A prospective, multicenter, randomized trial of the Onyx liquid embolic system and N-butyl cyanoacrylate embolization of cerebral arteriovenous malformations

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.

Comparison of conservative management, microsurgery only, and microsurgery with preoperative embolization for unruptured arteriovenous malformations: A propensity score weighted prospective cohort study

AIMS

To compare the efficacy and deficiency of conservative management (CM), microsurgery (MS) only, and microsurgery with preoperative embolization (E + MS) for unruptured arteriovenous malformations (AVMs).

METHODS

We prospectively included unruptured AVMs undergoing CM, MS, and E + MS from our institution between August 2011 and August 2021. The primary outcomes were long-term neurofunctional outcomes and hemorrhagic stroke and death. In addition to the comparisons among CM, MS, and E + MS, E + MS was divided into single-staged hybrid and multi-staged E + MS for further analysis. Stabilized inverse probability of treatment weighting using propensity scores was applied to control for confounders by treatment indication across the three groups.

RESULTS

Of 3758 consecutive AVMs admitted, 718 patients were included finally (266 CM, 364 MS, and 88 E + MS). The median follow-up duration was 5.4 years. Compared with CM, interventions (MS and E + MS) were associated with neurological deterioration. MS could lower the risk of hemorrhagic stroke and death. Multi-staged E + MS was associated with neurological deterioration and higher hemorrhagic risks compared with MS, but the hybrid E + MS operation significantly reduced the hemorrhage risk.

CONCLUSION

In this study, unruptured AVMs receiving CM would expect better neurofunctional outcomes but bear higher risks of hemorrhage than MS or E + MS. The single-staged hybrid E + MS might be promising in reducing inter-procedural and subsequent hemorrhage.

A Review of Preoperative Embolization Effectiveness in Patients With Arteriovenous Malformations

BACKGROUND AND OBJECTIVES

Preoperative embolization of arteriovenous malformations (AVMs) remains controversial. This study sought to analyze the cost-effectiveness of preoperative embolization of AVMs.

METHODS

Patients who underwent AVM resection at a single institute (January 1, 2015-December 31, 2020) were analyzed. Patients with preoperative embolization (embolization cohort) were compared with those without preoperative embolization (nonembolization cohort). Cost-effectiveness score (CE) was the primary outcome of interest and was determined by dividing the total 1-year cost by effectiveness, which was derived from a validated preoperative to last follow-up change in the modified Rankin Scale utility score. A lower CE signifies a more cost-effective treatment strategy.

RESULTS

Of 188 patients, 88 (47%) underwent preoperative embolization. The mean (SD) total cost was higher in the embolization group than in the nonembolization group ($117 594 [$102 295] vs $84 348 [$82 326]; P < .001). The mean (SD) CE was higher in the embolization cohort ($336 476 [$1 303 842]) than in the nonembolization cohort ($100 237 [$246 255]; P < .001). Among patients with Spetzler-Martin (SM) grade I and II AVMs, the mean (SD) CE was higher in the embolization (n = 40) than in the nonembolization (n = 72) cohort ($164 950 [$348 286] vs $69 021 [$114 938]; P = .004). Among patients with SM grade III AVMs, the mean (SD) CE was lower in the embolization (n = 33) than in the nonembolization (n = 25) cohort ($151 577 [$219 130] vs $189 195 [$446 335]; P = .006). The mean (SD) CE was not significantly different between cohorts among patients with higher-grade AVMs (embolization cohort [n = 3] vs nonembolization cohort [n = 15]: $503 639 [$776 492] vs $2 048 419 [$4 794 758]; P = .49). The mean CE for embolized SM grade III aneurysms was nonsignificant in the ruptured group; however, for the unruptured group, CE was significantly higher in the embolization cohort (n = 26; $160 871 [$240 535]) relative to the nonembolization cohort (n = 15; $108 152 [$166 446]) ( P = .006).

CONCLUSION

Preoperative embolization was cost-effective for patients with SM grade III AVMs but not for patients with lower-grade AVMs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

REGISTRATION-URL

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

Cervical extradural arteriovenous fistula with radiculopathy managed endovascularly

BACKGROUND

Extradural arteriovenous fistulas (AVFs) of the cervical spine are extremely rare, and typically manifest as slowly progressive myelopathy caused by mass effect. This is a unique case of extradural AVF of the cervical spine manifesting with purely radicular symptoms and treated endovascularly with coil and liquid embolization.

CASE DESCRIPTION

A 55-year-old woman presented with neck pain and right upper extremity radiculopathy persisting for 9 months. Imaging studies demonstrated an AVF spanning from C4-C6 with extension into the C5-C6 foramen supplied primarily from the deep cervical branch of the costocervical trunk. The patient underwent successful coil and liquid (Onyx) embolization. Six-week postoperatively, the patient's symptoms completely resolved and magnetic resonance imaging and angiographic imaging confirmed complete obliteration of the fistula.

CONCLUSION

While extradural AVFs typically present with myelopathic symptoms, they may present with solely radicular symptoms and can be successfully treated endovascularly.

Head and Neck Arteriovenous Malformations: Clinical Manifestations and Endovascular Treatments

Arteriovenous malformations (AVMs) are vascular malformations that present high-flow direct communication between the arteries and veins, not involving the capillary beds. They can be progressive and lead to various manifestations, including abnormal skin or mucosal findings, ischemia, hemorrhage, and high-output heart failure in severe cases. AVMs often involve the head and neck region. Head and neck AVMs can present region-specific clinical manifestations, angioarchitecture, and complications, especially in cosmetic appearance and ingestion, respiratory, and neuronal functions. Therefore, when planning endovascular treatment of head and neck AVMs, physicians should consider not only the treatment strategy but also the preservation of the cosmetic appearance and critical functions. Knowledge of the functional vascular anatomy as well as treatment techniques should facilitate a successful management. This review summarizes AVMs' clinical manifestations, imaging findings, treatment strategy, and complications.

Liquid Embolic Agents for Endovascular Embolization: A Review

Endovascular embolization (EE) has been used for the treatment of blood vessel abnormalities, including aneurysms, AVMs, tumors, etc. The aim of this process is to occlude the affected vessel using biocompatible embolic agents. Two types of embolic agents, solid and liquid, are used for endovascular embolization. Liquid embolic agents are usually injectable and delivered into the vascular malformation sites using a catheter guided by X-ray imaging (i.e., angiography). After injection, the liquid embolic agent transforms into a solid implant in situ based on a variety of mechanisms, including polymerization, precipitation, and cross-linking, through ionic or thermal process. Until now, several polymers have been designed successfully for the development of liquid embolic agents. Both natural and synthetic polymers have been used for this purpose. In this review, we discuss embolization procedures with liquid embolic agents in different clinical applications, as well as in pre-clinical research studies.

Efficiency of endovascular management with a combination of Onyx and coils for direct and indirect carotid cavernous fistula treatment: experience of a single center

BACKGROUND

To evaluate the safety and efficacy of endovascular treatment with a combination of Onyx and coils for carotid cavernous fistulas (CCFs), and to characterize the factors associated with clinical and angiographic outcomes for direct and indirect CCFs.

METHODS

This retrospective study included 31 patients with CCF treated with an endovascular procedure between December 2017 and March 2022.

