Nonadhesive liquid embolic agent for cerebral arteriovenous malformations: preliminary histopathological studies in swine rete mirabile

Preoperative Direct Puncture Embolization Using a Nonadhesive Ethylene Vinyl Alcohol (EVOH) Liquid Embolic Agent for Head and Neck Paragangliomas

PURPOSE

This retrospective study aimed to assess the safety and technical efficacy of preoperative direct puncture embolization using a nonadhesive ethylene vinyl alcohol (EVOH) copolymer-based liquid embolic agent (LEA) combined with balloon occlusion at the origin of the external carotid artery for head and neck paragangliomas (HNP).

METHODS

We conducted a review of all consecutive cases of HNPs treated with direct puncture embolization using EVOH-based LEAs between 2017 and 2022 in 2 tertiary high-volume hospitals.

RESULTS

A total of 25 cases of HNPs in 24 patients underwent direct puncture embolization (12 males, 12 females, mean age 50.9 ± 15.6 years). The average lesion volume was 299.95 mm3. The mean procedure time was 139.11 min, and the mean volume of EVOHs used per case was 19.38 mL. Successful complete devascularization was achieved in all cases, with a homogeneous and deep penetration of the embolic agent into the tumor vessel bed regardless of the LEA type.

CONCLUSION

Preoperative embolization of HNPs using a direct puncture technique and EVOHs is a safe, efficient, and feasible treatment option with a low risk of complications. This procedure facilitates surgery by transforming tumors into avascular masses that are well-delineated against the surrounding normal tissue.

Brain Arteriovenous Malformation In Vitro Model for Transvenous Embolization Using 3D Printing and Real Patient Data

BACKGROUND AND PURPOSE

Transvenous embolization has emerged as a novel technique for treating selected brain AVMs with high reported occlusion rates. However, it requires anatomic and technical skills to be successful and to ensure patient safety. Therefore, training and testing are essential for preparing clinicians to perform these procedures. Our aim was to develop and test a novel, patient-specific brain AVM in vitro model for transvenous embolization by using 3D printing technology.

MATERIALS AND METHODS

We developed a brain AVM in vitro model based on real patient data by using stereolithography resin 3D printing. We created a closed pulsed circuit with flow passing from the arterial side to the venous side, and we tested the effect of mean arterial pressure on retrograde nidal filling with contrast injections. Transvenous embolization simulations were conducted for each of the 12 identical models divided into 2 groups (2×6). This involved the use of an ethylene-vinyl alcohol liquid embolic agent injected through microcatheters either without or with a coil in the vein (groups 1 and 2, respectively).

RESULTS

Retrograde contrast advance to nidus was directly related to lower mean arterial pressure. Transvenous embolization tests with a liquid embolic agent adequately reproduced the usual embolization plug and push technique. We found no differences between the 2 group conditions, and additional venous coil neither increased nidus penetration nor reduced injection time in the model (57.6 versus 61.2% nidus occlusion rate, respectively).

CONCLUSIONS

We were able to develop and test a functional in vitro brain AVM model for transvenous embolization by using 3D printing to emulate its conditions and characteristics. Better contrast penetration was achieved with less mean arterial pressure, and no embolization advantage was found by adding coil to the vein in this model.

Large, Wide-Neck, Side-Wall Aneurysm Treatment in Canines Using NeuroCURE: A Novel Liquid Embolic

BACKGROUND

Untreated intracranial aneurysms can rupture and result in high rates of morbidity and mortality. Although there are numerous approved endovascular aneurysm treatment devices, most require dual anti-platelet therapy, are minimally biocompatible, or are prone to recanalization. Neurovascular Controlled Uniform Rapid Embolic (NeuroCURE) is an innovative polymer gel material with long-term stability, biocompatibility, and hemocompatibility developed for the treatment of large, wide-neck aneurysms.

METHODS

Sidewall aneurysms were surgically created in 10 canines and NeuroCURE was injected through a 0.025 microcatheter under a single balloon inflation period. Aneurysm treatment was angiographically assessed post-embolization and pre-term with Raymond-Roy occlusion classification and a qualitative flow grade scale. Aneurysm neck stability and biocompatibility was histologically assessed to grade platelet/fibrin thrombus, percent endothelialization, and neointimal formation. Aneurysm sac stability was assessed by NeuroCURE sac content, inflammation, and neo-angiogenesis scales.

RESULTS

Explanted aneurysms exhibited a smooth surface at the aneurysm neck with nearly complete neointimal coverage at 3-months. By 6-months, neck endothelialization was 100% in all animals (average Raymond-Roy occlusion classification of 1.2), with no instances of aneurysm recanalization or parent vessel flow compromise. Biocompatibility assessments verified a lack of inflammatory response, neo-angiogenesis, and platelet/fibrin thrombus formation.

CONCLUSION

The NeuroCURE material promotes progressive occlusion of wide-necked side wall aneurysms over time without the need for dual antiplatelet agents. NeuroCURE also promotes neointimal tissue infill without dependence on thrombus formation and thus resists aneurysm recanalization. NeuroCURE remains a compelling investigational device for the treatment of intracranial aneurysms.

