The natural history of symptomatic arteriovenous malformations of the brain: a 24-year follow-up assessment

A Scalp Mass Leading to the Discovery of a Giant Intracranial Arteriovenous Malformation

Scalp masses are common clinical findings with a broad differential diagnosis, often benign in nature. However, in rare cases, they can be the initial presentation of an underlying intracranial pathology. We report the case of a patient presenting with a painless scalp mass, which led to the incidental discovery of a giant intracranial arteriovenous malformation (AVM). Imaging studies revealed an extensive high-flow vascular lesion with multiple arterial feeders and venous drainage, consistent with a giant AVM. Given the size and complexity of the malformation, a multidisciplinary approach was required for evaluation and management. Giant intracranial AVMs are rare and often diagnosed following neurological symptoms such as seizures, headaches, or hemorrhage. In this case, the scalp mass served as an external marker of a deep-seated vascular anomaly, highlighting the importance of thorough clinical and imaging investigations in atypical presentations. This case emphasizes the need for vigilance when evaluating scalp masses, as they may be the first indication of significant intracranial pathology. Early recognition and appropriate imaging can lead to timely diagnosis and intervention, potentially preventing life-threatening complications.

Outcomes of arteriovenous malformation patients with multiple versus single feeders: A multicenter retrospective study with propensity-score matching

INTRODUCTION

The impact of multiple feeding arteries on clinical outcomes of cerebral arteriovenous malformations (AVMs) is not well understood. This study aims to compare outcomes between AVMs with multiple versus single feeding arteries.

PATIENTS AND METHODS

Data from the Multicenter International Study for Treatment of Brain AVMs (MISTA) consortium were analyzed. Propensity score matching (PSM) was used to balance cohorts. Subgroup analysis was conducted for ruptured and unruptured AVMs and different treatment options, and multivariable logistic regression was applied to assess the impact of feeding artery origin.

RESULTS

Among 953 patients, 661(69.4%) had multiple feeding arteries, and 292 (30.6%) had a single feeding artery. After PSM, which included 422 matched patients (211 in each group), the differences in obliteration rates (68.7% vs 74.8%, OR 0.73, 95% CI: 0.48-1.12, p = 0.16) and symptomatic complications (15.6% vs 11.8%, OR 1.37, 95% CI: 0.78-2.41, p = 0.25) were not significant. Subgroup analysis comparing ruptured and unruptured AVMs and different treatment options showed no significant differences across all subgroups. Multivariable analysis identified PICA feeders as significantly associated with increased odds of all complications (OR 7.33, 95% CI: 2.14-25.1, p = 0.002).

DISCUSSION AND CONCLUSION

AVMs with a single feeding artery were more likely to present with rupture, but no significant differences in obliteration rates or complications were observed between the groups after PSM. These findings suggest that while the number of feeding arteries may influence the initial presentation, it does not appear to impact overall treatment success or patient prognosis. Further prospective studies are needed to confirm these findings.

Evaluating post-treatment residual intracranial arteriovenous shunting: a comparison of arterial spin labeling MRI and digital subtraction angiography

PURPOSE

To evaluate the efficacy of arterial spin labeling (ASL) MRI in detecting residual arteriovenous (AV) shunting in treated arteriovenous malformations (AVMs) and fistulas (AVFs).

METHODS

A retrospective institutional review identified 29 patients with DSA-confirmed AV shunt lesions treated via embolization (n = 17), stereotactic radiosurgery (n = 2), surgical resection (n = 8), or combined embolization and surgical resection (n = 4), with corresponding baseline and post-treatment ASL and DSA studies. Two neuroradiologists independently assessed ASL images for residual AV shunting, with inter-rater agreement calculated. Disagreements were jointly reviewed to reach consensus. Sensitivity and specificity for using ASL to detect residual AV shunting were then determined using DSA as the gold standard reference.

RESULTS

Seventeen patients with Spetzler-Martin grades II-V AVMs were included: 76.5% with supratentorial nidus, and 52.9% with prior hemorrhage. Twelve AVF patients were included, including eight dural, one vein of Galen, two perimedullary, and one cavernous-carotid fistula. Inter-rater agreement for presence of residual AV shunting was strong (93.5%, κ = 0.87). Two disagreements involved AVM patients after surgical resection. Sensitivity and specificity of ASL for detecting residual was 94% and 93%, respectively. Within the AVM group, both metrics reached 100%, while for AVFs, they both decreased to 83%, with one false positive and one false negative.

