Enhancing the quality of evidence, comparability, and reproducibility in brain arteriovenous malformations treated with open surgery research: a systematic review and proposal of a reporting guideline for surgical and clinical outcomes

Brain Arteriovenous Malformations (bAVMs) are rare but high-risk developmental anomalies of the vascular system. Microsurgery through craniotomy is believed to be the mainstay standard treatment for many grades of bAVMs. However, a significant challenge emerges in the existing body of clinical studies on open surgery for bAVMs: the lack of reproducibility and comparability. This study aims to assess the quality of studies reporting clinical and surgical outcomes for bAVMs treated by open surgery and develop a reporting guideline checklist focusing on essential elements to ensure comparability and reproducibility. This is a systematic literature review that followed the PRISMA guidelines with the search in Medline, Embase, and Web of Science databases, for studies published between January 1, 2018, and December 1, 2023. Included studies were scrutinized focusing on seven domains: (1) Assessment of How Studies Reported on the Baseline Characteristics of the Patient Sample; (2) Assessment and reporting on bAVMs grading, anatomical characteristics, and radiological aspects; (3) Angioarchitecture Assessment and Reporting; (4) Reporting on Pivotal Concepts Definitions; (5) Reporting on Neurosurgeon(s) and Staff Characteristics; (6) Reporting on Surgical Details; (7) Assessing and Reporting Clinical and Surgical Outcomes and AEs. A total of 47 studies comprising 5,884 patients were included. The scrutiny of the studies identified that the current literature in bAVM open surgery is deficient in many aspects, ranging from fundamental pieces of information of methodology to baseline characteristics of included patients and data reporting. Included studies demonstrated a lack of reproducibility that hinders building cumulative evidence. A bAVM Open Surgery Reporting Guideline with 65 items distributed across eight domains was developed and is proposed in this study aiming to address these shortcomings. This systematic review identified that the available literature regarding microsurgery for bAVM treatment, particularly in studies reporting clinical and surgical outcomes, lacks rigorous scientific methodology and quality in reporting. The proposed bAVM Open Surgery Reporting Guideline covers all essential aspects and is a potential solution to address these shortcomings and increase transparency, comparability, and reproducibility in this scenario. This proposal aims to advance the level of evidence and enhance knowledge regarding the Open Surgery treatment for bAVMs.

Risk factors for delayed postoperative hemorrhage in patients with brain arteriovenous malformations: an analysis of the nationwide multicenter prospective registry MATCH study

OBJECTIVE

Reducing the incidence of delayed postoperative hemorrhage (DPH) is one of the challenges in the surgical treatment of patients with brain arteriovenous malformations (bAVMs). This study aimed to identify several risk factors for DPH after bAVM resection and evaluate the impact of these risk factors in patients with bAVMs.

METHODS

The authors retrospectively reviewed consecutive patients with bAVMs who underwent microsurgical resection between August 2011 and September 2021. Patients were divided into either the DPH group or non-DPH group based on whether they experienced a postoperative intracerebral hemorrhage into the bAVM bed within 14 days after bAVM resection. Factors associated with DPH were assessed using multivariate logistic regression analyses.

RESULTS

A total of 1284 consecutive patients with bAVMs were evaluated; DPH events occurred in 18 patients (1.4%). There were several differences in vascular architecture between the two cohorts. A giant nidus, a nidus involved in the eloquent area, a periventricular nidus, and a nidus accompanied by venous ectasia were more likely to be associated with DPH events. The multivariate analysis identified two independent factors associated with DPH: maximum diameter (OR 1.44 per 1-cm increase, 95% CI 1.13-1.83) and periventricular lesion (OR 4.10, 95% CI 1.33-12.59). The area under the receiver operating characteristic curve for the maximum lesion diameter and development of DPH was 0.71 (95% CI 0.58-0.84). The cutoff value for the maximum bAVM diameter was 4.15 cm. Furthermore, patients with a giant bAVM, of which the maximum diameter was ≥ 4.15 cm, had a higher DPH risk after surgery (HR 5.79, 95% CI 2.01-16.67; p < 0.01). The incidence rates of DPH for patients with periventricular lesions were higher than those for patients without periventricular lesions (HR 4.50, 95% CI 1.77-11.40; p < 0.01).

CONCLUSIONS

Patients with giant bAVMs or periventricular lesions are at higher risk for DPH after surgery. Strategies such as blood pressure control, preoperative embolization, intraoperative monitoring, and careful patient selection should be considered to reduce the risk of DPH in high-risk patients.

Vascular stability of brain arteriovenous malformations after partial embolization

INTRODUCTION

Brain arteriovenous malformation (bAVM) might have a higher risk of rupture after partial embolization, and previous studies have shown that some metrics of vascular stability are related to bAVM rupture risk.

OBJECTIVE

To analyze vascular stability of bAVM in patients after partial embolization.

METHODS

Twenty-four patients who underwent partial embolization were classified into the short-term, medium-term, and long-term groups, according to the time interval between partial embolization and surgery. The control group consisted of 9 bAVM patients who underwent surgery alone. Hemodynamic changes after partial embolization were measured by angiogram. The inflammatory infiltrates and cell-cell junctions were evaluated by MMP-9 and VE-cadherin. At the protein level, the proliferative and apoptotic events of bAVMs were analyzed by immunohistochemical staining of VEGFA, eNOS, and caspase-3. Finally, neovascularity and apoptotic cells were assessed by CD31 staining and TUNEL staining.

RESULTS

Immediately after partial embolization, the blood flow velocity of most bAVMs increased. The quantity of MMP-9 in the medium-term group was the highest, and VE-cadherin in the medium-term group was the lowest. The expression levels of VEGFA, eNOS, and neovascularity were highest in the medium-term group. Similarly, the expression level of caspase-3 and the number of apoptotic cells were highest in the medium-term group.

CONCLUSION

The biomarkers for bAVM vascular stability were most abnormal between 1 and 28 days after partial embolization.

Management outcomes of peripontine arteriovenous malformation patients presenting with trigeminal neuralgia

OBJECTIVE

Trigeminal neuralgia as the presenting symptom of brain arteriovenous malformation (bAVM) has been rarely reported. Treatment of reported cases has been skewed toward surgery for these scarce, deeply located bAVMs. Here, the authors report their management and outcomes of bAVM patients presenting with ipsilateral trigeminal neuralgia (TN) at their institution.

METHODS

This is a retrospective cohort study. The authors' institutional bAVM database was queried for non-hereditary hemorrhagic telangiectasia bAVMs in pontine, cistern, brainstem, trigeminal nerve, or tentorial locations. Patients with complete data were included in a search for trigeminal neuralgia or "facial pain" as the presenting symptom with TN being on the same side as the bAVM. Demographics, TN and bAVM characteristics, management strategies, and outcomes of bAVM and TN management were analyzed.

RESULTS

Fifty-seven peripontine bAVMs were identified; 8 (14.0%) of these bAVMs were discovered because of ipsilateral TN, including 4 patients (50%) with facial pain in the V2 distribution. Five patients (62.5%) were treated with carbamazepine as the initial medical therapy, 2 (25%) underwent multiple rhizotomies, and 1 (12.5%) underwent microvascular decompression. None of the patients with TN-associated bAVMs presented with hemorrhage, compared with 25 patients (51%) with bAVMs that were not associated with TN (p < 0.01). TN-associated bAVMs were overall smaller than non-TN-associated bAVMs, but the difference was not statistically significant (1.71 cm vs 2.22 cm, p = 0.117), and the Spetzler-Martin grades were similar. Six patients (75%) underwent radiosurgery to the bAVM (mean dose 1800 cGy, mean target volume 0.563 cm3) and had complete resolution of TN symptoms (100%). The mean time from radiosurgery to TN resolution was 193 (range 21-360) days, and 83.3% of treated TN-associated bAVMs were obliterated via radiosurgery. Two patients (12.5%) were recommended for conservative management, with one undergoing subsequent rhizotomies and another patient died of hemorrhage during follow-up.

CONCLUSIONS

TN-associated bAVM is a rare condition with limited evidence for management guidance. Radiosurgery can be safe and effective in achieving durable TN control in patients with TN-associated bAVMs. Despite their deep location and unruptured presentation, obliteration can reach 83.3% with radiosurgery.

