Natural history of brain arteriovenous malformations: a systematic review

Lesion-Filling Index from Quantitative DSA Correlates with Hemorrhage of Cerebral AVM

BACKGROUND AND PURPOSE

Rupture is the most life-threatening manifestation of cerebral AVMs. This study aimed to explore the hemodynamic mechanism of AVM rupture. We introduced a new quantitative DSA parameter that can reflect the degree of intranidal blood stasis, called the lesion-filling index.

MATERIALS AND METHODS

This study examined patients with AVMs who had undergone both DSA and MR imaging between 2013 and 2014. Clinical presentations, angioarchitecture, and hemodynamic parameters generated from quantitative DSA were analyzed using univariate and multivariable logistic regression. The lesion-filling index was defined as the arterial diagnostic window divided by the volume of the AVM. To assess the correlation between the lesion-filling index and rupture, we incorporated the lesion-filling index into 2 published prediction models widely recognized for predicting AVM rupture risk, R2eD and VALE. The DeLong test was used to examine whether the addition of the lesion-filling index improved predictive efficacy.

RESULTS

A total of 180 patients with AVMs were included. The mean lesion-filling index values in the ruptured group were higher compared with the unruptured group (390.27 [SD, 919.81] versus 49.40 [SD, 98.25]), P < .001). A higher lesion-filling index was significantly correlated with AVM rupture in 3 different multivariable logistic models, adjusting for angioarchitecture factors (OR = 1.004, P = .02); hemodynamic factors (OR = 1.005, P = .009); and combined factors (OR = 1.004, P = .03). Both R2eD (area under the curve, 0.601 versus 0.624; P = .15) and VALE (area under the curve, 0.603 versus 0.706; P < .001) predictive models showed improved predictive performance after incorporating the lesion-filling index and conducting 10-fold cross-validation.

CONCLUSIONS

The lesion-filling index showed a strong correlation with AVM rupture, suggesting that overperfusion is the hemodynamic mechanism leading to AVM rupture.

A comprehensive analysis of patients with cerebral arteriovenous malformation with headache: assessment of risk factors and treatment effectiveness

BACKGROUND

Due to the high mortality and disability rate of intracranial hemorrhage, headache is not the main focus of research on cerebral arteriovenous malformation (AVM), so research on headaches in AVM is still scarce, and the clinical understanding is shallow. This study aims to delineate the risk factors associated with headaches in AVM and to compare the effectiveness of various intervention treatments versus conservative treatment in alleviating headache symptoms.

METHODS

This study conducted a retrospective analysis of AVMs who were treated in our institution from August 2011 to December 2021. Multivariable logistic regression analysis was employed to assess the risk factors for headaches in AVMs with unruptured, non-epileptic. Additionally, the effectiveness of different intervention treatments compared to conservative management in alleviating headaches was evaluated through propensity score matching (PSM).

RESULTS

A total of 946 patients were included in the analysis of risk factors for headaches. Multivariate logistic regression analysis identified that female (OR 1.532, 95% CI 1.173-2.001, p = 0.002), supply artery dilatation (OR 1.423, 95% CI 1.082-1.872, p = 0.012), and occipital lobe (OR 1.785, 95% CI 1.307-2.439, p < 0.001) as independent risk factors for the occurrence of headaches. There were 443 AVMs with headache symptoms. After propensity score matching, the microsurgery group (OR 7.27, 95% CI 2.82-18.7 p < 0.001), stereotactic radiosurgery group(OR 9.46, 95% CI 2.26-39.6, p = 0.002), and multimodality treatment group (OR 8.34 95% CI 2.87-24.3, p < 0.001) demonstrate significant headache relief compared to the conservative group. However, there was no significant difference between the embolization group (OR 2.24 95% CI 0.88-5.69, p = 0.091) and the conservative group.

CONCLUSIONS

This study identified potential risk factors for headaches in AVMs and found that microsurgery, stereotactic radiosurgery, and multimodal therapy had significant benefits in headache relief compared to conservative treatment. These findings provide important guidance for clinicians when developing treatment options that can help improve overall treatment outcomes and quality of life for patients.

Natural history and clinical manifestation of Pediatric Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are aberrant arteriovenous shunts through a vascular nidus with no intervening capillary beds. They are one of the commonest causes of spontaneous intracranial haemorrhage in children and may be associated with significant morbidity and mortality in cases of rupture. Treatment strategies include microsurgical resection, endovascular embolisation, stereotactic radiosurgery, multimodality treatment with a combination thereof, and particularly in high-grade bAVMs, conservative management. Clinicians involved in treating bAVMs need to have familiarity with the natural history pertaining to bAVMs in terms of risk of rupture, risk factors elevating rupture risk as well as understanding the clinical manifestations of bAVMs. This invited review serves to provide a synthesis on natural history and clinical presentation of bAVMs with particular focus in children to inform decision-making pertaining to management.

Hematologic and Inflammatory Predictors of Outcome in Patients with Brain Arteriovenous Malformations

OBJECTIVE

This study investigated the prognostic value of admission blood counts for arteriovenous malformation (AVM) outcomes and compared admission blood counts for patients with ruptured and unruptured AVMs.

METHODS

A retrospective analysis of patients who underwent surgical treatment for a ruptured cerebral AVM between February 1, 2014, and March 31, 2020, was conducted. The primary outcome was poor neurologic outcome, defined as a modified Rankin Scale score ≥2 in patients with unruptured AVMs or >2 in patients with ruptured AVMs.

RESULTS

Of 235 included patients, 80 (34%) had ruptured AVMs. At admission, patients with ruptured AVMs had a significantly lower mean (SD) hemoglobin level (12.78 [2.07] g/dL vs. 13.71 [1.60] g/dL, P < 0.001), hematocrit (38.1% [5.9%] vs. 40.7% [4.6%], P < 0.001), lymphocyte count (16% [11%] vs. 26% [10%], P < 0.001), and absolute lymphocyte count (1.41 [0.72] × 103/μL vs. 1.79 [0.68] × 103/μL, P < 0.001), and they had a significantly higher mean (SD) white blood cell count (10.4 [3.8] × 103/μL vs. 7.6 [2.3] × 103/μL, P < 0.001), absolute neutrophil count (7.8 [3.8] × 103/μL vs. 5.0 [2.5] × 103/μL, P < 0.001), and neutrophil count (74% [14%] vs. 64% [13%], P < 0.001). Among patients with unruptured AVMs, white blood cell count ≥6.4 × 103/μL and absolute neutrophil count ≥3.4 × 103/μL were associated with a favorable neurologic outcome, whereas hemoglobin level ≥13.4 g/dL was associated with an unfavorable outcome. Among patients with ruptured AVMs, hypertension was associated with a 3-fold increase in odds of a poor neurologic outcome.

CONCLUSIONS

Patients with ruptured and unruptured AVMs present with characteristic profiles of hematologic and inflammatory parameters evident in their admission blood work.