CONCLUSION

ASL MRI is highly sensitive and specific for detection of residual AV shunting across a wide spectrum of AV shunt pathologies and treatment modalities. ASL can play an important role as a non-invasive adjunct to DSA, potentially reducing the frequency of DSA during the continuum of post-treatment care.

Stereotactic Radiosurgery for Intermediate (III) or High (IV-V) Spetzler-Martin Grade Arteriovenous Malformations: International Stereotactic Radiosurgery Society Practice Guideline

BACKGROUND AND OBJECTIVES

Consensus guidelines do not exist to guide the role of stereotactic radiosurgery (SRS) in the management of patients with Spetzler-Martin Grade III-V arteriovenous malformations (AVMs). We sought to establish SRS practice guidelines for Grade III-V AVMs based on a critical systematic review of the published literature.

METHODS

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant search of Medline, Embase, and Scopus, 1986 to 2023, for publications reporting post-SRS outcomes in ≥10 Grade III-V AVMs with the median follow-up ≥24 months was performed. Primary end points were AVM obliteration and post-SRS hemorrhage. Secondary end points included dosimetric variables, Spetzler-Martin parameters, and neurological outcome.

RESULTS

: In total, 2463 abstracts were screened, 196 manuscripts were reviewed, and 9 met the strict inclusion criteria. The overall sample of 1634 AVMs consisted of 1431 Grade III (88%), 186 Grade IV (11%), and 11 Grade V lesions (1%). Total median post-SRS follow-up was 53 months for Grade III and 43 months for Grade IV-V AVMs (ranges, 2-290; 12-262). For Grade III AVMs, the crude obliteration rate was 72%, and among Grade IV-V lesions, the crude obliteration rate was 46%. Post-SRS hemorrhage was observed in 7% of Grade III compared with 17% of Grade IV-V lesions. Major permanent deficits or death from hemorrhage or radiation-induced complications occurred in 86 Grade III (6%) and 22 Grade IV-V AVMs (12%).

CONCLUSION

Most patients with Spetzler-Martin Grade III AVMs have favorable SRS treatment outcomes; however, the obliteration rate for Grade IV-V AVMs is less than 50%. The available studies are heterogenous and lack nuanced, long-term, grade-specific outcomes.

Comparing stand-alone endovascular embolization versus stereotactic radiosurgery in the treatment of arteriovenous malformations with Spetzler-Martin grades I-III: a propensity score matched study

BACKGROUND

Arteriovenous malformations (AVMs) are uncommon cerebral lesions that can cause significant neurological complications. Surgical resection is the gold standard for treatment, but endovascular embolization and stereotactic radiosurgery (SRS) are viable alternatives.

OBJECTIVE

To compare the outcomes of endovascular embolization versus SRS in the treatment of AVMs with Spetzler-Martin grades I-III.

METHODS

This study combined retrospective data from 10 academic institutions in North America and Europe. Patients aged 1 to 90 years who underwent endovascular embolization or SRS for AVMs with Spetzler-Martin grades I-III between January 2010 and December 2023 were included.

RESULTS

The study included 244 patients, including 84 who had endovascular embolization and 160 who had SRS. Before propensity score matching (PSM), complete obliteration at the last follow-up was achieved in 74.5% of the SRS group compared with 57.8% of the embolization group (OR=0.47; 95% CI 0.26 to 0.48; P=0.01). After propensity score matching, SRS still achieved significantly higher occlusion rates at last follow-up (78.9% vs 55.3%; OR=0.32; 95% CI 0.12 to 0.90; P=0.03).Hemorrhagic complications were higher in the embolization group than in the SRS group, although this difference did not reach statistical significance after PSM (13.2% vs 2.6%; OR=5.6; 95% CI 0.62 to 50.47; P=0.12). Similarly, re-treatment rate was higher in the embolization group (10.5% vs 5.3%; OR=2.11; 95% CI 0.36 to 12.31; P=0.40) compared with the SRS group.

CONCLUSION

Our findings indicate that SRS has a significantly higher obliteration rate at last follow-up compared with endovascular embolization. Also, SRS has a higher tendency for fewer hemorrhagic complications and lower re-treatment rate. Further prospective studies are needed.

