Endovascular treatment of cerebral arteriovenous malformations with emphasis on the curative role of embolisation

Adenosine-assisted embolization of cerebral arteriovenous malformations: a systematic review and meta-analysis

BACKGROUND

Cerebral arteriovenous malformations (AVMs) are complex lesions that can cause hemorrhagic stroke and significant neurological disability. Adenosine induces cardiac standstill and hypotension, which are thought to be useful during cerebral AVM embolization. Herein, we conducted a systematic review and meta-analysis of the technique's safety.

METHODS

Following PRISMA guidelines, four databases were queried for studies describing the use of adenosine-assisted embolization of cerebral AVMs. Adenosine-related intraoperative complications, permanent neurological outcomes, morbidity, and mortality assessed the technique's safety. Single proportion analysis under a random-effects model was performed. Heterogeneity was assessed using I² statistics, and publication bias was evaluated through funnel plot analysis and Egger's regression test.

RESULTS

Ten studies were included, involving 79 patients (55.7% male) with 79 AVMs (54.4% unruptured and 70.9% Spetzler-Martin grade III-V) who underwent 123 embolizations (80.4% and 5.9% under transarterial and transvenous approaches, respectively) with n-butyl cyanoacrylate (80.4%), ethylene vinyl alcohol (14.4%), or both (5.2%). The incidence of transient adenosine-related intraoperative complications was 0% (95% CI 0% to 3%, I2=24%). Besides, the incidence of adenosine-related morbidity, mortality, and permanent outcomes was 0% (95% CI 0% to 3%, I2=0%). During follow-up, good functional outcomes were reported for 64 patients (81%).

CONCLUSIONS

Adenosine's effects on blood flow control can facilitate embolization and mitigate the risk of AVM rupture and embolic agent migration. Although current evidence stems from observational studies, the results of this meta-analysis suggest a safe drug profile due to minimal associated morbidity and mortality. Further research from larger randomized and controlled studies is warranted to attain a higher level of evidence.

PROSPERO REGISTRY NUMBER

CRD42023494116.

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.

Angiographic predictors of spontaneous obliteration of transarterial partially embolized brain arteriovenous malformations

BACKGROUND

Spontaneous obliteration of cerebral arteriovenous malformations is uncommon but could occur after partial embolization.

METHODS

A retrospective study of 140 patients that underwent embolization for cerebral AVMs from 2005 to August 2019 using liquid embolic agents. The angiographic outcome of patients was classified as regard complete embolization, partial embolization, and complete obliteration after partial embolization. The parameters studied included size, location, number of arterial feeders, number of draining veins, rupture status, embolic agent, and patient factors as well.

RESULTS

The study patients included 74 (53%) females and 66 (47%) males. Their age ranged from 7 to 43 years old. One hundred and eight patients (77%) presented with hemorrhage. The AVM grades were grade II in 57 (40.7%) patients and grade III in 56 (39.3%) patients. Sixty-one (43.57%) patients were treated by n-Butyl Cyanoacrylate and 71 (50.71%) patients were treated with Onyx, and both materials were used together in 8 cases. Follow-up angiography was done from 6 to 36 months after embolization. The rate of complete occlusion in all patients was 61.43% (86 patients). There were three groups of patients, the first group had complete occlusion of the nidus at the time of embolization and included 68 (48.57%) patients. The second group had partial embolization with partial occlusion of the nidus 54 patients (38.57%). The 3rd group included 18 patients (12.85%) with complete nidal occlusion on follow up after partial embolization. The delay in the venous drainage of the AVM to the late arterial phase or early venous phase with flow stasis was a significant predictor of future obliteration on follow up after partial embolization. Other significant parameters that were associated with the progressive disappearance of the AVM nidus on follow up after partial embolization are presentation with hemorrhage, AVMs size less than 3 cm, the presence of single draining or double draining veins, superficial venous drainage, and one or 2 arterial feeders.

CONCLUSION

Spontaneous closure of intracranial arteriovenous malformations after partial embolization may be encountered in cases of stasis of flow during embolization procedure with a delay of the venous drainage. A long-term follow-up of more cases over many years is required to confirm the validity of this conclusion.

Microsurgical Treatment of Deep and Eloquent AVMs

Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.

Single-center experience with endovascular treatment of cerebral arteriovenous malformations with intent to cure in pediatric patients

PURPOSE

This study aimed to report the incidence of technical complications and immediate complete angiographic occlusion, identify associated factors with failure of complete occlusion and identify predictors of technical complications in a single-center experience of pediatric arteriovenous malformations (AVM) treated with endovascular treatment with intent to cure.