Elucidating the pathogenesis behind arteriovenous malformations of the central nervous system: a bibliometric analysis

Arteriovenous malformations (AVMs) are vascular malformations of the central nervous system (CNS) with potential for significant consequences. The exact pathophysiologic mechanism of AVM formation is not fully understood. This study aims to evaluate bibliometric parameters and citations of the literature of AVMs to provide an overview of how the field has evolved. We performed an electronic search on Web of Science to identify the top 100 published and indexed articles with the highest number of citations discussing the pathogenesis of AVMs. This study yielded 1863 articles, of which the top 100 were selected based on the highest total citation count. These articles included 24% basic science, 46% clinical, and 30% review articles. The most-cited article was a clinical article from 2003, and the most recent was published in 2022. The median number of authors was 6, with the highest being 46 for a clinical article. The top 5 journals were identified, with the highest impact factor being 20.1. 13 countries were identified, with the US contributing the most articles (approximately 70%). Regarding genes of investigation, VEGF was one of the early genes investigated, while more interested in RAS/MAPK has been garnered since 2015. There is a growing interest in AVM genomics and pathogenesis research. While progress has been made in understanding clinical aspects and risk factors, the exact pathophysiological mechanisms and genetic basis of AVM formation remain incompletely understood. Further investigation of key genes in AVM pathogenesis can allow identification of potential therapeutic targets.

Current and Future Applications of Arterial Spin Labeling MRI in Cerebral Arteriovenous Malformations

Arterial spin labeling (ASL) has emerged as a promising noninvasive tool for the evaluation of both pediatric and adult arteriovenous malformations (AVMs). This paper reviews the advantages and challenges associated with the use of ASL in AVM assessment. An assessment of the diagnostic workup of AVMs and their variants in both adult and pediatric populations is proposed. Evaluation after treatments, whether endovascular or microsurgical, was similarly examined. ASL, with its endogenous tracer and favorable safety profile, offers functional assessment and arterial feeder identification. ASL has demonstrated strong performance in identifying feeder arteries and detecting arteriovenous shunting, although some studies report inferior performance compared with digital subtraction angiography (DSA) in delineating venous drainage. Challenges include uncertainties in sensitivity for specific AVM features. Detecting AVMs in challenging locations, such as the apical cranial convexity, is further complicated, demanding careful consideration due to the risk of underestimating total blood flow. Navigating these challenges, ASL provides a noninvasive avenue with undeniable merits, but a balanced approach considering its limitations is crucial. Larger-scale prospective studies are needed to comprehensively evaluate the diagnostic performance of ASL in AVM assessment.

Case Study of a Complex Neurovascular Disorder: Choroidal Arteriovenous Malformation

This study conducts an in-depth analysis of the management of a complex arteriovenous malformation (AVM) in a 44-year-old individual, who initially manifested with acute left hemiparesis and progressively declined into a comatose state. Diagnostic neuroimaging identified a substantial right fronto-temporal intraparenchymal hematoma via a CT scan. Cerebral angiography further elucidated a choroidal AVM originating from the anterior choroidal artery, accompanied by intranidal aneurysms. The elected treatment strategy was the surgical excision of the AVM. The procedure achieved complete removal of the intracranial AVM, situated in a neurologically sensitive region, leading to notable neurological recovery. This study thoroughly explores and critically evaluates a wide spectrum of treatment approaches for intracranial arteriovenous malformations, including novel endovascular therapies. Despite extensive discourse on AVM in contemporary literature, this report is among the few documenting the treatment of a choroidal AVM via a microsurgical technique, and highlights various therapeutic options.

APOE ε4 and Intracerebral Hemorrhage in Patients With Brain Arteriovenous Malformation

Importance

Intracerebral hemorrhage (ICH) is a serious complication of brain arteriovenous malformation (AVM). Apolipoprotein E (APOE) ε4 is a well-known genetic risk factor for ICH among persons without AVM, and cerebral amyloid angiopathy is a vasculopathy frequently observed in APOE ε4 carriers that may increase the risk of ICH.

Objective

To assess whether APOE ε4 is associated with a higher risk of ICH in patients with a known AVM.

Design, Setting, and Participants

This cross-sectional study including 412 participants was conducted in 2 stages (discovery and replication) using individual-level data from the UK Biobank (released March 2012 and last updated October 2023) and the All of Us Research Program (commenced on May 6, 2018, with its latest update provided in October 2023). The occurrence of AVM and ICH was ascertained at the time of enrollment using validated International Classification of Diseases, Ninth Revision and Tenth Revision, codes. Genotypic data on the APOE variants rs429358 and rs7412 were used to ascertain the ε status.

Main Outcomes and Measures

For each study, the association between APOE ε4 variants and ICH risk was assessed among patients with a known AVM by using multivariable logistic regression.

Results

The discovery phase included 253 UK Biobank participants with known AVM (mean [SD] age, 56.6 [8.0] years, 119 [47.0%] female), of whom 63 (24.9%) sustained an ICH. In the multivariable analysis of 240 participants of European ancestry, APOE ε4 was associated with a higher risk of ICH (odds ratio, 4.58; 95% CI, 2.13-10.34; P < .001). The replication phase included 159 participants with known AVM enrolled in All of Us (mean [SD] age, 57.1 [15.9] years; 106 [66.7%] female), of whom 29 (18.2%) sustained an ICH. In multivariable analysis of 101 participants of European ancestry, APOE ε4 was associated with higher risk of ICH (odds ratio, 4.52; 95% CI, 1.18-19.38; P = .03).

Conclusions and Relevance

The results of this cross-sectional study of patients from the UK Biobank and All of Us suggest that information on APOE ε4 status may help identify patients with brain AVM who are at particularly high risk of ICH and that cerebral amyloid angiopathy should be evaluated as a possible mediating mechanism of the observed association.

Treatment of Brain Arteriovenous Malformations

Brain arteriovenous malformations (AVMs) are a rare entity of vascular anomalies, characteristic of anatomical shunting where arterial blood directly flows into the venous circulation. The main aim of the active treatment policy of brain AVMs is the prevention of haemorrhage. There are well-established treatment strategies that continually improve in their safety and efficacy, primarily due to the advances in imaging modalities, targeted and novel techniques, the development of alternative treatment approaches, and even better experience with the disease itself. There are interesting imaging novelties that may be prospectively applicable in the decision-making and planning of the most effective treatment approach for individual patients with intracranial AVM. Surgery is often considered the first-line treatment; however, each patient should be evaluated individually, and the risks of the active treatment policy should not overcome the benefits of the spontaneous natural history of the disease. All treatment modalities, i.e., surgery, radiosurgery, endovascular embolization, and observation, are justified but need to be meticulously selected for each individual patient in order to deliver the best treatment outcome. This chapter deals with historical and currently applied dogmas, followed by introductions of advances in each available treatment modality of AVM management.

Magnetic resonance radiomics-derived sphericity correlates with seizure in brain arteriovenous malformations

OBJECTIVES

Angioarchitectural analysis of brain arteriovenous malformations (BAVMs) is qualitative and subject to interpretation. This study quantified the morphology of and signal changes in the nidal and perinidal areas by using MR radiomics and compared the performance of MR radiomics and angioarchitectural analysis in detecting epileptic BAVMs.

MATERIALS AND METHODS

From 2010 to 2020, a total of 111 patients with supratentorial BAVMs were retrospectively included and grouped in accordance with the initial presentation of seizure. Patients' angiograms and MR imaging results were analyzed to determine the corresponding angioarchitecture. The BAVM nidus was contoured on time-of-flight MR angiography images. The perinidal brain parenchyma was contoured on T2-weighted images, followed by radiomic analysis. Logistic regression analysis was performed to determine the independent risk factors for seizure. ROC curve analysis, decision curve analysis (DCA), and calibration curve were performed to compare the performance of angioarchitecture-based and radiomics-based models in diagnosing epileptic BAVMs.