Treatment outcomes for ARUBA-eligible brain arteriovenous malformations: a comparison of real-world data from the NVQI-QOD AVM registry with the ARUBA trial

BACKGROUND

Significant controversy exists about the management of unruptured cerebral arteriovenous malformations (AVMs). Results from A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) suggested that intervention increases the risk of stroke/death compared with medical management. However, numerous study limitations raised concerns about the trial's generalizability.

OBJECTIVE

To assess the rate of stroke/death and functional outcomes in ARUBA-eligible patients from a multicenter database, the Neurovascular Quality Initiative-Quality Outcomes Database (NVQI-QOD).

METHODS

We performed a retrospective analysis of prospectively collected data of ARUBA-eligible patients who underwent intervention at 18 participating centers. The primary endpoint was stroke/death from any cause. Secondary endpoints included neurologic, systemic, radiographic, and functional outcomes.

RESULTS

173 ARUBA-eligible patients underwent intervention with median follow-up of 269 (25-722.5) days. Seventy-five patients received microsurgery±embolization, 37 received radiosurgery, and 61 received embolization. Baseline demographics, risk factors, and general AVM characteristics were similar between groups. A total of 15 (8.7%) patients experienced stroke/death with no significant difference in primary outcome between treatment modalities. Microsurgery±embolization was more likely to achieve AVM obliteration (P<0.001). Kaplan-Meier survival curves demonstrated no difference in overall death/stroke outcomes between the different treatment modalities' 5-year period (P=0.087). Additionally, when compared with the ARUBA interventional arm, our patients were significantly less likely to experience death/stroke (8.7% vs 30.7%; P<0.001) and functional impairment (mRS score ≥2 25.4% vs 46.2%; P<0.01).

CONCLUSION

Our results suggest that intervention for unruptured brain AVMs at comprehensive stroke centers across the United States is safe.

Efficacy of radiosurgery with and without angioembolization: A subgroup analysis of effectiveness in ruptured versus unruptured arteriovenous malformations - An updated systematic review and meta-analysis

Background

Congenital arterial defects such as cerebral arteriovenous malformations (AVMs) increase brain bleeding risk. Conservative therapy, microsurgical removal, percutaneous embolization, stereotactic radiosurgery (SRS), or a combination may treat this serious disease. This study compares angioembolization with SRS to SRS alone in ruptured or unruptured brain ateriovenous malformations (BAVM) patients.

Methods

We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations for this study. Until September 2023, PubMed/Medline, Cochrane, and Clinicaltrials.gov were searched for literature. English-language studies comparing SRS alone to embolization with SRS on ruptured or non-ruptured AVMs that could not be operated on were considered. The Newcastle-Ottawa Scale assessed research study quality.

Results

Results included 46 studies with a total of 7077 participants. There was a greater obliteration rate in the SRS-only group (60.4%) than in the embolization plus SRS group (49.73%). Particularly in the SRS-only group, ruptured AVMs showed a noticeably greater obliteration rate than unruptured AVMs (P = 0.002). However, no notable differences were found in hemorrhagic events or radiation-induced changes between the two groups; however, the SRS-only group had a slightly greater, yet not statistically significant, mortality rate.

Conclusion

Our data showed that ruptured brain AVMs had a much greater obliteration rate than unruptured ones, mostly due to SRS alone, without embolization. The aggregated data showed no significant changes, whereas SRS alone decreased radiation-induced alterations and hemorrhagic rates but with increased mortality. SRS alone may have a higher risk-to-reward ratio for nidus obliteration in ruptured brain AVM patients, so it should be used without embolization, although more research is needed to determine the effects of immediate and late complications.

