Predictors of hemorrhage in patients with untreated brain arteriovenous malformation

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.

Clinical outcomes of posterior fossa arteriovenous malformations: a single center experience

BACKGROUND

Posterior fossa arterio-venous malformations (pfAVMs) are challenging lesions due to the anatomical particularities of the posterior fossa, and the high incidence of hemorrhagic presentation. The two most important goals when treating AVMs are preserving neurological function and preventing rupture, or a second hemorrhage. The aim of this study was to analyze the clinical and imaging features of pfAVMs to identify the factors that influence the prognosis of these patients.

METHODS

We conducted a single-center retrospective observational study that included patients treated at our institution with pfAVMs between January 1997 and December 2021.

RESULTS

A total of 48 patients were included. A good modified Rankin score (mRS) was observed in 33 cases (69%) at presentation. Thirty-four patients (71%) presented with a ruptured AVM. Out of these, 19 patients (40%) had intraventricular hemorrhage. Microsurgical resection was performed in 33 cases (69%), while in the other cases, the patients opted for conservative management (7 cases, 15%), stereotactic radiosurgery (SRS) (6 cases, 12%), or endovascular treatment (2 cases, 4%). Patients ≤ 30 years old were more prone to hemorrhagic presentation (OR: 5.23; 95% CI: 1.42-17.19; p = 0.024) and this remained an independent risk factor for rupture after multivariate analysis as well (OR: 4.81; 95% CI: 1.07-21.53; p = 0.040). Following multivariate analysis, the only factor independently associated with poor prognosis in the surgically treated subgroup was a poor clinical status (mRS 3-5) at admission (OR: 96.14; 95% CI: 5.15-1793.9; p = 0.002).

CONCLUSIONS

Management of posterior fossa AVMs is challenging, and patients who present with ruptured AVMs often have a poor clinical status at admission leading to a poor prognosis. Therefore, proper and timely management of these patients is essential.

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.

Risk of intracranial hemorrhage in brain arteriovenous malformations: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Brain arteriovenous malformations (bAVMs) carry a risk of hemorrhage. We aim to identify factors associated with subsequent hemorrhages.

METHODS

Systematic searches were conducted across the ScienceDirect, Medline, and Cochrane databases. Assessed risk factors included bAVM size, bAVM volume, hemorrhage and seizure presentations, presence of deep venous drainage, deep-seated bAVMs, associated aneurysms, and Spetzler-Martin grade. Subgroup analyses were conducted on prior treatments, hemorrhage presentation, AVM size, and type of management.

RESULTS

The meta-analysis included 8 cohort studies and 2 trials, with 4,240 participants. Initial hemorrhage presentation (HR 2.41; 95% CI 1.94-2.98; p < 0.001), any deep venous drainage (HR 1.52; 95% CI 1.09-2.13; p = 0.01), and associated aneurysms (HR 1.78; 95% CI 1.41-2.23; p < 0.001) increased secondary hemorrhage risk. Conversely, higher Spetzler-Martin grades (HR 0.77; 95% CI 0.68-0.87; p < 0.001) and larger malformation volumes (HR 0.87; 95% CI 0.76-0.99; p = 0.04) reduced risk. Subgroups showed any deep venous drainage in patients without prior treatment (HR 1.64; 95% CI 1.25-2.15; p < 0.001), bAVM > 3 cm (HR 1.79; 95% CI 1.15-2.78; p = 0.01), and multimodal interventions (HR 1.69; 95% CI 1.12-2.53; p = 0.01) increased risk. The reverse effect was found for patients initially presented without hemorrhage (HR 0.79; 95% CI 0.67-0.93; p = 0.01). Deep bAVM was a risk factor in > 3 cm cases (HR 2.72; 95% CI 1.61-4.59; p < 0.001) and multimodal management (HR 2.77; 95% CI 1.66-4.56; p < 0.001). Kaplan-Meier analysis revealed increased hemorrhage risk for initial hemorrhage presentation, while cumulative survival was higher in intervened patients over 72 months.

CONCLUSION

Significant risk factors for bAVMs hemorrhage include initial hemorrhage, any deep venous drainage, and associated aneurysms. Deep venous drainage involvement is a risk factor in cases without prior treatment, those with bAVM > 3 cm, and cases managed with multimodal interventions. Deep bAVM involvement also emerges as a risk factor in cases > 3 cm and those managed with multimodal approaches.

Machine Learning Models for Brain Arteriovenous Malformations Presenting with Hemorrhage Based on Clinical and Angioarchitectural Characteristics

RATIONALE AND OBJECTIVES

This study aims to develop the best diagnostic model for brain arteriovenous malformations (bAVMs) rupture by using machine learning (ML) algorithms.

MATERIALS AND METHODS

We retrospectively included 353 adult patients with ruptured and unruptured bAVMs. The clinical and radiological data on patients were collected. The significant variables were selected using univariable logistic regression. We constructed and compared the predictive models using five supervised ML algorithms, multivariable logistic regression, and R2eDAVM scoring system. A complementary systematic review and meta-analysis of studies was aggregated to explore the potential predictors for bAVMs rupture.

RESULTS

We found that a small nidus size of <3 cm, deep and infratentorial location, longer filling time, and deep and single venous drainage were associated with a higher risk of bAVMs rupture. The multilayer perceptron model showed the best performance with an area under the curve value of 0.736 (95% CI 0.67-0.801) and 0.713 (95% CI 0.647-0.779) in the training and test dataset, respectively. In our pooled analysis, we also found that the male sex, a single feeding artery, hypertension, non-White race, low Spetzler-Martin grade, and coexisting aneurysms are risk factors for bAVMs rupture.

CONCLUSION

This study further demonstrated the clinical and angioarchitectural characteristics in predicting bAVMs hemorrhage.

Clinical, Imaging Characteristics and Outcome of Intracerebral Hemorrhage Caused by Structural Vascular Lesions

BACKGROUND

The objective of this study was to investigate the clinical, imaging, and outcome characteristics of intracerebral hemorrhage (ICH) caused by structural vascular lesions.

METHODS

We retrospectively analyzed data from a prospective observational cohort study of patients with spontaneous ICH admitted to the First Affiliated Hospital of Chongqing Medical University between May 2016 and April 2021. Good outcome was defined as modified Rankin Scale score of 0-3 at 3 months. The clinical and imaging characteristics were compared between primary ICH and ICH caused by structural vascular lesions. Multivariable logistic regression analysis was performed to test the associations of etiology with clinical outcome.

RESULTS

All patients enrolled in this study were Asian. Compared with patients with primary ICH, those with structural vascular lesions were younger (48 vs. 62 years, P < 0.001), had a lower incidence of hypertension (26.4% vs. 81.7%, P < 0.001) and diabetes (7.4% vs. 16.2%, P = 0.003), and had mostly lobar hemorrhages (49.1% vs. 22.8%). ICH from structural vascular lesions had smaller baseline hematoma volume (8.4 ml vs. 13.8 ml, P = 0.010), had lower mortality rate at 30 days and 3 months (5.8% vs. 12.0%, P = 0.020; 6.7% vs. 14.8%, P = 0.007), and are associated with better functional outcome at 3 months (88% vs.70.3%, P < 0.001).

CONCLUSIONS

Compared with primary ICH, ICH due to vascular lesions has smaller hematoma volume and less severe neurological deficit at presentation and better functional outcomes.

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.