RESULTS

Direct and indirect CCFs were found in 14 (45.2%) and 17 (54.8%) cases, respectively. Direct CCFs included eleven traumatic carotid cavernous fistulas. The most common symptom on admission was chemosis, which was seen in 17 (54.8%) patients. Eight (25.7%) cases were treated by the transarterial approach. Fourteen (45.2%) cases were treated using the femoral vein-inferior petrosal sinus approach. Seven (22.6%) were treated by direct puncture of the superior ophthalmic vein. Two (6.5%) were treated by the femoral vein-facial vein approach. Immediate complete occlusion and follow-up rates were 93.5% and 96.7%, respectively. Twenty-nine (96.7%) patients experienced an improvement in their symptoms at clinical follow-up. Chemosis was significantly improved or resolved in 15 patients. Ophthalmoplegia was improved or resolved in 10 patients. Visual impairment was improved in 6 patients. Proptosis was improved or resolved in 5 patients. One case (3.2%) experienced procedure-related complication presented with transient oculomotor nerve palsy. In univariate subgroup analysis, use of balloon, treatment approach, and history of head trauma were significantly different between the direct and indirect CCF groups.

CONCLUSIONS

Endovascular treatment with a combination of Onyx and coils is a safe and effective therapy for CCFs. In this study, the transarterial approach was a favorable option for embolization of direct CCFs. In contrast, the transvenous approach may be the first choice of treatment for indirect CCFs.

Transarterial embolization of acute non-neurologic bleeding using Ethylene Vynil Alcohol Copolymer: a single-Centre retrospective study

BACKGROUND

To evaluate feasibility, safety and effectiveness of transarterial embolization of acute non-neurologic hemorrhage with Ethylene Vynil Alcohol Copolymer (EVOH).

METHODS

Between January 2018 and June 2021, 211 patients (male 123, mean age 69.7 y + 17.9) who underwent transarterial embolization with Onyx™ for acute non-neurologic arterial bleeding were retrospectively reviewed. Most frequent etiology of bleeding was post-operative (89/211, 42.2%), trauma (62/211, 29.4%) and tumor (18/211, 8.5%). Technical success was defined as the angiographic evidence of target vessel complete occlusion. Clinical success was defined as resolution of bleeding. Any rebleeding within the primitive site, requiring a new intervention during the first 30-days following embolization, was considered a clinical failure. Occurrence of procedure-related complication and mortality within 30 days of the embolization were examined.

RESULTS

A total of 229 embolization procedures was performed in 211 pts.; technical success rate was 99.5% (210/211 pts). Clinical success rate was 94.3% (199/211 pts). In 11 patients (5.2%) a reintervention was needed because of a rebleeding occurring within the primitive site, whereas in five patients (2.4%) rebleeding occurred within a site different from the primitive. Factors more often associated with clinical failure were coagulopathy/ongoing anticoagulant therapy (5/11, 45.4%), and post-operative etiology (3/11, 27.3%). EVOH was used as the sole embolic agent in 214/229 procedures (93.4%), in association with coils in 11 cases (4.8%), and with microparticles in 4 cases (1.7%). In the present series, major complications occurred in 6 cases (2.8%): respectively, four cases (1.9%) of colonic ischemia and two groin hematomas (0.9%) with active extravasation were observed. 26 (12.3%) patients died during the follow-up.

CONCLUSION

Embolization of acute arterial bleeding with EVOH as a first-line embolic agent is feasible, safe and effective.

Stereotactic Radiosurgery for A Randomized Trial of Unruptured Brain Arteriovenous Malformations-Eligible Patients: A Meta-Analysis

BACKGROUND

The outcomes of A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) were controversial, and they suggested that intervention is inferior to medical management for unruptured brain arteriovenous malformations (AVMs). However, several studies have shown that stereotactic radiosurgery (SRS) is an acceptable therapy for unruptured AVMs.

OBJECTIVE

To test the hypothesis that ARUBA intervention arm's SRS results are meaningfully inferior to those from similar populations reported by other studies.

METHODS

We performed a literature review to identify SRS studies of patients who met the eligibility criteria for ARUBA. Patient, AVM, treatment, and outcome data were extracted for statistical analysis. Regression analyses were pooled to identify factors associated with post-SRS obliteration and hemorrhage.

RESULTS

The study cohort included 8 studies comprising 1620 ARUBA-eligible patients who underwent SRS. At the time of AVM diagnosis, 36% of patients were asymptomatic. The mean follow-up duration was 80 months. Rates of radiologic, symptomatic, and permanent radiation-induced changes were 45%, 11%, and 2%, respectively. The obliteration rate was 68% at last follow-up. The post-SRS hemorrhage and mortality rates were 8%, and 2%, respectively. Lower Spetzler-Martin grade (odds ratios [OR] = 0.84 [0.74-0.95], P = .005), lower radiosurgery-based AVM score (OR = 0.75 [0.64-0.95], P = .011), lower Virginia Radiosurgery AVM Scale (OR = 0.86 [0.78-0.95], P = .003), and higher margin dose (OR = 1.13 [1.02-1.25], P = .025) were associated with obliteration.

CONCLUSION

SRS carries a favorable risk to benefit profile for appropriately selected ARUBA-eligible patients, particularly those with smaller volume AVMs. Our findings suggest that the results of ARUBA do not reflect the real-world safety and efficacy of SRS for unruptured AVMs.

Impact of Pre-operative Embolization With Onyx for Brain Arteriovenous Malformation Surgery

Objective

To clarify the safety and efficacy of pre-operative embolization using Onyx liquid embolic agent (Onyx; ev3) compared with N-butyl cyanoacrylate (NBCA; Cordis Neurovascular, Inc.) or coils in cerebral arteriovenous malformation (AVM) surgery.

Methods

This was a retrospective review of a prospectively collected clinical database of brain AVMs treated at our institute from January 2005 to March 2021. A total of 38 consecutive patients who underwent AVM resection after pre-operative embolization were included. Based on pre-operative embolization materials, the patients were divided into the pre-Onyx group (n = 16), in which NBCA or coils were used for embolization, and the Onyx group (n = 22). Patient characteristics and treatment results were compared between the two groups.

Results

Patient characteristics were comparable between the two groups in terms of age, sex, and rupture status. While the Spetzler-Martin grade was also similar between the two groups, the location of the AVM nidus in the eloquent area was slightly higher in patients in the Onyx group (72.7%) than in patients in the pre-Onyx group (43.8%) (P = 0.09). The embolization rate was higher in the pre-Onyx group (mean: 63.0%; range: 12.7-100%) than in the Onyx group (mean: 50.0%; range: 15.8-100%), but the difference was not statistically significant (P = 0.06). The time needed for surgical removal was shorter in the Onyx group (mean: 354.8 min; range: 144-884 min) than in the pre-Onyx group (mean: 457.9 min; range: 240-1,294 min); however, this difference was not statistically significant (P = 0.13). The amount of intraoperative bleeding was significantly lower in the Onyx group (mean: 129.8 ml; range: 20-540 mL) than in the pre-Onyx group (mean: 448.8 mL; range: 120-1,550 ml) (P = 0.0008). The surgical complication rates were comparable between the two groups (pre-Onyx group, 18.8%; Onyx group, 4.5%; P = 0.29).

Conclusions

Pre-operative embolization with Onyx can significantly reduce the amount of intraoperative bleeding in AVM resection and may contribute to safe AVM surgery.