RESULTS

In multivariate analyses, low sphericity (OR: 2012.07, p = .04) and angiogenesis (OR: 5.30, p = .01) were independently associated with a high risk of seizure after adjustment for age, sex, temporal location, and nidal volume. The AUC for the angioarchitecture-based, MR radiomics-based, and combined models was 0.672, 0.817, and 0.794, respectively. DCA confirmed the clinical utility of the MR radiomics-based and combined models.

CONCLUSIONS

Low nidal sphericity and angiogenesis were associated with high seizure risk in patients with BAVMs. MR radiomics-derived tools may be used for noninvasive and objective measurement for evaluating the risk of seizure due to BAVM.

CLINICAL RELEVANCE STATEMENT

Low nidal sphericity was associated with high seizure risk in patients with brain arteriovenous malformation and MR radiomics may be used as a noninvasive and objective measurement method for evaluating seizure risk in patients with brain arteriovenous malformation.

KEY POINTS

• Low nidal sphericity was associated with high seizure risk in patients with brain arteriovenous malformation. • The performance of MR radiomics in detecting epileptic brain arteriovenous malformations was more satisfactory than that of angioarchitectural analysis. • MR radiomics may be used as a noninvasive and objective measurement method for evaluating seizure risk in patients with brain arteriovenous malformation.

A case of brain arteriovenous malformation treated by high-pressure cooker technique assisted with anhydrous alcohol embolization: A case report

RATIONALE

Brain arteriovenous malformations (BAVMs) are a relatively rare but very dangerous developmental abnormality of the blood vessels. Intracranial hemorrhage is the most common clinical manifestation of BAVMs, and has a high rate of rebleeding, disability, and mortality, which has a serious impact on patients' quality of life and working ability. Endovascular intervention was a new technique that emerged in recent years. Anhydrous ethanol embolization has been used with satisfactory results in the treatment of peripheral arteriovenous malformations, but there is a lack of practice in the treatment of BAVMs. We tried to treat BAVMs by embolizing malformed vessels with anhydrous alcohol in order to provide a safe and effective treatment for more patients with BAVMs.

PATIENT CONCERNS

The patient was admitted to our hospital in the emergency department with "sudden onset of headache for more than 4 hours." At the time of admission, the patient was clearly conscious, not mentally alert, spoke fluently, and had a normal level of orientations. The direct and indirect responses to light were blunted. The patient's muscle strength, muscle tone, and sensation of the extremities were normal. National Institute of Health stroke scale score was 1. Head computed tomography at the onset suggested a right occipital hemorrhage and hematoma formation.

DIAGNOSES

Brain arteriovenous malformations (BAVMs) were suspected based on preoperative imaging findings.

INTERVENTIONS

After obtaining the consent of the patient and their family members, we performed whole brain angiography to determine the location of the lesion, and then, with the help of high-pressure cooker technology, targeted embolization of interventional BAVM was performed. The high-pressure cooker technology was achieved through spring coils, and the embolic material was anhydrous ethanol.

OUTCOMES

The surgery was successful, and the patient recovered well without recurrence.

LESSON

The successful performance of this surgery illustrates the feasibility of anhydrous ethanol-targeted ablation for BAVMs.

Multi-modality treatment approach for paediatric AVMs with quality-of-life outcome measures

PURPOSE

Despite the potentially devastating and permanently disabling effects of paediatric arteriovenous malformations (pAVMs), there is a paucity of studies reporting long-term quality-of-life (QoL) outcomes in AVM patients. We aim to evaluate the management strategies for paediatric intracranial pAVMs in the UK and long-term QoL outcomes using a validated paediatric quality-of-life outcome measure.

METHODS

In this single-centre case-series, we retrospectively reviewed a prospectively maintained database of all paediatric patients (i.e. 0-18 years old) with intracranial AVMs, who were managed at Alder Hey Children's Hospital from July 2007 to December 2021. We also collected the PedsQL 4.0 score for these patients as a measure of QoL.

RESULTS

Fifty-two AVMs were included in our analysis. Forty (80%) were ruptured, 8 (16%) required emergency intervention, 17 (35%) required elective surgery, 15 (30%) underwent endovascular embolisation, and 15 (30%) patients underwent stereotactic radiosurgery. There was an 88% overall obliteration rate. Two (4%) pAVMs rebled, and there were no mortalities. Overall, the mean time from diagnosis to definitive treatment was 144 days (median 119; range 0-586). QoL outcomes were collected for 26 (51%) patients. Ruptured pAVM presentation was associated with worse QoL (p = 0.0008). Location impacted psychosocial scores significantly (71.4, 56.9, and 46.6 for right supratentorial, left supratentorial, and infratentorial, respectively; p = 0.04).

CONCLUSION

This study shows a staged multi-modality treatment approach to pAVMs is safe and effective, with superior obliteration rates with surgery alone. QoL scores are impacted by AVM presentation and location regardless of treatment modality.

Endovascular Management of Brain Arteriovenous Malformations

Due to the risk of cerebral hemorrhage, and its related morbidity-mortality, brain arteriovenous malformations (bAVMs) are a rare and potentially life-threatening disease. Despite this, there is only one randomized controlled trial on bAVM management, A Randomized trial of Unruptured Brain Arteriovenous malformations (ARUBA). The results of the ARUBA trial favor a noninterventional approach in the case of an unruptured bAVM; however, implementation of these findings is challenging in daily practice. Instead, management of bAVM relies on multidisciplinary discussions that lead to patient-specific strategies based on patient preferences, local expertise, and experience in referral centers. Considering the diverse patterns of presentation and numerous treatment modalities, implementing standardized guidelines in this context proves challenging, notwithstanding the recommendations or expert opinions offered. Endovascular treatment (EVT) of bAVM can be curative, or can serve as an adjunct treatment prior to surgery or radiosurgery ("pre-EVT"). EVT practice is in constant evolution (i.e., venous approach, combination with surgery during the same anesthesia, etc.). Liquid embolic agents such as ethylene vinyl alcohol (EVOH) copolymer and cyanoacrylates (CYA), and their method of injection to increase bAVM occlusion have also benefited from technical evolutions such as the use of adjunctive flow arrest techniques (mini balloons, pressure cooker technique, and multiple catheters). Further research is necessary to evaluate the advantages and disadvantages of EVT for bAVM.

Angiographic factors leading to hemorrhage in AVMs: A systematic review and meta-analysis

For patients with unruptured intracranial arteriovenous malformations (AVMs), the risk of a hemorrhagic event is approximately 2% to 4% annually. These events have an associated 20-50% morbidity and 10% mortality rate. An understanding of risk factors that predispose these lesions to rupture is important for optimal management. We aimed to pool a large cohort of both ruptured and unruptured AVMs from the literature with the goal of identifying angiographic risk factors that contribute to rupture. A systematic review of the literature was conducted in accordance with the PRISMA guidelines using Pubmed, Embase, Scopus, and Web of Science databases. Studies that presented patient-level data from ruptured AVMs from January 1990 to January 2022 were considered for inclusion. The initial screening of 8,304 papers resulted in a quantitative analysis of 25 papers, which identified six angiographic risk factors for AVM rupture. Characteristics that significantly increase the odds of rupture include the presence of aneurysm (OR = 1.45 [1.19, 1.77], p < 0.001, deep location (OR = 3.08 [2.56, 3.70], p < 0.001), infratentorial location (OR = 2.79 [2.08, 3.75], p < 0.001), exclusive deep venous drainage (OR = 2.50 [1.73, 3.61], p < 0.001), single venous drainage (OR = 2.97 [1.93, 4.56], p < 0.001), and nidus size less than 3 cm (OR = 2.54 [1.41, 4.57], p = 0.002). Although previous literature has provided insight into AVM rupture risk factors, obscurity still exists regarding which risk factors pose the greatest risk. We have identified six major angiographic risk factors (presence of an aneurysm, deep location, infratentorial location, exclusive deep venous drainage, single venous drainage, and nidus size less than 3 cm) that, when identified by a clinician, may help to tailor patient-specific approaches and guide clinical decisions.

