Embolization of intracranial arteriovenous malformations with ethylene-vinyl alcohol copolymer (Onyx)

Giant vascular malformations invading the skull: A case report

BACKGROUND

Vascular malformations (VMs) arise as a result of errors in the process of angiogenesis and are usually present at birth, but may not become apparent until after birth. However, giant VMs of the head and face are uncommon, with few reported cases, and the prognosis for their surgical intervention is unclear.

CASE SUMMARY

A 12-year-old girl was admitted to the hospital with findings of an enlarged right temporal scalp. After admission, computed tomography (CT) angiography of cerebral ateries showed a right occlusal gap and a right temporal artery venous malformation. Furthermore, cerebral angiography showed a right temporal lobe VM with multiple vessels supplying blood. The patient underwent surgery to remove the malformed vessels and the eroded skull. Two hours after the surgery, the patient's right pupil was dilated, and an urgent CT scan of the skull showed a right subdural haematoma under the incision, which was urgently removed by a second operation. After surgery, we gave continuous antibiotic anti-infection treatment, and the patient recovered well and was discharged two weeks later.

CONCLUSION

Surgical removal of giant haemangiomas is risky and adequate preoperative (including interventional embolisation) and intraoperative preparations should be made.

Preshaped 4D Photocurable Ultratough Organogel Microcoils for Personalized Endovascular Embolization

Endovascular embolization using microcoils can be an effective technique to treat artery aneurysms. However, microcoils with fixed designs are difficult to adapt to all aneurysm types. In this paper, a photocurable ultratough shape memory organogel with a curing time of only 2 s and megapascal-level mechanical properties is proposed. Then, it is used to manufacture the personalized 4D microcoil with a wire diameter of only 0.3 mm. The improved mechanical modulus (511.63 MPa) can reduce the possibility of microcoils' fracture during embolization. Besides, the fast body-temperature-triggering shape memory ability makes the 4D microcoil applicable in vivo. These 4D microcoils are finally delivered into the rabbit, and successfully blocked the blood flow inside different aneurysms, with neoendothelial cells and collagen fibers growing on the microcoil surface snugly, indicating full aneurysm recovery. This 4D organogel microcoil can potentially be used in personalized clinical translation on human beings.

Comparative cost analysis of liquid embolization systems for brain arteriovenous malformation using a real-world US hospital database: TRUFILL® versus OnyxTM

BACKGROUND

Liquid embolic systems (LES) such as n-butyl cyanoacrylate-based TRUFILL® and ethylene vinyl-alcohol copolymer-based OnyxTM are widely used for the embolization of brain arteriovenous malformations (bAVMs). The purpose of this study was to compare hospital cost and length of stay (LOS) among unruptured bAVM patients undergoing embolization procedures with TRUFILL versus Onyx LES.

METHODS

Adult patients with unruptured bAVMs undergoing endovascular embolization with TRUFILL or Onyx LES between January 1, 2010 and June 30, 2020 were identified from the Premier Healthcare Database. Baseline covariates among the two groups were balanced using propensity score matching. Outcomes including total procedure cost, supply cost, and LOS were examined. A Generalized Estimating Equation model was used to assess outcomes in the matched cohorts.

RESULTS

A total of 1072 patients were included in the study; 140 embolized with TRUFILL (mean age 47.06 [15.72] years, 45.70% male) and 932 embolized with Onyx (mean age 46.80 [16.65] years, 52.30% male). In the post-match cohort, the total procedure costs were lower for the TRUFILL (n = 130) versus Onyx (n = 333) group, though not significantly ($36,798 vs. $40,988; odds ratio [OR] = 0.90, 95% confidence interval [CI]: 0.73-1.10; p = 0.30). However, supply cost was significantly lower for hospitalizations with TRUFILL compared to Onyx use ($13,281 vs. $16,371, OR = 0.81, 95% CI: 0.68, 0.98; p = 0.026). Hospital LOS was similar in these two groups (TRUFILL: 4.05 vs. Onyx: 4.06 days; OR = 1.00, 95% CI: 0.70, 1.42; p = 0.99).

CONCLUSIONS

In a large, multi-center, real-world sample of patients undergoing bAVM embolization, TRUFILL use was associated with significantly lower supply cost compared to Onyx use.

Embolization of brain arteriovenous malformations with squid co-polymer embolic material: Initial experience

Objective

To analyze the safety and effectiveness of the ethylene-vinyl alcohol copolymer (EVOH) liquid embolic agent Squid (Emboflu, Switzerland) for the treatment of brain arteriovenous malformations.

Materials and procedures

Between April 2015 and July 2017, 46 embolization treatments for brain arteriovenous malformations (BAVM) were performed in 25 patients using two Squid formulations (18 and 12). Six female and 19 male patients with a mean age of 34 years (range, 9-62 years) were included. A total of 46 procedures were performed. The BAVMs were classified as Spetzler-Martin grade II in 4 procedures, III in 27 procedures, and 1V in 15 procedures. Among the 25 patients, 15 presented with hemorrhage, 5 with seizures, and 5 with headache and neurology. The BAVMs were located in the temporal lobe in 5 patients, parietal lobe in 7 patients, frontal lobe in 3 patients, posterior fossa in 6 patients, basal ganglia in 3 patients, and parasagittal lobe in 1 patient.

