure monitoring. The measurements were performed by dual-sensor guidewire. The "Combomap" (Volcano) system with Combowire microguidewires was chosen for measurements, as there is a documented experience of safe use of said guidewires in the cerebral vasculature. The findings observed during the study matched empirical data as well as the current physiological hypothesis of AVM hemorrhage. In conjunction with DSA runs, intraluminal flow velocity and pressure monitoring has the potential to become a valuable tool in AVM treatment.

Onyx embolization with the Apollo detachable tip microcatheter: A single-center experience

Purpose The Apollo Onyx Delivery Microcatheter (Ev3, Irvine, CA) is a detachable-tip microcatheter that was developed to reduce the risk of microcatheter entrapment during ethylene-vinyl alcohol copolymer (Onyx) embolizations. We report our experience with the microcatheter in a variety of neurointerventional procedures. Methods We retrospectively reviewed all Onyx embolizations performed in the head, neck, and spine using the Apollo Onyx Delivery Microcatheter from its introduction at our institution in July 2014 to August 2016. Information regarding patient diagnoses, procedural details, as well as clinical outcomes were obtained from the electronic medical record, procedure reports, and relevant angiographic imaging. Results A total of 58 arterial pedicle Onyx embolizations were performed in 37 patients. There were no cases of microcatheter entrapment, early/inadvertent tip detachment, or vessel injury upon removal of the device. There were two instances (3.5%) of leakage of Onyx from the microcatheter detachment site during embolization, which did not result in adverse sequelae. Clinical outcomes were excellent, with nearly all embolizations achieving the intended goal. In multivariate analysis, length of Onyx reflux along the microcatheter tip and utilization of a higher viscosity agent, Onyx 34, were significantly associated with tip detachment. Conclusion The use of the Apollo Microcatheter is both safe and effective during neurointerventional embolizations using Onyx. Leakage of liquid embolic agent from the detachment site is an infrequent technical complication that may be encountered with the device.

Assessment of human placenta as an ex-vivo vascular model for testing of liquid embolic agent injections with adjunctive techniques

PURPOSE

This project sought to test the utility of post-delivery human placenta (HP) as a vascular model for liquid embolic agent (LEA) simulation, along with adjunctive techniques.

MATERIALS AND METHODS

Twelve LEA injections were performed under fluoroscopy in HP with two reflux control methods: dual lumen 'mini' balloon-catheter (n=9); and injection after proximal nBCA plug formation through a second microcatheter ('pressure cooker') (n=3). Measured outcomes included liquid embolic agent (LEA) advancement and reflux. Reflux was categorized into three grades: grade 0=no reflux; grade 1=occlusion of side branches without reflux beyond the balloon or plug; and grade 2=reflux beyond the balloon or plug.

RESULTS

Simulation success was greater when a balloon was used rather than with a nBCA plug (89% vs 33%, P=0.054). In eight successful balloon-assisted injections, the reflux grades were: 50% grade 0; 12.5% grade 1; and 37.5% grade 2. The one successful nBCA plug injection had grade 2 reflux. All grade 2 balloon injections occurred when the balloon was positioned across a vessel bifurcation.

CONCLUSIONS

HP provides excellent simulation for liquid embolic agents with a dual lumen balloon catheter.

Treatment Outcomes of A Randomized Trial of Unruptured Brain Arteriovenous Malformation-Eligible Unruptured Brain Arteriovenous Malformation Patients

BACKGROUND

The guideline for treating unruptured brain arteriovenous malformations (ubAVMs) remains controversial. A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) reported lower risk of stroke or death with conservative management compared to interventional treatment. There were numerous limitations to the study, including short follow-up period and disproportionate number of patients treated with surgery and embolization.

OBJECTIVE

To evaluate whether treatment of ARUBA-eligible patients have acceptable outcomes at our institution.

METHODS

Retrospective analysis was performed on 673 patients with brain AVMs treated at our institution between 2001 and 2014. One hundred five patients were ARUBA eligible and included in the study. Patients were divided into the microsurgery or Gamma Knife Radiosurgery (GKS; Elekta, Stockholm, Sweden) arm depending on their final treatment. Mean follow-up period was 43 mo (range 4-136 mo). Primary outcome was stroke or death.

RESULTS

A total of 8 (7.6%) patients had a stroke or died. The overall risk of stroke or death was 11.4% (5 of 44 patients) for the microsurgery arm and 4.9% (3 of 61 patients) for the GKS arm. The annual rates of stroke or death were 2.1%, 4.0%, and 1.2% for the entire patient cohort, microsurgery arm, and GKS arm, respectively. AVM obliteration rates at the end of the follow-up period were 95.5% and 47.5% for the microsurgery and GKS arms, respectively.