Quantified flow and angioarchitecture show similar associations with hemorrhagic presentation of brain arteriovenous malformations

INTRODUCTION

The purpose of our study was to elucidate the impact of brain arteriovenous malformation (BAVM) flow and wall shear stress (WSS) on angioarchitecture and to evaluate their association with hemorrhagic presentations.

MATERIALS AND METHODS

Forty-one patients with BAVMs were evaluated by phase-contrast MR angiography. Volume flow rate and WSS were quantified. Angioarchitectural features such as location, angiogenesis, venous stenosis, venous ectasia, venous phlebitis, venous rerouting, exclusive deep vein and venous sac were evaluated by two neuroradiologists. The correlation between BAVM flow and size was evaluated with Spearman correlation coefficients. Differences of size, flow, and WSS between the hemorrhagic and non-hemorrhagic groups, the seizure and non-seizure groups, and between the different groups based on angioarchitecture were evaluated with Mann-Whitney U tests. Accuracy in predicting hemorrhage was evaluated with receiver operating characteristic curves.

RESULT

BAVM flow was highly correlated with volume (ρ = 0.77). Higher flow was more commonly associated with angiogenesis, venous ectasia, venous rerouting, and venous phlebitis. Flow and angioarchitecture showed similar efficacy in differentiating hemorrhagic from non-hemorrhagic BAVMs. WSS did not demonstrate differences across any clinical groups.

CONCLUSION

Flow quantification and angioarchitecture analysis of BAVMs showed similar efficacy as evaluated by associations with hemorrhagic presentation. High flow affects both arterial and venous angioarchitecture, reflecting the nature of low vascular resistance in BAVMs.

Multiple brain arteriovenous malformations: systematic review and individual patient data meta-analysis

Multiple brain arteriovenous malformations (bAVM) are rare neurovascular lesions usually related to genetic syndromes. Its management is not well established given its rarity. The objective of this study was to describe the clinical and angiographic features of published cases and to explore their associations with treatment outcomes. We performed a literature search of published cases in Medline and the Regional Index Medici. Additional cases were searched in our single-center registry. Data on the proportions of patients and clinical and angiographic characteristics were extracted. The study outcomes were nidal instability in patients who underwent staged treatment and radiological cure in patients who underwent treatment using any treatment modality. Logistic regression models for the study outcomes were analyzed. Data on the proportions of multiple bAVM patients were summarized with meta-analyses of proportions. We included 118 patients (reported in 68 studies) from the literature and 6 cases identified in our registry. A total of 124 patients harboring 339 bAVM nidi were included in the analyses. Differences between syndromic and non-syndromic cases were observed. The logistic regression analyses showed that angiographically occult untreated bAVM was associated (OR 14.37; 95% CI 2.17 to 95.4) with nidal instability after staged treatment, and deep (OR 5.11; 95% CI 1.51 to 17.27) and eloquent (OR 3.91; 95% CI 1.22 to 12.52) locations were associated with residual disease after treatment. Inconsistent reporting of relevant data throughout the included studies undermined the planned analyses. Some prognostic factors were found to be related to the study outcomes. Study Registration: The protocol of the systematic review was registered in PROSPERO as CRD42021245814.

Microsurgery versus Microsurgery With Preoperative Embolization for Brain Arteriovenous Malformation Treatment: A Systematic Review and Meta-analysis

BACKGROUND

Preoperative embolization has traditionally been regarded as a safe and effective adjunct to microsurgical treatment of brain arteriovenous malformations (bAVM). However, there is currently no high-level evidence to ascertain this presumption.

OBJECTIVE

To compare the outcomes of microsurgery (MS) vs microsurgery with preoperative embolization (E + MS) in patients with bAVM through systematic review.

METHODS

We searched MEDLINE, PubMed, and Embase. The primary outcome was bAVM obliteration. Secondary outcomes were intraoperative bleeding (mL), complications, worsened modified Rankin Scale (mRS), and mortality. The pooled proportions of outcomes were calculated through the logit transformation method. The odds ratio (OR) of categorical data and mean difference of continuous data were estimated through the Mantel-Haenszel and the inverse variance methods, respectively.

RESULTS

Thirty-two studies met the eligibility criteria. One thousand eight hundred twenty-eight patients were treated by microsurgery alone, and 1088 were treated by microsurgery with preoperative embolization, respectively. The meta-analysis revealed no significant difference in AVM obliteration (94.1% vs 95.6%, OR = 1.15 [0.63-2.11], P = .65), mortality (1.7% vs 2%, OR = 0.88 [0.30-2.58], P = .82), procedural complications (18.2% vs 27.2%, OR = 0.47 [0.19-1.17], P = .10), worsened mRS (21.2% vs 18.5%, OR = 1.08 [0.33-3.54], P = .9), and intraoperative blood loss (mean difference = 182.89 [-87.76, 453.55], P = .19).

CONCLUSION

The meta-analysis showed no significant difference in AVM obliteration, mortality, complications, worse mRS, and intraoperative blood loss between MS and E + MS groups. For AVMs where MS alone has acceptable results, it is reasonable to bypass unnecessary preoperative embolization given higher postoperative complication risk.

Comparison of Single- and Multi-Echo Susceptibility-Weighted Imaging in Detecting Cerebral Arteriovenous Shunts: A Preliminary Study

Purpose

To compare the sensitivities of T2-weighted image (T2WI) and susceptibility-weighted imaging (SWI) in detecting cerebral arteriovenous fistula (AVF), cerebral arteriovenous malformation (AVM), and carotid-cavernous sinus fistula (CCF), and to qualitatively evaluate single-echo SWI (s-SWI) and multi-echo SWI (m-SWI) in characterizing vascular lesions.

Materials and Methods

From January 2016 to December 2021, cerebral angiography-proven lesions were recruited. The sensitivities of T2WI and SWI in detecting vascular lesions were compared using McNemar's test. Qualitative evaluations of s-SWI and m-SWI were categorized to be of poor, average, or good quality and compared using Fisher's exact test.

Results

A total of 24 patients (mean age: 61 years, 12 female, and 12 male) were enrolled. Twenty patients underwent s-SWI or m-SWI, and four patients underwent both. AVF, AVM, and CCF were diagnosed in 10, 11, and 3 patients, respectively. SWI demonstrated higher sensitivity compared to that of T2WI (82.1% vs. 53.6%, p = 0.013). m-SWI showed better image quality compared to that of s-SWI (good quality, 83.3% vs. 25.0%, p = 0.009).

Conclusion

SWI demonstrated a higher sensitivity for detecting cerebral arteriovenous shunts compared to that of T2WI. m-SWI exhibited better image quality compared to that of s-SWI in characterizing vascular lesions.