Increased Collagen I/Collagen III Ratio Is Associated with Hemorrhage in Brain Arteriovenous Malformations in Human and Mouse

Background: The increase in the collagen I (COL I)/COL III ratio enhances vessel wall stiffness and renders vessels less resistant to blood flow and pressure changes. Activated microglia enhance inflammation-induced fibrosis. Hypotheses: The COL I/COL III ratio in human and mouse brain arteriovenous malformations (bAVMs) is associated with bAVM hemorrhage, and the depletion of microglia decreases the COL I/COL III ratio and hemorrhage. Method: COL I, COL III, and hemorrhages were analyzed in 12 human bAVMs and 6 control brains, and mouse bAVMs induced in three mouse lines with activin receptor-like kinase 1 (n = 7) or endoglin (n = 7) deleted in the endothelial cells or brain focally (n = 5). The controls for the mouse study were no-gene-deleted litter mates. Mouse bAVMs were used to test the relationships between the Col I/Col III ratio and hemorrhage and whether the transient depletion of microglia reduces the Col I/Col III ratio and hemorrhage. Results: The COL I/COL III ratio was higher in the human and mouse bAVMs than in controls. The microhemorrhage in mouse bAVMs was positively correlated with the Col I/Col III ratio. Transient depletion of microglia reduced the Col I/Col III ratio and microhemorrhage. Conclusions: The COL I/COL III ratio in the bAVMs was associated with bAVM hemorrhage. The depletion of microglia reduced the bAVM Col I/Col III ratio and hemorrhage.

Machine Learning Approach for Analyzing 3-Year Outcomes of Patients with Brain Arteriovenous Malformation (AVM) after Stereotactic Radiosurgery (SRS)

A cerebral arteriovenous malformation (AVM) is a tangle of abnormal blood vessels that irregularly connects arteries and veins. Stereotactic radiosurgery (SRS) has been shown to be an effective treatment for AVM patients, but the factors associated with AVM obliteration remains a matter of debate. In this study, we aimed to develop a model that can predict whether patients with AVM will be cured 36 months after intervention by means of SRS and identify the most important predictors that explain the probability of being cured. A machine learning (ML) approach was applied using decision tree (DT) and logistic regression (LR) techniques on historical data (sociodemographic, clinical, treatment, angioarchitecture, and radiosurgery procedure) of 202 patients with AVM who underwent SRS at the Instituto de Radiocirugía del Perú (IRP) between 2005 and 2018. The LR model obtained the best results for predicting AVM cure with an accuracy of 0.92, sensitivity of 0.93, specificity of 0.89, and an area under the curve (AUC) of 0.98, which shows that ML models are suitable for predicting the prognosis of medical conditions such as AVM and can be a support tool for medical decision-making. In addition, several factors were identified that could explain whether patients with AVM would be cured at 36 months with the highest likelihood: the location of the AVM, the occupation of the patient, and the presence of hemorrhage.

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.

VEGFR2 Expression Correlates with Postnatal Development of Brain Arteriovenous Malformations in a Mouse Model of Type I Hereditary Hemorrhagic Telangiectasia

Brain arteriovenous malformations (BAVMs) are a critical concern in hereditary hemorrhagic telangiectasia (HHT) patients, carrying the risk of life-threatening intracranial hemorrhage. While traditionally seen as congenital, the debate continues due to documented de novo cases. Our primary goal was to identify the precise postnatal window in which deletion of the HHT gene Endoglin (Eng) triggers BAVM development. We employed SclCreER(+);Eng2f/2f mice, enabling timed Eng gene deletion in endothelial cells via tamoxifen. Tamoxifen was given during four postnatal periods: P1-3, P8-10, P15-17, and P22-24. BAVM development was assessed at 2-3 months using latex dye perfusion. We examined the angiogenic activity by assessing vascular endothelial growth factor receptor 2 (VEGFR2) expression via Western blotting and Flk1-LacZ reporter mice. Longitudinal magnetic resonance angiography (MRA) was conducted up to 9 months. BAVMs emerged in 88% (P1-3), 86% (P8-10), and 55% (P15-17) of cases, with varying localization. Notably, the P22-24 group did not develop BAVMs but exhibited skin AVMs. VEGFR2 expression peaked in the initial 2 postnatal weeks, coinciding with BAVM onset. These findings support the "second hit" theory, highlighting the role of early postnatal angiogenesis in initiating BAVM development in HHT type I mice.

The Role and Therapeutic Implications of Inflammation in the Pathogenesis of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are focal vascular lesions composed of abnormal vascular channels without an intervening capillary network. As a result, high-pressure arterial blood shunts directly into the venous outflow system. These high-flow, low-resistance shunts are composed of dilated, tortuous, and fragile vessels, which are prone to rupture. BAVMs are a leading cause of hemorrhagic stroke in children and young adults. Current treatments for bAVMs are limited to surgery, embolization, and radiosurgery, although even these options are not viable for ~20% of AVM patients due to excessive risk. Critically, inflammation has been suggested to contribute to lesion progression. Here we summarize the current literature discussing the role of the immune system in bAVM pathogenesis and lesion progression, as well as the potential for targeting inflammation to prevent bAVM rupture and intracranial hemorrhage. We conclude by proposing that a dysfunctional endothelium, which harbors the somatic mutations that have been shown to give rise to sporadic bAVMs, may drive disease development and progression by altering the immune status of the brain.

Nicotinic Acid-Mediated Modulation of Metastasis-Associated Protein 1 Methylation and Inflammation in Brain Arteriovenous Malformation

We explored metastasis-associated protein 1 (MTA1) promoter methylation in the development of brain arteriovenous malformation (BAVM). The clinical data of 148 sex- and age-matched BAVMs and controls were collected, and the MTA1 DNA methylation in peripheral white blood cells (WBC) was assessed by bisulfite pyrosequencing. Among them, 18 pairs of case-control samples were used for WBC mRNA detection, 32 pairs were used for WBC MTA1 protein measurement, and 50 pairs were used for plasma inflammatory factor analysis. Lipopolysaccharide (LPS) treatment was used to induce an inflammatory injury cell model of human brain microvascular endothelial cells (BMECS). 5-Aza-2'-deoxycytidine (5-AZA), nicotinic acid (NA), and MTA1 siRNAs were used in functional experiments to examine BMECS behaviors. RT-qPCR, Western blot, and ELISA or cytometric bead arrays were used to measure the expression levels of MTA1, cytokines, and signaling pathway proteins in human blood or BMECS. The degree of MTA1 promoter methylation was reduced in BAVM compared with the control group and was inversely proportional to MTA1 expression. Plasma ApoA concentrations in BAVM patients were significantly lower than those in controls and correlated positively with MTA1 promoter methylation and negatively with MTA1 expression. The expression of cytokine was markedly higher in BAVM than in controls. Cell experiments showed that 5-AZA decreased the methylation level of MTA1 and increased the expression of MTA1 protein. LPS treatment significantly increased cytokine concentrations (p < 0.05). NA and MTA1 silencing could effectively reverse the LPS-mediated increase in IL-6 and TNF-α expression through the NF-κB pathway. Our study indicated that NA may regulate MTA1 expression by affecting promoter DNA methylation, improve vascular inflammation through the NF-κB pathway, and alleviate the pathological development of BAVM.

Evaluating the safety and efficacy of transvenous embolization for brain arteriovenous malformation: A systematic review and meta-analysis

BACKGROUND

Transvenous embolization is a potential therapy for brain arteriovenous malformation, involving the use of microcatheters to guide an ethylene vinyl alcohol coil for vessel occlusion. However, the safety and efficacy of transvenous embolization are not fully established.

OBJECTIVE

To evaluate the safety and efficacy of transvenous embolization for brain arteriovenous malformation.

METHODS

A systematic review of the literature of studies investigating the safety and efficacy of transvenous embolization for brain arteriovenous malformation was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Databases, including PubMed, Cochrane Library, Web of Science, and Embase were queried.

RESULTS

In the final analysis of 16 studies involving 368 brain arteriovenous malformation cases who received transvenous embolization, the complete occlusion was achieved in 91% (95% CI: 88%, 94%; I2 = 43%, p = 0.04) of cases. The overall rate of good outcomes after discharge was high at 89% (95% CI: 82%, 95%; I2 = 60%, p < 0.01). Ischemic complications were reported in 1% of cases (95% CI: 0%, 2%; I2 = 0%, p = 0.96), while hemorrhagic complications occurred in 6% of cases (95% CI: 3%, 8%; I2 = 8%, p = 0.37), and technical complications rate of 8% (95% CI: 4%, 11%; I2 = 8%, p = 0.36). Finally, only one death was related to the procedure.

CONCLUSION

Transvenous embolization for brain arteriovenous malformation shows promising safety and effectiveness, with low mortality, a considerable rate of positive outcomes, and a relatively low incidence of complications. The majority of patients achieved complete occlusion, indicating transvenous embolization as a potential option, especially for challenging deep-seated lesions.

Corrigendum: Development and validation of a model for predicting the risk of brain arteriovenous malformation rupture based on three-dimensional morphological features

[This corrects the article DOI: 10.3389/fneur.2022.979014.].

Rbpj Deficiency Disrupts Vascular Remodeling via Abnormal Apelin and Cdc42 (Cell Division Cycle 42) Activity in Brain Arteriovenous Malformation

BACKGROUND

Brain arteriovenous malformations (bAVM) are characterized by enlarged blood vessels, which direct blood through arteriovenous shunts, bypassing the artery-capillary-vein network and disrupting blood flow. Clinically, bAVM treatments are invasive and not routinely applicable. There is critical need to understand mechanisms of bAVM pathologies and develop pharmacological therapies.