Material characterization of GPX®: A versatile in situ solidifying embolic platform technology

Endovascular embolization is a minimally invasive procedure during which blood flow to targeted tissues is selectively occluded. The list of clinical indications for embolization continues to expand. Liquid embolic agents are injectable compositions that transition into a solid or semi-solid form when introduced into blood vessels. The mechanism that triggers the liquid-to-solid transition is a key distinguishing feature of liquid embolic agents. GPX is a waterborne liquid embolic agent comprising oppositely charged polyelectrolytes: polyguanidinum and inorganic polyphoshate. In situ solidification is driven by electrostatic condensation of the polyelectrolytes, triggered by ionic strength differentials. We report in vitro characterization of the material properties of GPX, it is in vivo effectiveness in acute animal studies, and its potential for chemoembolization. The viscosity of GPX can be varied over a wide range by adjusting the polyguanidinium MW and/or concentration. Formulation of GPX with either tantalum microparticles (30 wt%) or iodinated radiocontrast agents (300 mgI ml^-1) did not significantly change the flow behavior of GPX; the viscosity was independent of shear rate and remained within a clinically practical range (80-160 cP). Formulation of GPX with doxorubicin substantially increased viscosity at low shear rates and resulted in a power law dependence on shear rate. High contrast and effective vascular occlusion were demonstrated in both swine kidneys and rete mirabile. Contrast from iodinated compounds was temporary, dissipating within hours. The doxorubicin in vitro release profile was linear over 90 days. The results demonstrate that GPX is a versatile liquid embolic platform that can be formulated with a wide range of viscosities injectable at clinically practical flow rates, with either transient or permanent contrast, and that can provide prolonged zero-order delivery of doxorubicin to embolized tissues.

Acute and chronic changes in porcine rete mirabile after embolization with the Menox system: angiographic and histopathological analyses

Objective

To evaluate acute and chronic changes seen on angiographic and histopathological studies of porcine rete mirabile, comparing those treated with the Menox liquid embolic system (LES) and those treated with the Onyx LES.

Materials and Methods

Five pigs, each weighing approximately 35 kg, were submitted to rete mirabile embolization under general anesthesia and fluoroscopic guidance, with the Menox LES or Onyx LES. Four animals were treated with the Menox LES and underwent cerebral angiography, followed by euthanasia, at 1, 30, 60, and 90 days after embolization. One animal was treated with the Onyx LES underwent the same procedures at 30 days after embolization. In a subsequent histopathological analysis, we compared the Menox LES and Onyx LES in terms of the acute and chronic changes observed.

Results

We observed no significant changes in blood pressure, heart rate, or electrocardiographic parameters that could be attributed to the super-selective infusion of dimethyl sulfoxide or the Menox embolic agent. Fluoroscopy showed adequate material opacity, appropriate progression to the center of the rete mirabile and complete unilateral embolization. Microcatheters were uneventfully detached from the embolized nidus. We observed mild to moderate intravascular and extravascular inflammatory responses, without histological evidence of necrotizing arteritis. There were no adverse neurovascular events.

Conclusion

The Menox LES appears to be safe and effective, as well as being apparently equivalent to the Onyx LES in terms of the postprocedure angiographic and histopathological findings.

In situ crosslinking temperature-responsive hydrogels with improved delivery, swelling, and elasticity for endovascular embolization

Endovascular embolization of cerebral aneurysms is a common approach for reducing the risk of often-fatal hemorrhage. However, currently available materials used to occlude these aneurysms provide incomplete filling (coils) or require a complicated, time-consuming delivery procedure (solvent-exchange precipitating polymers). The objective of this work was to develop an easily deliverable in situ forming hydrogel that can occlude the entire volume of an aneurysm. The hydrogel is formed by mixing a solution of a temperature-responsive polymer containing pendent thiol groups (poly(NIPAAm-co-cysteamine) or poly(NIPAAm-co-cysteamine-co-JAAm)) with a solution of poly(ethylene glycol) diacrylate (PEGDA). Incorporation of hydrophilic grafts of polyetheramine acrylamide (JAAm) in the temperature-responsive polymer caused weaker physical crosslinking, facilitated faster and more complete chemical crosslinking, and increased gel swelling. One formulation (30 wt % PNCJ20 + PEGDA) could be delivered for over 220 s after mixing, formed a strong and elastic hydrogel (G' > 6000 Pa) within 30 min and once set, maintained its shape and volume in a model aneurysm under flow. This gel represents a promising candidate water-based material utilizing both physical and chemical crosslinking that warrants further investigation as an embolic agent for saccular aneurysms.

Non-Adhesive Liquid Embolic Agents in Extra-Cranial District: State of the Art and Review of the Literature

This review focuses on the use of “new” generation of non-adhesive liquid embolic agents (NALEA). In literature, non-adhesive liquid embolic agents have mainly been used in the cerebral district; however, multiple papers describing the use of NALEA in the extracranial district have been published recently and the aim of this review is to explore and analyze this field of application. There are a few NALEA liquids such as Onyx, Squid, and Phil currently available in the market, and they are used in the following applications: mainly arteriovenous malformations, endoleaks, visceral aneurysm or pseudoaneurysm, presurgical and hypervascular lesions embolization, and a niche of percutaneous approaches. These types of embolizing fluids can be used alone or in combination with other embolizing agents (such as coils or particles) so as to enhance its embolizing effect or improve its possible defects. The primary purpose of this paper is to evaluate the use of NALEAs, predominantly used alone, in elective embolization procedures. We did not attempt a meta-analysis due to the data heterogeneity, high number of case reports, and the lack of a consistent follow-up time period.