Results

The obliteration rate of the BAVMs ranged from 10% to 100%, with a mean of 33%. Most patients underwent their first or second embolization procedure. Four patients (8%) developed intracranial bleeding post-procedure, with one death (2%). One patient (2%) experienced a seizure during the procedure; however, no intracranial bleeding was observed. Seven patients (15%) experienced perforations during catheter manipulation. One case (2%) of a fractured catheter was recorded, but no significant complications were observed. The average volume of copolymer injected was 0.6 ​ml per nidus. Thirteen procedures used the Squid-12 formulation, 29 procedures used the Squid-18 formulation, and 3 procedures used a combination of Squid-12 and -18 formulations.

Conclusion

Squid is a safe and effective embolic agent for treating BAVMs.

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.

Swarming self-adhesive microgels enabled aneurysm on-demand embolization in physiological blood flow

The recent rise of swarming microrobotics offers great promise in the revolution of minimally invasive embolization procedure for treating aneurysm. However, targeted embolization treatment of aneurysm using microrobots has significant challenges in the delivery capability and filling controllability. Here, we develop an interventional catheterization-integrated swarming microrobotic platform for aneurysm on-demand embolization in physiological blood flow. A pH-responsive self-healing hydrogel doped with magnetic and imaging agents is developed as the embolic microgels, which enables long-term self-adhesion under biological condition in a controllable manner. The embolization strategy is initiated by catheter-assisted deployment of swarming microgels, followed by the application of external magnetic field for targeted aggregation of microrobots into aneurysm sac under the real-time guidance of ultrasound and fluoroscopy imaging. Mild acidic stimulus is applied to trigger the welding of microgels with satisfactory bio-/hemocompatibility and physical stability and realize complete embolization. Our work presents a promising connection between the design and control of microrobotic swarms toward practical applications in dynamic environments.

Embolization before Gamma Knife radiosurgery for cerebral arteriovenous malformations does not negatively impact its obliteration rate: a series of 190 patients

PURPOSE

Embolization of arteriovenous malformations (AVMs) before radiosurgery has been reported to negatively impact the obliteration rate. This study aims to assess treatment outcomes in a series of 190 patients treated by Gamma Knife radiosurgery (GKRS) for previously embolized AVMs.

METHODS

The institutional database of AVMs was retrospectively reviewed between January 2004 and March 2018. The clinical and radiological data of patients treated with GKRS for previously embolized AVMs were analyzed. Predicting factors of obliteration and hemorrhage following GKRS were assessed with univariate and multivariate regression analyses.

RESULTS

The mean AVM size was significantly reduced after embolization (p < 0.001). The obliteration rate was 78.4%. Multivariate analyses showed that a lower Spetzler-Martin grade (p = 0.035) and a higher marginal dose (p = 0.007) were associated with obliteration. Post-GKRS hemorrhages occurred in 14 patients (7.4%). A longer time between diagnosis and GKRS was the only factor associated with post-GKRS hemorrhages in multivariate analysis (p = 0.022). Complications related to the combined treatment were responsible for a new permanent neurological disability in 20 patients (10.5%), and a case of death (0.5%).

CONCLUSIONS

This study shows that the embolization of AVMs does not have a negative impact on the obliteration rate after radiosurgery. Embolization reduces the AVM size to a treatable volume by GKRS. However, the combined treatment results in an increased complication rate related to the addition of the risks of each treatment modality.

The Era of Onyx Embolization: A Systematic and Literature Review of Preoperative Embolization Before Stereotactic Radiosurgery for the Management of Cerebral Arteriovenous Malformations

INTRODUCTION

The current treatment paradigm for intracranial arteriovenous malformations (AVMs) focuses on reducing the risk of intracranial hemorrhage using various therapeutic means including embolization, stereotactic radiosurgery (SRS), and microsurgical resection. To improve AVM obliteration rates with SRS, pre-radiosurgical embolization has been trialed in a number of studies to reduce the volume of the AVM nidus prior to radiosurgery. This study aimed to review the efficacy of pre-radiosurgical embolization in the pre-Onyx era compared to the current Onyx era.

METHODS

A systematic review was performed using PubMed to identify studies with 20 or more AVM patients, embolization material, and obliteration rates for both embolization + stereotactic radiosurgery (E+SRS) and SRS-only groups.

RESULTS

Seventeen articles consisting of 1133 eligible patients were included in this study. A total of 914 (80.7%) patients underwent embolization prior to SRS. Onyx was used as the embolysate in 340 (37.2%) patients in the E+SRS cohorts. Mean obliteration rate for the embolized cohort was 46.9% versus 46.5% in the SRS-only cohort. When comparing obliteration rates based on embolysate material, obliteration rate was 42.1% with Onyx+SRS and 50.0% in the non-Onyx embolysate + SRS cohort.

CONCLUSIONS

Onyx (ethylene vinyl-alcohol copolymer dissolved in dimethyl sulfoxide and suspended in micronized tantalum powder) has been increasingly used for the embolization of intracranial AVMs with increased success regarding its ease of use from a technical standpoint and performs similarly to other embolysate materials.