METHODS

We used an in vivo mouse model of Rbpj-mediated bAVM, which develops pathologies in the early postnatal period and an siRNA in vitro system to knockdown RBPJ in human brain microvascular endothelial cells (ECs). To understand molecular events regulated by endothelial Rbpj, we conducted RNA-Seq and chromatin immunoprecipitation-Seq analyses from isolated brain ECs.

RESULTS

Rbpj-deficient (mutant) brain ECs acquired abnormally rounded shape (with no change to cell area), altered basement membrane dynamics, and increased endothelial cell density along arteriovenous shunts, compared to controls, suggesting impaired remodeling of neonatal brain vasculature. Consistent with impaired endothelial cell dynamics, we found increased Cdc42 (cell division cycle 42) activity in isolated mutant ECs, suggesting that Rbpj regulates small GTPase (guanosine triphosphate hydrolase)-mediated cellular functions in brain ECs. siRNA-treated, RBPJ-deficient human brain ECs displayed increased Cdc42 activity, disrupted cell polarity and focal adhesion properties, and impaired migration in vitro. RNA-Seq analysis from isolated brain ECs identified differentially expressed genes in mutants, including Apelin, which encodes a ligand for G protein-coupled receptor signaling known to influence small GTPase activity. Chromatin immunoprecipitation-Seq analysis revealed chromatin loci occupied by Rbpj in brain ECs that corresponded to G-protein and Apelin signaling molecules. In vivo administration of a competitive peptide antagonist against the Apelin receptor (Aplnr/Apj) attenuated Cdc42 activity and restored endothelial cell morphology and arteriovenous connection diameter in Rbpj-mutant brain vessels.

CONCLUSIONS

Our data suggest that endothelial Rbpj promotes rearrangement of brain ECs during cerebrovascular remodeling, through Apelin/Apj-mediated small GTPase activity, and prevents bAVM. By inhibiting Apelin/Apj signaling in vivo, we demonstrated pharmacological prevention of Rbpj-mediated bAVM.

Age-dependent hemorrhage risk and obliteration benefit after radiosurgery for brain arteriovenous malformation

BACKGROUND

Since patients with untreated brain arteriovenous malformations (BAVMs) are at variable risks of cerebral hemorrhage and associated mortality and morbidity, it is essential to identify patient populations who benefit most from prophylactic interventions. This study aimed to examine age-dependent differences in the therapeutic effect of stereotactic radiosurgery (SRS) on BAVMs.

METHODS

This retrospective observational study enrolled patients with BAVMs who underwent SRS at our institution between 1990 and 2017. The primary outcome was post-SRS hemorrhage, and the secondary outcome included nidus obliteration, post-SRS early signal changes, and mortality. To investigate age-related differences in outcomes following SRS, we performed age-stratified analyses using the Kaplan-Meier analysis and weighted logistic regression with the inverse probability of censoring weighting (IPCW). To address significant differences in patient baseline characteristics, we also performed inverse probability of treatment weighting (IPTW) adjusted for possible confounders to investigate age-related differences in outcomes following SRS.

RESULTS

A total of 735 patients with 738 BAVMs were stratified by age. Age-stratified analysis using weighted logistic regression model with IPCW showed a direct correlation between patient age and post-SRS hemorrhage (odds ratio [OR], 95% confidence interval [CI], and P-value: 2.20, 1.34-3.63, and 0.002 at 18 months; 1.86, 1.17-2.93, and 0.008 at 36 months; and 1.61, 1.05-2.48, and 0.030 at 54 months, respectively). The age-stratified analysis also showed an inverse relationship between age and obliteration over the first 42 months after SRS (OR, 95% CI, and P-value: 0.05, 0.02-0.12, and <0.001 at 6 months; 0.55, 0.44-0.70, and <0.001 at 24 months; and 0.76, 0.63-0.91, and 0.002 at 42 months, respectively). These results were also confirmed with the IPTW analyses.

CONCLUSIONS

Our analysis demonstrated that patients' age at SRS is significantly associated with hemorrhage and the nidus obliteration rate after treatment. In particular, younger patients are more likely to exhibit reduced cerebral hemorrhages and achieve earlier nidus obliteration compared to older patients.

Application of the pressure cooker technique for transarterial embolization of brain arteriovenous malformations: Factors affecting obliteration and outcomes

Objective

The typical pressure cooker technique (PCT) and several modifications with similar mechanisms have been introduced to enhance the embolization of brain arteriovenous malformations (bAVMs). This study aimed to assess the effectiveness of transarterial embolization of bAVMs with the PCT.

Method

From January 2019 to December 2021, 125 consecutive patients with bAVM managed by transarterial embolization in the prospective database on cerebral vascular diseases of a single center were retrospectively reviewed. Patient data and lesion characteristics were collected. According to the treatment strategy, the patients were assigned to the PCT group (46 patients) and conventional embolization technique (CET) group (79 patients).

Results

Baseline patient features were comparable between the two groups. After the first procedure, complete obliteration immediately was observed in 61 and 42% of patients in the PCT and CET groups, respectively. The rate was markedly elevated in the PCT group (p = 0.04). In subgroup analysis, the rate of immediate complete obliteration was starkly increased in PCT group patients with Spetzler-Martin grade I/II bAVM (86 and 53% in the PCT and CET groups, respectively; p = 0.0036). The overall complication rates were similar in the two groups (13 and 10% in the PCT and CET groups, respectively; p = 0.77). In multivariable analysis, nidus size >3 cm (OR = 8.826, 95% CI: 1.250-62.312; p = 0.03) and deep location (OR = 8.576, 95% CI: 1.480-49.690; p = 0.02) were significant factors affecting complete obliteration in the PCT group.

Conclusion

The PCT may yield a higher rate of immediate complete obliteration with transarterial embolization of bAVMs, without increasing the rate of procedure-related complications.

Methodological quality assessment of genetic studies on brain arteriovenous malformation related hemorrhage: A cross-sectional study

Objectives: Rupture of a brain arteriovenous malformation (bAVM) can cause intracranial hemorrhage and severe clinical outcomes. At present, the mechanisms of bAVM-related hemorrhage are poorly understood. This study aimed to summarize the potential genetic risk factors for bAVM-related hemorrhage and appraise the methodological quality of existing genetic studies on bAVM-related hemorrhage using a cross-sectional design. Methods: A systematic literature search was conducted on genetic studies associated with bAVM-related hemorrhage published in PubMed, Embase, Web of Science, China National Knowledge Internet, and Wangfang databases, up to November 2022. Subsequently, a cross-sectional study was performed to describe the potential candidate genetic variants of bAVM associated with risk of hemorrhage and to evaluate the methodological quality of the identified studies using the Newcastle-Ottawa quality assessment scale and Q-genie tool. Results: Of the 1811 records identified in the initial search, nine studies met the filtering criteria and were included. Twelve single nucleotide polymorphisms (SNPs), including IL6 rs1800795, IL17A rs2275913, MMP9 rs9509, VEGFA rs1547651, and EPHB4 rs314353, rs314308, and rs314313, were associated with bAVM-related hemorrhage. However, only 12.5% of the evaluated SNPs showed statistical power> 0.80 (α = 0.05). Methodological quality assessment revealed significant flaws in the designs of the included studies, such as less reliable representativeness of recruited individuals, short follow-up periods in cohort studies, and less comparability between groups of hemorrhagic and non-hemorrhagic patients. Conclusion: IL1B, IL6, IL17A, APOE, MMP9, VEGFA and EPHB4 were potentially associated with bAVM-related hemorrhage. The methodological designs of the analyzed studies required improvement in order to obtain more reliable results. Regional alliances and rare disease banks need to be established to recruit large numbers of bAVM patients (especially familial and extreme-trait cases) in a multicenter, prospective cohort study with an adequate follow-up period. Furthermore, it is important to use advanced sequencing techniques and efficient measures to filter candidate genetic variants.

Effect of Targeted Embolization on Seizure Outcomes in Patients with Brain Arteriovenous Malformations

BACKGROUND

Seizures are one of the most debilitating manifestations of brain arteriovenous malformations (AVMs). This study aimed to evaluate the effect of curative embolization on brain AVM patients presenting with seizures.

METHODS

The records of patients who underwent embolization for brain AVM from January 2012 to December 2020 were evaluated and patients presenting with seizures were interviewed. Patient responses were evaluated according to the International League Against Epilepsy (ILAE) and Engel classifications. Statistical analyses of factors associated with seizure outcomes and complications were performed using ANOVA and Fischer's exact tests.

