Critical appraisal of endovascular treatment of brain arteriovenous malformation using Onyx in a series of 92 consecutive patients

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Primary Embolization of Cerebral Arteriovenous Malformations With Intention to Cure: A Systematic Review of Literature and Meta-Analysis

BACKGROUND AND OBJECTIVES

The treatment of brain arteriovenous malformations (AVMs) involves multiple approaches, including embolization, microsurgical resection, and radiosurgery. With the advent of new embolisates, dual-lumen balloon catheters, detachable tip microcatheters, and transvenous embolization, endovascular AVM obliteration has become more effective. Although adjuvant embolization and embolization are commonly used, the safety and effectiveness of curative embolization remain unclear.

METHODS

We conducted a systematic literature review using PubMed, Ovid Medline, and Web of Science to identify studies reporting outcomes in patients with AVMs who underwent primary embolization with the intention to cure. We collected data on patient characteristics, AVM features, complications, and radiographic and clinical outcomes for meta-analysis.

RESULTS

We identified 25 studies with a total of 1425 patients with 1427 AVMs who underwent curative embolization. Of these patients, 70% were low grade (pooled = 61% [39-82]), 67% were <3 cm (pooled = 78% [60-92]), and 75% were in superficial locations (pooled = 80% [72-86]). At last radiographic follow-up (mean, 16.7 ± 10.9 months), the full obliteration rate was 52% (pooled = 61% [43-77]) and retreatment rate was 25% (pooled = 17% [8.3-27]). At last clinical follow-up (mean, 24.2 ± 13.3 months), the poor clinical outcome rate was 7.9% (pooled = 4.4% [1.3-8.7]) and symptomatic complication rate was 13% (pooled = 13% [8-19]). There was no significant difference in the rate of radiographic cure, need for retreatment, and poor outcomes between ruptured and unruptured AVMs. Symptomatic complications were more common in the treatment of unruptured AVMs. The primary outcomes showed high heterogeneity (I2 = 72%-94%).

CONCLUSION

Curative embolization of AVM is primarily reserved for small and low-grade AVMs, with highly variable outcomes. Our findings suggest poor radiographic outcomes and increased risk of complications. Outcomes are highly dependent on patient selection and technique used. Large multicenter prospective studies are required to further guide patient selection, categorize clinical and radiographic outcomes, and identify subgroup of patients that may benefit from curative embolization.

Most Promising Approaches to Improve Brain AVM Management: ARISE I Consensus Recommendations

Brain arteriovenous malformations (bAVMs) are complex, and rare arteriovenous shunts that present with a wide range of signs and symptoms, with intracerebral hemorrhage being the most severe. Despite prior societal position statements, there is no consensus on the management of these lesions. ARISE (Aneurysm/bAVM/cSDH Roundtable Discussion With Industry and Stroke Experts) was convened to discuss evidence-based approaches and enhance our understanding of these complex lesions. ARISE identified the need to develop scales to predict the risk of rupture of bAVMs, and the use of common data elements to perform prospective registries and clinical studies. Additionally, the group underscored the need for comprehensive patient management with specialized centers with expertise in cranial and spinal microsurgery, neurological endovascular surgery, and stereotactic radiosurgery. The collection of prospective multicenter data and gross specimens was deemed essential for improving bAVM characterization, genetic evaluation, and phenotyping. Finally, bAVMs should be managed within a multidisciplinary framework, with clinical studies and research conducted collaboratively across multiple centers, harnessing the collective expertise and centralization of resources.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Geometrical Characteristics of Grade III Arteriovenous Malformations That Contribute to Better Outcomes in Endovascular Treatment

BACKGROUND

Grade III brain arteriovenous malformation (AVM) is a distinct subgroup of AVMs that encompasses multiple subtypes according to the Spetzler-Martin classification.

METHODS

This retrospective study included 61 patients with grade III AVM who underwent embolization between 2010 and 2022. The study analyzed the angioarchitecture of the AVM nidus and evaluated the outcomes of the embolization procedures.