State of the Art in the Role of Endovascular Embolization in the Management of Brain Arteriovenous Malformations-A Systematic Review

As a significant cause of intracerebral hemorrhages, seizures, and neurological decline, brain arteriovenous malformations (bAVMs) are a rare group of complex vascular lesions with devastating implications for patients' quality of life. Although the concerted effort of the scientific community has improved our understanding of bAVM biology, the exact mechanism continues to be elucidated. Furthermore, to this day, due to the high heterogeneity of bAVMs as well as the lack of objective data brought by the lack of evaluative and comparative studies, there is no clear consensus on the treatment of this life-threatening and dynamic disease. As a consequence, patients often fall short of obtaining the optimal treatment. Endovascular embolization is an inherent part of multidisciplinary bAVM management that can be used in various clinical scenarios, each with different objectives. Well-trained neuro-interventional centers are proficient at curing bAVMs that are smaller than 3 cm; are located superficially in noneloquent areas; and have fewer, larger, and less tortuous feeding arteries. The transvenous approach is an emerging effective and safe technique that potentially offers a chance to cure previously untreatable bAVMs. This review provides the state of the art in all aspects of endovascular embolization in the management of bAVMs.

Rupture of a detachable-tip microcatheter away from the detachment zone during Onyx 18 embolization of an arteriovenous malformation and management of the complication

Leakage of liquid embolic material is a rare but dreaded complication during embolization of an arteriovenous malformation (AVM). We describe the rupture of a microcatheter away from the detachment site and the successful removal of the cast of Onyx 18 in the carotid artery by aspiration. A young adult patient diagnosed with a right temporal unruptured AVM underwent endovascular embolization using Onyx 18. The AVM was approached using an Apollo microcatheter. After 4 min of Onyx 18 injection, leakage of Onyx 18 in the petrous segment of the internal carotid artery was noticed while the distal tip of the microcatheter remained patent. The plug of Onyx was successfully removed using an aspiration technique via the Envoy DA catheter. Analysis of the microcatheter confirmed that the rupture occurred away from the detachment site. However, no definite cause for the rupture has been identified.

Injectable hydrogels for vascular embolization and cell delivery: The potential for advances in cerebral aneurysm treatment

Cerebral aneurysms are vascular lesions caused by the biomechanical failure of the vessel wall due to hemodynamic stress and inflammation. Aneurysmal rupture results in subarachnoid hemorrhage often leading to death or disability. Current treatment options include open surgery and minimally invasive endovascular options aimed at secluding the aneurysm from the circulation. Cerebral aneurysm embolization with appropriate materials is a therapeutic approach to prevent rupture and the resultant clinical sequelae. Metallic platinum coils are a typical, practical option to embolize cerebral aneurysms. However, the development of an alternative treatment modality is of interest because of poor occlusion permanence, coil migration, and coil compaction. Moreover, minimizing the implanted foreign materials during therapy is of importance not just to patients, but also to clinicians in the event an open surgical approach has to be pursued in the future. Polymeric injectable hydrogels have been investigated for transcatheter embolization and cell therapy with the potential for permanent aneurysm repair. This review focuses on how the combination of injectable embolic biomaterials and cell therapy may achieve minimally invasive remodeling of a degenerated cerebral artery with promise for superior outcomes in treatment of this devastating disease.

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.

Embolization of Vascular Malformations via In Situ Photocrosslinking of Mechanically Reinforced Alginate Microfibers using an Optical-Fiber-Integrated Microfluidic Device

Embolization, which is a minimally invasive endovascular treatment, is a safe and effective procedure for treating vascular malformations (e.g., aneurysms). Hydrogel microfibers obtained via spatiotemporally controllable in situ photocrosslinking exhibit great potential for embolizing aneurysms. However, this process is challenging because of the absence of biocompatible and morphologically stable hydrogels and the difficulty in continuously spinning the microfibers via in situ photocrosslinking in extreme endovascular environments such as those involving a tortuous geometry and high absorbance. A double-crosslinked alginate-based hydrogel with tantalum nanopowder (DAT) that exploits the synergistic effect of covalent crosslinking by visible-light irradiation and ionic crosslinking using Ca²⁺ , which is present in the blood, is developed in this study. Furthermore, an effective strategy to design and produce an optical-fiber-integrated microfluidic device (OFI-MD) that can continuously spin hydrogel microfibers via in situ photocrosslinking in extreme endovascular environments is proposed. As an embolic material, DAT exhibits promising characteristics such as radiopacity, nondissociation, nonswelling, and constant mechanical strength in blood, in addition to excellent cyto- and hemo-compatibilities. Using OFI-MD to spin DAT microfibers continuously can help fill aneurysms safely, uniformly, and completely within the endovascular simulator without generating microscopic fragments, which demonstrates its potential as an effective embolization strategy.

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.

Foreign body granuloma reaction after endovascular therapy of an unruptured right frontal arteriovenous malformation

Foreign body reactions after endovascular procedures for brain arteriovenous malformations are extremely rare. We report the case of a cerebral foreign body granuloma reaction after embolization of a frontal arteriovenous malformation with Onyx. A previously treated 36-year-old man underwent re-embolization of a residual and recurrent unruptured right frontal vascular malformation with Onyx. The post-procedural imaging revealed a right frontotemporal heterogeneously enhancing expansive lesion associated with a residual malformation. Following microsurgical resection, the histopathological examination of the expansive lesion revealed basophilic foreign body like deposits adjacent to multi-nucleated giant cells, highly compatible with cerebral foreign body granulomas reaction to Onyx. The clinical and radiological follow-up of the patient was favorable after complete resection of the lesions.

Delayed Fragmentation and Distal Embolization of Retained Microcatheter Causing Lower Limb Ischemia: Case Report and Review of the Literature

BACKGROUND

Endovascular microcatheter adherence and retention is an uncommon complication during brain arteriovenous malformation (AVM) embolization with glue or ethylene-vinyl alcohol copolymer that has previously reported, although there are sparse reports of symptomatic complications thereafter.