RESULTS

The mean age of the participants was 35.2 ± 10.7 years. More than 80% of the patients received no or suboptimal dosages of antiepileptic drugs (AEDs) prior to embolization. Positive seizure dynamics were observed in 50% of the patients post-procedure. A correlation was found between length of seizures in anamnesis and outcomes of both Engel and ILAE score, where shorter length was associated with better outcomes. Post-embolization hemorrhage was associated with initial presentation with hemorrhage.

CONCLUSIONS

The embolization of brain AVMs had a positive effect on seizure presentation and a relatively low prevalence of complications. However, the results of the study are obscured by inadequate AED treatment received by the patients, which prompts prospective studies on the topic with careful patient selection.

Whole-Exome Sequencing Reveals Pathogenic SIRT1 Variant in Brain Arteriovenous Malformation: A Case Report

Arteriovenous malformations of the brain (bAVMs) are plexuses of pathological arteries and veins that lack a normal capillary system between them. Intracranial hemorrhage (hemorrhagic stroke) is the most frequent clinical manifestation of AVM, leading to lethal outcomes that are especially high among children and young people. Recently, high-throughput genome sequencing methods have made a notable contribution to the research progress in this subject. In particular, whole-exome sequencing (WES) methods allow the identification of novel mutations. However, the genetic mechanism causing AVM is still unclear. Therefore, the aim of this study was to investigate the potential genetic mechanism underlying AVM. We analyzed the WES data of blood and tissue samples of a 30-year-old Central Asian male diagnosed with AVM. We identified 54 polymorphisms in 43 genes. After in-silica overrepresentation enrichment analysis of the polymorphisms, the SIRT1 gene variant (g.67884831C>T) indicated a possible molecular mechanism of bAVM. Further studies are required to evaluate the functional impact of SIRT1 g.67884831C>T, which may warrant further replication and biological investigations related to sporadic bAVM.

Surgical treatment of brain arteriovenous malformations: clinical outcomes of patients included in the registry of a pragmatic randomized trial

OBJECTIVE

The Treatment of Brain Arteriovenous Malformations Study (TOBAS) is a pragmatic study that includes 2 randomized trials and registries of treated or conservatively managed patients. The authors report the results of the surgical registry.

METHODS

TOBAS patients are managed according to an algorithm that combines clinical judgment and randomized allocation. For patients considered for curative treatment, clinicians selected from surgery, endovascular therapy, or radiation therapy as the primary curative method, and whether observation was a reasonable alternative. When surgery was selected and observation was deemed unreasonable, the patient was not included in the randomized controlled trial but placed in the surgical registry. The primary outcome of the trial was mRS score > 2 at 10 years (at last follow-up for the current report). Secondary outcomes include angiographic results, perioperative serious adverse events, and permanent treatment-related complications leading to mRS score > 2.

RESULTS

From June 2014 to May 2021, 1010 patients were recruited at 30 TOBAS centers. Surgery was selected for 229/512 patients (44%) considered for curative treatment; 77 (34%) were included in the surgery versus observation randomized trial and 152 (66%) were placed in the surgical registry. Surgical registry patients had 124/152 (82%) ruptured and 28/152 (18%) unruptured arteriovenous malformations (AVMs), with the majority categorized as low-grade Spetzler-Martin grade I-II AVM (118/152 [78%]). Thirteen patients were excluded, leaving 139 patients for analysis. Embolization was performed prior to surgery in 78/139 (56%) patients. Surgical angiographic cure was obtained in 123/139 all-grade (89%, 95% CI 82%-93%) and 105/110 low-grade (95%, 95% CI 90%-98%) AVM patients. At the mean follow-up of 18.1 months, 16 patients (12%, 95% CI 7%-18%) had reached the primary safety outcome of mRS score > 2, including 11/16 who had a baseline mRS score ≥ 3 due to previous AVM rupture. Serious adverse events occurred in 29 patients (21%, 95% CI 15%-28%). Permanent treatment-related complications leading to mRS score > 2 occurred in 6/139 patients (4%, 95% CI 2%-9%), 5 (83%) of whom had complications due to preoperative embolization.

CONCLUSIONS

The surgical treatment of brain AVMs in the TOBAS registry was curative in 88% of patients. The participation of more patients, surgeons, and centers in randomized trials is needed to definitively establish the role of surgery in the treatment of unruptured brain AVMs. Clinical trial registration no.: NCT02098252 (ClinicalTrials.gov).

Endovascular treatment as the first-line approach for cure of low-grade brain arteriovenous malformation

OBJECTIVE

While microsurgery has been proposed as the first-line treatment for patients with low-grade (Spetzler-Martin grade I or II) brain arteriovenous malformations (bAVMs), recent studies have shown promising results for endovascular treatment (EVT) as a single proper choice for the management of this group of bAVMs. In this study, the authors evaluated the safety and efficacy of EVT as a first-line strategy for curing low-grade bAVMs at their center.

METHODS

All patients with low-grade bAVMs managed primarily by EVT between 2015 and 2021 were enrolled in this study. Patients were evaluated and treated by the same team and followed with the same protocol. The primary endpoint was the efficacy of EVT on the cure of low-grade bAVMs. The second endpoint was the safety of EVT for the treatment of low-grade bAVMs, including procedural complications and long-term clinical outcomes.

RESULTS

A total of 109 patients were enrolled and represented in the study population. The mean patient age was 31.6 ± 14.8 years. Forty-eight AVMs (44%) were Spetzler-Martin grade I and 61 (56%) were grade II. Of 99 patients who completed their EVT sessions, complete exclusion was achieved in 89 patients (89.9%). Overall, complete exclusion was achieved in 59.6% of patients after a single EVT session. At the 6-month follow-up, 106 patients (97.2%) had a favorable outcome. Four patients (4.6%) experienced transient neurological deficits, and 1 patient (0.9%) had a permanent neurological deficit.

CONCLUSIONS

EVT can be offered as the first choice of treatment for select patients with low-grade bAVMs, with a high cure rate and low morbidity.

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.

Endovascular treatment of brain arteriovenous malformations involving the anterior cerebral artery

To date, at least to the best of our knowledge, there are only limited studies available on the endovascular treatment (EVT) of brain arteriovenous malformations (BAVMs) involving the anterior cerebral artery (ACA), thus termed ACA-BAVMs. The present study retrospectively examined 60 patients with ACA-BAVMs treated with EVT. The patients were aged between 10 and 72 years (mean age, 35.4±7.0 years) and included 28 females (46.7%, 28/60). The ACA-BAVMs were divided into three types: Type I BAVMs were those located below and in front of the corpus callosum genu, type II BAVMs were those located at the upper area of the corpus callosum from the genu to the anterior portion of corpus callosum body, and type III BAVMs were those located from the anterior portion of corpus callosum body to the splenium of the corpus callosum. There were 9 (15%, 9/60), 15 (25%, 15/60) and 36 (60%, 36/60) patients with type I, II and III ACA-BAVMs, respectively. Statistical analysis revealed that the posterior cerebral artery (PCA) tended to be involved in type II and III BAVMs. All patients were treated using EVT. During EVT, there were 3 cases of intraoperative bleeding (5%, 3/60), which tended to occur in type I and II ACA-BAVMs. The other 57 cases (95%, 57/60) had no complications and new neurological deficits. At the time of discharge, 48 (80%, 48/60) patients had a Glasgow Outcome Scale score of 5. During the clinical follow-up period, 47 patients were classified according to the modified Rankin Scale (mRS) score; 39 (83%, 39/47) patients presented with an mRS score of 0. On the whole, the present study demonstrated that EVT may be a safe treatment for ACA-BAVMs.

Without Prior Embolization for Brain Arteriovenous Malformations: A Propensity Score Matching Analysis

Objective: Whether partial embolization could facilitate the post-stereotactic radiosurgery (SRS) obliteration for brain arteriovenous malformations (bAVMs) remains controversial. We performed this study to compare the outcomes of SRS with and without prior embolization for bAVMs.

Methods: We retrospectively reviewed the Beijing Tiantan AVMs prospective registration research database from September 2011 to October 2014. Patients were categorized into two groups, combined upfront embolization and SRS (Em+SRS group) and SRS alone (SRS group), and we performed a propensity score matching analysis based on pre-embolization baseline characteristics; the matched groups each comprised 76 patients.

Results: The obliteration rate was similar between SRS and Em+SRS (44.7 vs. 31.6%; OR, 1.754; 95% CI, 0.905–3.401; p = 0.096). However, the SRS group was superior to the Em+SRS group in terms of cumulative obliteration rate at a follow-up of 5 years (HR,1.778; 95% CI, 1.017–3.110; p = 0.033). The secondary outcomes, including functional state, post-SRS hemorrhage, all-cause mortality, and edema or cyst formation were similar between the matched cohorts. In the ruptured subgroup, the SRS group could achieve higher obliteration rate than Em+SRS group (56.5 vs. 31.9%; OR, 2.773; 95% CI, 1.190–6.464; p = 0.018). The cumulative obliteration rate at 5 years was also higher in the SRS group (64.5 vs. 41.3%; HR, 2.012; 95% CI, 1.037–3.903; p = 0.038), and the secondary outcomes were also similar between the matched cohorts.