Risk factors for intracerebral hemorrhage in small-vessel disease and non-small-vessel disease etiologies-an observational proof-of-concept study

Background

Sporadic cerebral small-vessel disease (CSVD), i.e., hypertensive arteriopathy (HA) and cerebral amyloid angiopathy (CAA), is the main cause of spontaneous intracerebral hemorrhage (ICH). Nevertheless, a substantial portion of ICH cases arises from non-CSVD etiologies, such as trauma, vascular malformations, and brain tumors. While studies compared HA- and CAA-related ICH, non-CSVD etiologies were excluded from these comparisons and are consequently underexamined with regard to additional factors contributing to increased bleeding risk beyond their main pathology.

Methods

As a proof of concept, we conducted a retrospective observational study in 922 patients to compare HA, CAA, and non-CSVD-related ICH with regard to factors that are known to contribute to spontaneous ICH onset. Medical records (available for n = 861) were screened for demographics, antithrombotic medication, and vascular risk profile, and CSVD pathology was rated on magnetic resonance imaging (MRI) in a subgroup of 185 patients. The severity of CSVD was assessed with a sum score ranging from 0 to 6, where a score of ≥2 was defined as advanced pathology.

Results

In 922 patients with ICH (median age of 71 years), HA and CAA caused the majority of cases (n = 670, 73%); non-CSVD etiologies made up the remaining quarter (n = 252, 27%). Individuals with HA- and CAA-related ICH exhibited a higher prevalence of predisposing factors than those with non-CSVD etiologies. This includes advanced age (median age: 71 vs. 75 vs. 63 years, p < 0.001), antithrombotic medication usage (33 vs. 37 vs. 19%, p < 0.001), prevalence of vascular risk factors (70 vs. 67 vs. 50%, p < 0.001), and advanced CSVD pathology on MRI (80 vs. 89 vs. 51%, p > 0.001). However, in particular, half of non-CSVD ICH patients were either aged over 60 years, presented with vascular risk factors, or had advanced CSVD on MRI.

Conclusion

Risk factors for spontaneous ICH are less common in non-CSVD ICH etiologies than in HA- and CAA-related ICH, but are still frequent. Future studies should incorporate these factors, in addition to the main pathology, to stratify an individual's risk of bleeding.

Quantitative Assessment of Hemodynamics Associated With Embolization Degree in Brain Arteriovenous Malformations

BACKGROUND AND OBJECTIVES

Grading systems, including the novel brain arteriovenous malformation endovascular grading scale (NBAVMES) and arteriovenous malformation embocure score (AVMES), predict embolization outcomes based on arteriovenous malformation (AVM) morphological features. The influence of hemodynamics on embolization outcomes remains unexplored. In this study, we investigated the relationship between hemodynamics and embolization outcomes.

METHODS

We conducted a retrospective study of 99 consecutive patients who underwent transarterial embolization at our institution between 2012 and 2018. Hemodynamic features of AVMs were derived from pre-embolization digital subtraction angiography sequences using quantitative digital subtraction angiography. Multivariate logistic regression analysis was performed to determine the significant factors associated with embolization outcomes.

RESULTS

Complete embolization (CE) was achieved in 17 (17.2%) patients, and near-complete embolization was achieved in 18 (18.2%) patients. A slower transnidal relative velocity (TRV, odds ratio [OR] = 0.71, P = .002) was significantly associated with CE. Moreover, higher stasis index of the drainage vein (OR = 16.53, P = .023), shorter transnidal time (OR = 0.15, P = .013), and slower TRV (OR = 0.9, P = .049) were significantly associated with complete or near-complete embolization (C/nCE). The area under the receiver operating characteristic curve for predicting CE was 0.87 for TRV, 0.72 for NBAVMES scores (ρ = 0.287, P = .004), and 0.76 for AVMES scores. The area under the receiver operating characteristic curve for predicting C/nCE was 0.77 for TRV, 0.61 for NBAVMES scores, and 0.75 for AVMES scores. Significant Spearman correlation was observed between TRV and NBAVMES scores and AVMES scores (ρ = 0.512, P < .001).

CONCLUSION

Preoperative hemodynamic factors have the potential to predict the outcomes of AVM embolization. A higher stasis index of the drainage vein, slower TRV, and shorter transnidal time may indicate a moderate blood flow status or favorable AVM characteristics that can potentially facilitate embolization.

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.

The Natural History of Hemorrhage in Brain Arteriovenous Malformations-Poisson Regression Analysis of 1066 Patients in a Single Institution

BACKGROUND AND OBJECTIVES

Natural history of hemorrhage in brain arteriovenous malformations (bAVM) is reported at 2%-4% per year. Published studies using survival analysis fail to account for recurrent hemorrhagic events. In this study, we present a large, single institution series to elucidate the natural history of bAVM using multivariable Poisson regression.

METHODS

This is a retrospective cohort study. All patients with bAVM seen at our institution from 1990 to 2021 were included. Hemorrhages after detection of bAVM during the untreated interval were recorded. Natural history of hemorrhage was calculated by dividing number of hemorrhages by untreated interval. The frequency of hemorrhages followed a Poisson distribution. Multivariable Poisson regression with an offset variable of untreated interval in patient-years was constructed. Model selection was through a stepwise Akaike information criterion method. Stratified hemorrhagic rate was presented using different combinations of significant factors.

RESULTS

A total of 1066 patients with nonhereditary hemorrhagic telangiectasia harboring a single bAVM were included. Ninety (8.44%) patients had 101 hemorrhages during an untreated interval of 3596.3344 patient-years, translating to an overall hemorrhagic rate of 2.81% per year. Significant factors increasing hemorrhage risk included ruptured presentation ( P < .001), increasing age ( P < .001), female sex ( P = .043), and deep location ( P = .040). Adult male patients with ruptured presentation and deep bAVMs sustained the highest annual risk at 10.81%, whereas no hemorrhages occurred in unruptured pediatric male patients or ruptured pediatric (younger than 18 years) male patients with superficial bAVMs.

CONCLUSION

Hemorrhage after bAVM detection occurs in 8.41% of all patients, and the rate averages 2.81% per year. However, this risk varies from 0.00% to 10.81% per year depending on various risk factor combinations. Efforts should be made to stratify bAVM hemorrhage rate by risk factors for more precise estimation of bleeding risk if left untreated.

Seizures, Psychosis, and Cerebral Vascular Malformation: A Rare Chain of Events

Background

In psychiatry, anatomical abnormalities are sometimes forgotten, and this can mislead doctors into thinking that the diagnosis is purely psychiatric. A physical examination is important whenever it is possible. Even though cerebral arteriovenous malformations (cAVMs) are rare and can go unnoticed, in some cases they can cause clinical symptoms, which is a complication. Case Presentation. In this case, we describe a patient with no prior medical or psychiatric history having a cAVM diagnosed after showing psychotic symptoms (delusion and disorganized thoughts and behavior). The deep 4 × 5 cm cAVM was discovered after admitting the patient to psychiatric ward, the neurological cause has been considered after a recorded seizure, which brings the following question: Is the clinical presentation a direct result of the cAVM or is it postictal?

Conclusions

An abnormality leading to another, here is how we could describe our patient's psychopathology leading to psychotic symptoms. The two hypotheses explaining this case report have a low rate of occurring making this a rare case. Either way, neurological cause cannot be overlooked even if the clinical presentation is typical.

Stereotactic radiosurgery for brain arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia

OBJECTIVE

Brain arteriovenous malformations (AVMs) in patients with hereditary hemorrhagic telangiectasia (HHT) present different characteristics from sporadic AVMs, and they have lower initial bleeding rates. Conservative management is usually preferred for the treatment of these lesions. In this case study, we present the largest series of HHT patients treated with stereotactic radiosurgery to date.

METHODS

We identified eight patients with HHT and 14 AVMs. We retrospectively collected clinical, radiographic, and treatment characteristics of the patients and each AVM.