Lesion filling index predicts brain arteriovenous malformation obliteration after Gamma knife radiosurgery: a hemodynamic analysis

Hemodynamics significantly influences the clinical outcomes of brain arteriovenous malformations (AVM). This study aimed to determine if the lesion filling index (LFI), obtained via quantitative digital subtraction angiography (QDSA), can predict complete complete obliteration after Gamma knife radiosurgery (GKRS). We retrospectively reviewed AVM patients who underwent GKRS and DSA exams from 2011 to 2021. Clinical, angioarchitectural, and QDSA hemodynamic features were analyzed. The LFI, derived from QDSA, was evaluated as a predictor of complete complete obliteration post-SRS using Cox proportional hazards and Kaplan-Meier analyses. Among 118 AVMs with a mean follow-up of 5.76 ± 2.76 years, post-SRS complete obliteration was linked to reduced nidus volume (7.27 ± 12.3 vs. 19.2 ± 35.7 mm³, p = 0.049), smaller nidus diameter (26.0 ± 14.9 vs. 34.1 ± 19.8 mm, p = 0.015), and absence of feeding artery dilation (21.1% vs. 46.3%, p = 0.008). Higher Arterial Diagnostic Window (ADW) (972.27 ± 1615.53 vs. 515.29 ± 730.26, p = 0.036), higher LFI (905.31 ± 2288.37 vs. 249.65 ± 1092.46, p = 0.037), and lower Transnidal Relative Velocity (TRV), a parameter defined as the maximum diameter of AVM divided by the full width at half maximum (74.31 ± 95.67 vs. 137.80 ± 152.01, p = 0.021), were also associated with complete obliteration. After adjusting for confounders, only two variables-absence of feeding artery dilation (HR 0.35, 95%CI 0.16-0.78, p = 0.010) and higher LFI (HR 1.00, 95%CI 1.00-1.00, p = 0.006) remained significant predictors. The ROC curve identified 188.4 as the LFI cutoff, and Kaplan-Meier analysis confirmed LFI's predictive value (log-rank test, χ² = 12.776, p < 0.001). Elevated LFI and absence of feeding artery dilation predict AVM complete obliteration after GKRS, indicating that overfilling and low blood flow in the nidus may promote complete obliteration.

Spontaneous resolution of cerebral arteriovenous malformation after liver transplant: illustrative case

BACKGROUND

Cerebral arteriovenous malformations (AVMs) have historically been considered congenital lesions with treatment options including surgery, radiation therapy, and observation. Spontaneous resolution of cerebral AVMs remains an exceedingly rare event with poorly understood pathophysiology.

MATERIALS AND METHODS

Herein we report a retrospective case review of a 28-year-old man with alcoholic cirrhosis who presented with a seizure 3 weeks after liver transplantation. Neuroimaging confirmed the presence of a Spetzler-Martin grade 2 AVM in the right frontal lobe. Due to the recent liver transplantation, treatment was deferred at the time of initial diagnosis and the patient was observed for a course of 1 year. Follow-up imaging 1 year later showed resolution of the AVM, confirmed by a catheter angiogram.

CONCLUSION

Spontaneous resolution of cerebral AVMs is a rare event. Treatment of chronic liver disease resulted in the normalization of angiogenic factors that likely led to AVM resolution. This case provides valuable insight into the vital role of angiogenesis in the natural history of AVMs.

Linear Accelerator (LINAC) Radiosurgical Management of Brain Arteriovenous Malformations: An Experience From a Tertiary Care Center

INTRODUCTION

Brain arteriovenous malformations (AVM) are complex vascular pathologies with a significant risk of hemorrhage. Stereotactic radiosurgery (SRS) is an effective treatment modality for AVM, initially popularized on the Gamma Knife (Elekta AB, Stockholm, Sweden) platform, and now benefits from the modern advances in linear accelerator (LINAC)-based platforms. This study evaluates the outcomes of LINAC-based SRS/hypofractionated stereotactic radiotherapy (hFSRT) for cerebral AVMs.

MATERIALS AND METHODS

Between December 2018 and April 2024, 15 patients with cerebral AVMs underwent SRS/hFSRT at a tertiary government hospital. Patient selection was based on AVM size, location, surgical unsuitability, and patient preference. All patients underwent MRI and cerebral angiography for nidus delineation. SRS was planned using Monaco TPS (treatment planning system) (Elekta AB, Stockholm, Sweden) with VMAT (volumetric modulated arc therapy) technique, delivering a median dose of 20 Gy in single fractions for small AVMs and 28 Gy in four fractions for large AVMs. Patients were followed up with annual MRI and angiography to assess obliteration.