In Vivo Experimental Endovascular Uses of Cyanoacrylate in Non-Modified Arteries: A Systematic Review

Cyanoacrylates were first used for medical purposes during World War II to close skin wounds. Over time, medical applications were developed, specifically in the vascular field. Uses now range from extravascular instillation in vascular grafting to intravascular injection for embolization. These applications were made possible by the conduct of numerous preclinical studies involving a variety of tests and outcome measures, including angiographic and histological criteria. Cyanoacrylates were first harshly criticized by vascular surgeons, chiefly due to their fast and irreversible polymerization. Over the past five years, however, cyanoacrylates have earned an established place in endovascular interventional radiology. Given the irreversible effects of cyanoacrylates, studies in animal models are ethically acceptable only if supported by reliable preliminary data. Many animal studies of cyanoacrylates involved the experimental creation of aneurysms or arteriovenous fistulas, whose treatment by endovascular embolization was then assessed. In clinical practice, however, injection into non-modified arteries may be desirable, for instance, to deprive a tumor of its vascular supply. To help investigators in this field select the animal models and procedures that are most appropriate for their objectives, we have reviewed all published in vivo animal studies that involved the injection of cyanoacrylates into non-modified arteries to discuss their main characteristics and endpoints.

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.

A Damp-and-Push Technique for the Copolymer (Onyx) Embolization of Dural Arteriovenous Fistula

BACKGROUND

Copolymer (Onyx) embolization is an effective treatment for dural arteriovenous fistula (dAVF), however, some dAVFs have multiple, high-flow feeding vessels, resulting in insufficient embolization. For the treatment of such patients, we have developed a novel flow-control technique, the 'damp-and-push technique'. The purpose of this study was to evaluate the technical efficiency and safety of this technique.

METHODS

Seven patients who had been diagnosed with intracranial dAVF were treated by transarterial Onyx embolization using the damp-and-push technique between 2016 and 2019. This technique was designed to reduce blood flow to the shunt site using a balloon catheter in the major feeding vessel other than the one injected with Onyx, leading to better Onyx penetration and enabling more controlled embolization of complex dAVFs. Retrospectively collected data were reviewed to assess the occlusion rates and clinical outcomes.

RESULTS

The dAVF was at a transverse sinus-sigmoid sinus junction in four patients, in the superior sagittal sinus in two, and in the tentorium in one. Five cases were Cognard type Ⅱb and two cases were Cognard type Ⅳ. All the patients were treated by transarterial Onyx injection via the main feeding vessel, combined with flow reduction in the other main feeding vessel using a balloon catheter. Complete occlusion was achieved in six patients and elimination of cerebral venous reflux was achieved in all the patients. There were no immediate or delayed post-interventional complications.

CONCLUSIONS

Transarterial Onyx embolization of dAVF using the damp-and-push technique is safe and yields a high complete occlusion rate.

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.

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.

Single institutional experience of peripheral applications of a liquid embolic agent: Ethylene Vinyl Alcohol Copolymer

OBJECTIVE

To evaluate the safety and efficacy of ethylene vinyl alcohol (EVOH) copolymer for the treatment of a variety of peripheral vascular pathologies.

RESULTS

Between October 2010 and October 2017, 43 patients who underwent total 54 EVOH embolization procedures for the treatment of peripheral vascular pathologies were included. The cases which involved the use of EVOH for the treatment of nonvascular, neurologic, ophthalmologic, otolaryngologic or head-neck pathologies were excluded. The demographic data, technical and clinical success rates, and procedure-related details and complications were obtained. The most common indications for EVOH embolization were type II endoleaks (n = 18) and peripheral arteriovenous malformations (n = 14). The majority of cases (62.5%) used EVOH without any adjunct embolic material. The results of this study showed 100% technical success rates and 89% clinical success rates. No events of nontarget embolization or other procedure-related complications were noted. The mortality & morbidity rates were 0%. The loss to follow up rate was 16% (9 /54). The mean follow-up period was 134 days (range, 30 to 522 days).

CONCLUSION

The single institutional experience supports the safety and efficacy of EVOH embolization in the treatment of various peripheral vascular conditions.

Percutaneous embolization using a combination of liquid embolic agents for the treatment of a large disfiguring venous malformation

A 25-year-old man with a venous malformation (VM) along the anterior and posterolateral aspects of the right chest wall presented with progressive enlargement of VM, chest wall pain, and physical disfigurement. Because of the complexity and size of the VM, a staged multidisciplinary team approach (ie, percutaneous embolization) followed by surgical resection and tissue-skin grafting was used. The percutaneous embolization was achieved with a combination of liquid embolic agents including n-butyl cyanoacrylate for the superficial cutaneous component and ethylene vinyl alcohol copolymer for the deeper subcutaneous component of the VM. Such a combination can achieve safe occlusion of the VM, facilitate surgical resection without blood loss, and contribute to a cosmetically desirable result.

A Case of Anterior Cranial Fossa Dural Arteriovenous Fistula with Transient Ocular Movement Disorder after Embolization

Objective

We report a case of anterior cranial fossa dural arteriovenous fistula (dAVF) in which ocular movement was impaired after Onyx embolization from the ophthalmic artery (OphA).

Case Presentation

A 76-year-old male was admitted to our hospital for treatment of an incidentally found anterior cranial fossa dAVF. Onyx was injected from the right anterior ethmoidal artery (AEA) to close the shunt. Onyx refluxed to the third portion of the OphA to make a plug, but was unable to reach the venous side beyond the shunt; therefore, a small shunt remained. Although his visual acuity and field were normal, vertical diplopia developed after embolization and disappeared 1 month later. Diplopia worsened when the patient tilted his head to the right. Neuro-ophthalmological examination confirmed right superior oblique muscle impairment. The cause of diplopia was considered to be ischemic injury of the superior oblique muscle associated with embolization of the AEA, which provides nutrients to the superior oblique muscle and trochlear nerve.