CONCLUSION

We report a lower overall risk of stroke or death in our ARUBA-eligible patients following treatment than ARUBA. Our results suggest that microsurgery and GKS may be appropriate treatments for patients with ubAVM.

Impact of Onyx Embolization on Radiosurgical Management of Cerebral Arteriovenous Malformations: Treatment and Outcome

BACKGROUND

Stereotactic radiosurgery (SRS) is a well-established treatment modality for cerebral arteriovenous malformations (AVMs). The main limiting factor in the radiosurgical treatment of AVMs is the volume of the nidus, with high-grade lesions often requiring combined treatment to reduce the SRS target volume. To overcome this limitation, we have been using a combined treatment approach consisting of endovascular embolization with Onyx followed by SRS.

OBJECTIVE

To evaluate our clinical experience for safety and feasibility of this multimodality treatment approach.

METHODS

This is a retrospective review of all adult patients with cerebral AVMs who received SRS treatment to their AVM after endovascular embolization with Onyx between June 2007 and June 2014.

RESULTS

Thirty-five consecutive patients were identified. The mean follow-up period was 52.4 ± 22.6 months (range 18-97 months). We confirmed 18 (51.4%) complete nidus closures at a median time of 49.5 months (range 6.5-81 months) from SRS. High-resolution Magnetic resonance imaging/magnetic resonance angiography was performed routinely in all patients until closure of the nidus. Digital subtraction angiography was performed to confirm complete obliteration in 5 of the patients (28%); 13 patients are either planned for digital subtraction angiography or have refused it. In 6 patients (17%) a significant flow reduction was noted after a mean of 32 ± 16 months. No significant improvement was observed in 9 patients (26%) during the follow-up period. Two patients were lost to follow-up.

CONCLUSIONS

The multimodality treatment of cerebral AVMs using embolization with Onyx followed by SRS is feasible and safe. The use of Onyx significantly reduced the SRS treatment target volume.

Early outcomes and periprocedural complications of transarterial embolization of brain arteriovenous malformations with Onyx®

BACKGROUND

Brain arteriovenous malformation (BAVM) is a rare pathology diagnosed mostly in young adults. However, due to its hemorrhagic complications, it constitutes an important clinical problem. Treatment modalities available include endovascular, surgery and radiosurgery. The aim of the study was to assess the efficacy and safety of endovascular treatment of BAVM with Onyx^® by reporting one-center experience.

MATERIAL AND METHODS

Between 2006 and 2013, 54 patients with BAVM were embolized with Onyx. The group consisted of 24 males and 30 females, aged 10 to 65 years (mean 42.6±15.4). Clinical manifestations of BAVMs were: hemorrhage in 27 (50.0%), headaches in 12 (22.2%), seizures in 7 (13.0%) and focal neurologic deficits in 2 (3.7%) patients. Six (11.1%) patients were asymptomatic. A majority of BAVMs were of II and III grade in Spetzler-Martin scale (19 and 22 cases respectively).

RESULTS

A total number of 108 endovascular procedures were performed (mean 2.00±0.98 sessions/patient). Complete obliteration of malformation was achieved in 25 (46.3%) patients, mostly with grade II and III BAVMs. In 29 (53.7%) patients, embolization led to a decrease in size of BAVM that made it feasible for other treatment modality. Morbidity and mortality rates were 5.6% and 1.8% respectively. The rate of hemorrhagic complications was 9.3%.

CONCLUSION

Embolization of BAVM with Onyx^® is an effective and safe method of treatment. However, regarding type and consequences of complications, the technique needs further improvement.

Spontaneous occlusion of cerebral arteriovenous malformation following partial embolization with Onyx

Management options for brain arteriovenous malformations (AVMs) are surgery, radiosurgery, and endovascular embolization. The aim of partial embolization in endovascular treatment is to make total resection possible. However, increased risk of bleeding in partial embolization creates some controversies about treatment options. Spontaneous total occlusion of cerebral AVMs following partial obliteration with embolization agents is a rarely seen condition. We present a case with an AVM vanishing from right posterior cerebral artery which spontaneously occluded following partial embolization with Onyx liquid agent.