RESULTS

The cohort had a median age of 22 years, with a median nidus volume of 3.76 cc. The crude obliteration rate was 60%, confirmed by MRI/angiography. Actuarial obliteration rates at two, three, and five years were 65.71%, 73.57%, and 77.14%, respectively. Smaller AVMs (<3 cc) and those with a modified AVM radiosurgery score <1.5 had nearly 100% obliteration rates. Large AVMs (>10 cc) treated with hypofractionated SRT showed partial responses only. Significant predictors of obliteration included prescription dose, AVM volume, and modified AVM radiosurgery score.

CONCLUSION

LINAC-based SRS demonstrates comparable efficacy to other modalities for treating cerebral AVMs, with obliteration rates influenced by dose, AVM volume, and pre-treatment radiosurgery score. Larger AVMs pose a greater challenge, suggesting a need for adjunctive treatments or higher fractionated doses to improve outcomes.

Growth of Flow-Related Aneurysms Following Occlusion of Cerebral Arteriovenous Malformation

BACKGROUND

 Flow-related aneurysms (FRAs) associated with cerebral arteriovenous malformations (AVMs) pose a significant therapeutic challenge. Both their natural history and management strategy are still unclear and underreported. FRAs generally increase the risk of brain hemorrhage. However, following AVM obliteration these vascular lesions are expected to disappear or remain stable.

METHODS

We present two cases where growth of FRAs was detected following complete obliteration of an unruptured AVM.

RESULTS

 The first patient presented with proximal middle cerebral artery (MCA) aneurysm growth after spontaneous and asymptomatic thrombosis of the AVM. In our second case, a very small aneurysmal-like dilation located at the basilar apex enlarged to a saccular aneurysm following complete endovascular and radiosurgical obliteration of the AVM.

CONCLUSION

 The natural history of flow-related aneurysms is unpredictable. In the cases where these lesions are not managed first, there should be close follow-up. When aneurysm growth is evident, active management strategy seems mandatory.

Surgical outcomes and risk factors for overall mortality in brain arteriovenous malformations patients: a retrospective analysis

Background

Brain arteriovenous malformations (AVMs) are challenging vascular lesions. Extensive follow-up studies are necessary to refine the therapeutic algorithm, and to improve long-term survival in these patients. The aim of the study was to assess surgical outcomes, and to evaluate overall long-term mortality in patients treated for brain AVMs.

Methods

This retrospective single-center study included 191 patients with brain AVMs, admitted between 2012 and 2022. Clinical and angiographical particularities have been analyzed, to identify factors that might influence early outcome and overall long-term mortality.

Results

Out of 79 patients undergoing surgery, 51 had ruptured AVMs with total resection achieved in 68 cases (86.1%). Deep venous drainage was associated with incomplete resection. Female sex, admission modified Rankin Scale (mRS) > 2, and eloquent location were independent predictors of poor outcomes. Multiple venous drainage was associated with a higher risk of worsened early outcome. Eloquent brain region involvement, conservative treatment, increasing age, admission mRS > 2, and comorbidities significantly decrease survival in brain AVM patients. Patients treated with interventional treatments had significantly better survival than the conservatively managed ones, when adjusting for age and admission mRS.

Conclusion

The study identified female sex, poor neurologic status on admission and eloquence as independent prognostic factors for a negative outcome after surgery. Patients who received interventional treatment had significantly better survival than patients managed conservatively. We recommend employing tailored, proactive management strategies as they significantly enhance long-term survival in brain AVM patients.

Repeat single-session stereotactic radiosurgery for arteriovenous malformation: a systematic review and meta-analysis

BACKGROUND

Stereotactic radiosurgery is the preferred option for treating brain arteriovenous malformation (AVM) when the risks associated with surgery outweigh the potential benefits. However, some patients require repeat radiosurgery due to residual AVM after the first procedure. This systematic review and meta-analysis aimed to investigate the safety and efficacy of repeated procedure of radiosurgery for AVM.

METHOD

A systematic review was conducted according to the PRISMA guideline. The search was conducted on PubMed, Scopus, Embase, and Web of Science, using a pre-designed search string. Studies investigating the efficacy of repeat radiosurgery for residual AVM following initial single session radiosurgery were included. The risk of bias was assessed using the JBI tool. Meta-analysis and met-regression were performed to pool and inspect data.