CASE DESCRIPTION

We present a unique complication 6 years after initial embolization of a cerebral AVM. The patient presented with acute lower limb insufficiency with computed tomography angiogram revealing fragmentation of the microcatheter and associated popliteal aneurysm. The patient underwent an emergency grafting and removal of the retained fragment and recovered without deficit postoperatively.

CONCLUSIONS

Fragmentation over retained microcatheters remains a concern that may be worth monitoring in the long term, although there are no recommendations for timing.

Complications of Endovascular Treatments for Brain Arteriovenous Malformations: A Nationwide Surveillance

BACKGROUND AND PURPOSE

Embolization is widely performed to treat brain arteriovenous malformations, but little has been reported on factors contributing to complications. We retrospectively reviewed a nationwide surveillance to identify risk factors contributing to complications and short-term clinical outcomes in the endovascular treatment of brain arteriovenous malformations.

MATERIALS AND METHODS

Data for endovascular treatment of brain arteriovenous malformations were extracted from the Japanese nationwide surveillance. Patient characteristics, brain arteriovenous malformation features, procedures, angiographic results, complications, and clinical outcomes at 30 days postprocedure were analyzed.

RESULTS

A total of 1042 endovascular procedures (788 patients; mean, 1.43 ± 0.85 procedures per patient) performed in 111 institutions from 2010 to 2014 were reviewed. Liquid materials were used in 976 procedures (93.7%): to perform presurgical embolization in 638 procedures (61.2%), preradiosurgical embolization in 160 (15.4%), and as sole endovascular treatment in 231 (22.2%). Complete or near-complete obliteration of brain arteriovenous malformations was obtained in 386 procedures (37.0%). Procedure-related complications occurred in 136 procedures (13.1%), including hemorrhagic complications in 59 (5.7%) and ischemic complications in 57 (5.5%). Univariate analysis identified deep venous drainage, associated aneurysms, infratentorial location, and preradiosurgical embolization as statistically significant risk factors for complications. Multivariate analysis showed that embolization of brain arteriovenous malformations in the infratentorial location was significantly associated with complications. Patients with complications due to endovascular procedures had worse clinical outcomes 30 days after the procedures than those without complications.

CONCLUSIONS

Complications arising after endovascular treatment of brain arteriovenous malformations are not negligible even though they may play a role in adjunctive therapy, especially in the management of infratentorial brain arteriovenous malformations.

Therapeutic occlusion of the vertebral artery using a new penumbra occlusion device system and ruby coils (penumbra): A technical note

There are several methods to achieve the therapeutic sacrifice of the vessel, coiling brings the most commonly used. Penumbra occlusion device (POD) system is a newer modality for therapeutic large vessel occlusion, and it is the Food and Drug Administration approved only for peripheral vessels. We report a case where therapeutic vertebral artery (VA) occlusion was achieved with the POD system and Ruby coils for the first time. A patient was diagnosed with a new malignant-appearing tumor of the cervical spine. A conventional angiogram showed multiple tiny arterial feeders from the VA beyond scope of coil/onyx embolization, so we performed a balloon occlusion test followed by therapeutic sacrifice of the VA. A successful VA occlusion was achieved with significant reduction in the tumor blush, followed by open resection of the tumor. The patient had favorable postoperative course and without any neurological symptoms attributed to the VA occlusion.

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%.

Liquid Embolic Agents in Spectral X-Ray Photon-Counting Computed Tomography using Tantalum K-Edge Imaging

The aim was to evaluate the potential of Spectral Photon-Counting Computed Tomography (SPCCT) to differentiate between liquid embolic agents and iodinated contrast medium by using tantalum-characteristic K-edge imaging. Tubes with a concentration series of tantalum and inserts with different concentrations of iodine were scanned with a preclinical SPCCT system. Tantalum density maps (TDM) and iodine density maps (IDM) were generated from a SPCCT acquisition. Furthermore, region-of-interest (ROI) analysis was performed within the tubes in the conventional CT, the TDM and IDM. TDM and IDM enable clear differentiation between both substances. Quantitative measurements of different tantalum concentrations match well with those of actually diluted mixtures. SPCCT allows for differentiation between tantalum and iodine and may enable for an improved follow-up diagnosis in patients after vascular occlusion therapy.

Impact of trivalent ions on the stability and cohesion of calcium polyphosphate coacervates for embolization applications

Polyphosphates (PPs) are of interest as temporary in situ setting embolic agents for which cohesive characteristics are vital. Trivalent ions Al³⁺ and Ga³⁺ were substituted into calcium PP up to 10 mol % for two PP chain lengths (degree of polymerization, D_p 200 and 9000) and the effect on the dissolution rate of the resulting coacervate was examined. High levels of trivalent ions were found to increase the dissolution rate, especially with aluminum (Al) where the coacervate with the greatest Al content (10 mol %) and larger D_p completely dissolved within the first few hours in tris(hydroxymethyl)aminomethane buffered saline. Conversely, small amounts of trivalent ions slowed the dissolution rate of the coacervates compared to those containing calcium only. The coacervate compositions determined to have the fastest and slowest ion release were evaluated for cohesion upon injection into a simulated blood vessel using a dual lumen needle. PPs with lower trivalent content had a higher coacervate yield overall, with 5% Ga and D_p 200 yielding the smallest proportion of coacervate particulates that could be implicated in unwanted distal embolization. However, further studies are required to evaluate the formation and duration of occlusions in vivo so that the PP composition can best be tailored to meet clinical requirements. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2638-2648, 2019.