Therapeutic progress in pediatric intracranial dural arteriovenous shunts: A review

Pediatric dural arteriovenous shunts (dAVSs) are a rare form of vascular disease: Fewer than 100 cases are reported in PubMed and the understanding of pediatric dAVS is limited. For this study, we searched in PubMed, reviewed and summarized the literature related to pediatric dAVSs. Our review revealed that pediatric dAVSs have an unfavorable natural history: If left untreated, the majority of pediatric dAVSs deteriorate. In a widely accepted classification scheme developed by Lasjaunias et al., pediatric dAVSs are divided into three types: Dural sinus malformation (DMS) with dAVS, infantile dAVS (IDAVS) and adult-type dAVS (ADAVS). In general, the clinical manifestations of dAVS can be summarized as having symptoms due to high-flow arteriovenous shunts, symptoms from retrograde venous drainage, symptoms from cavernous sinus involvement and hydrocephalus, among other signs and symptoms. The pediatric dAVSs may be identified with several imaging techniques; however, the gold standard is digital subtraction angiography (DSA), which indicates unique anatomical details and hemodynamic features. Effectively treating pediatric dAVS is difficult and the prognosis is often unsatisfactory. Transarterial embolization with liquid embolic agents and coils is the treatment of choice for the safe stabilization and/or improvement of the symptoms of pediatric dAVS. In some cases, transumbilical arterial and transvenous approaches have been effective, and surgical resection is also an effective alternative in some cases. Nevertheless, pediatric dAVS can have an unsatisfactory prognosis, even when timely and appropriate treatment is administered; however, with the development of embolization materials and techniques, the potential for improved treatments and prognoses is increasing.

Outcome of microsurgical excision of unruptured brain arteriovenous malformations in ARUBA-eligible patients

OBJECTIVES

To determine the outcome of microsurgical excision of selected unruptured brain arteriovenous malformations (AVMs), and to compare the results with those of the ARUBA trial.

METHODS

Prospective data collection for all patients undergoing microsurgical excision of unruptured brain AVMs by two neurovascular surgeons. Outcome measures similar to those assessed in the ARUBA trial (death and stroke) as well as modified Rankin scores (mRS) at 6 months were assessed.

RESULTS

Between September 2004 and September 2014, 45 patients with unruptured brain AVMs underwent microsurgical excision. 11 patients (eight children and three with mRS >2 at presentation) were excluded to match ARUBA eligibility criteria. 34 patients were included in this study. AVM characteristics closely matched those in the ARUBA trial with 70.5% Spetzler-Martin (SM) grade I or II AVMs, 68% AVM size <3 cm. However, compared to ARUBA, a larger proportion of our patients presented with seizures, and a lower proportion with headaches. 8(23%) had preoperative embolization. There were no deaths and no strokes (as defined in ARUBA). 5 (14.7%) had permanent neurological deficit related to surgery within/near eloquent cortex. At 6 months follow-up, 32 (94%) had mRS score of 0-1. Two (6%) had mRS 2 and none had mRS> 2. Postoperative digital DSA confirmed complete AVM excision in all cases. None of the patients have suffered intracranial hemorrhage during the follow-up period of 6-126 (median 69) months.

CONCLUSIONS

Microsurgical excision of unruptured brain AVMs can be performed with low morbidity in selected cases. Our study has limitations particularly the small number of patients with selected AVMs for microsurgical excision. However, our results suggest that ARUBA results may not be applicable to microsurgical excision when cases are appropriately selected for this treatment modality.

Detachable-Tip Microcatheters for Liquid Embolization of Brain Arteriovenous Malformations and Fistulas: A United States Single-Center Experience

BACKGROUND

The US Food and Drug Administration recently approved a detachable-tip microcatheter, the Apollo microcatheter (eV3, Inc, Irvine, California), to prevent catheter entrapment during embolization of brain arteriovenous malformations (AVMs) using liquid embolic systems.

OBJECTIVE

To report technical aspects and clinical results of cerebral embolizations with the Apollo microcatheter in 7 embolizations in 3 adult patients.

METHODS

A 62-year-old man presented with an AVM in the parieto-occipital region measuring 3.6 × 1.6 cm with major cortical feeders from the right middle cerebral artery (MCA) and minor contribution from the distal right anterior cerebral artery. Two pedicles originating from the MCA were embolized. A 48-year-old woman presented with a left frontal AVM measuring 3.3 × 1.8 cm with arterial feeders from the left MCA, left middle meningeal artery, and contralateral anterior cerebral artery. Three pedicles originating from the left MCA were embolized. A 76-year-old man presented with an arteriovenous fistula with multiple fistulous connections and feeders from both vertebral and occipital arteries and the left posterior cerebral artery draining into the left transverse, torcula, and left sigmoid sinus. Two major occipital artery feeders were embolized.

RESULTS

Seven Apollo microcatheters were used with the Onyx 18 liquid embolic system. The length of the detachable tip was 15 mm in 2 and 30 mm in 5 embolizations. The mean microcatheter in-position time within the pedicle was 20 minutes. Detachment of tip occurred in 3 instances. No limitations in accessing target arterial feeders and safe tip disengagement were noted despite prolonged injection times.

CONCLUSION

Our initial experience supports the feasibility, safety, and effectiveness of detachable-tip microcatheters in treating brain AVMs and arteriovenous fistulas.