Economic analysis of n-butyl cyanoacrylate compared with ethylene vinyl alcohol copolymer liquid embolic embolization of brain arteriovenous malformations (bAVMs) from a US hospital perspective

BACKGROUND

In US hospitals, the liquid embolic systems (LESs) n-butyl cyanoacrylate (n-BCA) and ethylene vinyl alcohol copolymer (EVOH) are used for brain arteriovenous malformation (bAVM) embolization to achieve presurgical devascularization. The aim of this study was to perform an economic analysis comparing four techniques for bAVM embolization based on LES, ancillary device, and angiography suite time costs.

METHODS

An economic model was developed comparing the embolization costs for n-BCA, EVOH with the plug and push technique, EVOH with detachable-tip microcatheters, and EVOH with balloon microcatheters. Per procedure costs were calculated for bAVMs with one to four pedicles. Annual cohort analyses were performed to evaluate the potential impact for low and high-volume centers. Sensitivity analyses were performed to determine cost drivers.

RESULTS

The analyses showed that the n-BCA technique was the least costly of the four techniques. Total per procedure costs for one to four embolized pedicles ranged from $5941 to $10,074 for the n-BCA technique, $8428 to $30,345 for the EVOH balloon microcatheter technique, $12,711 to $47,477 for the EVOH plug and push technique, and $13,900 to $52,233 for the EVOH detachable-tip microcatheter technique. Cohort analyses costs for 52 annual cases ranged from $308,953 to $523,838 with the n-BCA technique and from $722,816 to $2,716,096 with the EVOH detachable-tip microcatheter technique.

CONCLUSIONS

Procedure costs associated with n-BCA are lower than those with each of the three EVOH techniques examined. Future cost analyses should compare the costs of new LES products once available.

Preoperative embolisation of brain arteriovenous malformations: a systematic review and meta-analysis

Preoperative embolisation is a commonly performed adjunct to microsurgical excision of brain arteriovenous malformations (bAVMs), with aims such as lessening the technical difficulty of the microsurgical procedure, reducing operative time, decreasing blood loss, and improving patient functional outcomes. We aim to perform a systematic review of randomised trials and cohort studies evaluating preoperative embolisation of bAVMs published between 01 January 2000 and 31 March 2021 and appraise its role in clinical practice. A MEDLINE search was performed, and articles reporting on outcomes following preoperative embolisation, as an adjunct to microsurgery, were eligible for inclusion. PRISMA reporting and Cochrane Handbook guidelines were followed. The primary outcome measure was the risk of complications associated with preoperative embolisation. The study was registered with PROSPERO (CRD42021244231). Of the 1661 citations, 8 studies with 588 patients met predefined inclusion criteria. No studies specifically compared outcomes of surgical excision of bAVMs between those with and without preoperative embolisation. Spetzler Martin (SM) grading was available in 301 cases. 123 of 298 (41⋅28%) patients presented with haemorrhage. Complications related to embolisation occurred in 175/588 patients (29.4%, 95% CI 19.6–40.2). Permanent neurological deficits occurred in 36/541 (6%, 95% CI 3.9–8.5) and mortality in 6/588 (0.41%, 95% CI 0–1.4). This is the first systematic review evaluating preoperative embolisation of bAVMs. Existing studies assessing this intervention are of poor quality. Associated complication rates are significant. Based on published literature, there is currently insufficient evidence to recommend preoperative embolisation of AVMs. Further studies are required to ascertain if there are benefits of this procedure and if so, in which cases.

Endovascular Management of Hemorrhagic Stroke

Significant advances in endovascular neurosurgery tools, devices, and techniques are changing the approach to the management of acute hemorrhagic stroke. The endovascular treatment of intracranial aneurysms emerged in the early 1990s with Guglielmi detachable coils, and since then, it gained rapid popularity that surpassed open surgery. Stent-assisted coiling and balloon remodeling techniques have made the treatment of wide-necked aneurysms more durable. With the introduction of flow diverters and flow disrupters, many aneurysms with complex geometrics can now be reliably managed. Arteriovenous malformations and fistulae can also benefit from endovascular therapy by embolization using n-butyl cyanoacrylate (NBCA), Onyx, polyvinyl alcohol (PVA), and coils. In this article, we describe the role of endovascular treatment for the most common causes of intracerebral and subarachnoid hemorrhages, particularly ruptured aneurysms and vascular malformations.

Effects of Preoperative Embolization on Spetzler-Martin Grade I and II Arteriovenous Malformations: A Propensity-Adjusted Analysis

BACKGROUND

Cerebral arteriovenous malformations (AVMs) with low Spetzler-Martin grades (I and II) are associated with good neurological outcomes after microsurgical resection; however, the use of preoperative embolization for these lesions is controversial.

OBJECTIVE

To compare the neurological outcomes of preoperative embolization with no embolization in patients with low-grade AVMs.

METHODS

Patients with a Spetzler-Martin grade I or II AVM who underwent microsurgical resection during January 1, 1997, through December 31, 2019, were analyzed. Patients undergoing preoperative embolization were compared with patients not undergoing embolization. A propensity score was constructed from baseline characteristics and used to match intervention (embolization) and control (nonembolization) groups in a 1:1 ratio. The primary outcome was poor neurological status on last follow-up examination, defined as a modified Rankin Scale score >2 and a modified Rankin Scale score worse at follow-up than at the preoperative examination.

RESULTS

Of the 603 patients analyzed, 310 (51.4%) underwent preoperative embolization and 293 (48.6%) did not. Patients in the embolization cohort compared with those in the nonembolization cohort had a higher percentage of Spetzler-Martin grade II AVMs (71.6% vs 52.6%, P < .001) and a lower percentage of hemorrhage (41% vs 55%, P = .001). After propensity score matching, no differences were found between paired cohorts (each N = 203) for baseline characteristics with a significant reduction in absolute standardized mean differences. No significant differences were found in primary outcomes between treatment groups in the matched or unmatched cohorts.

CONCLUSION

Preoperative embolization of low-grade Spetzler-Martin AVMs is not associated with improved neurological outcomes after microsurgical resection.

Migration of n-BCA glue as a complication of venous malformation treatment in children

Preoperative n-butyl cyanoacrylate (n-BCA) embolization of venous malformations facilitates surgical resection. Although embolization is generally well-tolerated, central venous n-BCA migration can occur. The purpose of this article is to describe 3 cases of glue migration requiring glue embolectomy. Strategies for prevention and treatment of glue migration during embolization of venous malformations are reviewed.

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

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

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

Background

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

Material and Methods

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

Results

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

Conclusion

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

Spetzler-Martin Grade III Arteriovenous Malformations: A Multicenter Propensity-Adjusted Analysis of the Effects of Preoperative Embolization

BACKGROUND

Spetzler-Martin (SM) grade III arteriovenous malformations (AVMs) are at the boundary of safe operability, and preoperative embolization may reduce surgical risks.

OBJECTIVE

To evaluate the benefits of preoperative AVM embolization by comparing neurological outcomes in patients with grade III AVMs treated with or without preoperative embolization.

METHODS

All microsurgically treated grade III AVMs were identified from 2011 to 2018 at 2 medical centers. Neurological outcomes, measured as final modified Rankin Scale scores (mRS) and changes in mRS from preoperative baseline to last follow-up evaluation, were compared in patients with and without preoperative embolization.