Conclusion

Embolization from the OphA beyond the third portion may cause external ophthalmoplegia, although it may heal spontaneously.

Resection of a posterior fossa arteriovenous malformation complicated by leaked Onyx: a case report and review of literature

Extravasation of Onyx is a rare complication during embolization of arteriovenous malformations (AVM). We present a case of embolization that was complicated by leakage of Onyx into the cerebellum which was later encountered during surgical excision of the AVM. Our goal is to report this rare event and to outline successful treatment of this complication. The patient's records were reviewed for medical history, laboratory and radiologic workup, and outpatient clinical follow-up. A 62-year-old female presented with Hunt Hess grade 2 and modified Fisher grade 2 subarachnoid hemorrhage (SAH) secondary to ruptured left posterior inferior cerebellar artery (PICA) aneurysm associated with a superior cerebellar vermian AVM. Following endovascular intervention, the aneurysm was completely embolized; however, only 75% of the AVM could be safely obliterated. Extravasation of Onyx from the ruptured aneurysm was noted on her initial angiogram. Elective suboccipital craniectomy was subsequently planned for resection of the residual AVM where the extravasated Onyx posed an operative nuisance during resection. Post-op angiogram confirmed complete resection of the AVM, as well as the bulk of the extravasated Onyx. Patient did well post-operatively, remaining neurologically intact throughout her hospital course. Although infrequently reported in the literature, Onyx extravasation is a potential complication that neurosurgeons should be ready to face. Adherence of Onyx to surrounding parenchyma could hinder optimal surgical resection of AVM and increase complications. Therefore, careful surgical dissection should be performed with special care to delicate neurovasculature. In this case, complete resection of the AVM and Onyx mass was safely achieved.

Feasibility and Effectiveness of Direct Puncture and Onyx Embolization for Transverse Sinus Dural Arteriovenous Fistula

Direct puncture and embolization of the transverse sinus (TS) for treatment of dural arteriovenous fistula (DAVF) is typically performed with coils with or without glue. We report a case of DAVF at the left TS that was treated with Onyx embolization via direct puncture of the TS. A 75-year-old woman presented with tremor, festinating gait, and dysarthria. A left TS-DAVF with retrograde superior sagittal sinus and cortical venous reflux (Cognard type IIa+b) was identified on cerebral angiography, and both TSs were occluded with thrombi. We considered that achieving complete cure by transvenous embolization via the femoral vein or transarterial embolization via occipital feeders would be difficult. Thus, we performed a small craniotomy at the occipital bone to puncture the TS. The midportion of the TS was directly punctured with a 21-G microneedle under fluoroscopic guidance. We inserted a 5-F sheath into the TS. A microcatheter was then navigated into the affected sinus. Coils were placed through the microcatheter to support Onyx formation by reducing the pressure of shunting flow. Onyx embolization was performed with the same microcatheter. The DAVF was almost completely occluded except for the presence of minimal shunting flow to the proximal TS. After 1 week, time-of-flight magnetic resonance angiography showed complete resolution of DAVF. The patient showed resolved tremor and markedly improved mental status at 1-month follow up. Direct puncture and embolization of the TS using coils and Onyx is effective and feasible method for the treatment of DAVF when other approaches seem difficult.

Initial experience with the new ethylene vinyl alcohol copolymer based liquid embolic agent Menox in the endovascular treatment of cerebral arteriovenous malformations

Background and Purpose

Liquid embolic agents (LEAs) are the determinant tool for successful embolization of cranial arteriovenous shunts. There are few currently available LEAs. The aim of the study was to summarize our initial experience with a recently introduced non-adhesive ethylene vinyl alcohol (EVOH) copolymer based LEA (Menox 18) in the endovascular treatment of cerebral arteriovenous malformations.

Methods

From April 2018 to November 2018, 24 patients harboring cerebral arteriovenous malformations underwent endovascular embolization with Menox 18. Clinical features, angiographic results, procedural details, complications, and follow-up details were prospectively collected and retrospectively analyzed.

Results

Curative embolization in one endovascular session was achieved in 14/24 (58.3%) of the treated patients. Partial embolization was achieved in 10 patients (42.6%) in whom staged treatment with radiosurgery or microsurgical resection was planned. No mortality was recorded in our series. Clinical complications after embolization occurred in 1/24 (4.66%) patients. No technical complications were noted

Conclusions

Our pilot study suggests that the Menox embolization system offers similar technical and clinical results in comparison with the other currently available LEAs. Further studies with larger cohorts and long term follow-up data are needed to fully evaluate its efficacy

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.

MR Coagulation: A Novel Minimally Invasive Approach to Aneurysm Repair

PURPOSE

To demonstrate a proof of concept of magnetic resonance (MR) coagulation, in which MR imaging scanner-induced radiofrequency (RF) heating at the end of an intracatheter long wire heats and coagulates a protein solution to effect a vascular repair by embolization.

MATERIALS AND METHODS

MR coagulation was simulated by finite-element modeling of electromagnetic fields and specific absorption rate (SAR) in a phantom. A glass phantom consisting of a spherical cavity joined to the side of a tube was incorporated into a flow system to simulate an aneurysm and flowing blood with velocities of 0-1.7 mL/s. A double-lumen catheter containing the wire and fiberoptic temperature sensor in 1 lumen was passed through the flow system into the aneurysm, and 9 cm³ of protein solution was injected into the aneurysm through the second lumen. The distal end of the wire was laid on the patient table as an antenna to couple RF from the body coil or was connected to a separate tuned RF pickup coil. A high RF duty-cycle turbo spin-echo pulse sequence excited the wire such that RF energy deposited at the tip of the wire coagulated the protein solution, embolizing the aneurysm.