RESULTS

There were 29 patients (47.5%) with subtype S1E1V1, 20 patients (32.8%) with subtype S2E1V0, and 12 patients (19.7%) with subtype S2E0V1. The rate of complete occlusion in all patients was 47.5% (29 patients). The rate of complete occlusion was higher in cases with a compact nidus (P < 0.001). Several parameters were associated with occlusion of the AVM nidus, including ≤3 arterial feeders (P = 0.017) and presentation with hemorrhage (P = 0.007), with the majority of patients with a compact nidus presenting with hemorrhage. Other factors associated with compact geometry were the presence of a single deep vein, ≤3 arterial feeders, ≤2 superficial draining veins, and an AVM nidus size ≤3 cm.

CONCLUSIONS

The compact nature of grade III AVM is a crucial predictor for the success of embolization. Several characteristics associated with a compact nidus, such as presentation with hemorrhage and a lower number of arterial feeders, have a significantly higher closure rate. Other factors, such as a single deep draining vein, reduced superficial venous drainage, and small size, show a strong association with complete obliteration.

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

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

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

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

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

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

Curative Embolization for Pediatric Spetzler-Martin Grade III Cerebral Arteriovenous Malformations

OBJECTIVE

Spetzler-Martin (SM) grade III arteriovenous malformations (AVMs) represent a gray zone due to their high variability in location, size, and angioarchitecture. In addition, there is a lack of information on curative embolization in the pediatric population, especially in this subgroup of lesions. Here we present our experience treating grade III AVMs by curative embolization in pediatric patients.

METHODS

Clinical and angiographic data from pediatric patients with grade III SM AVMs were retrospectively collected between 2011 and 2020 in a referral institution. We grouped the AVMs into subtypes according to size (S), venous drainage (V), and eloquence (E) and obtained subtypes: IIIA (S1V1E1), IIIB (S2V1E0), IIIC (S2V0E1), and IIID (S3V0E0).

RESULTS

A total of 61 embolization sessions were performed in 35 pediatric patients. There were 25 females (64%), and the mean age was 12.2 years (range 5-18). Complete angiographic occlusion was achieved in 16 patients (47%). In 13 patients (37%), the AVM was occluded with a single embolization session and most (12/13) had small lesions (IIIA subtype). Among the 19 patients with incomplete occlusion, most (58%) had large lesions (IIIB, IIIC, and IIID). Large AVMs (IIIB, IIIC, and IIID) underwent 36 sessions; however, only 3 patients (21%) achieved complete occlusion in 11 sessions. Eight intraoperative complications (13% procedures) occurred mainly in ruptured AVMs (7/8) and eloquent zones (7/8).

CONCLUSIONS

Curative embolization for SM grade III AVMs in children carries a high complication rate, especially in small, ruptured, and eloquent lesions. In addition, acceptable immediate complete angiographic occlusion rates were achieved, especially in small AVMs.

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.

Complications in pediatric interventional neuroradiology management. Reflections on a personal experience

Pediatric interventional neuroradiology is a rewarding but demanding specialty. It cannot be classified as a miniaturized technical procedure simply because it deals with small vessels in small patients but remains a field requiring specific knowledge combining clinical, anatomical, physiologic, and technical features. Complications that occur remain terrible experiences in this population whose patients have not personally requested to be treated for their vascular malformations. The aim of this article is to evoke the various possible groups of complications that may occur during a pediatric endovascular procedure in order to make physicians aware of these problems and help them to avoid them.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL TRIAL REGISTRATION NUMBER

NCT02879071.

Embolic Agents and Microcatheters for Endovascular Treatment of Cerebral Arteriovenous Malformations

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

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

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

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.

Comparison of Hemorrhagic Risk in Intracranial Arteriovenous Malformations Between Conservative Management and Embolization as the Single Treatment Modality

BACKGROUND

Embolization has been discussed as a feasible single modality treatment for intracranial arteriovenous malformations (AVMs).

OBJECTIVE

To compare hemorrhagic risk between embolization and conservative management in a multivariate survival analysis.