RESULTS

Of the 102 patients with grade III AVMs who were treated microsurgically, 57 (56%) underwent preoperative embolization. Significant differences were found between the patients with and without embolization in AVM eloquence (74% vs 93%, P = .02), size ≥ 3 cm (47% vs 73%, P = .01), diffuseness (7% vs 22%, P = .04), and mean final mRS (1.1 vs 2.0, P = .005). Poor outcomes were more frequent in patients without embolization (38%) than with embolization (7%) (final mRS > 2; P < .001). Propensity-adjusted analysis revealed AVM resection without embolization was a risk factor for poor outcome (mRS score > 2; odds ratio, 4.2; 95% CI, 1.1-16; P = .03).

CONCLUSION

Nonembolization of SM grade III AVMs is associated with an increased risk of poor neurological outcomes after microsurgical resection. Preoperative embolization of intermediate-grade AVMs selected because of large AVM size, surgical inaccessibility of feeding arteries, and high flow should be employed more often than anticipated, even in the context of increasing microsurgical experience with AVMs.

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.

Single institution early clinical experience with the Scepter Mini balloon catheter

BACKGROUND

The use of liquid embolic agents in the endovascular treatment of dural arteriovenous (dAVFs) fistulas and brain arteriovenous malformations (AVMs) has become common practice. The use of dual lumen balloon microcatheters has greatly improved the efficacy of liquid embolization. The purpose of this series is to discuss our early experience with the Scepter Mini dual lumen balloon microcatheter.

METHODS

A retrospective chart review was performed of all patients who underwent embolization with the Scepter Mini dual lumen balloon at a single institution. Technical details and procedural complications were recorded for each case.

RESULTS

In total, 10 Scepter Mini dual lumen balloon microcatheters were used in nine patients. All patients except two were treated for AVMs. Technical success was achieved in all but one case where one balloon had to be discarded due to precipitation of the tantalum powder. Average vessel diameter where the balloon was inflated was 1.1 mm (0.8-2.4 mm). It provided flow arrest in 100% of cases with no cases of reflux of embolic material. Balloon "jump back" was found to occur in 44.4% (4/9) of cases. Seven out of nine cases used Onyx, and two cases used n-butyl cyanoacrylate.

CONCLUSIONS

The Scepter Mini is a new dual lumen balloon ideal for distal access and can be used for embolization with liquid embolic agents with a high degree of technical success. Its great benefit is the immediate and safe flow arrest of distal vasculature upon balloon inflation. One important consideration for effective embolization is early identification of balloon jump back.

Comparing N-hexyl cyanoacrylate (Magic Glue) and N-butyl cyanoacrylate (NBCA) for neurovascular embolization using the pressure cooker technique: An experimental study in swine

BACKGROUND

The pressure cooker (PC) technique uses a second microcatheter to produce a proximal occlusion to prevent the reflux of liquid embolic agent (LEA) injected through a more distal microcatheter, and can be used to treat arteriovenous malformations and dural arteriovenous fistulae. The liquid embolic Magic Glue (MG) (N-hexyl cyanoacrylate (NHCA)) has been introduced as an alternative to N-butyl cyanoacrylate (NBCA). Our goals were to compare the extent of embolization of rete mirabile with or without the PC technique using NBCA or MG, and to compare the proximal occlusions obtained with MG or NBCA while using the PC technique in a renal arterial model.

METHODS

Rete mirabile were embolized with (n = 4) and without (n = 4) the PC technique, using MG (n = 4) or NBCA (n = 4). A renal arterial model was then used to study the characteristics of the MG plug (n = 10) used for the PC technique, and resistance to catheter withdrawal as compared to NBCA (n = 4). Specimens were analyzed macro- and microscopically and compared to angiographic results.

RESULTS

Extent of rete embolization with CYA agents was not significantly greater when using the PC technique. Results were similar with both types of cyanoacrylate (p = 0.657). The force necessary to withdraw the microcatheter was less with MG than with NBCA (p = 0.035).

CONCLUSION

MG was similar to NBCA in extent of rete embolization. Less traction force was necessary to withdraw trapped non-detachable microcatheters using MG compared to NBCA.

Pial arteriovenous fistula: A clinical and neuro-interventional experience of outcomes in a rare entity

Purpose:

Pial arteriovenous fistulae (PAVF) are rare intracranial vascular malformations, predominantly seen in children and distinct from arteriovenous malformations and dural arteriovenous fistulae. PAVF often leads to high morbidity and mortality. The aim of our study was to describe the clinical features and endovascular management of PAVF at various intracranial locations; to analyze the use of liquid embolic agents and coils alone or in combination in the treatment of PAVF and to analyze the outcome of embolization.

Materials and Methods:

Retrospective review of diagnostic angiography and neurointerventional database of our institution identified a cohort of 15 patients with non-galenic PAVF from 2008 to 2014 out of 6750 patients. Fourteen patients were treated endovascularly with coils and liquid embolic materials in combination or alone. Patients were followed up for evaluation of prognosis.

Results:

Age of the patients ranged from 3 to 37 years. Most patients were male and most common presentation was headache followed by seizure. Most common location of fistula was frontal lobe. The most common type was single artery single hole fistula with venous varix. Satisfactory obliteration was seen in all cases. One patient developed intraparenchymal hematoma on the first post procedural day and outcome was poor.

Conclusions:

PAVF are rare intracranial vascular malformations which can effectively be managed endovascularly with liquid embolic, coils alone, or in combination. Complete occlusion of the fistula can be achieved in most cases in a single sitting with a reasonable morbidity related to the procedure, compared with the natural history of this disease.

Brain arteriovenous malformations: A review of natural history, pathobiology, and interventions

Brain arteriovenous malformations (AVMs) are anomalous direct shunts between cerebral arteries and veins that convalesce into a vascular nidus. The treatment strategies for AVMs are challenging and variable. Intracranial hemorrhage and seizures comprise the most common presentations of AVMs. However, incidental AVMs are being diagnosed with increasing frequency due to widespread use of noninvasive neuroimaging. The balance between the estimated cumulative lifetime hemorrhage risk vs the risk of intervention is often the major determinant for treatment. Current management options include surgical resection, embolization, stereotactic radiosurgery (SRS), and observation. Complete nidal obliteration is the goal of AVM intervention. The risks and benefits of interventions vary and can be used in a combinatorial fashion. Resection of the AVM nidus affords high rates of immediate obliteration, but it is invasive and carries a moderate risk of neurologic morbidity. AVM embolization is minimally invasive, but cure can only be achieved in a minority of lesions. SRS is also minimally invasive and has little immediate morbidity, but AVM obliteration occurs in a delayed fashion, so the patient remains at risk of hemorrhage during the latency period. Whether obliteration can be achieved in unruptured AVMs with a lower risk of stroke or death compared with the natural history of AVMs remains controversial. Over the past 5 years, multicenter prospective and retrospective studies describing AVM natural history and treatment outcomes have been published. This review provides a contemporary and comprehensive discussion of the natural history, pathobiology, and interventions for brain AVMs.