RESULTS

The protein coagulation temperature of 60°C was reached in the aneurysm in ∼12 seconds, yielding a coagulated mass that largely filled the aneurysm. The heating rate was controlled by adjusting pulse-sequence parameters.

CONCLUSIONS

MR coagulation has the potential to embolize vascular defects by coagulating a protein solution delivered by catheter using MR imaging scanner-induced RF heating of an intracatheter wire.

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.

In Vitro Quantification of the Radiopacity of Onyx during Embolization

Purpose

Onyx has been successfully applied in the treatment of various neurovascular lesions. However, some experience is required to get accustomed to its unpredictable fluoroscopic visibility during injection. This in vitro study aimed to evaluate the characteristics of radiopacity change in a simulated embolization procedure.

Materials and Methods

Using a bench-top Onyx injection experiment simulating a typical brain arteriovenous malformation embolization, nine cycles of casting modes (continuous injection) and plugging modes (injection with intermittent pauses) were performed. Radiodensity of Onyx droplets collected from the microcatheter tip and the distal head portion of the microcatheter were measured as time lapsed. Distribution of droplet radiodensity (radiodensity) and distribution of radiographic grade (grade) were analyzed and compared by repeated measurements.

Results

Within-group analysis revealed no significant radiodensity change with time (P>0.05). The radiodensity was significantly higher in the casting mode than in the plugging mode (P<0.01). The lateral radiograph of the microcatheter showed higher radiopacity (P<0.01) and better evenness (P<0.01) in the casting mode than in the plugging mode. A significant difference in microcatheter attenuation (both radiographic grade mean and SD; P<0.01) was noted between the two modes. Radiodensity had a significant influence on the radiopacity and radiopacity evenness of the microcatheter.

Conclusion

The radiopacity of the Onyx can vary significantly over time because of early precipitation of tantalum powder. Radiopacity decreased significantly during plugging modes, characterized by pauses between injections.

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.

Onyx extravasation during embolization of a brain arteriovenous malformation

During Onyx embolization to treat brain arteriovenous malformation (AVM), carefully observing the penetration of Onyx to the nidus is important in order to avoid complications such as hemorrhage, ischemia, and difficulty with microcatheter removal. We encountered a case of Onyx extravasation during embolization of a cerebellar AVM confirmed by surgical resection and pathological analysis. The patient was a 44-year-old man with Spetzler-Martin grade I cerebellar AVM who underwent Onyx embolization prior to resection of the brain AVM. While injecting Onyx into the nidus using the "plug-and-push" technique, Onyx extravasation was observed. Onyx injection was paused and subsequently restarted, thereby allowing continuation of embolization. An oblate Onyx cast that was entirely covered in cerebellar tissue was removed during total resection of the AVM, performed the same day. The surgically removed oblate Onyx cast did not contain brain tissue or vessel wall, and immunohistochemical staining against glial fibrillary acidic protein (GFAP) showed Onyx penetration into GFAP-positive cerebellar tissue. Onyx extravasation was confirmed based on intraoperative findings during resection as well as pathological findings. The patient has been followed for four years postoperatively, and adverse events caused by Onyx extravasation have not been observed. Unexpected cast of Onyx, remote from the vascular architecture of the AVM, may represent an intra-parenchymal extravasation.

Transarterial venous sinus occlusion of dural arteriovenous fistulas using ONYX

PURPOSE

The purpose of this article is to present a case series of transarterial venous sinus occlusion for dural arteriovenous fistulas (DAVFs) of the transverse and sigmoid sinuses.

MATERIALS AND METHODS

From 2006 to 2012, 11 patients with DAVF of the transverse and sigmoid sinuses were treated with transarterial closure of the affected venous sinus using ethylene vinyl alcohol copolymer (ONYX). The consecutive retrospective cohort included six female and five male patients with an age range of 30-79. Patients presented with stroke, intracranial hemorrhage, seizure, headache, focal neurologic deficit or cognitive change. Lesions were categorized as Cognard II a + b (n = 5) or Cognard II b (n = 6). Four of this latter group consisted of isolated sinus segments. Selection criteria for dural sinus occlusion included direct multi-hole fistulas involving a broad surface in length or circumference of the sinus wall. External carotid artery (ECA) branches were directly embolized when considered safe. High-risk arterial supply from ICA, PICA, AICA or ECA cranial nerve branches were closed via retrograde approach during sinus occlusion.

RESULTS

DAVF closure was accomplished in all 11 patients with a total of 17 embolization procedures using ONYX. High-risk arterial collaterals were closed via artery-artery or artery-sinus-artery embolization. The vein of Labbe was spared in the four cases with initial antegrade flow. No neurologic complications occurred, and DAVF closures were durable on three-month angiography.

CONCLUSION

Transarterial closure of the transverse and sigmoid sinuses.

Innovation in Neurosurgery: Intellectual Property Strategy and Academia/Industrial Collaboration

Neurosurgery has tremendous possibilities for development of innovative medical devices. However, most of the neurosurgical devices used in Japan are imported products. Promotion and development of domestic medical devices is highly encouraged and it is one of the pillars of Prime Minister Shinzo Abe's growth strategy of Japanese economy. Innovative "Made in Japan" medical devices can be developed by interdisciplinary collaboration between industries and academic institutions. Proper orientation of medical and engineering education, social and administrative awareness of the need of facilitating the medical devices creative process with corresponding regulatory changes, and appropriate medical and technological infrastructure establishment are needed for stimulating medical device innovation.