METHODS

We retrospectively reviewed records of patients with intracranial AVMs evaluated at our institution from 1990 to 2013. We included patients recommended to undergo embolization without other treatment modalities and patients managed conservatively. Multivariate Cox regression analysis of hemorrhage-free survival was performed, with the survival interval right-censored to date of either last follow-up or salvage treatment.

RESULTS

We identified 205 patients matching our inclusion criteria, with 160 patients in the noninterventional group and 45 in the embolization group. The average age of all patients was 40.2 ± 19.5 yr, with younger patients undergoing embolization more often (P = .026). Fifty-one (31.9%) conservatively managed patients and 13 (28.9%) patients treated by embolization (P = .703) presented with hemorrhage. Other baseline characteristics were similar between the 2 management groups. During an average follow-up period of 7.7 yr, 30 patients (14.6%) experienced hemorrhage recurrence. Multivariate Cox regression revealed older age (P = .031) and hemorrhagic presentation (P &lt; .001) to be statistically associated with follow-up hemorrhage. In a subset analysis of unruptured AVMs, embolization was associated with a 4-fold hazard ratio of hemorrhage compared to conservative management (P = .044).

CONCLUSION

Older age and initial presentation with hemorrhage were associated with increased risk of hemorrhage during follow-up. Treatment of AVMs with embolization as the sole modality may increase hemorrhagic risk compared with conservative management, especially in unruptured AVMs.

Multimodal Treatment Strategy for Spetzler-Martin Grade III Arteriovenous Malformations of the Brain

The Spetzler–Martin (S–M) grading scale was developed to assess the risk of postoperative neurological complications after the surgical treatment of arteriovenous malformations (AVMs) of the brain. Treatment-associated morbidity and poor outcomes are particularly relevant to Grade III AVMs and improving the safety while attaining acceptable cure rates still poses a challenge. A multimodal treatment strategy combining surgery, embolization, and radiosurgery is recommended for S–M Grade III AVMs because of the surgical risk. Grade III AVMs are the heterogeneous group that has been further divided into subgroups according to the size, the location in eloquent cortex, and the presence of deep venous drainage. The risks associated with different treatment modalities vary depending on the subgroup, and the rating scales have been further refined to predict the risk more accurately and help determine the most appropriate treatment choice. Previous results for the treatment of S–M Grade III AVMs vary widely among studies, and the treatment modalities are also different in each study. Being familiar with previous treatment results is essential for improving treatment outcomes.

Advances in Embolization of bAVMs

Brain AVMs are complex malformations, usually congenital, that need a deep understanding of anatomy and pathophysiology to be safely treated. Nowadays, embolization and radiosurgery are carried out more frequently due to their reduced invasiveness as compared to conventional neurosurgery. This paper aims to describe different and new endovascular approaches that allow the interventionalist to treat almost all the small AVMs and to reduce the nidus of the bigger ones in order to facilitate the surgical or radiosurgical intervention.

Therapeutic management of cerebral arteriovenous malformations: a review

The therapeutic management of cerebral arteriovenous malformations has undergone significant change over the past 40 years. Embolization, radiosurgery, advanced imaging modalities, neuropsychological testing and advances in surgical technique has both significantly improved our ability to treat patients, as well as confounding the landscape as to what constitutes best medical practice. Variability in natural history provides additional challenges in that it is challenging to determine an accurate estimate of the risk of hemorrhage, morbidity and mortality. It is clear that the complexity of the treatment of these lesions demands a multidisciplinary approach. The need for a team of neurosurgeons, interventional and diagnostic neuroradiologists, neurologists, radiation oncologists and neuropsychologists will improve outcomes and aid in determining best therapy for patients.

Prioritized Venous Coiling Facilitating Endovascular Treatment of Brain Arteriovenous Malformations with a Fistulous Component

BACKGROUND

Brain arteriovenous malformation (AVM) with a fistulous component presents a treatment challenge. The presence of the fistulous component may be related to either a complication from endovascular treatment, perioperative hemorrhagic events during surgical resection, or incomplete obliteration after radiosurgery.