METHODS

Patients between 1 and 18 years of age undergoing endovascular embolization between 2011 and 2020 were included.

RESULTS

A total of 120 embolizations were performed in 69 patients. The most frequent clinical presentation was intracerebral hemorrhage (76.8%). Immediate obliteration of the malformations was achieved in 40 (58%) cases. The technical complication rate was 15%. AVM nidus size between 3 and 6 cm (OR: 3.91; 95% CI 1.1-13.85; p = 0.035) and the presence of multiple feeders (OR: 5.08; 95% CI 1.41-18.28; p = 0.074) were predictive of failure of immediate complete occlusion. The location of the temporal lobe (OR: 7.83; p = 0.048), deep venous drainage (OR: 4.67; p = 0.112), and the presence of an intranidal aneurysm (OR: 3.58; p = 0.134) were predictors of technical complications.

CONCLUSIONS

Embolization of pediatric AVMs with intent to cure shows a high rate of technical complications and acceptable immediate occlusion rates. Nidus size and the presence of multiple feeders were predictive of failure of complete occlusion, while temporal lobe location, deep venous drainage, and the presence of an intranidal aneurysm were predictors of technical complications. Further studies are needed to determine the best therapeutic approach in the pediatric population.

4D Flat Panel Conebeam CTA for Analysis of the Angioarchitecture of Cerebral AVMs with a Novel Software Prototype

BACKGROUND AND PURPOSE

Time-resolved 3DRA (4D-DSA) and flat panel conebeam CTA are new methods for visualizing the microangioarchitecture of cerebral AVMs. We applied a 4D software prototype to a series of cases of AVMs to assess the utility of this method in relation to treatment planning.

MATERIALS AND METHODS

In 33 patients with AVMs, 4D volumes and flat panel conebeam CTA images were recalculated from existing 3D rotational angiography data. The multiplanar reconstructions were used to determine intranidal arteriovenous branching patterns, categorize them according to common classifications of AVM angioarchitecture, and compare the results with those from 2D-DSA.

RESULTS

4D flat panel conebeam CTA showed angioarchitectural features equal to or better than those of 2D-DSA in 30 of 33 cases. In particular, the reconstructions helped in understanding the intranidal microvasculature. Fistulous direct arteriovenous connections with a low degree of arterial branching (n = 22) could be distinguished from plexiform arterial networks before the transition to draining veins (n = 11). We identified AVMs with a single draining vein (n = 20) or multiple draining veins (n = 10). Arteriovenous shunts in the lateral wall of the draining veins (n = 22) could be distinguished from cases with increased venous branching and shunts between corresponding intranidal arteries and veins (n = 11). Limitations were the time-consuming postprocessing and the difficulties in correctly tracing intranidal vessels in larger and complex AVMs.

CONCLUSIONS

4D flat panel conebeam CTA reconstructions allow detailed analysis of the nidal angioarchitecture of AVMs. However, further improvements in temporal resolution and automated reconstruction techniques are needed to use the method generally in clinical practice.

Chinese Cerebrovascular Neurosurgery Society and Chinese Interventional & Hybrid Operation Society, of Chinese Stroke Association Clinical Practice Guidelines for Management of Brain Arteriovenous Malformations in Eloquent Areas

Aim: The aim of this guideline is to present current and comprehensive recommendations for the management of brain arteriovenous malformations (bAVMs) located in eloquent areas. Methods: An extended literature search on MEDLINE was performed between Jan 1970 and May 2020. Eloquence-related literature was further screened and interpreted in different subcategories of this guideline. The writing group discussed narrative text and recommendations through group meetings and online video conferences. Recommendations followed the Applying Classification of Recommendations and Level of Evidence proposed by the American Heart Association/American Stroke Association. Prerelease review of the draft guideline was performed by four expert peer reviewers and by the members of Chinese Stroke Association. Results: In total, 809 out of 2,493 publications were identified to be related to eloquent structure or neurological functions of bAVMs. Three-hundred and forty-one publications were comprehensively interpreted and cited by this guideline. Evidence-based guidelines were presented for the clinical evaluation and treatment of bAVMs with eloquence involved. Topics focused on neuroanatomy of activated eloquent structure, functional neuroimaging, neurological assessment, indication, and recommendations of different therapeutic managements. Fifty-nine recommendations were summarized, including 20 in Class I, 30 in Class IIa, 9 in Class IIb, and 2 in Class III. Conclusions: The management of eloquent bAVMs remains challenging. With the evolutionary understanding of eloquent areas, the guideline highlights the assessment of eloquent bAVMs, and a strategy for decision-making in the management of eloquent bAVMs.