Morbidity and mortality associated with sequential flow reduction embolization technique of cerebral arteriovenous malformations using n-butyl cyanoacrylate

BACKGROUND

Endovascular embolization of cerebral arteriovenous malformations (AVM) with liquid n-butyl cyanoacrylate (n-BCA) serves multiple purposes including AVM occlusion and flow reduction in preparation for other treatment modalities. The objective was to study the clinical, structural, and angiographic factors affecting complications associated with AVM treatment by sequential n-BCA embolizations for nidal occlusion versus quantitative flow reduction in preparation for surgical resection or radiosurgery.

METHODS

We performed a retrospective review of all patients who underwent endovascular embolization of cerebral AVM at our institution between 1998 and 2019, during which time the technique of traditional embolization evolved to a strategy of targeted sequential flow reduction guided by serial flow imaging based on quantitative magnetic resonance angiography, in conjunction with a shift away from nidal penetration.

RESULTS

Among 251 patients, 47.8% of patients presented with ruptured AVM. On average, each patient underwent 2.4 embolizations, for a total of 613 sessions. Major morbidity related to embolization occurred in 18 (7.2%) patients, but this occurred disproportionately in the traditional embolization strategy (n=16, 8%) in contrast with the flow-targeting strategy (n=2, 3.8%). Four patients (1.6%) died in the overall group, and these all occurred with the traditional embolization strategy (2% of 199 patients); no deaths occurred in the flow-targeting strategy (n=52).

CONCLUSION

Embolization with n-BCA targeted to sequential flow reduction and feeder occlusion with limited nidal penetration prior to definitive surgical or radiosurgical treatment can be safely performed with low overall morbidity and mortality.

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.

Medical management with interventional therapy versus medical management alone for unruptured brain arteriovenous malformations (ARUBA): final follow-up of a multicentre, non-blinded, randomised controlled trial

BACKGROUND

In A Randomized trial of Unruptured Brain Arteriovenous malformations (ARUBA), randomisation was halted at a mean follow-up of 33·3 months after a prespecified interim analysis showed that medical management alone was superior to the combination of medical management and interventional therapy in preventing symptomatic stroke or death. We aimed to study whether these differences persisted through 5-years' follow-up.

METHODS

ARUBA was a non-blinded, randomised trial done at 39 clinical centres in nine countries. Adults (age ≥18 years) diagnosed with an unruptured brain arteriovenous malformation, who had never undergone interventional therapy, and were considered by participating clinical centres to be suitable for intervention to eradicate the lesion, were eligible for inclusion. Patients were randomly assigned (1:1) by a web-based data collection system, stratified by clinical centre in a random permuted block design with block sizes of two, four, and six, to medical management alone or with interventional therapy (neurosurgery, embolisation, or stereotactic radiotherapy, alone or in any combination, sequence, or number). Although patients and investigators at a given centre were not masked to treatment assignment, investigators at other centres and those in the clinical coordinating centre were not informed of assignment or outcomes at any of the centres. The primary outcome was time to death or symptomatic stroke confirmed by imaging, assessed by a neurologist at each centre not involved in the management of participants' care, and monitored by an independent committee using an adaptive approach with interim analyses. Enrolment began on April 4, 2007, and was halted on April 15, 2013, after which follow-up continued until July 15, 2015. All analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, NCT00389181.

FINDINGS

Of 1740 patients screened, 226 were randomly assigned to medical management alone (n=110) or medical management plus interventional therapy (n=116). During a mean follow-up of 50·4 months (SD 22·9), the incidence of death or symptomatic stroke was lower with medical management alone (15 of 110, 3·39 per 100 patient-years) than with medical management with interventional therapy (41 of 116, 12·32 per 100 patient-years; hazard ratio 0·31, 95% CI 0·17 to 0·56). Two patients in the medical management group and four in the interventional therapy group (two attributed to intervention) died during follow-up. Adverse events were observed less often in patients allocated to medical management compared with interventional therapy (283 vs 369; 58·97 vs 78·73 per 100 patient-years; risk difference -19·76, 95% CI -30·33 to -9·19).

INTERPRETATION

After extended follow-up, ARUBA showed that medical management alone remained superior to interventional therapy for the prevention of death or symptomatic stroke in patients with an unruptured brain arteriovenous malformation. The data concerning the disparity in outcomes should affect standard specialist practice and the information presented to patients. The even longer-term risks and differences between the two therapeutic approaches remains uncertain.

FUNDING

National Institute of Neurological Disorders and Stroke for the randomisation phase and Vital Projects Fund for the follow-up phase.

Estimation of dosimetric discrepancy due to use of Onyx™ embolic system in Stereotactic Radiosurgery/Radiotherapy (SRS/SRT) planning

More often the embolic materials in the brain create artefacts in the planning CT images that could lead to a dose variation in planned and delivered dose. The aim of the study was to evaluate the dosimetric effect of artefacts generated by the Onyx™ embolization material during Stereotactic Radiosurgery/Radiotherapy (SRS/SRT) planning. An in-house made novel Polymethyl Methacrylate (PMMA) head phantom (specially designed for SRS/SRT plans) was used for this purpose. For the evaluation process, we have created concentric ring structures around the central Onyx materials on both the CT sets (with and without Onyx material). The verification plans were generated using different algorithms namely Analytical Anisotropic Algorithm (AAA), Acuros XB and Monaco based Monte Carlo on both CT sets. Mean integral dose over the region of interest were calculated in both CT sets. The dosimetric results shows, due to the presence of Onyx material, relative variation in mean integral dose to the proximal structure (Ring 1) were -4.02%, -2.98%, and -2.49% for Monte Carlo, Acuros XB, and AAA respectively. Observed variations are attributed to the presence of artefacts due to Onyx material. Artefacts influence the accuracy of dose calculation during the planning. All the calculation algorithms are not equally capable to account such variations. Special cares are to be taken while choosing the calculation algorithms as it impacts the results of treatment outcome.

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.

Intermixed Dimethyl-Sulfoxide-Based Nonadhesive Liquid Embolic Agents Delivered Serially via the Same Microcatheter for Cerebral AVM Treatment

BACKGROUND AND PURPOSE

Conventional nonadhesive liquid embolic agents currently are the criterion standard for endovascular embolization of cerebral AVMs. However, inadequate distal penetration into the nidus and unstable proximal plug formation are the major limitations of this approach and of the currently available embolic materials. The aim of this study was to evaluate the hypothetic efficacy of combining liquid embolic agents with different properties and viscosities for use in endovascular embolization of cerebral AVMs.

MATERIALS AND METHODS

From March 2018 to March 2019, sixteen patients with cerebral AVMs (12 women, 4 men; age range, 33-61 years) underwent endovascular embolization with combined liquid embolic agents delivered serially via a single microcatheter. The procedure consists of initial embolization with PHIL 30%, followed by Menox 18 through the same microcatheter. According to the Spetzler-Martin scale, 11 (68.75%) AVMs were grades I-II, 4 (25%) were grade III, and 1 (6.25%) was grade IV. Angiographic, technical, and clinical outcomes were analyzed independently.

RESULTS

Combined PHIL and Menox embolization through the same microcatheter via 21 pedicles was performed in these 16 patients. Once the length of the reflux reached approximately 2 cm, PHIL 30% was switched to Menox 18. Antegrade flow and distal penetration of the serially applied liquid embolic agents were observed in all 16 cases. The ability to completely control the flow of the materials and avoid any dangerous proximal reflux was noted in all performed embolizations. The estimated average size reduction of the treated AVMs was 85%, ranging from 50% to 100%. Complete embolization was achieved in 10/16 or 62.5% of the cases. There was no procedure-related complication during or after the embolization. No mortality or postprocedural clinical worsening was seen. Clinical success and complete obliteration were confirmed with at least 1 follow-up angiography in 10/16 patients.