Embolization of brain arteriovenous malformations with the diluted Onyx technique: initial experience

PURPOSE

Insufficient nidus occlusion is a matter of great concern to routine Onyx embolization of brain arteriovenous malformations (AVMs). This paper described an efficient method which using the diluted Onyx embolization technique to treat brain AVM.

METHODS

The diluted Onyx technique was performed in a series of 15 patients with brain AVMs (10 males, 5 females; age range, 11-44 years). It consists of initial embolization with routine Onyx-18, followed by the diluted Onyx (1.5 mL of Onyx-18 diluted with 0.5 mL of DMSO) through the same microcatheter. The technical skills and angiographic and clinical outcomes were analyzed.

RESULTS

A total of 15 embolization sessions were performed with diluted Onyx via 16 arterial feeders in these 15 patients. Each patient underwent one attempt of diluted Onyx through a single feeder except one patient. In this patient, the AVM was simultaneously embolized with diluted Onyx through double microcatheters which were placed in two feeders. When the length of reflux reached to 2 cm (or close to the determined length) and the embolic material could not move distally any more despite some rounds of "injection-reflux-waiting," regular Onyx 18 was changed to diluted Onyx. Antegrade flow of embolic material into the nidus was observed in 12 cases but failed in 3. An average of 90% (range 55-100%) estimated size reduction was achieved, and 6 AVMs were completely obliterated. No functionally relevant complications occurred.

CONCLUSION

The diluted Onyx technique could be a useful adjunct to routine Onyx embolization which may offer more embolic material penetrating into the nidus of AVM, but additional work is needed to validate this technique.

Feasibility of attenuated total reflection-fourier transform infrared (ATR-FTIR) chemical imaging and partial least squares regression (PLSR) to predict protein adhesion on polymeric surfaces

PLSR with ATR-FTIR chemical imaging predicts protein adhesion on polymeric surfaces well (R² = 0.99, RMSECV = 0.16).

Single-stage planning for total cure of grade III-V brain arteriovenous malformations by embolization alone or in combination with microsurgical resection

PURPOSE

There are no established guidelines for treatment of Spetzler-Martin grade III-V brain arteriovenous malformations (bAVMs). The purpose of this study is to report our institutional experience in total obliteration/eradication of grade III-V bAVMs by single-stage planning of embolization combined with microsurgical resection when necessary.

METHODS

All patients harboring Spetzler-Martin (S-M) grade III-V bAVMs treated with single-stage planning between January 2006 and January 2018 were retrospectively reviewed. This treatment paradigm is applicable only to surgically accessible bAVMs and does not include deep-seated bAVMs. Indications for treatment, clinical presentation, imaging characteristics, and treatment outcomes were analyzed. Outcomes were assessed based on modified Rankin Scale.

RESULTS

A total of 31 patients were identified. Seventeen patients (54.8%) presented with hemorrhage, 10 (32.3%) with seizures, 3 (9.7%) with headaches, and 1 (3.2%) with progressive neurological deficit. Based on S-M grading system, 25 patients (80.6%) harbored grade III bAVM, 5 patients had grade IV bAVMs (16.1%), and 1 patient (3.2%) had a grade V bAVM. There were no treatment-related complications in 24/31 (77.4%) patients. Of the total of seven patients with complications, four patients had clinical deterioration. The long-term (> 6-month), non-disabling morbidity (mRS ≤ 2) rate was 6.5%. The long-term, disabling morbidity rate was 3.2% with a mortality of 3.2%. Complete angiographic obliteration was achieved in 30/31 (96.8%) patients.

CONCLUSION

Single-stage treatment strategy can be considered as an alternative to multistage embolization prior to surgery in grade III-V bAVMs. In this study, a high rate of total obliteration with relatively low rates of permanent morbidity and mortality was achieved.

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.

Imaging artifacts of Onyx and PHIL on conventional CT, cone-beam CT and MRI in an animal model

BACKGROUND AND PURPOSE

A frequently reported drawback of ethylene vinyl alcohol copolymer-based liquid embolic agents is the production of artifacts in diagnostic imaging. New embolic agents, such as Precipitating hydrophobic injectable liquid (PHIL; MicroVention, Tustin, CA, USA), are supposed to induce significantly fewer artifacts. The purpose of this study is to assess the degree of artifacts induced by the liquid embolic agents Onyx (Medtronic Neurovascular, Irvine, CA, USA) and PHIL in conventional computed tomography (CT), cone-beam CT and magnetic resonance imaging (MRI) in an experimental in vivo model.

MATERIALS AND METHODS

In 10 pigs the rete mirabile was embolized with Onyx ( n = 5) or PHIL ( n = 5). After embolization, conventional CT, cone-beam CT and MRI were performed. The degree of artifacts was graded qualitatively (five-point scale; for CT and MRI) and quantitatively (HUs of well-defined regions of interest (ROIs); for CT only).

RESULTS

Artifacts were significantly more severe for Onyx both in the qualitative (e.g. conventional CT: 2 versus 5 (medians); p = 0.008) and in the quantitative image analysis (e.g. cone-beam CT: standard deviation of a ROI near to the embolic agent cast, 94 HU versus 38 HU (medians); p = 0.008). Neither Onyx nor PHIL produced any apparent artifacts in MRI.