RESULTS

Most patients in our sample presented with small AVMs. The median volume of these AVMs was 0.22 cm3 (IQR 0.08-0.59). Three out of eight patients presented with initial intracerebral hemorrhage (ICH). The majority of lesions had low (12/14) Spetzler-Martin grades (I-II). Median maximum and margin doses used for treatment were 36.2 (IQR 35.25-44.4) and 20 (IQR 18-22.5) Gy, respectively. The overall obliteration rate after SRS was 11/14, and the median time to obliteration across all 11 obliterated AVMs was 35.83 months (IQR, 17-39.99). Neurological status was favorable with all patients having a mRS of 0 or 1 at the last follow-up. Symptomatic radiation-induced changes (RIC) after SRS were low (7.1%), and there were no permanent RIC.

CONCLUSIONS

Patients with HHT who present with multiple brain AVMs are generally well served by SRS. Obliteration can be achieved in the majority of HHT patients and with a low complication rate. In the current study, initial hemorrhage rates prior to SRS were noticeable which supports the decision to treat these AVMs. Future studies are needed to better address the role of SRS for HHT patients harboring ruptured and unruptured AVMs.

Current perspectives and trends in the treatment of brain arteriovenous malformations: a review and bibliometric analysis

Background

Currently, there is a lack of intuitive analysis regarding the development trend, main authors, and research hotspots in the field of cerebral arteriovenous malformation treatment, as well as a detailed elaboration of possible research hotspots.

Methods

A bibliometric analysis was conducted on data retrieved from the Web of Science core collection database between 2000 and 2022. The analysis was performed using R, VOSviewer, CiteSpace software, and an online bibliometric platform.

Results

A total of 1,356 articles were collected, and the number of publications has increased over time. The United States and the University of Pittsburgh are the most prolific countries and institutions in the field. The top three cited authors are Kondziolka D, Sheehan JP, and Lunsford LD. The Journal of Neurosurgery and Neurosurgery are two of the most influential journals in the field of brain arteriovenous malformation treatment research, with higher H-index, total citations, and number of publications. Furthermore, the analysis of keywords indicates that "aruba trial," "randomised trial," "microsurgery," "onyx embolization," and "Spetzler-Martin grade" may become research focal points. Additionally, this paper discusses the current research status, existing issues, and potential future research directions for the treatment of brain arteriovenous malformations.

Conclusion

This bibliometric study comprehensively analyses the publication trend of cerebral arteriovenous malformation treatment in the past 20 years. It covers the trend of international cooperation, publications, and research hotspots. This information provides an important reference for scholars to further study cerebral arteriovenous malformation.

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.

Rupture-Risk Stratifying Patients with Cerebral Arteriovenous Malformations Using Quantitative Hemodynamic Flow Measurements

Arteriovenous malformations (AVMs) are high-pressure, low-resistance arterial-venous shunts without intervening capillaries. Up to 60% of AVMs present with an intracranial hemorrhage; however, noninvasive neuroimaging has increasingly diagnosed incidental AVMs. AVM management depends on weighing the lifetime rupture risk against the risks of intervention. Although AVM rupture risk relies primarily on angioarchitectural features, measuring hemodynamic flow is gaining traction. Accurate understanding of AVM hemodynamic flow parameters will help endovascular neurosurgeons and interventional neuroradiologists stratify patients by rupture risk and select treatment plans. This review examines various neuroimaging modalities and their capabilities to quantify AVM flow, as well as the relationship between AVM flow and rupture risk. Quantitative hemodynamic studies on the relationship between AVM flow and rupture risk have not reached a clear consensus; however, the preponderance of data suggests that higher arterial inflow and lower venous outflow in the AVM nidus contribute to increased hemorrhagic risk. Future studies should consider using larger sample sizes and standardized definitions of hemodynamic parameters to reach a consensus. In the meantime, classic angioarchitectural features may be more strongly correlated with AVM rupture than the amount of blood flow.

Re-rupture in ruptured brain arteriovenous malformations: a retrospective cohort study based on a nationwide multicenter prospective registry

BACKGROUND

This study aimed to investigate the natural history of re-rupture in ruptured brain arteriovenous malformations (AVMs) and to provide comprehensive insights into its associated factors and prevention.

METHODS

This study included 1712 eligible ruptured AVMs from a nationwide multicenter prospective collaboration registry between August 2011 and September 2021. The natural rupture risk before intervention and the annual rupture risk after intervention were both assessed. Cox proportional hazard regression models and Kaplan-Meier survival curves were used to explore independent factors associated with AVM re-rupture. The correlation between these factors and AVM re-rupture was verified in multiple independent cohorts, and the prevention effect of intervention timing and intervention strategies on AVM re-rupture was further analyzed.

RESULTS

The annual re-rupture risk in ruptured AVMs was 7.6%, and the cumulative re-rupture risk in the first 1, 3, 5, and 10 years following the initial rupture were 10%, 25%, 37.5%, and 50%, respectively. Cox proportional hazard regression analysis confirmed adult patients, ventricular system involvement, and any deep venous drainage as independent factors associated with AVM re-rupture. The intervention was found to significantly reduce the risk of AVM re-rupture (annual rupture risk 11.34% vs 1.70%, p<0.001), especially in those who underwent surgical resection (annual rupture risk 0.13%).

CONCLUSIONS

The risk of re-rupture in ruptured AVMs is high. Adult patients, ventricular system involvement, and any deep venous drainage are independent risk factors for re-rupture. Applying the results universally to all ruptured AVM cases may be biased. Intervention could effectively reduce the risk of re-rupture.

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.

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

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

Factors Associated with Unfavorable Clinical Presentations in Patients with Ruptured BrainArteriovenous Malformations

BACKGROUND

Rupture of brain arteriovenous malformations (bAVMs) carries potentially devastating consequences. For patients presenting with ruptured bAVMs, several clinical grading systems have been shown to predict long-term patient morbidity and may be taken into consideration when making clinical decisions. Unfortunately, use of these scoring systems is typically limited to their prognostic value and offer little to patients in therapeutic benefit. Tools are needed not only to predict prognosis for patients experiencing ruptured bAVMs but to gain insight into what characteristics predispose patients to poor long-term outcomes before they rupture. Our objective was to find clinical, morphologic, and demographic variables that correlate with unfavorable clinical grades on presentation in patients with ruptured bAVMs.

METHODS

We retrospectively reviewed a cohort of patients with ruptured bAVMs. Linear regression models were used to test whether Glasgow Coma Scale (GCS) and Hunt-Hess scores on presentation(outcomes) were associated with patient and arteriovenous malformation (AVM) characteristics (predictors) individually.

RESULTS

GCS and Hunt-Hess were assessed following bAVM rupture for 121 brain cases. The median age at rupture was 28.5 years, and 62 (51%) were female. Smoking history was associated with worse GCS; current and past smokers had GCS scores 1.33 points lower on average than nonsmokers (95% confidence interval [CI] -2.59 to -0.07, P = 0.039) and had worse Hunt-Hess scores (0.42, 95% CI 0.07-0.77, P = 0.019). Associated aneurysms were associated with worse GCS (-1.60, 95% CI -3.16 to -0.05, P = 0.043) and trended towards worse Hunt-Hess scores (0.42 points, 95% CI -0.01 to 0.86, P = 0.057).

CONCLUSIONS

Patient smoking status and presence of an AVM associated aneurysm were shown to have modest correlations with unfavorable clinical grades (Hunt-Hess, GCS) on presentation, with unfavorable clinical grades being associated with long-term patient prognosis following bAVM rupture. Further investigation using AVM-specific grading scales and external data are needed to determine the utility of these and other variables in clinical practice for patients with bAVM.