CONCLUSIONS

Serial delivery of nonadhesive liquid embolic agents via the same microcatheter was safe and effective in our study and may be a potential technique for routine AVM treatment. However, further investigations are required to validate the safety and the efficacy of the method.

Embolized cerebral arteriovenous malformations: a multivariate analysis of 101 excised specimens

OBJECTIVE

Endovascular approaches have evolved from a technique practiced at very few centers to a widely available option in the management of arteriovenous malformations (AVMs) of the central nervous system. Embolization can be employed as definitive therapy or as an adjunct to surgical excision. A wide variety of embolic agents have been successfully developed and used in the clinical setting. In addition to facilitating vascular occlusion, embolic agents induce a number of reactive and destructive changes in vessel walls and the surrounding tissue. However, studies examining the pathological changes induced by different embolic agents and varying times of exposure are scarce. The goal of the present study was to compare embolic agents and time of exposure on the pathology in excised specimens.

METHODS

The records of the Department of Pathology at the London Health Sciences Centre were searched for embolized AVMs for the 35-year period 1980–2015. All cases were reevaluated for clinical and technical variables and standardized histopathological findings. Cases were grouped by embolic agent, volume of agent used, and time to excision.

RESULTS

A total of 101 specimens were identified. Embolic agents were invariably associated with a range of pathological findings, some of which may affect the integrity of vessel walls or the reestablishment of flow, thrombosis, acute and chronic inflammatory changes, angionecrosis, extravasation, and recanalization. The type of embolic agent did not predict differences in the incidence or severity of histopathological changes. Larger volumes of embolic agent were associated with a greater proportion of vessels containing embolic material. AVMs excised early (< 1 week postembolization) contained more acute vasculitis, while those excised later (≥ 1 week postembolization) were more likely to exhibit recanalization and foreign body giant cell infiltrates.

CONCLUSIONS

Embolic agents induce a predictable range and temporal progression of pathological changes in cerebral AVMs. The embolic agents studied are indistinguishable in terms of the range and frequency of pathological reactions induced. Greater volumes of embolic agent are associated with more abundant agent within the lesion, but the proportion of vessels and vascular cross-sectional areas containing agent is small. Several changes are significantly associated with time postembolization. Acute vasculitis is a more common finding in the 1st week, while recanalization and foreign body–type granulomatous inflammation are more common at 1 week and beyond.

Outcomes of Onyx® Embolization of Type II Endoleaks After Endovascular Repair of Abdominal Aortic Aneurysms

BACKGROUND

Type II endoleaks (T2ELs) are common following endovascular repair of abdominal aortic aneurysms (EVAR). Embolization with ethylene vinyl alcohol copolymer (Onyx) may present an effective treatment alternative for T2ELs. Due to limited data supporting its use, we sought to analyze outcomes of Onyx embolization for T2ELs.

METHODS

Retrospective review of consecutive patients treated for T2ELs utilizing Onyx embolization agent from 2009-2018. All pre- and post-Onyx intervention CT scans were analyzed for diameter and volume changes with 3D reconstruction software. The primary outcomes were change in maximum AAA diameter and volume. Secondary outcomes included additional interventions, rupture, and mortality. A subset analysis was performed with patients with isolated T2ELs (no other types of endoleaks present).

RESULTS

We identified 85 patients (73 males, mean age 77.6 ± 7.6 years) who underwent 112 Onyx interventions. Average time to first Onyx intervention after index EVAR was 3.3 ± 2.6 years and average sac growth was 6.3 ± 6.7 mm. Patients underwent mean 1.3 Onyx interventions using a mean of 4.9 ± 4.7 ml for treatment. Three complications occurred (Onyx extravasation, colon ischemia, and access site hematoma). Mean follow-up was 2.5 ± 2.1 years after initial Onyx treatment. At the most recent follow-up, sac diameter stabilization was seen in 47% and reduction >5 mm was seen in 19%. Sac growth of >5 mm was seen in 34% of patients following the first Onyx intervention. In our subset of isolated T2EL, 72% had sac stabilization or reduction >5 mm. Four patients experienced a ruptured aneurysm (3 had active type 1 endoleaks). Rupture-free survival was 95% at 5 years, and overall survival was 54% at 5 years. Notably, increasing Onyx interventions were not associated with sac stabilization or reduction (OR 0.6, P = 0.1). On multivariable analysis, AAA sac diameter stabilization or reduction was independently associated with BMI >30 kg/m² (OR 4.2, P = 0.01) and having only 1 Onyx intervention (OR 3.8, P = 0.02).

CONCLUSIONS

Onyx for embolization of T2ELs resulted in AAA sac diameter stabilization or reduction in 66% of patients, and up to 72% in isolated T2ELs. Further, increasing Onyx interventions were not associated with either aneurysm sac stabilization or reduction. Given its similar outcomes to other embolization strategies in the literature, Onyx embolization for management of T2ELs needs to be judiciously considered, particularly for T2ELs persisting after an initial Onyx embolization intervention.

Immediate and 1-year success rate of type 2 endoleak treatment using three-dimensional image fusion guidance

PURPOSE

To retrospectively assess immediate and 1-year success rate of type 2 endoleak (T2E) treatment with ethylene-vinyl-alcohol-polymer using three-dimensional (3D) image fusion guidance with cone beam computed tomography via trans-arterial embolization (TAE) or direct percutaneous sac injection (DPSI).

MATERIALS AND METHODS

A total of 37 patients with T2E who were treated either using TAE (34/37; 92%) or DPSI (9/37; 8%) were included. There were 34 men and 3 women with a mean age of 86±9 (SD) years (range: 67-104years). Mean aneurysm diameter was 67±14 (SD) mm (range: 42-101mm) at pre-procedure evaluation. Immediate success was complete embolization of the sac and feeding artery. 1-year success was reduction or stability of the aneurysmal sac diameter based on pre-procedure and 12-month follow-up examinations. Safety (treatment-related complications), patient demographics, duration of procedure and contrast volume were reported.

RESULTS

Immediate and 1-year successful outcomes were reported in 94% (n=32) and 88% (n=28) of patients after TAE and 100% (n=9) and 89% (n=8) after DPSI. T2E treatments were immediately successful for 95% of the procedures (41/43) and for 88% (36/41) at 1year. Overall, T2E treatment was effective in 33 patients (89%). No major complications occurred. Mean procedure time and contrast volume were significantly different between the 2 techniques with respectively 87±16 (SD) min (range: 65-120min) and 75±26 (SD) mL (range: 40-130mL) for TAE and 32±10 (SD) min (range: 20-50min) (P<0.01) and 6±6 (SD) mL (range: 2-22mL) (P<0.01) for DPSI. Mean aneurysm diameter at 1-year was 68±17 (SD) mm (range: 43-101mm). No significant differences in the pre-procedure sac diameter were found at long-term follow-up between patients without T2E and those with persistent T2E (P=0.1) in the successful embolization group (n=33).