Conclusion: Although there was no significant difference in the overall obliteration rate between the two strategies, this study suggested that pre-SRS embolization may have a negative effect on post-SRS obliteration. Furthermore, the obliteration rates of the SRS only strategy was significantly higher than that of the Em+SRS strategy in the ruptured cohort, while no such phenomenon was found in the unruptured cohort.

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.

Retrospective Study and Outcome Predictor after Microsurgical Resection of Cerebral Arteriovenous Malformations in Nepal

Objective:

The purpose of this study is to assess demographic, clinical, and morphological characteristics of patients with brain arteriovenous malformations (bAVMs). The relation of outcome using modified Ranklin Scale (mRS) at time of discharge, early and last follow ups with respect to various factors.

Materials and Methods:

Demographic data, arteriovenous malformation characteristics, and treatment outcomes were evaluated in 43 bAVMs treated with microsurgery between 2009 and 2019. For this series, 43 patients were retrospectively reviewed. A subgroup analysis for Spetzler-Martin grades (SMG) I/II, III, IV/V and III–V were performed. The mRS was used to assess functional outcomes.

Results:

Overall, mean age at diagnosis was 33 years (standard deviation = 19). Transient deficit, mRS deterioration and impaired functional outcome occurred less frequently in SMG I–II patients compared with Grade III–V patients combined (29% vs. 32% respectively, P = 0.00). All patients with SMG Grade I, Supplemented SMG Grade 2, 3, 4 and 6 had a mRS score of 2 or less at the last follow-up. Age was the only significant predictor of overall outcome after bAVM surgery on Chi-square test (P = 0.046), i.e: all patients <20 years had mRS score of 2 or less on last follow-up. Unfavorable outcome (mRS score of 3 or more than 3) level increased with higher grades in SMG on long term follow-up.

Conclusion:

The results of our case series of bAVM with SMG Grade I and Suplemented Grade 2, 3, 4 and even higher grade i.e., 6 can have excellent overall outcome after microsurgical resection. Association of factors which increases the grading system of bAVM like eloquence, deep venous drainage and increasing sizes did not correlate with the predicted unfavorable outcomes, whereas age of patients was a predictor of overall outcome. Although the small sample size of this study is a limitation, age of patient plays important role on the overall outcome.

Imaging Characteristics and Endovascular Treatment of Brain Arteriovenous Malformations Mainly Fed by the Posterior Cerebral Artery

Background: A BAVM that is mainly supplied by the posterior cerebral artery (PCA) lies deeply in the middle of the bilateral posterior hemispheres. Few studies have investigated the imaging characteristics and endovascular treatment (EVT) of brain arteriovenous malformations (BAVMs) in this area.

Methods: A retrospective study was performed for patients who were diagnosed with PCA-BAVMs from January 2015 to December 2019. The PCA-BAVMs were divided into type I and type II according to their feeding arteries. Type I PCA-BAVMs were supplied by the posterior choroidal artery (PchA) from the PCA. They could be further subdivided into type Ia and type Ib. Type II PCA-BAVMs were supplied by the temporal or occipital branch from the PCA. They could also be further subdivided into type IIa and IIb. Targeted embolization of the risk factors was the main aim of EVT.

Results: Forty-two patients were identified, with age ranging from 6 to 63 years. Twenty-four cases belonged to type I (57.1%, 24/42), including 6 Ia cases and 18 Ib cases. Eighteen cases belonged to type II (42.9%, 18/42), including 7 IIa cases and 11 IIb cases. Immediate complete or nearly complete embolization was achieved in 17 (40.5%, 17/42) cases. Partial embolization was achieved in 25 (59.5%, 25/42) cases. Two (4.8%, 2/42) patients experienced intraoperative or postoperative bleeding. The GOS scores at discharge were 3, 4, and 5 in 2 (4.8%, 2/42), 2 (4.8%, 2/42), and 38 (90.4%, 38/42) cases, respectively. There was no statistical difference between patients in type I and type II groups regarding age, BAVM rupture, SM grade, immediate extent of obliteration, and prognosis. Deep venous drainage was more common in patients of the type I group (P < 0.001).

Conclusions: Our classification of the PCA-BAVMs was based on the segmentation of the PCA, which is a reasonable approach and could guide the strategy of EVT. EVT is a reasonable option for the PCA-BAVMs. The main aim of EVT is to secure the weak structures. A targeted EVT aimed at the ruptured part of the BAVM can reduce the risk of early rebleeding.

Angiographic Evaluation and Endovascular Treatment Considerations of Brain Arteriovenous Malformations With a Transdural Blood Supply: A Single-Center Experience

Background: In rare circumstances, brain arteriovenous malformations (BAVMs) can recruit a transdural blood supply (TBS). The clinical and radiologic characteristics of BAVMs with a TBS are poorly understood.

Methods: A retrospective review of the medical records was conducted for adult patients who were admitted for BAVMs from Jan 2013 to Dec 2019. TBSs for BAVMs were divided into 3 types: (1) unilateral TBSs from the external carotid artery (ECA) and/or meningeal branch of the vertebral artery (VA); (2) bilateral TBSs from the ECA and/or meningeal branch of the VA; and (3) meningohypophyseal trunk TBSs of the internal carotid artery.

Results: Four hundred and twenty-eight patients were diagnosed with BAVMs during the study period, of whom 30 (7.0%, 30/428) were identified as having a TBS. Type 1, type 2, and type 3 TBSs were identified in 21 (70%, 21/30), 7 (23.3%, 7/30), and 2 (6.7%, 2/30) patients, respectively. Six (20%, 6/30) patients were conservatively managed. Twelve (40%, 12/30) patients underwent endovascular treatment (EVT) of the BAVM through non-TBS feeders. Eight (26.8%, 8/30) patients underwent EVT of the BAVM both through the TBS and non-TBS feeders. The modified Rankin Scale scores at the 3-month follow-up were 0, 1, 2, 4, and 5 in 24 (80%, 24/30), 2 (6.7%, 2/30), 2 (6.7%, 2/30), 1 (3.3%, 1/30), and 1 (3.3%, 1/30) patients, respectively. Good short-term recovery was achieved in 86.7% (26/30) of the patients. The size of the BAVMs with a TBS was larger than that of BAVMs without a TBS. Patients with higher Spetzler-Martin grades tended to have a TBS. No statistical difference was noted between the patients with and without a TBS with regard to age, sex, location, or concurrent aneurysms.

Conclusions: This study showed that a TBS was likely to develop in patients with larger BAVMs and that a TBS was likely to be located in the temporal lobe in patients BAVMs with higher SM grades. Weak structures were the primary targets of management. In addition, a BAVM could be embolized via the TBS.

KRAS/BRAF mutations in brain arteriovenous malformations: A systematic review and meta-analysis

INTRODUCTION

Somatic KRAS mutations have been identified in the majority of brain arteriovenous malformations (AVM) specimens. The aim of our study was to evaluate the prevalence of Kirsten rat sarcoma (KRAS)/murine sarcoma viral oncogene homolog B1 (BRAF) mutations in brain AVM.

METHODS

A systematic literature review was performed in November 2019. We reviewed MEDLINE/PubMed, Cochrane Library, and ClinicalTrials.gov for citation or ongoing trials from January 2010 to March 2020.

RESULTS

6 studies were identified as meeting the inclusion criteria of this review. The total frequency of KRAS mutations in 1726 patients with AVM was 55%. The prevalence of BRAF mutation was 7.5%. The prevalence of AVMs with grade 2 was the most (39%). Frontal and parietal lobes were the commonest sites of AVMs (21%). the most prevalent presentation of patients with AVM was hemorrhage (62%).

CONCLUSION

Our findings support a high prevalence of somatic activating mutations in KRAS and less commonly, BRAF in the overwhelming majority of brain AVMs. Practically and importantly, this pathway homogeneity in CNS arteriovenous malformations also supports the development of targeted therapies with RAS/RAF pathway inhibitors. However, more studies are needed to confirm this hypothesis.

Metabolic Disorder of Extracellular Matrix Mediated by Decorin Upregulation Is Associated With Brain Arteriovenous Malformation Diffuseness

Background and Objective

Diffuse brain arteriovenous malformations (BAVMs) are mixed up with normal brain parenchyma and therefore increase the difficulty of surgical resection, leading to poor surgical prognosis. Since the mechanism underlying BAVM diffuseness remains unknown, a quantitative proteomic analysis was performed to investigate the altered expression of proteins in diffuse BAVMs compared to compact ones.

Methods

We performed proteomic analysis on five diffuse BAVMs and five compact BAVMs. Bioinformatics analysis was conducted to identify potential signals related to BAVM diffuseness. Candidate proteins were then investigated in BAVM specimens using immunofluorescence and Western blot analysis. Tube formation assays were used to investigate the effects of candidate proteins on the angiogenesis of human umbilical endothelial cells (HUVECs). Finally, Masson, Sirius red staining, and immunofluorescence were used to evaluate the characteristics of extracellular matrix (ECM) in BAVM tissues.