Central nervous system vascular malformations: A clinical review

CNS vascular malformation is an umbrella term that encompasses a wide variety of pathologies, with a wide range of therapeutic and diagnostic importance. This range spans lesions with a risk of devastating neurological compromise to lesions with a slow, static or benign course. Advances in neurovascular imaging along with increased utilization of these advances, have resulted in more frequent identification of these lesions. In this article, we provide an overview on definitions and classifications of CNS vascular malformations and outline the etiologic, diagnostic, prognostic, and therapeutic features for each entity. This review covers intracranial and spinal cord vascular malformations and discusses syndromes associated with CNS vascular malformations.

Early Outcomes and Complications of Endovascular Treatment of Cerebral Arteriovenous Malformations in Pediatric Patients

INTRODUCTION

Arteriovenous malformations (AVMs) are the commonest cause of hemorrhagic stroke in children. Endovascular embolization is a feasible treatment modality, but cure rates are heterogenous from one series to another. We aimed to describe the immediate obliteration rates and periprocedural complications of embolization of pediatric AVMs.

METHODS

Between 2011 and 2019, participants below 18 years of age with AVMs treated by the same neurosurgeon at a single center were included. The clinical features, immediate angiographic results, and periprocedural complications were retrospectively collected from the clinical records.

RESULTS

Thirty-four embolization sessions were performed on 20 children (12 females with a mean age of 13). Intracranial hemorrhage was the most common presentation (75%), and the majority were frontal (30%) and basal ganglia (30%) lesions. An immediate complete angiographic obliteration was achieved in 9 patients (45%) with low-grade lesions (Spetzler-Martin grade I and II). NBCA was the most common embolic agent used (52.9%). Complications were reported in 3 (8.8%) out of 34 sessions. Two of them were intraoperative perforations with clinical consequences. A slight cortical hemorrhage during the procedure was observed in 1 patient without clinical repercussions.

DISCUSSION

This single-surgeon single-center experience suggests that endovascular treatment is a safe and efficient treatment for pediatric AVMs. Pediatric prognostic scores for a suitable selection of candidates are needed. Further studies are required to validate these results.

Perinidal Angiogenesis Is a Predictor for Neurovascular Uncoupling in the Periphery of Brain Arteriovenous Malformations: A Task-Based and Resting-State fMRI Study

BACKGROUND

Potential neurovascular uncoupling (NVU) related to perinidal angiogenesis (PA) of brain arteriovenous malformations (AVMs) may cause inappropriate presurgical mapping using functional magnetic resonance imaging (fMRI), resulting in overconfident resection and postoperative morbidity.

PURPOSE

To evaluate the potential impact of PA upon fMRI blood oxygen level-dependent signal in the periphery of AVMs.

STUDY TYPE

Prospective.

POPULATION

Twenty-one patients with AVMs located in the primary sensorimotor cortex (SM1) undergoing task-based fMRI (hand motor), and 19 patients with supratentorial AVMs undergoing resting-state fMRI.

FIELD STRENGTH/SEQUENCE

3.0T, echo-planar, time-of-flight, and magnetization-prepared rapid gradient-echo.

ASSESSMENT

The presence of PA was determined by three observers (Y.C., J.W., and X.C.) according to digital subtraction angiography and MR angiography. Interhemispheric asymmetry of fMRI activations contralateral to hand movements was evaluated with the interhemispheric ratio of the average t-value within ipsilesional SM1 to contralesional SM1. Regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuations (fALFF) were extracted from ring-shaped perinidal regions and contralateral homologous regions, and the corresponding interhemispheric ratios were calculated. The effect of PA on the interhemispheric asymmetry of motor activations, ReHo, and fALFF was estimated.

STATISTICAL TESTS

Pearson analysis, paired and independent t-test, multiple linear regression, Friedman test, and factorial analysis of variance were used.

RESULTS

Motor activations were significantly reduced in ipsilesional SM1 compared to contralesional SM1 (P < 0.05). The presence of PA was the independent predictor of activation loss in ipsilateral SM1(P < 0.05). Furthermore, perinidal regions exhibited reduced ReHo compared to the homologous regions (P < 0.05). PA was significantly associated with the decline of ReHo and fALFF in perinidal regions (P < 0.05, for both).