CONCLUSION

TAE or DPSI treatments of T2E with ethylene-vinyl-alcohol-polymer using 3D-image fusion guidance were immediately successful for 95% of the procedures and remained effective for 88%. Longer follow-up is necessary to assess sac stability in the case of persistent endoleak.

Neuroendovascular surgery

Neuroendovascular surgery and interventional neuroradiology both describe the catheter-based (most often) endovascular diagnosis and treatment of vascular lesions affecting the brain and spinal cord. This article traces the evolution of these techniques and their current role as the dominant and frequently standard approach for many of these conditions. The article also discusses the important changes that have been brought to bear on open cerebrovascular neurosurgery by neuroendovascular surgery and their effects on resident and fellow training and describes new concepts for clinical care.

Interventions for treating brain arteriovenous malformations in adults

BACKGROUND

Brain arteriovenous malformations (AVMs) are the single most common cause of intracerebral haemorrhage in young adults. Brain AVMs also cause seizure(s) and focal neurological deficits (in the absence of haemorrhage, migraine or an epileptic seizure); approximately one-fifth are incidental discoveries. Various interventions are used in an attempt to eradicate brain AVMs: neurosurgical excision, stereotactic radiosurgery, endovascular embolization, and staged combinations of these interventions. This is an update of a Cochrane Review first published in 2006, and last updated in 2009.

OBJECTIVES

To determine the effectiveness and safety of the different interventions, alone or in combination, for treating brain AVMs in adults compared against either each other, or conservative management, in randomized controlled trials (RCTs).

SEARCH METHODS

The Cochrane Stroke Group Information Specialist searched the Cochrane Stroke Group Trials Register (last searched 7 January 2019), the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 1) in the Cochrane Library, MEDLINE Ovid (1980 to 14 January 2019), and Embase OVID (1980 to 14 January 2019). We searched international registers of clinical trials, the contents pages of relevant journals, and bibliographies of relevant articles (November 2009). We also contacted manufacturers of interventional treatments for brain AVMs (March 2005).

SELECTION CRITERIA

We sought RCTs of any intervention for brain AVMs (used alone or in combination), compared against each other or against conservative management, with relevant clinical outcome measures.

DATA COLLECTION AND ANALYSIS

One author screened the results of the updated searches for potentially eligible RCTs for this updated review. Both authors independently read the potentially eligible RCTs in full and confirmed their inclusion according to the inclusion criteria. We resolved disagreement by discussion. We assessed the risk of bias in included studies and applied GRADE.

MAIN RESULTS

We included one trial with 226 participants: A Randomized trial of Unruptured Brain Arteriovenous Malformations (ARUBA), comparing intervention versus conservative management for unruptured brain AVMs (that had never bled). The quality of evidence was moderate because we found just one trial that was at low risk of bias other than a high risk of performance bias due to participants and treating physicians not being blinded to allocated treatment. Data on functional outcome and death at a follow-up of 12 months were provided for 218 (96%) of the participants in ARUBA. In this randomized controlled trial (RCT), intervention compared to conservative management increased death or dependency (modified Rankin Scale score ≥ 2, risk ratio (RR) 2.53, 95% confidence interval (CI) 1.28 to 4.98; 1 trial, 226 participants; moderate-quality evidence) and the proportion of participants with symptomatic intracranial haemorrhage (RR 6.75, 95% CI 2.07 to 21.96; 1 trial, 226 participants; moderate-quality evidence), but there was no difference in the frequency of epileptic seizures (RR 1.14, 95% CI 0.63 to 2.06; 1 trial, 226 participants; moderate-quality evidence). Three RCTs are ongoing.

AUTHORS' CONCLUSIONS

We found moderate-quality evidence from one RCT including adults with unruptured brain AVMs that conservative management was superior to intervention with respect to functional outcome and symptomatic intracranial haemorrhage over one year after randomization. More RCTs will help to confirm or refute these findings.

Risk factors for hemorrhage of brain arteriovenous malformation

Patients with brain arteriovenous malformation (bAVM) are at risk of intracranial hemorrhage (ICH). Overall, bAVM accounts for 25% of hemorrhagic strokes in adults <50 years of age. The treatment of unruptured bAVMs has become controversial, because the natural history of these patients may be less morbid than invasive therapies. Available treatments include observation, surgical resection, endovascular embolization, stereotactic radiosurgery, or combination thereof. Knowing the risk factors for bAVM hemorrhage is crucial for selecting appropriate therapeutic strategies. In this review, we discussed several biological risk factors, which may contribute to bAVM hemorrhage.

The effect of preoperative embolization and flow dynamics on resection of brain arteriovenous malformations

OBJECTIVE

Preoperative embolization of brain arteriovenous malformations (AVMs) is performed to facilitate resection, although its impact on surgical performance has not been clearly defined. The authors tested for associations between embolization and surgical performance metrics.

METHODS

The authors analyzed AVM cases resected by one neurosurgeon from 2006 to 2017. They tested whether cases with and without embolization differed from one another with respect to patient and AVM characteristics using t-tests for continuous variables and Fisher's exact tests for categorical variables. They used simple and multivariable regression models to test whether surgical outcomes (blood loss, resection time, surgical clip usage, and modified Rankin Scale [mRS] score) were associated with embolization. Additional regression analyses integrated the peak arterial afferent contrast normalized for the size of the region of interest (Cmax/ROI) into models as an additional predictor.

RESULTS

The authors included 319 patients, of whom 151 (47%) had preoperative embolization. Embolized AVMs tended to be larger (38% with diameter > 3 cm vs 19%, p = 0.001), less likely to have hemorrhaged (48% vs 63%, p = 0.013), or be diffuse (19% vs 29%, p = 0.045). Embolized AVMs were more likely to have both superficial and deep venous drainage and less likely to have exclusively deep drainage (32% vs 17% and 12% vs 23%, respectively; p = 0.002). In multivariable analysis, embolization was not a significant predictor of blood loss or mRS score changes, but did predict longer operating times (+29 minutes, 95% CI 2-56 minutes; p = 0.034) and increased clip usage (OR 2.61, 95% CI 1.45-4.71; p = 0.001). Cmax/ROI was not a significant predictor, although cases with large Cmax/ROI tended to have longer procedure times (+25 minutes per doubling of Cmax/ROI, 95% CI 0-50 minutes; p = 0.051).

CONCLUSIONS

In this series, preoperative embolization was associated with longer median resection times and had no association with intraoperative blood loss or mRS score changes.