Multi-Stage Treatment for Spetzler-Martin Grades III, IV, and V Arteriovenous Malformations: Preoperative Embolization and Microsurgical Resection in a Consecutive Series of 250 Patients

PURPOSE

The treatment of high-grade brain AVMs is challenging and has no guidelines available to date. This study was aimed at reporting the experience of two centers in treating these AVMs through a multi-stage approach consisting of preoperative embolization and microsurgical resection.

METHODS

A retrospective review was performed for 250 consecutive patients with a diagnosis of high-grade brain AVM (Spetzler-Martin grades III, IV, and V) treated in two centers in Germany between January 1989 and February 2023. The analyzed data included demographic, clinical, morphological, and neurological data.

RESULTS

A total of 150 cases (60%) were classified as Spetzler-Martin grade III, 82 cases (32.8%) were classified as grade IV, and 18 cases (7.2%) were classified as grade V. Eighty-seven cases (34.8%) presented with hemorrhage. The devascularization percentages achieved were <50% in 24 (9.6%), 50-80% in 55 (22%), and >80% in 171 (68.4%) cases. The average number of sessions was 5.65 ± 5.50 and 1.11 ± 0.32 endovascular and surgical procedures, respectively, and did not significantly differ by rupture status. Death or dependency (mRS score ≥ 3) after the last follow-up was observed in 18.8% of patients and was significantly associated with age > 80 years and poor baseline neurological condition. The complete resection rate was 82.3% and was significantly associated with age > 80 years, large nidus, and deep venous drainage. Permanent disabling neurological deficit after at least 3 months of follow-up was diagnosed in 13.2% of patients and was significantly associated with age > 80 years and infratentorial locations.

CONCLUSION

A multi-stage treatment for high-grade AVMs is feasible for selected cases but comes at a functional cost. The devascularization percentage was not associated with the investigated outcomes. Age > 80 years was associated with poor safety and effectiveness outcomes; consequently, this treatment should be offered only in exceptional circumstances.

Association of nidus size and rupture in brain arteriovenous malformations: Insight from angioarchitecture and hemodynamics

This study aims to investigate the correlation between AVM size and rupture by examining natural history, angioarchitecture characteristics, and quantitative hemodynamics. A retrospective review of 90 consecutive AVMs from the MATCH registry was conducted. Patients were categorized into small nidus (< 3 cm) and large nidus (≥ 3 cm) groups based on the Spetzler-Martin grading system. Natural history analysis used prospective cohort survival data, while imaging analysis examined angioarchitecture characteristics and quantitative hemodynamic parameters measured with QDSA. The small-nidus group had a significantly higher annualized rupture risk (2.3% vs. 1.0%; p = 0.011). Cross-sectional imaging revealed independent hemorrhagic risk factors, including small nidus (OR, 4.801; 95%CI, 1.280-18.008; p = 0.020) and draining vein stenosis (OR, 6.773; 95%CI, 1.179-38.911; p = 0.032). Hemodynamic analysis identified higher stasis index in the feeding artery (OR, 2.442; 95%CI, 1.074-5.550; p = 0.033), higher stasis index in the draining vein (OR, 11.812; 95%CI, 1.907-73.170; p = 0.008), and lower outflow gradient in the draining vein (OR, 1.658; 95%CI, 1.068-2.574; p = 0.024) as independent predictors of AVM rupture. The small nidus group also showed a higher likelihood of being associated with hemorrhagic risk factors. Small AVM nidus has a higher risk of rupture based on natural history, angioarchitecture, and hemodynamics. Clinical Trial Registration-URL: http://www.clinicaltrials.gov . Unique identifier: NCT04572568.

Quantitative evaluation of the subsequent hemorrhage with arteriography-derived hemodynamic features in patients with untreated cerebral arteriovenous malformation

Background

Patients with untreated cerebral arteriovenous malformations (AVMs) are at risk of intracerebral hemorrhage. However, treatment to prevent AVM hemorrhage carries risks.

Objective

This study aimed to analyze the AVM nidus-related hemodynamic features and identify the risk factors for subsequent hemorrhage.

Methods

We retrospectively identified patients with untreated AVMs who were assessed at our institution between March 2010 and March 2021. Patients with ≥6 months of treatment-free and hemorrhage-free follow-up after diagnosed by digital subtraction angiography were included in subsequent examinations. The hemodynamic features were extracted from five contrast flow-related parameter maps. The Kaplan-Meier analyses and Cox proportional hazards regression models were used to find the potential risk factors for subsequent hemorrhage.

Results

Overall, 104 patients with a mean follow-up duration of 3.37 years (median, 2.42 years; range, 6-117 months) were included in study, and the annual risk of rupture was 3.7%. Previous rupture (hazard ratio [HR], 4.89; 95% confidence interval [CI], 1.16-20.72), deep AVM location (HR, 4.02; 95% CI, 1.01-15.99), higher cerebral blood volume (HR, 3.35; 95% CI, 1.15-9.74) in the nidus, and higher stasis index (HR, 1.54; 95% CI, 1.06-2.24) in the nidus were associated with subsequent hemorrhage in untreated AVMs.

Conclusion

Higher cerebral blood volume and stasis index in the nidus suggest increased blood inflow and stagnant blood drainage. The combination of these factors may cause subsequent hemorrhage of AVMs.

Pericytes and vascular smooth muscle cells in central nervous system arteriovenous malformations

Previously considered passive support cells, mural cells-pericytes and vascular smooth muscle cells-have started to garner more attention in disease research, as more subclassifications, based on morphology, gene expression, and function, have been discovered. Central nervous system (CNS) arteriovenous malformations (AVMs) represent a neurovascular disorder in which mural cells have been shown to be affected, both in animal models and in human patients. To study consequences to mural cells in the context of AVMs, various animal models have been developed to mimic and predict human AVM pathologies. A key takeaway from recently published work is that AVMs and mural cells are heterogeneous in their molecular, cellular, and functional characteristics. In this review, we summarize the observed perturbations to mural cells in human CNS AVM samples and CNS AVM animal models, and we discuss various potential mechanisms relating mural cell pathologies to AVMs.

National reduction in cerebral arteriovenous malformation treatment correlated with increased rupture incidence

BACKGROUND

Recently, there has been a shift in management of unruptured cerebral arteriovenous malformations (AVMs) following studies suggesting that medical management alone was superior to interventional therapy.

OBJECTIVE

To evaluate the influence of contemporary AVM management on AVM rupture patterns in the United States.

METHODS

154 297 AVM admissions were identified between 2003 and 2017 in the National Inpatient Sample. Annual AVM intervention and rupture rates were computed and multivariable logistic regression assessed the likelihood of AVM intervention pre- and post-2014. Segmented regression identified significant change points and fitted segmented linear models for annual intervention and rupture rates. Correlation coefficients assessed the relationship between annual AVM intervention and rupture rates.

RESULTS

For unruptured AVMs, intervention likelihood and proportion decreased after 2014 (28.1% to 22.3%, p<0.0001; adjusted OR=0.857, 95% CI 0.751 to 0.977, p=0.02). Ruptured AVM admissions increased from 14.7% to 18.6% after 2014 (p<0.0001). Between 2003 and 2017, segmented linear regression identified one significant change point in intervention rate between 2014 and 2015. Average annual percent change for rupture incidence and intervention rate increased by 0.49% (p=0.0001) and decreased by 1.17% (p=0.0001), respectively. Annual AVM intervention rates were inversely correlated with annual AVM rupture incidence (Pearson coefficient=-0.82, p=0.0002). In 2017, the annual AVM rupture rate (20.6%) surpassed the annual AVM intervention rate (19.7%).