RESULTS

Our meta-analysis, with a mean follow-up of 45.57 months, reveals repeat radiosurgery as a viable option for arteriovenous malformations (AVMs), achieving a 60.82% obliteration rate with a mean time to obliteration of 33.18 months. Meta-regression identifies AVM volume and Spetzler-Martin (SM) grade as factors influencing obliteration, with smaller volume and lower SM grades associated with higher rates. Complications include 10.33% radiation-induced changes, 5.26% post-radiosurgery hemorrhage, 2.56% neurologic deficits, and 0.67% cyst formation. Heterogeneity in complications is primarily attributed to male proportion and SM grade, while factors influencing post-radiosurgery hemorrhage remain unclear. The type of radiosurgery, whether Gamma Knife Radiosurgery (GKRS) or LINAC, does not significantly impact outcomes.

CONCLUSION

Repeat radiosurgery is a feasible, effective, and safe treatment for AVMs following failure of initial radiosurgery. When utilized in appropriate patient subgroups, it provides an acceptable risk-to-benefit profile. Feature studies are required to clarify its clear indications.

Feasibility of awake craniotomy for brain arteriovenous malformations: A scoping review

Background

Brain Arteriovenous Malformations (AVMs) located in proximity to eloquent brain regions are associated with poor surgical outcomes, which may be due to higher rates of postoperative neurological deterioration. Current treatment protocols include stereotactic radiosurgery, transarterial embolization, and surgical resection under general anesthesia. Awake Craniotomy (AC) allows intraoperative mapping of eloquent areas to improve post-operative neurologic outcomes.

Objectives

We reviewed the current literature reporting surgical outcomes and assessed the feasibility of AC for AVM resection.

Methods

The PRISMA guidelines were utilized as a template for the review. Three databases including PubMed, Scopus, and Cochrane Library were searched using a predefined search strategy. After removing duplicates and screening, full texts were analyzed. Outcomes including the extent of resection, intra-operative and post-operative complications, and long-term neurologic outcomes were assessed.

Results

12 studies were included with a total of 122 AVM cases. Spetzler-Martin grading was used for the classification of the AVMs. The asleep-awake-asleep protocol was most commonly used for AC. Complete resection was achieved in all cases except 5. Intraoperative complications included seizures (n = 2) and bleeding (n = 4). Short-term post-operative complications included hemorrhage (n = 3), neurologic dysfunctions including paresis (n = 3), hemiplegia (n = 10), dysphasia/aphasia (n = 6), cranial nerve dysfunction (n = 3), and pulmonary embolism (n = 1). Almost all neurological deficits after surgery gradually improved on subsequent follow-ups.

Conclusion

AVMs may shift the anatomical location of eloquent brain areas which may be mapped during AC. All studies recommended AC for the resection of AVMs in close proximity to eloquent areas as mapping during AC identifies the eloquent cortex thus promoting careful tissue handling which may preserve neurologic function and/or predict the postoperative functional status of the patients We, therefore, conclude that AC is a viable modality for AVMs resection near eloquent language and motor areas.

Vascular compactness of unruptured brain arteriovenous malformation predicts risk of hemorrhage after stereotactic radiosurgery

The aim of the study was to investigate whether morphology (i.e. compact/diffuse) of brain arteriovenous malformations (bAVMs) correlates with the incidence of hemorrhagic events in patients receiving Stereotactic Radiosurgery (SRS) for unruptured bAVMs. This retrospective study included 262 adult patients with unruptured bAVMs who underwent upfront SRS. Hemorrhagic events were defined as evidence of blood on CT or MRI. The morphology of bAVMs was evaluated using automated segmentation which calculated the proportion of vessel, brain tissue, and cerebrospinal fluid in bAVMs on T2-weighted MRI. Compactness index, defined as the ratio of vessel to brain tissue, categorized bAVMs into compact and diffuse types based on the optimal cutoff. Cox proportional hazard model was used to identify the independent factors for post-SRS hemorrhage. The median clinical follow-ups was 62.1 months. Post-SRS hemorrhage occurred in 13 (5.0%) patients and one of them had two bleeds, resulting in an annual bleeding rate of 0.8%. Multivariable analysis revealed bAVM morphology (compact versus diffuse), bAVM volume, and prescribed margin dose were significant predictors. The post-SRS hemorrhage rate increased with larger bAVM volume only among the diffuse nidi (1.7 versus 14.9 versus 30.6 hemorrhage per 1000 person-years in bAVM volume < 20 cm3 versus 20-40 cm3 versus > 40 cm3; p = 0.022). The significantly higher post-SRS hemorrhage rate of Spetzler-Martin grade IV-V compared with grade I-III bAVMs (20.0 versus 3.3 hemorrhages per 1000 person-years; p = 0.001) mainly originated from the diffuse bAVMs rather than the compact subgroup (30.9 versus 4.8 hemorrhages per 1000 person-years; p = 0.035). Compact and smaller bAVMs, with higher prescribed margin dose harbor lower risks of post-SRS hemorrhage. The post-SRS hemorrhage rate exceeded 2.2% annually within the diffuse and large (> 40 cm3) bAVMs and the diffuse Spetzler-Martin IV-V bAVMs. These findings may help guide patient selection of SRS for the unruptured bAVMs.