Onyx removal after embolization of a superior sagittal sinus dural arteriovenous fistula involving scalp artery

BACKGROUND

Most dural arteriovenous fistula (DAVF) in superior sagittal sinus (SSS) requires multimodal treatment. Onyx embolization is useful for DAVF; however, scalp artery embolization has cast extrusion risk.

CASE DESCRIPTION

A 59-year-old male presented with involuntary movements of both legs and progressive dementia. Cerebral angiography demonstrated the DAVF in the SSS fed by bilateral superficial temporal, occipital, and middle meningeal arteries. The posterior SSS was thrombosed, and the main drainers were cortical veins. Combined treatment with transarterial embolization using Onyx and transvenous embolization using coils was performed. Although symptoms were improved, a small DAVF remained. Two months later, Onyx cast extrusion through the scalp was observed, requiring removal and debridement because of infection at the extrusion sites. Surgery for the residual DAVF would be difficult because of scalp condition; therefore, an additional endovascular treatment was conducted, completely occluding DAVF.

CONCLUSION

Onyx embolization is useful for DAVF; however, scalp artery embolization has cast extrusion risk. Therefore, scalp infection should be considered because it may preclude additional surgical procedures.

Developing an in situ forming polyphosphate coacervate as a new liquid embolic agent: From experimental design to pilot animal study

A radiopaque temporary liquid embolic agent was synthesized from polyphosphate (PP) coacervates and optimized using a design of experiments approach. Variables studied were: strontium substitution (0-15 mol%), barium substitution (0-15 mol%), PP concentration and degree of polymerization of the polyphosphate (Dp). The viscosity, radiopacity and cell viability of the resulting coacervates were measured for 60 formulations and response surface modeling was used to determine the optimum coacervate that maximized radiopacity and cell viability. The optimum coacervate made from PP with a large Dp (9.5 g NaPP/100mL, 2.2 mol% Sr, 9 mol% Ba and 3.8 mol% Ca) was taken forward to a pilot animal trial. In this rabbit model, PP embolic agent successfully occluded the central auricular artery with promising biocompatibility. Further study is required to optimize the cohesiveness and clinical effectiveness of PP as an in situ setting temporary embolic agent.

STATEMENT OF SIGNIFICANCE

This article describes the development of a new radiopaque temporary liquid embolic agent from the optimization using design of experiments to a pilot animal study. Embolization is a minimally invasive interventional radiology procedure used to block blood flow in a targeted blood vessel. This procedure is used to treat many conditions including: tumors, aneurysms and arteriovenous malformations. Currently, no inherent radiopaque embolic agents are available in the clinic, which would allow for direct imaging of the material during the procedure and follow up treatment.

Animal Models in Studying Cerebral Arteriovenous Malformation

Brain arteriovenous malformation (AVM) is an important cause of hemorrhagic stroke. The etiology is largely unknown and the therapeutics are controversial. A review of AVM-associated animal models may be helpful in order to understand the up-to-date knowledge and promote further research about the disease. We searched PubMed till December 31, 2014, with the term “arteriovenous malformation,” limiting results to animals and English language. Publications that described creations of AVM animal models or investigated AVM-related mechanisms and treatments using these models were reviewed. More than 100 articles fulfilling our inclusion criteria were identified, and from them eight different types of the original models were summarized. The backgrounds and procedures of these models, their applications, and research findings were demonstrated. Animal models are useful in studying the pathogenesis of AVM formation, growth, and rupture, as well as in developing and testing new treatments. Creations of preferable models are expected.

Onyx extrusion through the scalp after embolization of dural arteriovenous fistula

A man in his sixties referred with symptoms of episodic left lip numbness and left arm weakness was diagnosed with a Borden type 3 dural arteriovenous fistula (DAVF) on DSA. Successful Onyx embolization of the DAVF was performed via the distal left occipital artery using an ev3 Apollo detachable tip microcatheter. He underwent surgical obliteration for the residual DAVF 3 days later. Three months later during a routine postoperative clinic visit, the patient produced a plastic bag containing multiple small pieces of Onyx cast and the detached tip of the Apollo microcatheter that had extruded out from his scalp through small spontaneous holes about 5 weeks after the embolization procedure. This spontaneous extrusion of Onyx can be alarming to the patient not expecting it; however, prior knowledge and discussion can lessen the anxiety of both the treating physician and the patient dealing with such a situation.

Onyx extrusion through the scalp after embolization of dural arteriovenous fistula

A man in his sixties referred with symptoms of episodic left lip numbness and left arm weakness was diagnosed with a Borden type 3 dural arteriovenous fistula (DAVF) on DSA. Successful Onyx embolization of the DAVF was performed via the distal left occipital artery using an ev3 Apollo detachable tip microcatheter. He underwent surgical obliteration for the residual DAVF 3 days later. Three months later during a routine postoperative clinic visit, the patient produced a plastic bag containing multiple small pieces of Onyx cast and the detached tip of the Apollo microcatheter that had extruded out from his scalp through small spontaneous holes about 5 weeks after the embolization procedure. This spontaneous extrusion of Onyx can be alarming to the patient not expecting it; however, prior knowledge and discussion can lessen the anxiety of both the treating physician and the patient dealing with such a situation.