CONCLUSION

PHIL produces fewer artifacts than Onyx in conventional CT and cone-beam CT in an experimental in vivo model.

Cerebral arteriovenous malformations in the era of embolization for angiographic cure: a single-center experience in Egypt

Background

Embolization for cerebral arteriovenous malformations (AVMs) has evolved in the last decade with evolution in both equipment and material. Embolization targets have expanded to include angiographic cure.

Methods

To discuss the technical and management outcomes of our first cerebral AVM case series treated with embolization. The clinical, angiographic, treatment, and outcome variables of consecutive cerebral arteriovenous malformation cases, treated with curative embolization, between January 2011 and June 2017 in one regional center, were retrospectively analyzed.

Results

In 21 patients, 21 AVMs were identified, and 13 patients (61.9%) were males. The mean of the age was 34.24 ± 12.99. Fifteen patients (71.4%) had a history of intracranial hemorrhage, and 10 (47.6%) patients had seizures. Sixteen patients (76.2%) were at grade 1 of modified Rankin Scale (mRS) at admission. The median for modal Spetzler-Martin grade was 2. The average number of arterial feeders was 3. Direct arteriovenous fistulas were found in 4 cases (19.0%). Venous aneurysms were found in 4 cases (19.0%). Seventeen AVMs (80.9%) were considered high bleeding risk lesions. Forty-three embolization sessions were done. Early hemorrhage occurred in 3 sessions (7.0%). Vessel perforation occurred 1 session (2.3%). Poor outcome occurred in 1 patient that was discharged at grade 3 mRS. Angiographic cure was achieved in 9 patients (42.9%). The average size reduction was 65%.

Conclusions

Onyx embolization could serve as a curative option for AVM treatment with accepted morbidity and mortality.

Stereotactic radiosurgery alone or combined with embolization for brain arteriovenous malformations: a systematic review and meta-analysis

OBJECTIVE

Embolization of brain arteriovenous malformations (AVMs) prior to stereotactic radiosurgery (SRS) has been reported to negatively affect obliteration rates. The goal of this systematic review and meta-analysis was to compare the outcomes of AVMs treated with embolization plus SRS (E+SRS group) and those of AVMs treated with SRS alone (SRS group).

METHODS

A literature review was performed using PubMed to identify studies with 10 or more AVM patients and obliteration data for both E+SRS and SRS groups. A meta-analysis was performed to compare obliteration rates between the E+SRS and SRS groups.

RESULTS

Twelve articles comprising 1716 patients were eligible for analysis. Among the patients with radiological follow-up data, complete obliteration was achieved in 48.4% of patients (330/681) in the E+SRS group compared with 62.7% of patients (613/978) in the SRS group. A meta-analysis of the pooled data revealed that the obliteration rate was significantly lower in the E+SRS group (OR 0.51, 95% CI 0.41–0.64, p < 0.00001). Symptomatic adverse radiation effects were observed in 6.6% (27/412 patients) and 11.1% (48/433 patients) of the E+SRS and SRS groups, respectively. The annual post-SRS hemorrhage rate was 2.0%–6.5% and 0%–2.0% for the E+SRS and SRS groups, respectively. The rates of permanent morbidity were 0%–6.7% and 0%–13.5% for the E+SRS and SRS groups, respectively.

CONCLUSIONS

Arteriovenous malformation treatment with combined embolization and SRS is associated with lower obliteration rates than those with SRS treatment alone. However, this comparison does not fully account for differences in the initial AVM characteristics in the E+SRS group as compared with those in the SRS group. Further studies are warranted to address these limitations.

Indications for the Performance of Intracranial Endovascular Neurointerventional Procedures: A Scientific Statement From the American Heart Association

Intracranial endovascular interventions provide effective and minimally invasive treatment of a broad spectrum of diseases. This area of expertise has continued to gain both wider application and greater depth as new and better techniques are developed and as landmark clinical studies are performed to guide their use. Some of the greatest advances since the last American Heart Association scientific statement on this topic have been made in the treatment of ischemic stroke from large intracranial vessel occlusion, with more effective devices and large randomized clinical trials showing striking therapeutic benefit. The treatment of cerebral aneurysms has also seen substantial evolution, increasing the number of aneurysms that can be treated successfully with minimally invasive therapy. Endovascular therapies for such other diseases as arteriovenous malformations, dural arteriovenous fistulas, idiopathic intracranial hypertension, venous thrombosis, and neoplasms continue to improve. The purpose of the present document is to review current information on the efficacy and safety of procedures used for intracranial endovascular interventional treatment of cerebrovascular diseases and to summarize key aspects of best practice.

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.

Thermo-sensitive composite hydrogels based on poloxamer 407 and alginate and their therapeutic effect in embolization in rabbit VX2 liver tumors

Interventional embolization therapy is an effective, most widely used method for inoperable liver tumors. Blood-vessel-embolic agents were essential in transarterial embolization (TAE). In this work, thermo-sensitive composite hydrogels based on poloxamer 407, sodium alginate, hydroxymethyl cellulose and iodixanol (PSHI), together with Ca2+ (PSHI-Ca2+) were prepared as liquid embolic agents for TAE therapy to liver cancer. With increasing temperature, PSHI exhibited two phase states: a flowing sol and a shrunken gel. Rheology tests showed good fluidity and excellent viscoelastic behavior with a gelation temperature (GT) of 26.5°C. The studies of erosion indicated that PSHI had calcium ion-related erosion characteristics and showed a slow erosion rate in an aqueous environment. When incubated with L929 cells, the thermo-sensitive composite hydrogels had low cytotoxicity in vitro. The results of analyzing the digital subtraction angiography and computed tomography images obtained from in vitro and in vivo assays indicated a good embolic effect in the renal arteries of normal rabbits. Angiography and histological studies on VX2 tumor-bearing rabbits indicated that PSHI-Ca2+ successfully occluded the tumors, including the peripheral vessels. In conclusion, PSHI-Ca2+ was a promising embolic agent for transarterial embolization therapy.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