Brain arteriovenous malformation in hereditary hemorrhagic telangiectasia: Recent advances in cellular and molecular mechanisms

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by vessel dilatation, such as telangiectasia in skin and mucosa and arteriovenous malformations (AVM) in internal organs such as the gastrointestinal tract, lungs, and brain. AVMs are fragile and tortuous vascular anomalies that directly connect arteries and veins, bypassing healthy capillaries. Mutations in transforming growth factor β (TGFβ) signaling pathway components, such as ENG (ENDOGLIN), ACVRL1 (ALK1), and SMAD4 (SMAD4) genes, account for most of HHT cases. 10-20% of HHT patients develop brain AVMs (bAVMs), which can lead to vessel wall rupture and intracranial hemorrhages. Though the main mutations are known, mechanisms leading to AVM formation are unclear, partially due to lack of animal models. Recent mouse models allowed significant advances in our understanding of AVMs. Endothelial-specific deletion of either Acvrl1, Eng or Smad4 is sufficient to induce AVMs, identifying endothelial cells (ECs) as primary targets of BMP signaling to promote vascular integrity. Loss of ALK1/ENG/SMAD4 signaling is associated with NOTCH signaling defects and abnormal arteriovenous EC differentiation. Moreover, cumulative evidence suggests that AVMs originate from venous ECs with defective flow-migration coupling and excessive proliferation. Mutant ECs show an increase of PI3K/AKT signaling and inhibitors of this signaling pathway rescue AVMs in HHT mouse models, revealing new therapeutic avenues. In this review, we will summarize recent advances and current knowledge of mechanisms controlling the pathogenesis of bAVMs, and discuss unresolved questions.

Peri-procedure efficacy and safety of one-stop hybrid surgery for the treatment of brain arteriovenous malformations: A single-center preliminary experience

Background

Some deficiencies and shortcomings in treatment strategies of brain arteriovenous malformation (bAVM) remain. It is worth exploring whether the one-stop hybrid surgical platform can play a positive role in the treatment of bAVM.

Objective

This study investigated short clinical and angiographic results of one-stop hybrid surgery for the treatment of bAVM.

Methods

All patients with bAVM treated with one-stop hybrid surgery were reviewed from February 2017 to December 2021. Data including demographic information, clinical conditions, characteristics of AVM, procedure details, and clinical and angiographic results were collected.

Result

In total, 150 cerebral bAVM patients received one-stop hybrid surgery; among them, 122 received surgical resection assisted by intraoperative DSA, and 28 were treated with combination surgical resection and endovascular embolization. Complete angiographic obliteration of the AVM was achieved in 136 patients (90.7%), and procedure-related death and neurological deficit rates were 7.3%. Of all relevant variables, logistic regression analysis showed that the Spetzler & Martin (S&M) score was the only factor related to the cure rate (P < 0.001) and endpoint complication rate (P = 0.007).

Conclusions

In our preliminary experience, one-stop hybrid surgery for the treatment of brain AVMs achieves a high angiographic total occlusion rate, with acceptable peri-procedure morbidity and mortality. For S&M 4 and 5 lesions, more cases and further study are needed to investigate the effects and safety of hybrid surgery.

GNAQ mutations drive port wine birthmark-associated Sturge-Weber syndrome: A review of pathobiology, therapies, and current models

Port-wine birthmarks (PWBs) are caused by somatic, mosaic mutations in the G protein guanine nucleotide binding protein alpha subunit q (GNAQ) and are characterized by the formation of dilated, dysfunctional blood vessels in the dermis, eyes, and/or brain. Cutaneous PWBs can be treated by current dermatologic therapy, like laser intervention, to lighten the lesions and diminish nodules that occur in the lesion. Involvement of the eyes and/or brain can result in serious complications and this variation is termed Sturge-Weber syndrome (SWS). Some of the biggest hurdles preventing development of new therapeutics are unanswered questions regarding disease biology and lack of models for drug screening. In this review, we discuss the current understanding of GNAQ signaling, the standard of care for patients, overlap with other GNAQ-associated or phenotypically similar diseases, as well as deficiencies in current in vivo and in vitro vascular malformation models.

Non-Oncological Radiotherapy: A Review of Modern Approaches

Despite being usually delivered in oncological patients, radiotherapy can be used as a successful treatment for several non-malignant disorders. Even though this use of radiotherapy has been scarcely investigated since the 1950s, more recent interest has actually shed the light on this approach. Thus, the aim of this narrative review is to analyze the applications of non-oncological radiotherapy in different disorders. Key references were derived from a PubMed query. Hand searching and clinicaltrials.gov were also used. This review contains a narrative report and a critical discussion of non-oncological radiotherapy approaches. In conclusion, non-oncological radiotherapy is a safe and efficacious approach to treat several disorders that needs to be further investigated and used in clinical practice.

Hypofractionated Stereotactic Radiotherapy with CyberKnife for Large Arteriovenous Malformations and Arteriovenous Malformations Located in Eloquent Areas

Literature has yet to establish an appropriate treatment strategy for large arteriovenous malformations (AVMs) and AVMs located in eloquent areas. In this study, the treatment outcomes of hypofractionated stereotactic radiotherapy (HSRT) with CyberKnife (CK) for large AVMs and AVMs in eloquent areas were evaluated. This study retrospectively evaluated 38 consecutive patients with AVMs treated with HSRT in the Japanese Red Cross Medical Center between August 2010 and July 2015. Obliteration rates and hemorrhage rates at 3- and 5-years of follow-up were calculated. Factors for hemorrhage and obliteration were analyzed with logistic regression analysis. Fourteen (36.8%) patients had a history of hemorrhage. Twenty (52.6%) AVMs were larger than 10 mL, and 34 (89.5%) AVMs were located in eloquent areas. The majority of the AVMs (84.2%) were classified into high grades (grades 3, 4, and 5) using the Spetzler-Martin grading scale. The median modified radiosurgery-based AVM score was 2.05, and the median Virginia Radiosurgery AVM Score was 3. The mean marginal dose was 24.5 ± 2.5 Gy. Twenty-three and 15 patients received three- and five-fraction stereotactic radiotherapy, respectively. At 3 and 5 years posttreatment, two (2.0%/year) and six (6.7%/year) patients had hemorrhage with obliteration rates of 15.2% and 16.7%, respectively. AVM localization in eloquent areas was a risk factor for obliteration failure. This study revealed that HSRT with CK for large AVMs and AVMs located in eloquent areas contributed to hemorrhage risk reduction and obliteration, at least in the early stages.

Concurrent decompression and resection versus decompression with delayed resection of acutely ruptured brain arteriovenous malformations

OBJECTIVE

Brain arteriovenous malformations (bAVMs) most commonly present with rupture and intraparenchymal hemorrhage. In rare cases, the hemorrhage is large enough to cause clinical herniation or intractable intracranial hypertension. Patients in these cases require emergent surgical decompression as a life-saving measure. The surgeon must decide whether to perform concurrent or delayed resection of the bAVM. Theoretical benefits to concurrent resection include a favorable operative corridor created by the hematoma, avoiding a second surgery, and more rapid recovery and rehabilitation. The objective of this study was to compare the clinical and surgical outcomes of patients who had undergone concurrent emergent decompression and bAVM resection with those of patients who had undergone delayed bAVM resection.