CONCLUSIONS

After 2014, the likelihood of intervention for unruptured AVMs decreased while the incidence of ruptured AVMs increased. These findings suggest that fewer unruptured AVM treatments may lead to increases in AVM rupture incidence.

Ruptured bilateral brain arteriovenous malformations in a young woman with early pregnancy: a case report

BACKGROUND

Brain arteriovenous malformations (AVMs) are rare congenital developmental vascular lesions, and often presents with symptoms upon rupture. The controversy exists as to whether pregnancy confers an increased risk of intracranial hemorrhage. The diagnosis of brain AVMs, in the absence of brain imaging, is challenging in resource-limited settings, particularly in sub-Saharan Africa.

CASE PRESENTATION

A 22-year old black African woman, primigravida at 14 weeks of gestation, presented with a history of persistent throbbing headache which was treated at primary health care facilities with analgesics and anti-migraine medications without relief. She later developed severe headache 2 weeks prior to admission and one-day history of serial partial generalized tonic-clonic seizures which were followed by post-ictal confusion and persistent right upper limb weakness. Initial evaluation revealed her to be pregnant and she later underwent a brain magnetic resonance angiography (MRA) at a university teaching hospital which revealed bleeding bilateral parietal AMVs with intracerebral haematoma and associated perilesional vasogenic oedema. The patient was managed conservatively using antifibrinolytic drugs and prophylactic anti-seizure drugs. Seven months later, she underwent a control brain MRA which revealed resolution of intracranial haematoma and associated vasogenic oedema and had her seizures well controlled. The headache had subsided and the pregnancy was allowed to continue to term under close obstetric and neurological observation. On follow up visits she reported episodes of nasal bleeding which upon ENT examination revealed nasal AVMs, suggesting the diagnosis of hereditary hemorrhagic telangiectasia (HHT).

CONCLUSION

AVMs are rare but should prompt suspicion in young patients with atypical Central Nervous System (CNS) manifestations without evident underlying causes.

Ruptured arteriovenous malformation mortality: Incidence, risk factors, and inpatient outcome score

BACKGROUND

Limited literature exists on the morbidity and mortality of AVM associated intracerebral hemorrhage (ICH) compared with non-AVM ICH.

OBJECTIVE

We examine morbidity and mortality in cAVM in a large nationwide inpatient sample to create a prognostic inpatient ruptured AVM mortality score.

METHODS

This retrospective cohort study from 2008 to 2014 compares outcomes in cAVM related hemorrhages and ICH utilizing the National Inpatient Sample database. Diagnostic codes for ICH and AVM underlying ICH were identified. We compared case fatality according to medical complications. Multivariate analysis was used to derive hazard ratios and 95% confidence intervals to assess odds of mortality.

RESULTS

We identified 6496 patients with ruptured AVMs comparing them to 627,185 admitted with ICH. Mortality was lower for ruptured AVMs (11%) compared to ICH (22%) [p < 0.01]. Mortality associated factors were liver disease (OR 2.64, CI 1.81-3.85, p < .001), diabetes mellitus (OR 2.42, CI 1.38-4.22, p = 0.002), alcohol abuse (OR 1.81, CI 1.31-2.49, p = 0.001), hydrocephalus (OR 3.35 CI 2.81-4.00, p < 0.001), cerebral edema (OR 1.5, 1.25-1.85, p < 0.001), cardiac arrest (OR 15, CI 7.9-30, p < 0.001), and pneumonia (OR 1.93, CI 1.51-2.47, p < 0.001). A 0-5 ruptured AVM mortality score was developed: Cardiac arrest (=3), age >60 (=1), Black race (=1), chronic liver failure (=1) diabetes mellitus (=1), pneumonia (=1), alcohol abuse (=1) and cerebral edema (=1). Mortality increased with score. No patient with 5 or more points survived.

CONCLUSION

The Ruptured AVM Mortality Score allows for risk stratification on patients with ICH due to ruptured AVM. This scale could prove useful in prognostication and patient education.

Management of Unruptured Intracranial Aneurysms and Brain Arteriovenous Malformations

OBJECTIVE

Managing a patient with an unruptured brain aneurysm or brain arteriovenous malformation (AVM) can lead to uncertainty about preventive treatment. While the bleeding risks are low, the morbidity or mortality associated with a hemorrhagic event is not insignificant. The objective of this article is to review the natural history of these vascular entities, the risk factors for hemorrhage, preventive treatment options, and the risks of treatment.

LATEST DEVELOPMENTS

Randomized trials to inform preventive treatment strategies for unruptured intracranial aneurysms and brain AVMs are ongoing. Higher angiographic obliteration rates of unruptured intracranial aneurysms have been reported with the flow-diversion technique compared with alternative standard techniques. One randomized trial for unruptured brain AVMs showed a higher rate of morbidity and mortality in patients who underwent interventional treatment compared with observation.

ESSENTIAL POINTS

The decision to treat a patient with a brain aneurysm should consider patient factors, the patient's life expectancy, aneurysm anatomical factors, and treatment risks. Patients with unruptured brain AVMs should be observed in light of recent clinical trial data or enrolled in an ongoing clinical trial.

Delayed versus immediate intervention of ruptured brain arteriovenous malformations: A case report

BACKGROUND

Brain arteriovenous malformations (bAVMs) remains one of the most prevalent causes of intracranial hemorrhage and stroke-like syndromes in the young adult population. Although it has been agreed upon that definitive treatment using either single or multi-modal approach is warranted for successful bAVM management, much debate still revolves regarding the optimal timing of definitive treatment.

CASE SUMMARY

In this report, we present a case of delayed, definitive endovascular treatment for ruptured bAVM in a 21-year-old female, 3 mo post-ictus. The bAVM, with a left pericallosal feeding artery and cortical draining veins, was successfully obliterated through embolization using the Onyx 18. On follow-up the patient has recommenced her daily activities and experiences only mild occasional headaches with mild motor deficits. The report leads to our review on an important issue regarding the optimal timing of ruptured bAVM definitive management and bring forward the current evidence available on delayed vs immediate definitive bAVM intervention. We also highlight current issues that need to be addressed for clearer guidelines on definitive therapy initiation.

CONCLUSION

Current treatment paradigms of ruptured bAVM remains elusive, with substantial heterogeneity in the current literature. A consensus on the definition of “acute” vs “delayed”, management goal, follow-up length and outcome parameters are required to support formation of a clear paradigm.

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.

Development and Validation of a Scoring System for Hemorrhage Risk in Brain Arteriovenous Malformations

IMPORTANCE

The dilemma between natural rupture risk and adverse outcomes of intervention is of major concern for patients with unruptured arteriovenous malformations (AVMs). The existing risk score for AVM rupture includes factors that are controversial and lacks prospective validation.

OBJECTIVE

To develop and robustly validate a reliable scoring system to predict the rupture risk of AVMs.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study developed a prediction model derived from a single-center cohort (derivation cohort) and validated in a multicenter external cohort (multicenter external validation cohort) and a cohort of patients receiving conservative treatment management (conservative treatment validation cohort). Patients were recruited from a nationwide multicenter prospective collaboration registry in China. A total of 4135 patients were enrolled in the registry between August 1, 2011, and September 1, 2021. Of those, 3962 patients were included in the study (3585 in the derivation cohort and 377 in the multicenter external validation cohort); 1028 patients from the derivation cohort who had time-to-event data and prerupture imaging results were included in the conservative treatment validation cohort. Data were analyzed from March 10 to June 21, 2022.