An injectable shear-thinning biomaterial for endovascular embolization

Improved endovascular embolization of vascular conditions can generate better patient outcomes and minimize the need for repeat procedures. However, many embolic materials, such as metallic coils or liquid embolic agents, are associated with limitations and complications such as breakthrough bleeding, coil migration, coil compaction, recanalization, adhesion of the catheter to the embolic agent, or toxicity. Here, we engineered a shear-thinning biomaterial (STB), a nanocomposite hydrogel containing gelatin and silicate nanoplatelets, to function as an embolic agent for endovascular embolization procedures. STBs are injectable through clinical catheters and needles and have hemostatic activity comparable to metallic coils, the current gold standard. In addition, STBs withstand physiological pressures without fragmentation or displacement in elastomeric channels in vitro and in explant vessels ex vivo. In vitro experiments also indicated that STB embolization did not rely on intrinsic thrombosis as coils did for occlusion, suggesting that the biomaterial may be suitable for use in patients on anticoagulation therapy or those with coagulopathy. Using computed tomography imaging, the biomaterial was shown to fully occlude murine and porcine vasculature in vivo and remain at the site of injection without fragmentation or nontarget embolization. Given the advantages of rapid delivery, in vivo stability, and independent occlusion that does not rely on intrinsic thrombosis, STBs offer an alternative gel-based embolic agent with translational potential for endovascular embolization.

Hemodynamics Associated With Intracerebral Arteriovenous Malformations: The Effects of Treatment Modalities

The understanding of the physiology of cerebral arteriovenous malformations (AVMs) continues to expand. Knowledge of the hemodynamics of blood flow associated with AVMs is also progressing as imaging and treatment modalities advance. The authors present a comprehensive literature review that reveals the physical hemodynamics of AVMs, and the effect that various treatment modalities have on AVM hemodynamics and the surrounding cortex and vasculature. The authors discuss feeding arteries, flow through the nidus, venous outflow, and the relative effects of radiosurgical monotherapy, endovascular embolization alone, and combined microsurgical treatments. The hemodynamics associated with intracranial AVMs is complex and likely changes over time with changes in the physical morphology and angioarchitecture of the lesions. Hemodynamic change may be even more of a factor as it pertains to the vast array of single and multimodal treatment options available. An understanding of AVM hemodynamics associated with differing treatment modalities can affect treatment strategies and should be considered for optimal clinical outcomes.

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.

Stereotactic radiosurgery for cerebellar arteriovenous malformations: an international multicenter study

OBJECTIVE

Cerebellar arteriovenous malformations (AVMs) represent the majority of infratentorial AVMs and frequently have a hemorrhagic presentation. In this multicenter study, the authors review outcomes of cerebellar AVMs after stereotactic radiosurgery (SRS).

METHODS

Eight medical centers contributed data from 162 patients with cerebellar AVMs managed with SRS. Of these patients, 65% presented with hemorrhage. The median maximal nidus diameter was 2 cm. Favorable outcome was defined as AVM obliteration and no posttreatment hemorrhage or permanent radiation-induced complications (RICs). Patients were followed clinically and radiographically, with a median follow-up of 60 months (range 7–325 months).

RESULTS

The overall actuarial rates of obliteration at 3, 5, 7, and 10 years were 38.3%, 74.2%, 81.4%, and 86.1%, respectively, after single-session SRS. Obliteration and a favorable outcome were more likely to be achieved in patients treated with a margin dose greater than 18 Gy (p < 0.001 for both), demonstrating significantly better rates (83.3% and 79%, respectively). The rate of latency preobliteration hemorrhage was 0.85%/year. Symptomatic post-SRS RICs developed in 4.5% of patients (n = 7). Predictors of a favorable outcome were a smaller nidus (p = 0.0001), no pre-SRS embolization (p = 0.003), no prior hemorrhage (p = 0.0001), a higher margin dose (p = 0.0001), and a higher maximal dose (p = 0.009). The Spetzler-Martin grade was not found to be predictive of outcome. The Virginia Radiosurgery AVM Scale score (p = 0.0001) and the Radiosurgery-Based AVM Scale score (p = 0.0001) were predictive of a favorable outcome.

CONCLUSIONS

SRS results in successful obliteration and a favorable outcome in the majority of patients with cerebellar AVMs. Most patients will require a nidus dose of higher than 18 Gy to achieve these goals. Radiosurgical and not microsurgical scales were predictive of clinical outcome after SRS.

Onyx embolization prior to stereotactic radiosurgery for brain arteriovenous malformations: a single-center treatment algorithm

BACKGROUND

Embolization before stereotactic radiosurgery (SRS) for brain arteriovenous malformations (BAVMs) is controversial.

OBJECTIVE

To compare clinical and radiographic outcomes in patients undergoing pre-SRS embolization with ethylene copolymer (Onyx) with outcomes in patients undergoing SRS alone.