Experimental study of temperature-sensitive chitosan/β-glycerophosphate embolic material in embolizing the basicranial rete mirabile in swines

The aim of the present study was to evaluate the feasibility of the non-adhesive temperature-sensitive liquid embolic material, chitosan/β-glycerophosphate (C/GP), in embolizing the basicranial rete mirabile (REM) in a swine model of cerebral arteriovenous malformation (cAVM). A total of 24 domestic swines were used as the experimental animals, among which 12 pigs underwent direct embolization of one side of the REM, while the other 12 pigs underwent embolization of the bilateral REM following anastomosis of the carotid artery and jugular vein. A super-selective microcatheter was introduced into the REM during the embolization procedure, and the C/GP hydrogel was injected until an image of the REM disappeared in the angiography examination. Further angiography examinations were performed after 2 and 6 weeks, and histological examination of the REM was performed after 6 weeks. Of the 24 domestic swines, 23 cases underwent successful thrombosis. Convulsions occurred in one case and that pig died during the embolization procedure. Following embolization, the angiography observations revealed that the embolized REM was no longer able to be developed, and adhesion of the microcatheter tip with the embolic agent did not occur. In addition, no apparent revascularization was observed in the angiography examinations performed at weeks 2 and 6. Therefore, the current preliminary study indicated that use of the non-adhesive temperature-sensitive embolic material was feasible for the embolization of cAVM; thus, C/GP may be used as an ideal embolic material for the treatment of cAVM.

Endovascular and microsurgical treatment of cerebral arteriovenous malformations: Current recommendations

Background:

Cerebral arteriovenous malformations (AVMs) can be a heterogeneous pathological entity whose management requires a complex decision-making process due to the risks associated with their treatment and natural history. Despite the recently published conclusions of the aborted Randomized Trial of Brain Unruptured AVMs (ARUBA) trial, the authors of this article believe multimodality intervention in general and microsurgical resection in particular continue to play a major role in the management of carefully selected ruptured or unruptured AVMs.

Methods:

The authors provide an overview of their methodology for endovascular intervention and microsurgical resection and share their technical nuances for successful embolization and microsurgical resection of AVMs with special emphasis on complication avoidance.

Results:

The authors have achieved successful outcomes in embolization and resection of cerebral AVMs when using their methodology.

Conclusions:

These lesions are among the most technically difficult pathological entities handled by the cerebrovascular specialist, and an overview of technical concepts to help systematize this challenging and variable endeavor can improve the safety of their treatment.

Endovascular embolization of brain arteriovenous malformations with Eudragit-E

Eudragit-E was originally developed as a non-adhesive liquid embolic material in the late 1990s and is a copolymer of methyl and butyl methacrylate and dimethylaminoethyl methacrylate that is dissolved in ethanol and iopamidol. This material has been used for endovascular embolization of brain arteriovenous malformations (AVMs) for some time but is currently not widely used. Because safety and feasibility of Eudragit-E has not been well documented, we here report our experience using this material for treating 22 human brain AVMs. From June 1998 to February 2014, 30 endovascular procedures using Eudragit-E were performed to treat 22 patients, including 14 men and 8 women with a mean age of 41.1 years (15-70 years). The mean follow-up period was 56 months (12-129 months), and the Spetzler-Martin grades were I (4 patients), II (9 patients), III (5 patients), and IV (4 patients). Residual AVMs were treated with stereotactic radiosurgery or surgery. The rate of complete obliteration with embolization alone was 27.3%. The overall obliteration rate after endovascular embolization with/without subsequent stereotactic radiosurgery or surgery was 72.7%. Eudragit-E caused two cases of cerebral infarction. One case of intracerebral hemorrhage due to postoperative hemodynamic changes also occurred. The rate of complications directly related to embolization was 10.0%. The safety and effectiveness of Eudragit-E embolization were satisfactory.

Stereotactic radiosurgery for arteriovenous malformations after Onyx embolization: a case-control study

OBJECT

Onyx, an ethylene-vinyl alcohol copolymer mixed in a dimethyl sulfoxide solvent, is currently one of the most widely used liquid materials for embolization of intracranial arteriovenous malformations (AVMs). The goal of this study was to define the risks and benefits of stereotactic radiosurgery (SRS) for patients who have previously undergone partial AVM embolization with Onyx.

METHODS

Among a consecutive series of 199 patients who underwent SRS between January 2007 and December 2012 at the University of Virginia, 25 patients had Onyx embolization prior to SRS (the embolization group). To analyze the obliteration rates and complications, 50 patients who underwent SRS without prior embolization (the no-embolization group) were matched by propensity score method. The matched variables included age, sex, nidus volume before SRS, margin dose, Spetzler-Martin grade, Virginia Radiosurgery AVM Scale score, and median imaging follow-up period.

RESULTS

After Onyx embolization, 18 AVMs were reduced in size. Total obliteration was achieved in 6 cases (24%) at a median of 27.5 months after SRS. In the no-embolization group, total obliteration was achieved in 20 patients (40%) at a median of 22.4 months after SRS. Kaplan-Meier analysis demonstrated obliteration rates of 17.7% and 34.1% in the embolization group at 2 and 4 years, respectively. In the no-embolization group, the corresponding obliteration rates were 27.0% and 55.9%. The between-groups difference in obliteration rates after SRS did not achieve statistical significance. The difference in complications, including adverse radiation effects, hemorrhage episodes, seizure control, and patient mortality also did not reach statistical significance.

CONCLUSIONS

Onyx embolization can effectively reduce the size of many AVMs. This case-control study did not show any statistically significant difference in the rates of embolization or complications after SRS in patients who had previously undergone Onyx embolization and those who had not.