Results

A total of 58 proteins were found to be differentially expressed between diffuse and compact BAVMs via proteomic analysis. TGF-β (transforming growth factor-beta) signaling pathway, ECM–receptor pathway, relaxin signaling pathway, and several other pathways were associated with BAVM diffuseness. The TGF-β signaling pathway is associated with angiogenesis; the role of this pathway in the formation of diffuse BAVMs was investigated, and the decorin (DCN) upregulation played an important role in this process. Immunofluorescence showed that DCN was significantly upregulated within and around the malformed vessels of diffuse BAVMs. Functional assays showed that exogenous DCN could promote the tube formation ability of HUVECs through inhibiting the TGF-β signaling pathway and overproducing ECM. Histological staining demonstrated the overproduction of ECM in diffuse BAVMs.

Conclusion

TGF-β signaling pathway inhibited by DCN in vascular endothelial cells is related to BAVM diffuseness. The metabolic disorder of ECM caused by DCN upregulation may significantly contribute to the formation of diffuse BAVMs.

Perisylvian Arteriovenous Malformation Mimicking Carotid Cavernous Fistula: Operative Video

Brain arteriovenous malformations (AVM) commonly present for medical attention after a patient experiences a rupture that results in a focal neurologic deficit, an epileptic event, or is found incidentally on cranial imaging performed for an unrelated reason. In contrast, carotid-cavernous fistulas (CCF) can develop high-flow arteriovenous shunting with symptoms attributable to venous hypertension. We discuss a unique case of a 54-year-old female presenting with signs and symptoms suggestive of a CCF but was found to have a perisylvian AVM with an enlarged draining vein draining into the cavernous sinus. Our case report demonstrates a combined endovascular and open surgical approach to a unique presentation of a brain AVM with the resolution of ocular symptoms. 

Wilms' tumour 1-associating protein inhibits endothelial cell angiogenesis by m6A-dependent epigenetic silencing of desmoplakin in brain arteriovenous malformation

Brain arteriovenous malformations (AVMs) are congenital vascular abnormality in which arteries and veins connect directly without an intervening capillary bed. So far, the pathogenesis of brain AVMs remains unclear. Here, we found that Wilms' tumour 1‐associating protein (WTAP), which has been identified as a key subunit of the m6A methyltransferase complex, was down‐regulated in brain AVM lesions. Furthermore, the lack of WTAP could inhibit endothelial cell angiogenesis in vitro. In order to screen for downstream targets of WTAP, we performed RNA transcriptome sequencing (RNA‐seq) and Methylated RNA Immunoprecipitation Sequencing technology (MeRIP‐seq) using WTAP‐deficient and control endothelial cells. Finally, we determined that WTAP regulated Desmoplakin (DSP) expression through m6A modification, thereby affecting angiogenesis of endothelial cells. In addition, an increase in Wilms' tumour 1 (WT1) activity caused by WTAP deficiency resulted in substantial degradation of β‐catenin, which might also inhibit angiogenesis of endothelial cells. Collectively, our findings revealed the critical function of WTAP in angiogenesis and laid a solid foundation for the elucidation of the pathogenesis of brain AVMs.

Regression of a symptomatic varix after transarterial embolization of a brain arteriovenous malformation: A case report and literature review

RATIONALE

Brain arteriovenous malformation (BAVM)-associated varix is always asymptomatic, and no special treatment is needed. However, there is no consensus regarding how to address a varix that has led to clinical manifestation.

PATIENT CONCERNS

An 11-year-old girl was admitted complaining of left hemiparesis for 4 days. She was previously healthy and denied any history of similar ictus. She was alert, and a physical examination performed upon admission was unremarkable except for the left hemiparesis.

DIAGNOSES

Head magnetic resonance imaging (MRI) showed a linear and round flow void and perilesional edema in the region of the right basal ganglia, indicating a BAVM. Gadolinium-enhanced MRI showed peripheral enhancement of the round lesion. Computed tomography angiography (CTA) showed that the BAVM was fed by the ipsilateral posterior cerebral artery and anterior choroidal artery and drained into the vein of Galen. A large varix was also noted at the top of the BAVM and was consistent with the round flow void observed at the right basal ganglia on MRI. The Spetzler-Martin grading scale was grade IV INTERVENTIONS:: The patient experienced a TAE of the BAVM nidus with liquid embolic agent.

OUTCOMES

A follow-up investigation showed regression of the varix, although there was still some residual BAVM. The patient experienced a favorable recovery.

LESSONS

In the case of a BAVM-associated symptomatic varix, if surgical resection cannot readily be performed, initial TAE of the BAVM nidus can be attempted.

Radiation-Stimulated Translocation of CD166 and CRYAB to the Endothelial Surface Provides Potential Vascular Targets on Irradiated Brain Arteriovenous Malformations

Vascular targeting with pro-thrombotic antibody-conjugates is a promising biological treatment for brain arteriovenous malformations (bAVMs). However, targeted drug delivery relies on the identification of unique or overexpressed markers on the surface of a target cell. In the absence of inherent biological markers, stereotactic radiosurgery may be used to prime induction of site-specific and targetable molecular changes on the endothelial surface. To investigate lumen-accessible, endothelial targets induced by radiation, we combined Gamma knife surgery in an AVM animal model with in vivo biotin-labeling and comparative proteomics. Two proteins, αB-crystallin (CRYAB)-a small heat shock protein that normally acts as an intracellular chaperone to misfolded proteins-and activated leukocyte cell adhesion molecule CD166, were further validated for endothelial surface expression after irradiation. Immunostaining of endothelial cells in vitro and rat AVM tissue ex vivo confirmed de novo induction of CRYAB following irradiation (20 Gy). Western analysis demonstrated that CRYAB accumulated intracellularly as a 20 kDa monomer, but, at the cell surface, a novel 65 kDa protein was observed, suggesting radiation stimulates translocation of an atypical CRYAB isoform. In contrast, CD166 had relatively high expression in non-irradiated cells, localized predominantly to the lateral surfaces. Radiation increased CD166 surface exposure by inducing translocation from intercellular junctions to the apical surface without significantly altering total protein levels. These findings reinforce the dynamic molecular changes induced by radiation exposure, particularly at the cell surface, and support further investigation of radiation as a priming mechanism and these molecules as putative targets for focused drug delivery in irradiated tissue.

Recent Advances in Basic Research for Brain Arteriovenous Malformation

Arteriovenous malformations (AVMs) are abnormal connections of vessels that shunt blood directly from arteries into veins. Rupture of brain AVMs (bAVMs) can cause life-threatening intracranial bleeding. Even though the majority of bAVM cases are sporadic without a family history, some cases are familial. Most of the familial cases of bAVMs are associated with a genetic disorder called hereditary hemorrhagic telangiectasia (HHT). The mechanism of bAVM formation is not fully understood. The most important advances in bAVM basic science research is the identification of somatic mutations of genes in RAS-MAPK pathways. However, the mechanisms by which mutations of these genes lead to AVM formation are largely unknown. In this review, we summarized the latest advance in bAVM studies and discussed some pathways that play important roles in bAVM pathogenesis. We also discussed the therapeutic implications of these pathways.

Brain arteriovenous malformation with transdural blood supply: Current status

Arterial blood supply to a brain arteriovenous malformation (BAVM) is mainly derived from the internal carotid artery (ICA) and vertebral basilar artery (VBA) system. However, in certain cases, arteries supplying the meninges may also contribute to the blood supply of the BAVM, resulting in the formation of a BAVM with transdural blood supply (TBS). To review the current status of BAVM with TBS, a literature search was performed in the PubMed database. Articles were screened for relevance and suitability of data. According to recent studies, the mechanisms by which TBS to a BAVM forms are mainly classified into the congenital and acquired type. BAVM with TBS is common in elderly patients and is characterized by intracranial hemorrhage, epilepsy, chronic headache and increased intracranial pressure. Digital subtraction angiography is the gold standard for diagnosing BAVM with TBS. Superselective angiography is also important. Treatments for BAVM with TBS include surgical resection, endovascular treatment (EVT), stereotactic radiosurgery and combined treatment. Surgical resection is difficult to perform. EVT has become the major therapy for treating BAVM with TBS due to its low procedural invasiveness. Combination of surgical resection and EVT may be a good option. In addition, stereotactic radiosurgery is frequently used as a complementary treatment to surgical and endovascular interventions. The prognosis of BAVM with TBS is not favorable, as the defect involves a complex arterial supply system.