DATA CONCLUSION

The presence of PA can predict perinidal NVU that may confound the interpretation of both task-based and resting-state fMRI, highlighting the importance of alternative approaches of brain functional localization in improving treatment of AVMs.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

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.

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

Background and Purpose

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

Methods

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

Results

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

Conclusions

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

A Retrospective Cohort Analysis of Hemorrhagic Arteriovenous Malformations Treated with Combined Endovascular Embolization and Gamma Knife Stereotactic Radiosurgery

BACKGROUND

The management of brain arteriovenous malformations (AVMs) remains a controversial topic. Given the relatively low incidence, high heterogeneity, and high morbidity and mortality of these lesions, consensus on treatment strategies is an issue of concern to organized neurosurgery. The present retrospective analysis examined and quantified the outcomes of patients with an initial presentation of intracranial hemorrhage from a Spetzler-Martin grade III or IV AVM, later ruled out as surgical candidates.

METHODS

A total of 16 patients (5 females; 11 males) had presented with symptomatic hemorrhage confirmed by non-contrast-enhanced computed tomography and were deemed to not be surgical candidates owing to AVM location and/or architecture. The patients underwent combined endovascular embolization and gamma knife stereotactic radiosurgery (SRS). The modified Rankin scale was used to measure the clinical outcomes, comparing the scores at presentation, gamma knife treatment, and the last known follow-up examination. A radiographic evaluation was used to determine the level of AVM nidus involution after the procedure.

RESULTS

The present study identified 16 patients with ruptured high-grade AVMs of high surgical risk. All the patients had undergone immediate embolization with delayed SRS for treatment of the hemorrhage and nidus of the AVM. A statistically significant proportion of patients showed marked improvement in the modified Rankin scale scores. No subsequent repeat hemorrhage or any associated complications after embolization occurred in any patient.

CONCLUSION

These findings warrant consideration of endovascular embolization with adjuvant SRS as a powerful treatment option for cases with high surgical morbidity due to AVM characteristics.

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.

UniversitätsSpital Zürich: 80 years of neurosurgical patient care in Switzerland

Background

The predecessor of today’s Department of Neurosurgery, UniversitätsSpital Zürich (USZ), was founded 80 years ago as the first independent Swiss clinic dedicated to neurosurgical patient care. On the occasion of this anniversary, we aimed to highlight the history of neurosurgery as a specialty at the USZ, and to put it into the historical context of Swiss and European Neurosurgery.

Method

A literature review was conducted and we searched the archives of the USZ and the city of Zurich, as well as those of Swiss journals to extract relevant published articles, books, historical reports and pictures. The USZ Department of Medical History, the Museum of Medical History and the Swiss National Library were contacted to provide source material. To further verify the content, (emeritus) faculty from the USZ and external experts on the history of Swiss neurosurgery reviewed the manuscript.

Results

Surgeries of the head and spine had occasionally been conducted in Zurich by the general surgeons, Rudolf Ulrich Krönlein and Paul Clairmont, before an independent neurosurgical clinic was founded by Hugo Krayenbühl on 6 July 1937. This was the first Swiss department dedicated to neurosurgical patient care. Besides providing high-quality medicine for both the local and wider population, the department was chaired by eminent leaders of neurosurgery, who influenced the scientific and clinical neurosurgery of their time. As such, it has long been regarded as one of the top teaching and research hospitals in Switzerland and in Europe.

Conclusions

On the occasion of its 80th anniversary, we have performed an in-depth review of its development, successes and challenges, with a special focus on the early decades. Reflecting on the past, we have identified common denominators of success in neurosurgery that remain valid today.

Electronic supplementary material

The online version of this article (10.1007/s00701-017-3357-z) contains supplementary material, which is available to authorised users.

Computer simulation of Cerebral Arteriovenous Malformation-validation analysis of hemodynamics parameters

Problem

The purpose of this work is to provide some validation methods for evaluating the hemodynamic assessment of Cerebral Arteriovenous Malformation (CAVM). This article emphasizes the importance of validating noninvasive measurements for CAVM patients, which are designed using lumped models for complex vessel structure.

Methods

The validation of the hemodynamics assessment is based on invasive clinical measurements and cross-validation techniques with the Philips proprietary validated software’s Qflow and 2D Perfursion.