CASE DESCRIPTION

From December 2010 to May 2014, 7 consecutive patients (3 men, 4 women, average age, 28.7 years; age range, 11 months to 67 years) with AVMs with a high-flow fistulous component were treated at our institute with venous coiling before transarterial liquid embolization. One AVM was grade I based on the Spetzler-Martin grading system, 1 was grade II, 3 were grade III, and 2 were grade IV. The nidus size ranged from 1.7 to 6.0 cm. Four patients had pure fistulous-type lesions, and 3 had lesions of the mixed fistulous-plexiform type. All AVMs shared a common feature of a high-flow fistulous component with a large venous pouch emerging from the nidus. After endovascular embolization of the AVMs, 3 patients had complete occlusion, 3 patients had near-complete occlusion, and 1 patient had significant reduction in volume. There was no immediate complication after embolization, but 1 patient experienced delayed hemorrhage 3 days after the procedure.

CONCLUSIONS

Prioritized transarterial venous coiling is feasible for the embolization of AVMs with a high-flow fistulous component and the procedure had an acceptable complication rate.

Curing arteriovenous malformations using embolization

Endovascular embolization is typically reserved as an adjuvant therapy in the management of cerebral arteriovenous malformations (AVMs), either for preoperative devascularization or preradiosurgical volume reduction. Curative embolization plays a limited role in AVM treatment but several studies have shown that it is possible, especially with later-generation liquid embolic agents. Given the complexity of AVM anatomy and the recent controversies over the role of any intervention in AVM management, it is critical that the cerebrovascular community better define the indications of each treatment modality to provide quality AVM management. In this review, the authors evaluate the role of curative AVM embolization. Important considerations in the feasibility of curative AVM embolization include whether it can be performed reliably and safely, and whether it is a durable cure. Studies over the past 20 years have begun to define the anatomical factors that are amenable to complete endovascular occlusion, including size, feeding artery anatomy, AVM morphology, and endovascular accessibility. More recent studies have shown that highly selected patients with AVMs can be treated with curative intent, leading to occlusion rates as high as 100% of such prospectively identified lesions with minimal morbidity. Advances in endovascular technology and techniques that support the efficacy and safety of curative embolization are discussed, as is the importance of superselective diagnostic angiography. Finally, the durability of curative embolization is analyzed. Overall, while still unproven, endovascular embolization has the potential to be a safe, effective, and durable curative treatment for select AVMs, broadening the armamentarium with which one can treat this disease.

Safety and efficacy using a detachable tip microcatheter in the embolization of pediatric arteriovenous malformations

PURPOSE

The treatment of deep-seeded pediatric brain arteriovenous malformations (AVMs) remains a challenging task. We describe our experience using a new detachable tip microcatheter in the embolization of brain arteriovenous malformations, pial arteriovenous fistulas, and vein of Galen malformations. We describe the safety and efficacy using a new detachable tip microcatheter in the treatment of pediatric deep brain arteriovenous malformations, pial malformations, and vein of Galen malformations.

METHODS

During a period of 9 months from March 2013 through January 2014, 11 pediatric patients in 14 procedures with 27 total injections were selected for treatment with a detachable tip under Food and Drug Administration (FDA) compassionate use exemption and were admitted to our department for treatment of their brain AVM using a liquid embolic agent and a detachable tip microcatheter. The ages of the patients ranged from 3 months to 18 years old.

RESULTS

Of the 27 total injections done, the tip detached in seven cases. For the 16 n-BCA injections, the tip detached six times (37.5 %), and for the 11 Onyx injections, the tip detached one time (9 %). There were no cases of premature microcatheter detachment during normal vessel navigation.

CONCLUSIONS

The introduction of these detachable tip microcatheters allows for a safe and relaxed injection that permits a true circumferential occlusion, and may further permit filling a larger amount of angioarchitecture without the risk of distal migration, or vessel damage during the usual rapid removal of non detachable micocatheters.