MAIN OUTCOMES AND MEASURES

A scoring system was developed based on risk factors identified from a literature review and a robust selection process. Patients were stratified into different risk groups based on scores to calculate hemorrhage-free probability in future years, and Kaplan-Meier curves were plotted to visualize risk stratification. Receiver operating characteristic curves were used to assess the discrimination of models. Univariable analyses (logistic regression analysis for descriptive data and Cox regression analysis for survival data) were used to compare baseline information and assess bias.

RESULTS

Among 3962 patients (2311 men [58.3%]; median [IQR] age, 26.1 [14.6-35.5] years), 3585 patients (2100 men [58.6%]; median [IQR] age, 25.9 [14.6-35.0] years) were included in the derivation cohort, and 377 patients (211 men [56.0%]; median [IQR] age, 26.4 [14.5-39.2] years) were included in the multicenter external validation cohort. Thirty-six hemorrhages occurred over a median (IQR) follow-up of 4.2 (0.3-6.0) years among 1028 patients in the conservative treatment validation cohort. Four risk factors were used to develop the scoring system: ventricular system involvement, venous aneurysm, deep location, and exclusively deep drainage (VALE). The VALE scoring system performed well in all 3 cohorts, with areas under the receiver operating characteristic curve of 0.77 (95% CI, 0.75-0.78) in the derivation cohort, 0.85 (95% CI, 0.81-0.89) in the multicenter external validation cohort, and 0.73 (95% CI, 0.65-0.81) in the conservative treatment validation cohort. The 10-year hemorrhage-free rate was 95.5% (95% CI, 87.1%-100%) in the low-risk group, 92.8% (95% CI, 88.8%-97.0%) in the moderate-risk group, and 75.8% (95% CI, 65.1%-88.3%) in the high-risk group; the model discrimination was significant when comparing these rates between the high-risk group and the low- and moderate-risk groups (P < .001 for both comparisons).

CONCLUSIONS AND RELEVANCE

In this prognostic study, the VALE scoring system was developed to distinguish rupture risk among patients with AVMs. The stratification of unruptured AVMs may enable patients with low risk of rupture to avoid unnecessary interventions. These findings suggest that the scoring system is a reliable and applicable tool that can be used to facilitate patient and physician decision-making and reduce unnecessary interventions or unexpected AVM ruptures.

Neuromonitoring in Children with Cerebrovascular Disorders

BACKGROUND

Cerebrovascular disorders are an important cause of morbidity and mortality in children. The acute care of a child with an ischemic or hemorrhagic stroke or cerebral sinus venous thrombosis focuses on stabilizing the patient, determining the cause of the insult, and preventing secondary injury. Here, we review the use of both invasive and noninvasive neuromonitoring modalities in the care of pediatric patients with arterial ischemic stroke, nontraumatic intracranial hemorrhage, and cerebral sinus venous thrombosis.

METHODS

Narrative review of the literature on neuromonitoring in children with cerebrovascular disorders.

RESULTS

Neuroimaging, near-infrared spectroscopy, transcranial Doppler ultrasonography, continuous and quantitative electroencephalography, invasive intracranial pressure monitoring, and multimodal neuromonitoring may augment the acute care of children with cerebrovascular disorders. Neuromonitoring can play an essential role in the early identification of evolving injury in the aftermath of arterial ischemic stroke, intracranial hemorrhage, or sinus venous thrombosis, including recurrent infarction or infarct expansion, new or recurrent hemorrhage, vasospasm and delayed cerebral ischemia, status epilepticus, and intracranial hypertension, among others, and this, is turn, can facilitate real-time adjustments to treatment plans.

CONCLUSIONS

Our understanding of pediatric cerebrovascular disorders has increased dramatically over the past several years, in part due to advances in the neuromonitoring modalities that allow us to better understand these conditions. We are now poised, as a field, to take advantage of advances in neuromonitoring capabilities to determine how best to manage and treat acute cerebrovascular disorders in children.

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.

Incidental vascular findings on brain magnetic resonance angiography

Given the ever-increasing utilization of magnetic resonance angiography, incidental vascular findings are increasingly discovered on exams performed for unconnected indications. Some incidental lesions represent pathology and require further intervention and surveillance, such as aneurysm, certain vascular malformations, and arterial stenoses or occlusions. Others are benign or represent normal anatomic variation, and may warrant description, but not further work-up. This review describes the most commonly encountered incidental findings on magnetic resonance angiography, their prevalence, clinical implications, and any available management recommendations.

Diagnostic performance of dynamic 3D magnetic resonance angiography in daily practice for the detection of intracranial arteriovenous shunts in patients with non-traumatic intracranial hemorrhage

Introduction

Identification of treatable causes of intracranial hemorrhage (ICH) such as intracranial arteriovenous shunt is crucial to prevent recurrence. However, diagnostic approaches vary considerably across centers, partly because of limited knowledge of the diagnostic performance of first-line vascular imaging techniques. We assessed the diagnostic performance of dynamic three-dimensional magnetic resonance angiography (dynamic 3D MRA) in daily practice to detect intracranial arteriovenous shunts in ICH patients against subsequent digital subtraction angiography (DSA) as reference standard.

Methods

We reviewed all adult patients who underwent first-line dynamic 3D MRA and subsequent DSA for non-traumatic ICH between January 2016 and September 2021 in a tertiary center. Sensitivity, specificity, accuracy, positive and negative predictive values of dynamic 3D MRA for the detection of intracranial arteriovenous shunt were calculated with DSA as reference standard.

Results

Among 104 included patients, 29 (27.9%) had a DSA-confirmed arteriovenous shunt [19 pial arteriovenous malformations, 10 dural arteriovenous fistulae; median onset-to-DSA: 17 (IQR: 3-88) days]. The sensitivity and specificity of dynamic 3D MRA [median onset-to-dynamic 3D MRA: 14 (3-101) h] for the detection of intracranial arteriovenous shunt were 66% (95% CI: 48-83) and 91% (95% CI: 84-97), respectively. The corresponding accuracy, positive and negative predictive values were 84% (95% CI: 77-91), 73% (95% CI: 56-90), and 87% (95% CI: 80-95), respectively.

Conclusion

This study suggests that although first-line evaluation with dynamic 3D MRA may be helpful for the detection of intracranial arteriovenous shunts in patients with ICH, additional vascular imaging work-up should not be withheld if dynamic 3D MRA is negative. Comparative prospective studies are needed to determine the best imaging strategy to diagnose arteriovenous shunts after non-traumatic ICH.

Management of Brain Arteriovenous Malformations: A Review

Brain arteriovenous malformations (bAVM) are vascular malformations of the brain affecting all ages. The optimum management strategy is essentially devoid of high-quality evidence and is highly nuanced and embedded in local customs. This study summarizes the frequently employed management strategies, drawing conclusions on the utility of each method of treatment and delving into controversies surrounding them. A literature search on PubMed and Medline was done on January 3^rd, 2022. 11,767 articles were found, and abstracts were reviewed. Full-text review of 153 articles led to chapters from three books and 71 articles incorporated into a summative discussion. Spetzler-Ponce (S-P) Class A patients may be offered surgery if they are good surgical candidates and have a good number of high-quality years of life left. The exception is diffuse Spetzler-Martin (S-M) grade 2 in a patient older than 40 years: radiosurgery for unruptured and embolization for ruptured. S-P Class B may be offered surgery if a compact nidus or if younger than 40 years. If diffuse or age greater than 40, radiosurgery may be preferred if the Pollock-Flickinger score is less than 2.5. For the remainder of S-P Class B, conservative management may be preferred. S-P Class C is generally not treated unless young or those patients with poorly controlled seizures affecting their quality of life are willing to risk permanent neurological deficits. While the quality of studies is generally high, the level of evidence is concerning with only one randomized controlled trial (RCT). Most research output hails from high-income countries, i.e., perhaps not universally applicable to all settings owing to possible genetic, environmental, and resource differences. More research is needed: large volume studies in the pregnant population, validation of scoring systems in pediatric age groups, clinical trials focused on combination multi-staged treatment modalities, and studies originating from the developing world.