Results

The modeling results are validated for 30 CAVM patients for 150 vessel locations. Mean flow, diameter, and pressure were compared between modeling results and with clinical/cross validation measurements, using an independent two-tailed Student t test. Exponential regression analysis was used to assess the relationship between blood flow, vessel diameter, and pressure between them. Univariate analysis is used to assess the relationship between vessel diameter, vessel cross-sectional area, AVM volume, AVM pressure, and AVM flow results were performed with linear or exponential regression.

Discussion

Modeling results were compared with clinical measurements from vessel locations of cerebral regions. Also, the model is cross validated with Philips proprietary validated software’s Qflow and 2D Perfursion. Our results shows that modeling results and clinical results are nearly matching with a small deviation.

Conclusion

In this article, we have validated our modeling results with clinical measurements. The new approach for cross-validation is proposed by demonstrating the accuracy of our results with a validated product in a clinical environment.

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.

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.

Onyx(®) in endovascular treatment of cerebral arteriovenous malformations - a review

Arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. In most cases, the disorder may be asymptomatic. The objective of endovascular AVM treatment is set individually for each case upon consultations with a neurosurgeon and a neurologist. The endpoint of the treatment should consist in prevention of AVM bleeding in a management procedure characterized by a significantly lower risk of complications as compared to the natural history of AVM. Endovascular interventions within AVM may include curative exclusion of AVM from circulation, embolization adjuvant to resection or radiation therapy, targeted closure of a previously identified bleeding site as well as palliative embolization. Onyx was first described in the 1990s. It is a non-adhesive and radiolucent compound. Onyx-based closure of the lumen of the targeted vessel is obtained by means of precipitation. The process is enhanced peripherally to the main flux of the injected mixture. This facilitates angiographic monitoring of embolization at any stage. The degree of lumen closure is associated with the location of the vessel. Supratentorial and cortical locations are most advantageous. Dense and plexiform structure of AVM nidus as well as a low number of supplying vessels and a single superficial drainage vein are usually advantageous for Onyx administration. Unfavorable factors include nidus drainage into multiple compartments as well as multiarterial supply of the AVM, particularly from meningeal arteries, en-passant arteries or perforating feeders. Onyx appears to be a safe and efficient material for embolization of cerebral AVMs, also in cases of intracranial bleeding associated with AVM. Curative embolization of small cerebral AVMs is an efficient and safe alternative to neurosurgical and radiosurgical methods. Careful angiographic assessment of individual arteriovenous malformations should be performed before each Onyx administration.

Endovascular neurointervention success and complication rates in the first year of independent practice in a suburban hospital setup

CONTEXT

Endovascular neurointervention (interventional neuroradiology) is a highly demanding science requiring deep understanding of disease, anatomy, clinical skills and manual dexterity, consequently with a long learning curve and thus posing significant challenges to a physician entering new into the competitive arena.

AIM

To evaluate the procedural success, complications and outcome in the first year of independent endovascular neurointervention practice in a suburban hospital.

MATERIALS AND METHODS

Retrospective analysis of prospectively maintained data of all diagnostic and therapeutic neurointerventional cases performed by the author between the period of January 02, 2012 and December 31, 2012.

RESULTS

A total of 61 procedures were performed. The performance success rate of the diagnostic procedures was 100% (38/38) and that of therapeutic procedures was 82.6% (19/23). The periprocedural complication rates were nil and 13%, respectively, for diagnostic and therapeutic procedures. The 3-month patient outcome for therapeutic procedures was good outcome (Modified Rankin Scale <2) in 87% cases (20/23), and poor outcome in 13% (2 dead and 1 debilitated with Modified Rankin Scale of 3).

CONCLUSION

For a well-trained endovascular neurointerventionalist, the first year of practice had high procedural success rate and acceptable complication with patient outcome rates comparable to the existing literature.

Endovascular treatment of cranial arteriovenous malformations and dural arteriovenous fistulas

Pial arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs) are high-flow vascular lesions with abnormal communications between the arterial and venous system. AVMs are congenital lesions, whereas DAVFs are considered acquired lesions. Both can cause significant morbidity and mortality if they rupture and result in intracranial hemorrhage. The primary goal of treatment is to eliminate the risk of bleeding or at least decrease it. Because the epidemiology, clinical presentation, and classification of AVMs and DAVFs have been covered in previous articles in this issue, the authors only briefly touch on these subjects as they relate to endovascular treatment.