METHODS

The authors conducted a 15-year retrospective review of consecutive patients who had undergone microsurgical resection of a ruptured bAVM at their institution. Patients presenting in clinical herniation or with intractable intracranial hypertension were included and grouped according to the timing of bAVM resection: concurrent with decompression (hyperacute group) or separate resection surgery after decompression (delayed group). Demographic and clinical characteristics were recorded. Groups were compared in terms of the primary outcomes of hospital and intensive care unit (ICU) lengths of stay (LOSs). Secondary outcomes included complete obliteration (CO), Glasgow Coma Scale score, and modified Rankin Scale score at discharge and at the most recent follow-up.

RESULTS

A total of 35/269 reviewed patients met study inclusion criteria; 18 underwent concurrent decompression and resection (hyperacute group) and 17 patients underwent emergent decompression only with later resection of the bAVM (delayed group). Hyperacute and delayed groups differed only in the proportion that underwent preresection endovascular embolization (16.7% vs 76.5%, respectively; p < 0.05). There was no significant difference between the hyperacute and delayed groups in hospital LOS (26.1 vs 33.2 days, respectively; p = 0.93) or ICU LOS (10.6 vs 16.1 days, respectively; p = 0.69). Rates of CO were also comparable (78% vs 88%, respectively; p > 0.99). Medical complications were similar in the two groups (33% hyperacute vs 41% delayed, p > 0.99). Short-term clinical outcomes were better for the delayed group based on mRS score at discharge (4.2 vs 3.2, p < 0.05); however, long-term outcomes were similar between the groups.

CONCLUSIONS

Ruptured bAVM rarely presents in clinical herniation requiring surgical decompression and hematoma evacuation. Concurrent surgical decompression and resection of a ruptured bAVM can be performed on low-grade lesions without compromising LOS or long-term functional outcome; however, the surgeon may encounter a more challenging surgical environment.

Vessel wall MR imaging in neuroradiology

Vessel wall MR imaging (VW-MRI) has been introduced into clinical practice and applied to a variety of diseases, and its usefulness has been reported. High-resolution VW-MRI is essential in the diagnostic workup and provides more information than other routine MR imaging protocols. VW-MRI is useful in assessing lesion location, morphology, and severity. Additional information, such as vessel wall enhancement, which is useful in the differential diagnosis of atherosclerotic disease and vasculitis could be assessed by this special imaging technique. This review describes the VW-MRI technique and its clinical applications in arterial disease, venous disease, vasculitis, and leptomeningeal disease.

Plasma Matrix Metalloproeteinase-9 Is Associated with Seizure and Angioarchitecture Changes in Brain Arteriovenous Malformations

Both angiogenesis and inflammation contribute to activation of matrix metalloproeteinase-9 (MMP-9), which dissolves the extracellular matrix, disrupts the blood-brain barrier, and plays an important role in the pathogenesis of brain arteriovenous malformations (BAVMs). The key common cytokine in both angiogenesis and inflammation is interleukin 6 (IL-6). Previous studies have shown elevated systemic MMP-9 and decreased systemic vascular endothelial growth factor (VEGF) in BAVM patients. However, the clinical utility of plasma cytokines is unclear. The purpose of this study is to explore the relationship between plasma cytokines and the clinical presentations of BAVMs. Prospectively, we recruited naive BAVM patients without hemorrhage as the experimental group and unruptured intracranial aneurysm (UIA) patients as the control group. All patients received digital subtraction angiography, and plasma cytokines were collected from the lesional common carotid artery. Plasma cytokine levels were determined using a commercially available, monoclonal antibody-based enzyme-linked immunosorbent assay. Subgroup analysis based on hemorrhagic presentation and angiograchitecture was done for the BAVM group. Pearson correlations were calculated for the covariates. Means and differences for continuous and categorical variables were compared using Student's t and χ² tests respectively. Plasma MMP-9 levels were significantly higher in the BAVM group (42,945 ± 29,991 pg/mL) than in the UIA group (28,270 ± 17,119 pg/mL) (p < 0.001). Plasma MMP-9 levels in epileptic BAVMs (57,065 ± 35,732; n = 9) were higher than in non-epileptic BAVMs (35,032 ± 28,301; n = 19) (p = 0.049). Lower plasma MMP-9 levels were found in cases of BAVM with angiogenesis and with peudophlebitis. Plasma MMP-9 is a good biomarker reflecting ongoing vascular remodeling in BAVMs. Angiogenesis and pseudophlebitis are two angioarchitectural signs that reflect MMP-9 activities and can potentially serve as imaging biomarkers for epileptic BAVMs.

Ruptured brain arteriovenous malformation in a pregnant woman: a case report

BACKGROUND

Brain arteriovenous malformations (bAVMs) are vascular lesions that commonly present with intracranial haemorrhage. Pregnancy has been associated with an increased risk of bAVM rupture. However, their natural history in pregnant women is uncertain.

CASE DESCRIPTION

A 27-year-old female at 28 weeks of gestation presented with a compromised neurological status secondary to a ruptured left frontal Spetzler-Martin scale (SM) III + bAVM. An emergent caesarean section was performed due to the high risk of foetal distress. Endovascular treatment successfully controlled the bleeding site, and stereotactic radiosurgery was offered as a subsequent treatment option.

CONCLUSION

bAVMs should be considered in pregnant women with intracranial haemorrhage. The management of these lesions during pregnancy is controversial. Surgical risk and foetal development should be considered when selecting a management strategy.

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.

Shortened cerebral circulation time correlates with seizures in brain arteriovenous malformation: a cross-sectional quantitative digital subtraction angiography study

OBJECTIVE

Seizure is the most common clinical presentation in patients with nonhemorrhagic brain arteriovenous malformations (BAVMs) and it influences their quality of life. Angioarchitectural analysis of the seizure risk for BAVMs is subjective and does not consider hemodynamics. This study aimed to investigate the angioarchitectural and hemodynamic factors that may be associated with seizure in patients with BAVMs.

METHODS

From 2011 to 2019, 104 patients with supratentorial BAVMs without previous hemorrhage or treatment were included and grouped according to the initial presentation of seizure. Their angiograms and MRI results were analyzed for morphological characteristics and quantitative digital subtraction angiography (QDSA) parameters. Modified cerebral circulation time (mCCT) was defined as the difference between the bolus arrival time of the ipsilateral cavernous internal carotid artery and the parietal vein on lateral DSA. Logistic regression analysis was performed to estimate the odds ratio (OR) for BAVMs presenting with seizure.

RESULTS

The seizure group had shorter mCCT (1.98 s vs. 2.44 s, p = 0.005) and more BAVMs with temporal location (45% vs. 30.8%, p = 0.013), neoangiogenesis (55% vs. 33%, p = 0.03), and long draining veins (95% vs. 72%, p = 0.004) than did the nonseizure group. Shorter mCCT (OR: 3.4, p = 0.02), temporal location (OR: 13.4, p < 0.001), and neoangiogenesis (OR: 4.7, p = 0.013) were independently associated with higher risks of seizure, after adjustments for age, gender, BAVM volume, and long draining vein.

CONCLUSIONS

Shorter mCCT, temporal location, and neoangiogenesis were associated with epileptic BAVMs. QDSA can objectively evaluate hemodynamic changes in epileptic BAVMs.

KEY POINTS

• Quantitative digital subtraction angiography may be used to evaluate the hemodynamic differences between brain arteriovenous malformations presenting with and without seizure. • BAVMs with temporal location, neoangiogenesis, and shortened cerebral circulation time were more likely to present with seizure.