Long-term outcome of a tailored embolization strategy with Gamma Knife radiosurgery for high-grade brain arteriovenous malformations: a single-center experience

OBJECTIVE

The safety and efficacy of embolization with Gamma Knife radiosurgery (GKRS) for high-grade brain arteriovenous malformations (bAVMs) are uncertain. The purpose of this study was to elucidate the long-term outcome of a tailored embolization strategy with GKRS and identify the independent factors associated with bAVM obliteration.

METHODS

Between January 2014 and January 2017, a consecutive cohort of 159 patients with high-grade bAVMs who underwent embolization with GKRS was enrolled in this prospective single-center cohort study. All patients received a tailored embolization strategy with GKRS. The primary outcome was defined as bAVM obliteration. Secondary outcomes were neurological function and complications.

RESULTS

After a mean follow-up of 40.4 months, 5 patients were lost to follow-up. One hundred eighteen of the remaining 154 patients had favorable neurological outcomes with complete bAVM obliteration. A decrease in bAVM nidus size was observed in 36 patients. Five patients developed intracranial hemorrhage during the latency period, and 2 patients died. The Kaplan-Meier analysis showed that the obliteration rate increased each year and reached the peak point at approximately 3 years. The multivariate Cox regression analysis of factors affecting bAVM obliteration revealed that postembolization bAVM volume < 10 cm3 (p = 0.02), supratentorial location (p < 0.01), staged embolization prior to GKRS (p < 0.01), and mean Spetzler-Martin (SM) grade (p < 0.01) were independent factors associated with a high obliteration rate.

CONCLUSIONS

These data suggested that high-grade bAVMs treated using a tailored embolization strategy with GKRS were associated with a favorable clinical outcome and obliteration rate. Postembolization bAVM volume < 10 cm3, supratentorial location, staged embolization prior to GKRS, and low mean SM grade were associated with a high obliteration rate.

Clinical features and outcome in pediatric arteriovenous malformation: institutional multimodality treatment

PURPOSE

Intracranial arteriovenous-malformation (AVM) is a relatively rare condition in pediatrics, yet is a major cause of spontaneous intracranial hemorrhage with a risk of fatal hemorrhage reported to be between 4 and 29%. Little is known about vessel morphology and optimum treatment modalities including multimodality combination therapy and prognosis in children.

METHODS

A retrospective review of all children presenting to our institution from 2006 to 2020 that had an AVM was undertaken.

RESULTS

A total of 50 children were identified with median age of 11 (range 1-16) years. The mean follow-up was 7.6 years. Forty-one children presented as an emergency and of those, 40 had hemorrhage identified on initial brain imaging. The average nidus size was 25 mm, drainage was superficial in 51% of cases, and located in eloquent cortex in 56%. The supplemental Spetzler-Martin grading indicated 78% (39/50) were grade 4 and above (moderate to high risk). Primary treatment modalities included embolization in 50% (25) or SRS in 30% (15) and surgery in 20% (10).The AVM was obliterated on follow-up DSA in 66% children. Three children had post-treatment hemorrhage, two related to embolization and one the day following SRS, giving a re-bleed rate of 6%. The GOSE was available for 32 children at long term follow and 94% had a good outcome (GOSE 5-8). Two children died due to acute hemorrhage (4%).

CONCLUSION

The majority of children with AVM present with hemorrhage. The rebleed rate during definitive treatment is low at 6% over the study period. The selective use of the 3 modalities of treatment has significantly reduced mortality and severe disability.

Brain AVMs-Related microRNAs: Machine Learning Algorithm for Expression Profiles of Target Genes

INTRODUCTION

microRNAs (miRNAs) are a class of non-coding RNAs playing a myriad of important roles in regulating gene expression. Of note, recent work demonstrated a critical role of miRNAs in the genesis and progression of brain arteriovenous malformations (bAVMs). Accordingly, here we examine miRNA signatures related to bAVMs and associated gene expression. In so doing we expound on the potential prognostic, diagnostic, and therapeutic significance of miRNAs in the clinical management of bAVMs.

METHODS

A PRISMA-based literature review was performed using PubMed/Medline database with the following search terms: "brain arteriovenous malformations", "cerebral arteriovenous malformations", "microRNA", and "miRNA". All preclinical and clinical studies written in English, regardless of date, were selected. For our bioinformatic analyses, miRWalk and miRTarBase machine learning algorithms were employed; the Kyoto Encyclopedia of Genes and Genomes (KEGG) database was quired for associated pathways/functions.

RESULTS

four studies were ultimately included in the final analyses. Sequencing data consistently revealed the decreased expression of miR-18a in bAVM-endothelial cells, resulting in increased levels of vascular endodermal growth factor (VEGF), Id-1, matrix metalloproteinase, and growth signals. Our analyses also suggest that the downregulation of miR-137 and miR-195* within vascular smooth muscle cells (VSMCs) may foster the activation of inflammation, aberrant angiogenesis, and phenotypic switching. In the peripheral blood, the overexpression of miR-7-5p, miR-629-5p, miR-199a-5p, miR-200b-3p, and let-7b-5p may contribute to endothelial proliferation and nidus development. The machine learning algorithms employed confirmed associations between miRNA-related target networks, vascular rearrangement, and bAVM progression.

CONCLUSION

miRNAs expression appears to be critical in managing bAVMs' post-transcriptional signals. Targets of microRNAs regulate canonical vascular proliferation and reshaping. Although additional scientific evidence is needed, the identification of bAVM miRNA signatures may facilitate the development of novel prognostic/diagnostic tools and molecular therapies for bAVMs.

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

Objective

Brain arteriovenous malformation (bAVM) is an important reason for intracranial hemorrhage. This study aimed at developing and validating a model for predicting bAVMs rupture by using three-dimensional (3D) morphological features extracted from Computed Tomography (CT) angiography.

Materials and methods

The prediction model was developed in a cohort consisting of 412 patients with bAVM between January 2010 and December 2020. All cases were partitioned into training and testing sets in the ratio of 7:3. Features were extracted from the 3D model built on CT angiography. Logistic regression was used to develop the model, with features selected using L1 Regularization, presented with a nomogram, and assessed with calibration curve, receiver operating characteristic (ROC) curve and decision curve analyze (DCA).

Results

Significant variations in associated aneurysm, deep located, number of draining veins, type of venous drainage, deep drainage, drainage vein entrance diameter (Dv), type of feeding arteries, middle cerebral artery feeding, volume, Feret diameter, surface area, roundness, elongation, mean density (HU), and median density (HU) were found by univariate analysis (p &lt; 0.05). The prediction model consisted of associated aneurysm, deep located, number of draining veins, deep drainage, Dv, volume, Feret diameter, surface area, mean density, and median density. The model showed good discrimination, with a C-index of 0.873 (95% CI, 0.791–0.931) in the training set and 0.754 (95% CI, 0.710–0.795) in the testing set.

Conclusions

This study presented 3D morphological features could be conveniently used to predict hemorrhage from unruptured bAVMs.