Risk factors for hemorrhage of brain arteriovenous malformation

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

Sudden Death Due to Primary Intraventricular Hemorrhage: Report of Two Cases

Primary intraventricular hemorrhage (PIVH) is a rare type of stroke defined as bleeding within the ventricles of the brain without any associated parenchymal hemorrhage. Here, we reported two cases of sudden death due to PIVH. One of the patients was found dead under a highway bridge without witnesses, and the other patient was hospitalized with hemorrhage in the ventricular system, as revealed by a head computed tomography scan. In these two patients, autopsy and macroscopic examination only showed hemorrhages in the ventricular system without any traumatic brain injury or other intraparenchymal hemorrhage. The sources of bleeding for both patients were ultimately confirmed as ruptured brain arteriovenous malformations located in the subventricular zone. We reported these cases to broaden our understanding of sudden death associated with PIVH, especially when caused by brain arteriovenous malformation. We also summarized the essential details of the diagnoses and available technical methods for PIVH cases.

Epidemiology of ruptured brain arteriovenous malformation: a National Cohort Study in Korea

OBJECTIVEBrain arteriovenous malformation (BAVM) is a rare cerebrovascular disease that causes intracranial hemorrhage. Although several reports have demonstrated the epidemiological features of BAVM in Western countries, no epidemiological investigations regarding BAVM have been reported in Korea. The authors aimed to investigate the national epidemiology of ruptured BAVM in a Korean population.METHODSThe authors used data from the National Health Insurance Service-National Sample Cohort (NHIS-NSC). The original cohort included approximately 1 million individuals (2% of the Korean population) with 12-year claim data (2002-2013). To construct an initial cohort for investigation, the authors selected 1,016,820 registered individuals in 2005. Subjects with a history of cerebrovascular disease (code I6xx) and BAVM (Q282) between 2002 and 2004 were washed-out to identify incident cases. During the 9-year follow-up (2005-2013), the incidence of BAVM was calculated using the earliest date of diagnosis of ruptured or unruptured BAVM. Direct standardization was applied to the crude incidence. Mortality and disability were evaluated using registration data. Related diagnostic procedures were also analyzed.RESULTSA total of 8,802,696 person-years of observation were noted. During observation, 308 patients were diagnosed with a ruptured BAVM. The crude incidence of ruptured BAVM was 3.5 per 100,000 person-years. There was no sex difference in incidence. The mortality rate for patients with a ruptured BAVM 1 month after diagnosis was 12.7%. At 1-year and 5-year follow-up examinations, mortality rates were 17.2% and 22.1%, respectively. Severe disability-free survival rates of patients with ruptured AVMs were 75.3% and 69.8% at 1-year and 5-year follow-up, respectively.CONCLUSIONSThe standardized incidence of ruptured BAVMs was 3.6 per 100,000 person-years in Korea. Ruptured BAVMs resulted in high mortality and disability rates.

Utility of indocyanine green videoangiography in subcortical arteriovenous malformation resection

Subcortical arteriovenous malformations (AVMs) are surgically challenging. Localization is crucial for eloquent areas, and complete resection evaluation is uncertain. Indocyanine green videoangiography (ICG-VA) can assist this surgery. An illustrative video of a subcortical frontoparietal bleeding AVM resection assisted by ICG-VA is presented. A bleeding arterial feeder aneurysm was embolized in the acute phase to protect against rebleeding. ICG-VA helped to detect the AVM's superficial arterialized draining vein, distinguishing it from normal cortical veins. This enabled a customized sulcus approach. ICG-VA showed normalized flow through the previously arterialized vein, confirming the AVM's complete resection. This applies when there is a single drainage remaining. The video can be found here: https://youtu.be/L7yJEE66kV0 .

Predictors of intracranial hemorrhage volume and distribution in brain arteriovenous malformation

Background and purpose Despite evidence regarding risk factors for brain arteriovenous malformation (bAVM)-associated spontaneous intracranial hemorrhage (ICH), few data exist describing the spectrum of clinical outcomes that bAVM-associated ICH may manifest. This study aimed to identify the demographical, clinical, and bAVM anatomical variables associated with ICH volume and the presence of intraventricular hemorrhage (IVH) of ruptured bAVMs, two indicators of worse clinical outcome, to help better predict outcome for unruptured bAVMs. Methods Computed tomography images ( n = 169) of patients with ruptured bAVM in a prospectively maintained institutional database were retrospectively reviewed to calculate ICH volume and the presence or absence of IVH. Demographic, clinical, and bAVM characteristics information was summarized and analyzed with univariable and multivariable regression models to identify the associations of these features with ICH volume and the presence of IVH. Results Patient sex, exclusively deep venous drainage, and lobar location were associated with ICH volume in univariable analysis; exclusively deep venous drainage remained significant in multivariable analysis (PI = 0.33, 95% CI: 0.21-0.52, p < 0.001). Exclusively deep venous drainage, multiple feeding arteries, and venous stenosis were associated with IVH in univariable analysis; exclusively deep venous drainage (OR = 7.27, 95% CI: 1.94-27.29, p = 0.003) remained significant in multivariable analysis. Conclusions Variables associated with ICH volume and the presence of IVH in ruptured bAVMs were evaluated and identified. They impart information that may help predict the clinical outcome of unruptured bAVM, in turn aiding clinicians in treatment planning.

Development of three-dimensional brain arteriovenous malformation model for patient communication and young neurosurgeon education

PURPOSE

Rapid prototyping technology is used to fabricate three-dimensional (3D) brain arteriovenous malformation (AVM) models and facilitate presurgical patient communication and medical education for young surgeons.

METHODS

Two intracranial AVM cases were selected for this study. Using 3D CT angiography or 3D rotational angiography images, the brain AVM models were reconstructed on personal computer and the rapid prototyping process was completed using a 3D printer. The size and morphology of the models were compared to brain digital subtraction arteriography of the same patients. 3D brain AVM models were used for preoperative patient communication and young neurosurgeon education.

RESULTS

Two brain AVM models were successfully produced. By neurosurgeons' evaluation, the printed models have high fidelity with the actual brain AVM structures of the patients. The patient responded positively toward the brain AVM model specific to himself. Twenty surgical residents from residency programs tested the brain AVM models and provided positive feedback on their usefulness as educational tool and resemblance to real brain AVM structures.

CONCLUSIONS

Patient-specific 3D printed models of brain AVM can be constructed with high fidelity. 3D printed brain AVM models are proved to be helpful in preoperative patient consultation, surgical planning and resident training.

Three-dimensional brain arteriovenous malformation models for clinical use and resident training

BACKGROUND

To fabricate three-dimensional (3D) models of brain arteriovenous malformation (bAVM) and report our experience with customized 3D printed models of patients with bAVM as an educational and clinical tool for patients, doctors, and surgical residents.

METHODS

Using computerized tomography angiography (CTA) or digital subtraction angiography (DSA) images, the rapid prototyping process was completed with specialized software and "in-house" 3D printing service. Intraoperative validation of model fidelity was performed by comparing to DSA images of the same patient during the endovascular treatment process. 3D bAVM models were used for preoperative patient education and consultation, surgical planning, and resident training.

RESULTS

3D printed bAVM models were successful made. By neurosurgeons' evaluation, the printed models precisely replicated the actual bAVM structure of the same patients (n = 7, 97% concordance, range 95%-99% with average of < 2 mm variation). The use of 3D models was associated shorter time for preoperative patient education and consultation, higher acceptable of the procedure for patients and relatives, shorter time between obtaining intraoperative DSA data and the start of endovascular treatment. Thirty surgical residents from residency programs tested the bAVM models and provided feedback on their resemblance to real bAVM structures and the usefulness of printed solid model as an educational tool.

CONCLUSIONS

Patient-specific 3D printed models of bAVM can be constructed with high fidelity. 3D printed bAVM models were proven to be helpful in preoperative patient consultation, surgical planning, and resident training.

The Treatment of Brain AVMs Study (TOBAS): an all-inclusive framework to integrate clinical care and research

OBJECTIVE The management of brain arteriovenous malformations (bAVMs) remains controversial. The Treatment of Brain AVMs Study (TOBAS) was designed to manage patients with bAVMs within a clinical research framework. The objective of this study was to study trial feasibility, recruitment rates, patient allocation to the various management groups, and compliance with treatment allocation. METHODS TOBAS combines two randomized care trials (RCTs) and a registry. Designed to be all-inclusive, the study offers randomized allocation of interventional versus conservative management to patients eligible for both options (first RCT), a second RCT testing the role of preembolization as an adjunct to surgery or radiotherapy, and a registry of patients managed using clinical judgment alone. The primary outcome of the first RCT is death from any cause or disabling stroke (modified Rankin Scale score > 2) at 10 years. A pilot phase was initiated at one center to test study feasibility, record the number and characteristics of patients enrolled in the RCTs, and estimate the frequency of crossovers. RESULTS All patients discussed at the multidisciplinary bAVM committee between June 2014 and June 2016 (n = 107) were recruited into the study; 46 in the randomized trials (23 in the first RCT with 21 unruptured bAVMs, 40 in the second RCT with 17 unruptured bAVMs, and 17 in both RCTs), and 61 patients in the registry. Three patients crossed over from surgery to observation (first RCT). CONCLUSIONS Clinical research was successfully integrated with normal practice using TOBAS. Recruitment rates in a single center are encouraging. Whether the trial will provide meaningful results depends on the recruitment of a sufficient number of participating centers. Clinical trial registration no.: NCT02098252 (clinicaltrials.gov).