State of the Art and Future Direction in Diagnosis, Molecular Biology, Genetics, and Treatment of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are uncommon and represent a heterogeneous group of lesions. Although these 2 facts have delayed research on this topic, knowledge about the pathophysiology, diagnosis, and treatment of bAVMs has evolved in recent years. We conducted a review of the literature to update the knowledge about diagnosis, molecular biology, genetic, pathology, and treatment by searching for the following terms: "Epidemiology AND Natural History," "risk of hemorrhage," "intracranial hemorrhage," "diagnosis," "angiogenesis," "molecular genetics," "VEGF," "KRAS," "radiosurgery," "endovascular," "microsurgery," or "surgical resection." Our understanding of bAVMs has significantly evolved in recent years. The latest investigations have helped in defining some molecular pathways involved in the pathology of bAVM. Although there is still more to learn and discover, describing these pathways will allow the creation of targeted treatments that could improve the prognosis of patients with bAVMs.

Validation of the Ruptured Arteriovenous Malformation Grading Scale in a pediatric cohort

OBJECTIVE

Pediatric brain arteriovenous malformations (AVMs) are the leading cause of spontaneous intracranial hemorrhage (SICH) in children. Although the incidence of SICH is low in pediatric populations, such events cause substantial morbidity. The recently created Ruptured Arteriovenous Malformation Grading Scale (RAGS) is proposed as a reliable and novel grading system to specifically serve as a predictor of clinical outcomes in patients following AVM rupture, similar to the Hunt and Hess (HH) grade for ruptured aneurysms. While these data are promising, pediatric patients were notably absent from the original study validating the RAGS. Therefore, correlation of the RAGS score with clinical outcomes following AVM rupture in individuals younger than 18 years of age using the RAGS score is needed. The objective of this study was to validate the RAGS in a cohort of pediatric patients with AVMs who presented with hemorrhage, thereby demonstrating the score's generalizability, and expanding its external validity.

METHODS

A cohort of children with ruptured AVMs were retrospectively reviewed. Using disability, measured by the modified Rankin Scale (mRS), as the response variable, the area under the receiver operating characteristic curve (AUROC) was calculated for patients based on their RAGS scores for three time periods. The AUROC values were then compared with those generated by two commonly used clinical grading systems, the HH classification and Glasgow Coma Scale.

RESULTS

A total of 81 children who presented with ruptured AVMs were included in the study, with a mean follow-up duration of 4 years. The RAGS score outperformed other clinical grading scales in predicting mRS scores, with AUROC values of 0.81, 0.82, and 0.81 at three distinct follow-up periods.

CONCLUSIONS

The RAGS score correlated well with the clinical outcome after AVM rupture in pediatric patients. Additional validation studies across multiple treatment centers are needed to further demonstrate the generalizability of the scoring system.

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.

[Relationship between the features of venous drainage of supratentorial arteriovenous malformations and the risk of intracranial hemorrhage]

BACKGROUND

Intracranial hemorrhage is the most common complication of cerebral arteriovenous malformations (AVM). In recent years, most studies devoted to the features of AVM functioning consider venous drainage as important factor influencing the rupture of malformation.

OBJECTIVE

To review the literature data on the relationship between the features of venous drainage of cerebral arteriovenous malformations and intracranial hemorrhage.

MATERIAL AND METHODS

We found 43 studies discussing the features of AVM venous drainage for the period from 1982 to 2020. Most of reports were published between 2005 and 2020.

RESULTS

Deep venous drainage and a single drainage vein were the most significant factors influencing the risk of hemorrhage. Venous ectasia, reflux, stenosis, number, length and tortuosity of drainage veins were less important for the risk of AVM rupture.

CONCLUSION

Analysis of the features of AVM venous drainage can make it possible to predict the natural course of disease and risk of intracranial hemorrhage. These aspects are essential for neurosurgical treatment.

Upfront and Repeated Gamma-Knife Radiosurgery for Small (≤5 mL) Unruptured Brain Arteriovenous Malformation: A Cohort of 249 Consecutive Patients

OBJECTIVE

According to A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA), conservative treatment seems to be superior to any intervention for unruptured brain arteriovenous malformations (AVMs). This study aims to evaluate safety and efficacy of upfront and repeated Gamma-Knife Radiosurgery (GKRS) in patients harboring small AVMs fulfilling the inclusion criteria of ARUBA.

METHODS

A retrospective study was conducted to evaluate outcomes of unruptured naive brain AVM with a volume ⩽ 5 mL eligible to ARUBA treated by GKRS with at least 3 years of follow-up.

RESULTS

From 1992 to 2014, 249 patients fulfilled the inclusion criteria of this study. The median age was 36 years (range: 18-78 years). The median treated volume of the nidus was 1.3 mL (range: 0.4-5 mL) and 63% of the AVM were in eloquent areas. Radiosurgery-based AVM score was 1-1.8 (76%), the Spetzler-Martin grade was II-III (73%), and the Virginia Radiosurgery AVM scale was ≤1 point (75%). The overall AVM obliteration rate was 77.1% after up to 3 GKRS sessions. The median dose at the margin was 24 Gy (15-25 Gy) and the median follow-up was 45 months (range: 36-205 months). Eight patients (3.2%) experienced hemorrhage after GKRS, corresponding to a post-GKRS hemorrhage annual rate of 1.03%. Permanent symptomatic radio-induced changes rate was 2% (4 increased seizures, 1 neurologic deficit).

CONCLUSIONS

The very low toxicity rate and the high occlusion rate suggest in favor of upfront and repeated GKRS for unruptured small AVMs (⩽5 mL).

Molecular Signature of Brain Arteriovenous Malformation Hemorrhage: A Systematic Review

BACKGROUND

The mechanisms of brain arteriovenous malformation (bAVM) development, formation, and progress are still poorly understood. By gaining more knowledge about the molecular signature of bAVM in relation to hemorrhage, we might be able to find biomarkers associated with this serious complication, which can function as a goal for further research and can be a potential target for gene therapy.

AIMS

To provide a comprehensive overview of the molecular signature of bAVM-related hemorrhage We conducted a systematic review, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, of articles published in Embase, Medline, Cochrane central, Scopus, and Chinese databases (CNKI, Wanfang).

SUMMARY OF REVIEW

Our search identified 3944 articles, of which 3108 remained after removal of duplicates. After title, abstract, and full-text screening, 31 articles were included for analysis. The results show an overview of molecular characteristics. Several genetic polymorphisms are identified that increase the risk of bAVM rupture by increasing the expression of certain inflammatory cytokines (interleukin [IL]-6, IL-17A, IL-1β, and tumor necrosis factor-α), NOTCH pathways, matrix metalloproteinase-9, and vascular endothelial growth factor-α.

CONCLUSIONS

Several molecular factors are associated with the risk of bAVM-related hemorrhage. These factors are associated with increased inflammation on the cellular level and changes in the endothelium leading to instability of the vessel wall. Further investigation of these biomarkers regarding hemorrhage rates, together with their relationship with noninvasive diagnostic methods, should be a goal of future studies to improve the patient specific risk estimation and future treatment options.