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.

The Use of Intraoperative Microvascular Doppler in Vascular Neurosurgery: Rationale and Results-A Systematic Review

Surgical treatment of neurovascular lesions like intracranial aneurysms, arteriovenous malformations and arteriovenous dural fistulas is still associated with high morbidity. Several recent studies are providing increasing insights into reliable tools to improve surgery and reduce complications. Inadvertent vessel compromise and incomplete occlusion of the lesion represent the most possible complications in neurovascular surgery. It is clear that direct visual examination alone does not allow to identify all instances of vessel compromise. Various modalities, including angiography, microvascular Doppler and neurophysiological studies, have been utilized for hemodynamics of flow vessels in proper clipping of the aneurysm or complete obliteration of the lesion. We intended to review the current knowledge about the intraoperative microvascular Doppler (iMDS) employment in the most updated literature, and explore the most recent implications not only in intracranial aneurysms but also in neurovascular lesions like arteriovenous malformations (AVMs) and arteriovenous dural fistulas (AVDFs). According to the PRISMA guidelines, systematic research in the most updated platform was performed in order to provide a complete overview about iMDS employment in neurovascular surgery. Twelve articles were included in the present paper and analyzed according to specific research areas. iMDS employment could represent a crucial tool to improve surgery in neurovascular lesions. The safety and effectiveness of the surgical treatment of neurovascular lesions like intracranial aneurysm and other neurovascular lesions like AVMs and AVDFs requires careful and accurate consideration regarding the assessment of anatomy and blood flow. Prognosis may depend on suboptimal or incomplete exclusion of the lesion.

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.

Early Treatment of Ruptured Cerebral Arteriovenous Malformations: Analysis of Neurological Outcomes and Health Care Costs

BACKGROUND

The timing of surgical resection is controversial when managing ruptured arteriovenous malformations (AVMs) and varies considerably among centers.

OBJECTIVE

To retrospectively analyze clinical outcomes and hospital costs associated with delayed treatment in a ruptured cerebral AVM patient cohort.

METHODS

Patients undergoing surgical treatment for a ruptured cerebral AVM (January 1, 2015-December 31, 2020) were retrospectively analyzed. Patients who underwent emergent treatment of a ruptured AVM because of acute herniation were excluded, as were those treated >180 days after rupture. Patients were stratified by the timing of surgical intervention relative to AVM rupture into early (postbleed days 1-20) and delayed (postbleed days 21-180) treatment cohorts.

RESULTS

Eighty-seven patients were identified. The early treatment cohort comprised 75 (86%) patients. The mean (SD) length of time between AVM rupture and surgical resection was 5 (5) days in the early cohort and 73 (60) days in the delayed cohort ( P < .001). The cohorts did not differ with respect to patient demographics, AVM size, Spetzler-Martin grade, frequency of preoperative embolization, or severity of clinical presentation ( P ≥ .15). Follow-up neurological status was equivalent between the cohorts ( P = .65). The associated mean health care costs were higher in the delayed treatment cohort ($241 597 [$99 363]) than in the early treatment cohort ($133 989 [$110 947]) ( P = .02). After adjustment for length of stay, each day of delayed treatment increased cost by a mean of $2465 (95% CI = $967-$3964, P = .002).

CONCLUSION

Early treatment of ruptured AVMs was associated with significantly lower health care costs than delayed treatment, but surgical and neurological outcomes were equivalent.