Recent Trends in Neuro-endovascular Treatment for Acute Ischemic Stroke, Cerebral Aneurysms, Carotid Stenosis, and Brain Arteriovenous Malformations

The efficacy of mechanical thrombectomy with stent retrievers for emergent large vessel occlusion has been proved by randomized trials. Mechanical thrombectomy is increasingly being adopted in Japan since stent retrievers were first approved in 2014. An urgent clinical task is to offer structured systems of care to provide this treatment in a timely fashion to all patients with emergent large vessel occlusion. Treatment with flow-diverting stents is currently a preferred treatment option worldwide for large and giant unruptured aneurysms. Initial studies reported high rates of complete aneurysm occlusion, even in large and giant aneurysms, without delayed aneurysmal recanalization and/or growth. The Pipeline Embolic Device is a flow diverter recently approved in Japan for the treatment of large and giant wide-neck unruptured aneurysms in the internal carotid artery, from the petrous to superior hypophyseal segments. Carotid artery stenting is the preferred treatment approach for carotid stenosis in Japan, whereas it remains an alternative for carotid endarterectomy in Europe and the United States. Carotid artery stenting with embolic protection and plaque imaging is effective in achieving favorable outcomes. The design and conclusions of a randomized trial of unruptured brain arteriovenous malformations (ARUBA) trial, which compared medical management alone and medical management with interventional therapy in patients with an unruptured arteriovenous brain malformation, are controversial. However, the annual bleeding rate (2.2%) of the medical management group obtained from this study is worthy of consideration when deciding treatment strategy.

A supplementary grading scale combining lesion-to-eloquence distance for predicting surgical outcomes of patients with brain arteriovenous malformations

OBJECTIVE Case selection for the surgical treatment of brain arteriovenous malformations (BAVMs) remains challenging. This study aimed to construct a predictive grading system combining lesion-to-eloquence distance (LED) for selecting patients with BAVMs for surgery. METHODS Between September 2012 and September 2015, the authors retrospectively studied 201 consecutive patients with BAVMs. All patients had undergone preoperative functional MRI and diffusion tensor imaging (DTI), followed by resection. Both angioarchitectural factors and LED were analyzed with respect to the change between preoperative and final postoperative modified Rankin Scale (mRS) scores. LED refers to the distance between the lesion and the nearest eloquent area (eloquent cortex or eloquent fiber tracts) measured on preoperative fMRI and DTI. Based on logistic regression analysis, the authors constructed 3 new grading systems. The HDVL grading system includes the independent predictors of mRS change (hemorrhagic presentation, diffuseness, deep venous drainage, and LED). Full Score combines the variables in the Spetzler-Martin (S-M) grading system (nidus size, eloquence of adjacent brain, and venous drainage) and the HDVL. For the third grading system, the fS-M grading system, the authors added information regarding eloquent fiber tracts to the S-M grading system. The area under the receiver operating characteristic (ROC) curves was compared with those of the S-M grading system and the supplementary S-M grading system of Lawton et al. RESULTS LED was significantly correlated with a change in mRS score (p < 0.001). An LED of 4.95 mm was the cutoff point for the worsened mRS score. Hemorrhagic presentation, diffuseness, deep venous drainage, and LED were independent predictors of a change in mRS score. Predictive accuracy was highest for the HDVL grading system (area under the ROC curve 0.82), followed by the Full Score grading system (0.80), the fS-M grading system (0.79), the supplementary S-M grading system (0.76), and least for the S-M grading system (0.71). Predictive accuracy of the HDVL grading system was significantly better than that of the Spetzler-Martin grade (p = 0.040). CONCLUSIONS LED was a significant predictor for the preoperative risk evaluation for surgery. The HDVL system was a good predictor of neurological outcomes after BAVM surgery. Adding the consideration of the involvement of eloquent fiber tracts to preoperative evaluation can effectively improve its predictive accuracy.

Contemporary Imaging of Cerebral Arteriovenous Malformations

OBJECTIVE

Brain arteriovenous malformation (AVM) rupture results in substantial morbidity and mortality. The goal of AVM treatment is eradication of the AVM, but the risk of treatment must be weighed against the risk of future hemorrhage.

CONCLUSION

Imaging plays a vital role by providing the information necessary for AVM management. Here, we discuss the background, natural history, clinical presentation, and imaging of AVMs. In addition, we explain advances in techniques for imaging AVMs.

Epidemiology, genetics, pathophysiology, and prognostic classifications of cerebral arteriovenous malformations

Arteriovenous malformations (AVMs) are vascular deformities involving fistula formation of arterial to venous structures without an intervening capillary bed. Such anomalies can prove fatal as the high arterial flow can disrupt the integrity of venous walls, thus leading to dangerous sequelae such as hemorrhage. Diagnosis of these lesions in the central nervous system can often prove challenging as intracranial AVMs represent a heterogeneous vascular pathology with various presentations and symptomatology. The literature suggests that most brain AVMs (bAVMs) are identified following evaluation of the etiology of acute cerebral hemorrhage, or incidentally on imaging associated with seizure or headache workup. Given the low incidence of this disease, most of the data accrued on this pathology comes from single-center experiences. This chapter aims to distill the most important information from these studies as well as examine meta-analyses on bAVMs in order to provide a comprehensive introduction into the natural history, classification, genetic underpinnings of disease, and proposed pathophysiology. While there is yet much to be elucidated about AVMs of the central nervous system, we aim to provide an overview of bAVM etiology, classification, genetics, and pathophysiology inherent to the disease process.

Genome-wide association study of sporadic brain arteriovenous malformations

BACKGROUND

The pathogenesis of sporadic brain arteriovenous malformations (BAVMs) remains unknown, but studies suggest a genetic component. We estimated the heritability of sporadic BAVM and performed a genome-wide association study (GWAS) to investigate association of common single nucleotide polymorphisms (SNPs) with risk of sporadic BAVM in the international, multicentre Genetics of Arteriovenous Malformation (GEN-AVM) consortium.

METHODS

The Caucasian discovery cohort included 515 BAVM cases and 1191 controls genotyped using Affymetrix genome-wide SNP arrays. Genotype data were imputed to 1000 Genomes Project data, and well-imputed SNPs (>0.01 minor allele frequency) were analysed for association with BAVM. 57 top BAVM-associated SNPs (51 SNPs with p<10(-05) or p<10(-04) in candidate pathway genes, and 6 candidate BAVM SNPs) were tested in a replication cohort including 608 BAVM cases and 744 controls.

RESULTS

The estimated heritability of BAVM was 17.6% (SE 8.9%, age and sex-adjusted p=0.015). None of the SNPs were significantly associated with BAVM in the replication cohort after correction for multiple testing. 6 SNPs had a nominal p<0.1 in the replication cohort and map to introns in EGFEM1P, SP4 and CDKAL1 or near JAG1 and BNC2. Of the 6 candidate SNPs, 2 in ACVRL1 and MMP3 had a nominal p<0.05 in the replication cohort.

CONCLUSIONS

We performed the first GWAS of sporadic BAVM in the largest BAVM cohort assembled to date. No GWAS SNPs were replicated, suggesting that common SNPs do not contribute strongly to BAVM susceptibility. However, heritability estimates suggest a modest but significant genetic contribution.

Trigeminal neuralgia caused by brain arteriovenous malformations: A case report and literature review

Few cases of trigeminal neuralgia (TGN) induced by brain arteriovenous malformations (bAVMs) have previously been reported. The present case report described one case of TGN caused by bAVMs in a 32-year-old male patient who suffered from recurrent pain in his right cheek for a period of two years, for whom the seizure frequency and duration of pain increased for 6 months. Magnetic resonance imaging was performed, which demonstrated flow-void signals in the abnormal vessels in the right cerebellopontine angle. Subsequent digital subtraction angiography confirmed the diagnosis of bAVMs, and showed the nidus was fed by the right superior cerebellar and the right anterior inferior cerebellar, and drained into the adjacent venous sinuses on the same side. The patient underwent an interventional embolization treatment. TGN was completely relieved following embolization of the majority of the bAVMs. Pain relief may be associated with blocking of the pulsatile compression of the feeding arteries of the bAVMs, the arterialized draining veins or the malformed niduses following embolization, which is similar to the effects induced by microvascular decompression surgery of the trigeminal nerve. In the present case study and review, the underlying mechanism and treatment strategy of TGN caused by bAVMs were discussed in the context of present case, and a literature review was carried out.