The future of open vascular neurosurgery: perspectives on cavernous malformations, AVMs, and bypasses for complex aneurysms

Despite the erosion of microsurgical case volume because of advances in endovascular and radiosurgical therapies, indications remain for open resection of pathology and highly technical vascular repairs. Treatment risk, efficacy, and durability make open microsurgery a preferred option for cerebral cavernous malformations, arteriovenous malformations (AVMs), and many aneurysms. In this paper, a 21-year experience with 7348 cases was reviewed to identify trends in microsurgical management. Brainstem cavernous malformations (227 cases), once considered inoperable and managed conservatively, are now resected in increasing numbers through elegant skull base approaches and newly defined safe entry zones, demonstrating that microsurgical techniques can be applied in ways that generate entirely new areas of practice. Despite excellent results with microsurgery for low-grade AVMs, brain AVM management (836 cases) is being challenged by endovascular embolization and radiosurgery, as well as by randomized trials that show superior results with medical management. Reviews of ARUBA-eligible AVM patients treated at high-volume centers have demonstrated that open microsurgery with AVM resection is still better than many new techniques and less invasive approaches that are occlusive or obliterative. Although the volume of open aneurysm surgery is declining (4479 cases), complex aneurysms still require open microsurgery, often with bypass techniques. Intracranial arterial reconstructions with reimplantations, reanastomoses, in situ bypasses, and intracranial interpositional bypasses (third-generation bypasses) augment conventional extracranial-intracranial techniques (first- and second-generation bypasses) and generate innovative bypasses in deep locations, such as for anterior inferior cerebellar artery aneurysms. When conventional combinations of anastomoses and suturing techniques are reshuffled, a fourth generation of bypasses results, with eight new types of bypasses. Type 4A bypasses use in situ suturing techniques within the conventional anastomosis, whereas type 4B bypasses maintain the basic construct of reimplantations or reanastomoses but use an unconventional anastomosis. Bypass surgery (605 cases) demonstrates that open microsurgery will continue to evolve. The best neurosurgeons will be needed to tackle the complex lesions that cannot be managed with other modalities. Becoming an open vascular neurosurgeon will be intensely competitive. The microvascular practice of the future will require subspecialization, collaborative team effort, an academic medical center, regional prominence, and a large catchment population, as well as a health system that funnels patients from hospital networks outside the region. Dexterity and meticulous application of microsurgical technique will remain the fundamental skills of the open vascular neurosurgeon.

[Immediate outcomes of microsurgical treatment of cerebral arteriovenous malformations in non-hemorrhagic patients]

Arteriovenous malformations (AVMs) are some of the most frequent congenital abnormalities of the cerebral vascular system and usually occur at a young age. Given the fact that AVMs can manifest, in addition to hemorrhages, as symptomatic epilepsy (17-40%) that occurs more often at a young age and may lead to significant disability, investigation of this pathology remains topical. Particular attention has recently been paid to the management of AVM patients without clinical signs of hemorrhage at the time of pathology diagnosis.

OBJECTIVE

The objective of this study was to optimize the management of patients with unruptured AVMs based on analysis of the immediate outcomes of microsurgical treatment.

MATERIAL AND METHODS

We retrospectively analyzed the immediate outcomes of microsurgical treatment of AVM patients hospitalized to the Burdenko Neurosurgical Institute in the period from 2009 to 2017. The patients included in the study met the following criteria: age over 18 years; microsurgical resection of AVM. The main exclusion criterion was a hemorrhage history confirmed by clinical data or verified by a neuroimaging study (MRI/CT). The study included 160 patients (58.1% males and 41.9% females) aged 18 to 67 years (mean, 33.5 years). According to the clinical course, patients with epileptic syndrome prevailed: 99 (61.9%) cases. Headaches occurred in 49 (30.6%) patients; 8 (5%) patients had asymptomatic AVMs; 4 (2.5%) patients had ischemic stroke. The surgical risk was assessed by using the Spetzler-Martin (S-M) scale: Grade I - 18 (11.3%) patients, Grade II - 71 (44.4%) patients, Grade III - 60 (37.5%) patients, and Grade IV - 11 (6.8%) patients. Direct surgery in patients with AVMs classified as S-M V was not planned.

RESULTS

Postoperative analysis revealed that 33 patients included in the study group in accordance with the above criteria had silent AVM hemorrhage that was confirmed only based on the intraoperative picture. The best surgical treatment outcomes were observed in patients with S-M I and II AVMs. The outcome scored 4 and 5 on the Glasgow Outcome Scale (GOS) was in 100% of cases in the S-M I group, 98.6% in the S-M II group, 86.7% in the S-M III group, and 81.8% in the S-M IV group. The relatively good outcomes of S-M IV AVM resection are explained by careful selection of patients for surgery. In general, good postoperative outcomes (GOS score of 4 and 5) were in 93.2% of patients. The main newly developed postoperative symptoms were visual impairments - visual field defects (64.7% of all complications). Postoperative mortality was 1.3%.

CONCLUSION

Surgical treatment is indicated for patients with unruptured AVMs and S-M I or II surgical risk, regardless of clinical manifestations. In other cases, the treatment approach depends on a number of risk factors.

N-butyl cyanoacrylate embolotherapy: techniques, complications, and management

The purpose of this article is to describe acute complications associated with adhesive cyanoacrylate deposition in the peripheral circulation and their management. Despite best efforts, n-butyl cyanoacrylate glue embolization is inherently unpredictable and complications do occur. An understanding of preparation techniques that minimize adverse event rates and the technical skillset required to manage complications are necessary for the safe and efficient use of liquid embolic agents.

Transvenous embolization of brain arteriovenous malformations: a review of techniques, indications, and outcomes

Endovascular embolization of brain arteriovenous malformations (AVMs) is conventionally performed from a transarterial approach. Transarterial AVM embolization can be a standalone treatment or, more commonly, used as a neoadjuvant therapy prior to microsurgery or stereotactic radiosurgery. In contrast to the transarterial approach, curative embolization of AVMs may be more readily achieved from a transvenous approach. Transvenous embolization is considered a salvage therapy in contemporary AVM management. Proposed indications for this approach include a small (diameter < 3 cm) and compact AVM nidus, deep AVM location, hemorrhagic presentation, single draining vein, lack of an accessible arterial pedicle, exclusive arterial supply by perforators, and en passage feeding arteries. Available studies of transvenous AVM embolization in the literature have reported high complete obliteration rates, with reasonably low complication rates. However, evaluating the efficacy and safety of this approach is challenging due to the limited number of published cases. In this review the authors describe the technical considerations, indications, and outcomes of transvenous AVM embolization.

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pial Artery Supply as an Anatomic Risk Factor for Ischemic Stroke in the Treatment of Intracranial Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE

Although intracranial dural arteriovenous fistulas are principally supplied by dural branches of the external carotid, internal carotid, and vertebral arteries, they can also be fed by pial arteries that supply the brain. We sought to determine the frequency of neurologic deficits following treatment of intracranial dural arteriovenous fistulas with and without pial artery supply.

MATERIALS AND METHODS

One hundred twenty-two consecutive patients who underwent treatment for intracranial dural arteriovenous fistulas at our hospital from 2008 to 2015 were retrospectively reviewed. Patient data were examined for posttreatment neurologic deficits; patients with such deficits were evaluated for imaging evidence of cerebral infarction. Data were analyzed with multivariable logistic regression.

RESULTS

Of 122 treated patients, 29 (23.8%) had dural arteriovenous fistulas with pial artery supply and 93 (76.2%) had dural arteriovenous fistulas without pial arterial supply. Of patients with pial artery supply, 4 (13.8%) had posttreatment neurologic deficits, compared with 2 patients (2.2%) without pial artery supply (P = .04). Imaging confirmed that 3 patients with pial artery supply (10.3%) had cerebral infarcts, compared with only 1 patient without pial artery supply (1.1%, P = .03). Increasing patient age was also positively associated with pial supply and treatment-related complications.

CONCLUSIONS

Patients with dural arteriovenous fistulas supplied by the pial arteries were more likely to experience posttreatment complications, including ischemic strokes, than patients with no pial artery supply. The approach to dural arteriovenous fistula treatment should be made on a case-by-case basis so that the risk of complications can be minimized.