METHODS

Seventy consecutive patients with BAVMs who underwent SRS were retrospectively reviewed. Univariate and multivariate analyses were performed to assess the factors associated with radiographic obliteration and complication.

RESULTS

Forty-one (59%) patients presented without BAVM rupture and 29 (41%) patients presented with rupture. Pre-SRS embolization was used in 20 patients (28.6%; 7 unruptured and 13 ruptured). Twenty-five of 70 (36%) patients sustained a complication from treatment, including 6 (9%) patients with a post-SRS latency period hemorrhage. Ten (14%) patients had persistent neurological deficits after treatment. Functional outcome (as modified Rankin Scale), complication rate, and radiographic obliteration at last follow-up were not significantly different between embolized and non-embolized groups in both unruptured and ruptured BAVMs. For unruptured BAVMs, 3- and 5-year rates of radiographic obliteration were 23% and 73% for non-embolized patients and 20% and 60% for embolized patients, respectively. For ruptured BAVMs, 3- and 5-year rates of radiographic obliteration were 45% and 72% for non-embolized patients and 53% and 82% for embolized patients, respectively.

CONCLUSION

Pre-SRS embolization with Onyx was not associated with worse clinical or radiographic outcomes than SRS treatment without embolization. Pre-SRS embolization has a low complication rate and can safely be used to target high-risk BAVM features in carefully selected patients destined for SRS.

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.

Preliminary experience with precipitating hydrophobic injectable liquid in brain arteriovenous malformations

Advancement in microcatheter design and emergence of new embolic agents offer better results in endovascular treatment of brain arteriovenous malformations (AVMs). Precipitating hydrophobic injectable liquid (PHIL) (Microvention) is a newly introduced dimethyl sulfoxide-based embolic agent for endovascular use. Herein, we present three patients who underwent endovascular treatment of brain AVMs with PHIL, followed by surgical resection. Endovascular features and same-day surgical handling of the new embolic agent PHIL are presented along with histopathologic changes in the acute stage in brain AVMs are presented, and its major differences from Onyx. In our series, PHIL had moderate inflammatory reaction in the acute stage without any associated angionecrosis that is different than Onyx which cause mild inflammatory reaction with angionecrosis. Smallest vessel containing PHIL was 2.9 μm compared to 5 μm with Onyx, which suggests better penetration.

Transarterial Onyx Embolization for Patients with Cavernous Sinus Dural Arteriovenous Fistulas Who Have Failed Transvenous Embolization

Transvenous embolization is the treatment of choice for cavernous sinus dural arteriovenous fistulas (csDAVFs) despite occasional difficulty in transvenous catheterization. We reported our experience in the treatment of csDAVFs by transarterial Onyx embolization in patients who had failed transvenous catheterization. We reviewed the clinical and radiographic records of csDAVFs patients receiving transarterial Onyx embolization after failed transvenous Onyx embolization at our institution over a period of 31 months. Success was defined as complete or near complete occlusion upon angiographic examination. In seven cases, the microcatheter failed to reach the cavernous sinus; in the remaining case, the internal jugular vein was occlusive. Eight sessions of the embolization and catheterization procedures via the arterial routes were conducted. Among them, five cases via the middle meningeal artery and the other three via the accessory meningeal artery. Angiography, immediately after embolization, revealed complete occlusion in seven cases (87.5 %) and partial occlusion in the remaining case. Angiographic follow-up (range, 6-10 months) showed that all patients achieved complete embolization. In cases where transvenous embolization of the cavernous sinus is difficult, transarterial embolization of the fistulas offers a safe and effective alternative.

Staged-Volume Radiosurgery of Large Arteriovenous Malformations Improves Outcome by Reducing the Rate of Adverse Radiation Effects

BACKGROUND: The treatment of large arteriovenous malformations (AVMs) remains challenging. Recently, staged-volume radiosurgery (SVRS) has become an option.

OBJECTIVE: To compare the outcome of SVRS on large AVMs with our historical, single-stage radiosurgery (SSRS) series.

METHODS: We have been prospectively collecting data of patients treated by SVRS since 2007. There were 84 patients who had a median age of 37 years (range, 9-62 years) who were treated until July 2013. The outcomes of 76 of those who had follow-ups available were analyzed and compared with the outcomes of 122 patients treated with the best SSRS technique.

RESULTS: There were 21.5% of AVMs that were deep seated, and 44% presented with hemorrhage resulting in 45% fixed neurological deficit. There were 14% of patients who had undergone embolization before radiosurgery. The median nidus treatment volume was 19.7 cm3 (6.65-68.7) and 17.5 Gy (13-22.5) prescription isodose was given. Of the 44 lesions having radiological follow-up at 4 years, 61.4% were completely obliterated. Previous embolization (50% with and 63% without) and higher Spetzler-Martin grades appeared to be the negative factors in successful obliteration, but treatment volume was not. Within 3 years after radiosurgery, the annual bleed rates of unruptured and previously ruptured AVMs were 3.2% and 5.6%, respectively. Three bleeds were fatal and 2 resulted in significant modified Rankin scale 3 morbidity. These rates differ little from SSRS. Temporary adverse radiation effects (AREs) did not change significantly, but permanent AREs dropped from 15% to 6.5% (P = .03) compared with SSRS.

CONCLUSION: Obliteration and hemorrhage rates of large AVMs treated by SVRS are similar to historical SSRS. However, SVRS offers a lower rate of AREs.