Spontaneous disappearance of brain arteriovenous malformation: A case series

OBJECTIVE

Brain arteriovenous malformation (BAVM) is defined as abnormal communication between cerebral of arteries and veins, without capillaries. Clinically, it may involve intracranial hemorrhage or seizures. Complete spontaneous resolution, known as BAVM disappearance, has been reported in rare cases.

METHODS

We retrospectively collated all cases of BAVM in Lille University Hospital, from 2005 to 2018, and identified all cases of spontaneous BAVM disappearance on angiography (nidus and early venous drainage).

RESULTS

There were 4 cases of spontaneous BAVM disappearance, in 3573 patients: i.e., prevalence of 0.1%. Sex ratio was 2:2; ages ranged from 14 to 46 years; nidus size was generally small (<20mm); 3 of the 4 patients had superficial venous drainage. Revelation of BAVM was by hemorrhage in 3 cases and by seizure in 1. There were no cases of recanalization at 1 year's follow-up.

CONCLUSION

Spontaneous BAVM disappearance is rare. Associated factors may include small nidus, superficial venous drainage and hemorrhage.

Cerebral Arteriovenous Malformation Deep Draining Veins Not Observed on Preoperative Angiography Identified on Postoperative Angiography

Postoperative digital subtraction angiography (DSA) is the gold standard for establishing a cure of an arteriovenous malformation (AVM) after treatment. The incidence of residual AVM identified on postoperative DSA ranges from 1.8 to 11%. Although this is important for finalizing the treatment of AVMs, postoperative DSA rarely shows new findings that were not previously identified on preoperative imaging. We present a unique case where we identified residual AVM nidus on immediate postoperative DSA that drained into two deep veins that were not evident on preoperative DSA and increased the AVM grade from Spetzler-Martin grade II to III. To our knowledge, this finding has not been previously reported in the literature. We resected the residual AVM nidus identified on postoperative DSA, leading to an angiographic cure. The patient demonstrated a postoperative right-sided supplementary motor area syndrome that resolved over time with therapy. She made a complete functional recovery by her one-month follow-up appointment.

Current concepts and perspectives on brain arteriovenous malformations: A review of pathogenesis and multidisciplinary treatment

Brain arteriovenous malformations (bAVMs) are unusual vascular pathologies characterized by the abnormal aggregation of dilated arteries and veins in the brain parenchyma and for which the absence of a normal vascular structure and capillary bed leads to direct connections between arteries and veins. Although bAVMs have long been believed to be congenital anomalies that develop during the prenatal period, current studies show that inflammation is associated with AVM genesis, growth, and rupture. Interventional treatment options include microsurgery, stereotactic radiosurgery, and endovascular embolization, and management often comprises a multidisciplinary combination of these modalities. The appropriate selection of patients with brain arteriovenous malformations for interventional treatment requires balancing the risk of treatment complications against the risk of hemorrhaging during the natural course of the pathology; however, no definitive guidelines have been established for the management of brain arteriovenous malformations. In this paper, we comprehensively review the current basic and clinical studies on bAVMs and discuss the contemporary status of multidisciplinary management of bAVMs.

Effects of serum starvation and vascular endothelial growth factor stimulation on the expression of Notch signalling pathway components

Brain arteriovenous malformation (BAVM) is an abnormality in the cerebral vascular system. Although the upregulation of the Notch signalling pathway is a deterministic factor in BAVM, the mechanism by which this pathway is upregulated in patients with BAVM is uncertain. The effects of serum starvation and vascular endothelial growth factor (VEGF) stimulation on the Notch signalling pathway in brain microvascular endothelial cells (MECs) and mouse embryonic stem (mES)/embryoid body (EB)-derived endothelial cells were investigated in this study. The duration of serum starvation and VEGF concentration were changed, cell viability was measured, and reasonable time and concentration gradients were selected for subsequent studies. Protein and mRNA expression levels of Notch signalling pathway components in both MECs and mES/EB-derived endothelial cells were detected using western blotting and real-time PCR, respectively. Expression levels of the Notch1, Notch4, Jagged1, delta-like ligand 4 (Dll4) and Hes1 proteins and mRNAs were upregulated by lower VEGF concentrations and shorter-term serum starvation but inhibited by higher VEGF concentrations and longer-term serum starvation. This study revealed effects of changes in the duration of serum starvation and VEGF concentration on the expression of Notch signalling pathway components in both MECs and mES/EB-derived endothelial cells, potentially contributing to BAVM formation.

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.

Involvement of Microglia in the Pathophysiology of Intracranial Aneurysms and Vascular Malformations-A Short Overview

Aneurysms and vascular malformations of the brain represent an important source of intracranial hemorrhage and subsequent mortality and morbidity. We are only beginning to discern the involvement of microglia, the resident immune cell of the central nervous system, in these pathologies and their outcomes. Recent evidence suggests that activated proinflammatory microglia are implicated in the expansion of brain injury following subarachnoid hemorrhage (SAH) in both the acute and chronic phases, being also a main actor in vasospasm, considerably the most severe complication of SAH. On the other hand, anti-inflammatory microglia may be involved in the resolution of cerebral injury and hemorrhage. These immune cells have also been observed in high numbers in brain arteriovenous malformations (bAVM) and cerebral cavernomas (CCM), although their roles in these lesions are currently incompletely ascertained. The following review aims to shed a light on the most significant findings related to microglia and their roles in intracranial aneurysms and vascular malformations, as well as possibly establish the course for future research.

An Insight into the microRNAs Associated with Arteriovenous and Cavernous Malformations of the Brain

Background: Brain arteriovenous malformations (BAVMs) and cerebral cavernous malformations (CCMs) are rare developmental anomalies of the intracranial vasculature, with an irregular tendency to rupture, and as of yet incompletely deciphered pathophysiology. Because of their variety in location, morphology, and size, as well as unpredictable natural history, they represent a management challenge. MicroRNAs (miRNAs) are strands of non-coding RNA of around 20 nucleotides that are able to modulate the expression of target genes by binding completely or partially to their respective complementary sequences. Recent breakthroughs have been made on elucidating their contribution to BAVM and CCM occurrence, growth, and evolution; however, there are still countless gaps in our understanding of the mechanisms involved. Methods: We have searched the Medline (PubMed; PubMed Central) database for pertinent articles on miRNAs and their putative implications in BAVMs and CCMs. To this purpose, we employed various permutations of the terms and idioms: ‘arteriovenous malformation’, ‘AVM’, and ‘BAVM’, or ‘cavernous malformation’, ‘cavernoma’, and ‘cavernous angioma’ on the one hand; and ‘microRNA’, ‘miRNA’, and ‘miR’ on the other. Using cross-reference search; we then investigated additional articles concerning the individual miRNAs identified in other cerebral diseases. Results: Seven miRNAs were discovered to play a role in BAVMs, three of which were downregulated (miR-18a, miR-137, and miR-195*) and four upregulated (miR-7-5p, miR-199a-5p, miR-200b-3p, and let-7b-3p). Similarly, eight miRNAs were identified in CCM in humans and experimental animal models, two being upregulated (miR-27a and mmu-miR-3472a), and six downregulated (miR-125a, miR-361-5p, miR-370-3p, miR-181a-2-3p, miR-95-3p, and let-7b-3p). Conclusions: The following literature review endeavored to address the recent discoveries related to the various implications of miRNAs in the formation and growth of BAVMs and CCMs. Additionally, by presenting other cerebral pathologies correlated with these miRNAs, it aimed to emphasize the potential directions of upcoming research and biological therapies.