Dual-lumen balloon catheters may improve liquid embolization of vascular malformations: an experimental study in Swine

BACKGROUND AND PURPOSE

Liquid embolic agents are increasingly used to treat vascular malformations. We sought to assess embolization with these agents by using a dual-lumen balloon catheter in an experimental setting.

MATERIALS AND METHODS

Eighteen injections of liquid embolic agents were performed in the rete mirabile of swine. We used 3 methods to control liquid embolic agent reflux: 1) dual-lumen balloon-catheter (group A, n = 8); 2) injection of liquid embolic agent after proximal n-BCA plug formation through a second microcatheter (group B, n = 4); and 3) standard liquid embolic agent injection (group C, controls, n = 6). The following outcomes were graded by using ordinal scales by angiography, macrophotography, and radiography of retia after euthanasia: 1) angiographic and pathologic extent of liquid embolic agent embolization of the rete, 2) reflux of liquid embolic agents in the parent artery, and 3) density of liquid embolic agents in the proximal rete. Technical complications were also recorded. A successful injection was defined as an embolization that reached the contralateral rete without reflux into proximal external branches. Exact logistic regression analyses were performed to compare groups.

RESULTS

There were significant differences among groups for reflux (P = .029) and liquid embolic agent density in the proximal rete (P = .014), while extension to the contralateral rete did not reach statistical significance (P = .07). Injections differed among groups (P = .004), with dual-lumen balloon-catheter injections more frequently successful compared with control injections (P = .019).

CONCLUSIONS

Dual-lumen balloon catheters allowed better liquid embolic agent injections than standard injections.

Normal perfusion pressure breakthrough phenomenon: experimental models

One of the most life-threatening complications after the obliteration of intracranial arteriovenous malformations is the development of oedema and/or multifocal haemorrhage. Two main theories have been postulated so far in order to explain this situation. On one hand, "normal perfusion pressure breakthrough phenomenon" is based on the loss of cerebral vessel autoregulation due to the chronic vasodilation of perinidal microcirculation. On the other hand, the "occlusive hyperaemia" deals with thrombotic and venous obstruction phenomena that may also generate such manifestations. The aim of this study is to resume the main concepts of the "normal perfusion pressure breakthrough phenomenon" theory as well as the related animal models described up to date, their advantages and disadvantages, and the main conclusions obtained as a result of the experimental research.

Forcible intraarterial injection of a nonadhesive liquid embolic agent under microballoon occlusion: experimental study in swine liver

PURPOSE

To evaluate the feasibility and effectiveness of transcatheter embolization by forcible intraarterial injection of a mixture of ethylene vinyl alcohol copolymer (EVAL) and ethanol under microballoon occlusion compared with conventional transcatheter arterial embolization methods in nontumoral swine liver.

MATERIALS AND METHODS

Nine swine were divided into three groups: embolization with EVAL/ethanol mixture (EVAL group, n = 5), with ethiodized oil (ethiodized oil group, n = 2), and with microspheres (microspheres group, n = 2). Embolization was performed at the subsegmental hepatic artery. The EVAL/ethanol mixture was injected forcibly through a microcatheter with a balloon, which was inflated to prevent backflow of the mixture during the injection. Ethiodized oil or microspheres were injected into the artery using a microcatheter without balloon occlusion. Two animals of the EVAL group were euthanized immediately after embolization, and the distribution of EVAL was assessed microscopically. The remaining seven animals were euthanized 4 weeks after embolization, and the histopathologic changes were assessed.

RESULTS

All procedures were technically successful. EVAL occupied > 80% of the hepatic arterial, portal venous, and sinusoidal lumens after embolization. Ischemic coagulation necrosis was observed 4 weeks after embolization in the EVAL group. Parenchymal necrosis was not observed in the ethiodized oil and microspheres groups.

CONCLUSIONS

Transcatheter embolization by forcible intraarterial injection of an EVAL/ethanol mixture under microballoon occlusion was feasible and achieved the simultaneous embolization of hepatic artery, portal vein, and sinusoids in swine liver, resulting in complete necrosis of the segment that received embolization.

Onyx®: a unique neuroembolic agent

Rupture of a cerebral arteriovenous malformation can result in devastating hemorrhage with a possibility of serious neurological injury or death. Endovascular embolization is an important adjunct in the treatment of cerebral arteriovenous malformations, and in a small number of cases may provide definitive treatment. Currently available embolic agents have several shortcomings, including the possibility of recanalization, adhesiveness to the endovascular microcatheter and suboptimal handling at the time of surgical resection. Onyx is an ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide that was approved by the US FDA in July 2005 as an embolic agent for brain arteriovenous malformations. Although long-term follow-up is limited, this agent appears to offer several advantages over the other available embolic agents for the endovascular management of arteriovenous malformations and other vascular lesions.

[Potential and limitations of modern embolization therapy]

Correct clinical and angiographic classification of vascular anomalies, including consideration of their flow pattern (high-flow versus low-flow), is the basis of accurate indications for minimally invasive therapy modalities such as embolization. Technical advancements and miniaturization of catheter materials (including steerable microwires, flow-directed microcatheters and detachable tips) gained access for embolotherapy to lesions anywhere in the body. The aim of embolization, which is mainly indicated for therapy of high-flow arteriovenous malformations, is the complete, permanent occlusion of the lesion nidus. Nowadays, embolotherapy is performed using permanent liquid embolization agents, in multiple staged sessions. This technique reduces complications such as ischemic necrosis and peripheral nerve lesions compared to alcohol embolization. Sole occlusion of the arterial inflow by surgical resection or interventional coil application is considered obsolete. The size of the lesion and the high treatment costs limit the use of embolotherapy.