Correlation between arteriovenous malformation nidus size and intraparenchymal hematoma volume in the event of rupture

•Our study did not support the hypothesis that small AVMs lead to larger hematoma volumes in the event of a rupture.•AVM size did not correlate with the clinical severity of the bleeding as measured with HH and WFNS scores.•Larger supratentorial hematomas were associated with a more severe clinical manifestation and a poorer outcome.•In the event of a rupture, the AVM size did not correlate with the 2-4-month GOS.•AVICH score showed a good correlation with the 2-4-month GOS score.

Molecular and genetic mechanisms in brain arteriovenous malformations: new insights and future perspectives

Brain arteriovenous malformations (bAVMs) are rare vascular lesions made of shunts between cerebral arteries and veins without the interposition of a capillary bed. The majority of bAVMs are asymptomatic, but some may be revealed by seizures and potentially life-threatening brain hemorrhage. The management of unruptured bAVMs remains a matter of debate. Significant progress in the understanding of their pathogenesis has been made during the last decade, particularly using genome sequencing and biomolecular analysis. Herein, we comprehensively review the recent molecular and genetic advances in the study of bAVMs that not only allow a better understanding of the genesis and growth of bAVMs, but also open new insights in medical treatment perspectives.

Critical Appraisal of Randomized Controlled Trials on Unruptured Brain Arteriovenous Malformations

OBJECTIVE

Brain arteriovenous malformations management remains controversial despite the numerous, available treatment options. Randomized controlled trials (RCTs) theoretically provide the strongest evidence for the assessment of any therapeutic intervention. However, poorly designed RCTs may be associated with biases, inaccuracies, and misleading conclusions. The purpose of our study is to assess reporting transparency and methodological quality of the existing RCTs.

METHODS

A search was performed in the PubMed, Scopus, Embase, clinicaltrials.gov, and Cochrane databases. The search was limited to English literature. We included all published RCTs reporting on the management of unruptured brain arteriovenous malformations. The eligible studies were evaluated by 5 blinded raters with the CONsolidated Standards of Reporting Trials 2010 statement and the risk-of-bias 2 tool. The inter-rater agreement was assessed with the Fleiss' Kappa.

RESULTS

A randomized trial of unruptured brain arteriovenous malformations (ARUBA) and treatment of brain arteriovenous malformations (TOBAS) trials were evaluated. ARUBA achieved high CONsolidated standards of reporting trials compliance, while TOBAS showed a moderate one. In ARUBA the introduction, discussion, and other information sections reached the highest compliance rate (80%-86%). The lowest rates were recorded in the results and the methods (62% and 73%, respectively). The inter-rater agreement was moderate to substantial (54.1% to 78.4%). All the examined studies demonstrated a high risk of bias, mainly related to ill-defined intended interventions, missing outcome data, and selection of the reported results.

CONCLUSIONS

Our study confirmed the high risk of bias mainly attributed to several protocol violations, deviations, minimal external validity and selection, attrition, and allocation biases of the ARUBA trial. Analysis of the TOBAS trial revealed a moderate overall reporting clarity and a high risk of bias.

Remodeling of the Neurovascular Unit Following Cerebral Ischemia and Hemorrhage

Formulated as a group effort of the stroke community, the transforming concept of the neurovascular unit (NVU) depicts the structural and functional relationship between brain cells and the vascular structure. Composed of both neural and vascular elements, the NVU forms the blood-brain barrier that regulates cerebral blood flow to meet the oxygen demand of the brain in normal physiology and maintain brain homeostasis. Conversely, the dysregulation and dysfunction of the NVU is an essential pathological feature that underlies neurological disorders spanning from chronic neurodegeneration to acute cerebrovascular events such as ischemic stroke and cerebral hemorrhage, which were the focus of this review. We also discussed how common vascular risk factors of stroke predispose the NVU to pathological changes. We synthesized existing literature and first provided an overview of the basic structure and function of NVU, followed by knowledge of how these components remodel in response to ischemic stroke and brain hemorrhage. A greater understanding of the NVU dysfunction and remodeling will enable the design of targeted therapies and provide a valuable foundation for relevant research in this area.

Machine learning for predicting hemorrhage in pediatric patients with brain arteriovenous malformation

OBJECTIVE

Ruptured brain arteriovenous malformations (bAVMs) in a child are associated with substantial morbidity and mortality. Prior studies investigating predictors of hemorrhagic presentation of a bAVM during childhood are limited. Machine learning (ML), which has high predictive accuracy when applied to large data sets, can be a useful adjunct for predicting hemorrhagic presentation. The goal of this study was to use ML in conjunction with a traditional regression approach to identify predictors of hemorrhagic presentation in pediatric patients based on a retrospective cohort study design.

METHODS

Using data obtained from 186 pediatric patients over a 19-year study period, the authors implemented three ML algorithms (random forest models, gradient boosted decision trees, and AdaBoost) to identify features that were most important for predicting hemorrhagic presentation. Additionally, logistic regression analysis was used to ascertain significant predictors of hemorrhagic presentation as a comparison.

RESULTS

All three ML models were consistent in identifying bAVM size and patient age at presentation as the two most important factors for predicting hemorrhagic presentation. Age at presentation was not identified as a significant predictor of hemorrhagic presentation in multivariable logistic regression. Gradient boosted decision trees/AdaBoost and random forest models identified bAVM location and a concurrent arterial aneurysm as the third most important factors, respectively. Finally, logistic regression identified a left-sided bAVM, small bAVM size, and the presence of a concurrent arterial aneurysm as significant risk factors for hemorrhagic presentation.

CONCLUSIONS

By using an ML approach, the authors found predictors of hemorrhagic presentation that were not identified using a conventional regression approach.

Cerebral Digital Subtraction Angiography in Acute Intracranial Hemorrhage: Considerations in Critically Ill Children

Cerebrovascular disorders are an important cause of morbidity and mortality in children. Although minimally invasive, cerebral digital subtraction angiography (DSA) has been shown to be safe in children and is a valuable, and perhaps underutilized, technique for the diagnosis and management of pediatric cerebrovascular disorders in the critical care setting. Through a case-based approach, we explore the utility of DSA in critically ill children with acute intracranial hemorrhage (ICH). We discuss the use of DSA in the acute management of aneurysm and arteriovenous malformation rupture as well as cerebral vasospasm. Those caring for critically ill children with acute ICH should consider cerebral DSA as part of a comprehensive approach to the diagnosis and management of these conditions.

Is there an Influence of Match and Mismatch of Venous Drainage Pattern on AVM Hemorrhagic Presentation?

Objective

To analyze whether there is an influence of match and mismatch of venous drainage patterns on arteriovenous malformation (AVM) hemorrhagic presentation.

Methods

Consecutive 161 patients of AVM between 2014 and 2017 were retrospectively reviewed. Venous drainage was considered deep or superficial. Match of venous drainage pattern was defined as a superficial AVM with only superficial venous drainage or a deep AVM with deep venous drainage. Mismatch of venous drainage pattern was defined as a superficial AVM involving a deep venous drainage. Univariate analysis was used to assess the influence of match and mismatch of venous drainage pattern on AVM hemorrhagic presentation.

Results

AVM location and venous drainage were matched in 116 patients, including superficial location with superficial venous drainage or deep location with deep venous drainage, and were mismatched in 45 patients, including superficial location with deep venous drainage. The rupture proportion of mismatch venous drainage pattern was statistically comparable to that of deep location with deep drainage (P = 0.819). However, superficial location with deep venous drainage was statistically associated with a higher rupture percentage than that of superficial location with superficial venous drainage (P = 0.003).

Conclusions

Mismatch venous drainage pattern or an exclusively deep venous drainage is associated with an initial clinical presentation with an AVM hemorrhage.