Fractal-Based Analysis of Arteriovenous Malformations (AVMs)

Arteriovenous malformations (AVMs) are cerebrovascular lesions consisting of a pathologic tangle of the vessels characterized by a core termed the nidus, which is the "nest" where the fistulous connections occur. AVMs can cause headache, stroke, and/or seizures. Their treatment can be challenging requiring surgery, endovascular embolization, and/or radiosurgery as well. AVMs' morphology varies greatly among patients, and there is still a lack of standardization of angioarchitectural parameters, which can be used as morphometric parameters as well as potential clinical biomarkers (e.g., related to prognosis).In search of new diagnostic and prognostic neuroimaging biomarkers of AVMs, computational fractal-based models have been proposed for describing and quantifying the angioarchitecture of the nidus. In fact, the fractal dimension (FD) can be used to quantify AVMs' branching pattern. Higher FD values are related to AVMs characterized by an increased number and tortuosity of the intranidal vessels or to an increasing angioarchitectural complexity as a whole. Moreover, FD has been investigated in relation to the outcome after Gamma Knife radiosurgery, and an inverse relationship between FD and AVM obliteration was found.Taken altogether, FD is able to quantify in a single and objective value what neuroradiologists describe in qualitative and/or semiquantitative way, thus confirming FD as a reliable morphometric neuroimaging biomarker of AVMs and as a potential surrogate imaging biomarker. Moreover, computational fractal-based techniques are under investigation for the automatic segmentation and extraction of the edges of the nidus in neuroimaging, which can be relevant for surgery and/or radiosurgery planning.

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.

Rheological Properties of Non-Adhesive Embolizing Compounds-The Key to Fine-Tuning Embolization Process-Modeling in Endovascular Surgery

The study of polymers' rheological properties is of paramount importance both for the problems of their industrial production as well as for their practical application. Two polymers used for embolization of arteriovenous malformations (AVMs) are studied in this work: Onyx-18^® and Squid-12^®. Viscosity curve tests and computational fluid dynamics (CFD) were used to uncover viscosity law as a function of shear rate as well as behavior of the polymers in catheter or pathological tissue models. The property of thermal activation of viscosity was demonstrated, namely, the law of dependence of viscosity on temperature in the range from 20 °C to 37 °C was established. A zone of viscosity nonmonotonicity was identified, and a physical interpretation of the dependence of the embolic polymers' viscosity on the shear rate was given on the basis of Cisco's model. The obtained empirical constants will be useful for researchers based on the CFD of AVMs. A description of the process of temperature activation of the embolic polymers' viscosity is important for understanding the mechanics of the embolization process by practicing surgeons as well as for producing new prospective embolic agents.

Non-Angry Superficial Draining Veins: A New Technique in Identifying the Extent of Nidus Excision during Cerebral Arteriovenous Malformation Surgery

BACKGROUND

As essential techniques, intraoperative indocyanine green video angiography (ICG-VA) and FLOW 800 have been widely used in microsurgery for arteriovenous malformations (AVMs). In the present report, we introduced a supplementary technical trick for judging the degree of lesion resection when there were superficial drainage veins. FLOW 800 analysis is used to verify our conjecture.

METHODS

A retrospective analysis of a 33 case cohort treated surgically from June 2020 to September 2022 was conducted and their lesions were removed by superficial drainage veins as a supplementary technical trick and analyzed with FLOW800.

RESULTS

In our 33 AVMs, the feeding artery was visualized earlier than the draining vein. Intraoperatively, the T1/2 peak and slope of the draining vein were significantly higher than that of the lesion. However, the maximum fluorescence intensity (MFI) of the draining vein decreased as the procedure progressed (p < 0.001). After reducing the blood flow to the nidus by progressive dissection of the feeding artery, the arteriovenous transit time (AVTT) decreased from 0.64 ± 0.47 s, was prolonged to 2.38 ± 0.52 (p < 0.001), and the MFI and slope of the nidus decreased from the pre-resection 435.42 ± 43.90 AI and 139.77 ± 27.55 AI/s, and decreased to 386.70 ± 48.17 AI and 116.12 ± 17.46 AI/s (p < 0.001). After resection of the nidus, the T1/2 peak of the draining vein increased from 21.42 ± 4.70 s, prolonged to after dissection of the blood feeding artery, 23.07 ± 5.29 s (p = 0.424), and after resection of the lesion, 25.13 ± 5.46 s (p = 0.016), with a slope from 135.79 ± 28.17 AI/s increased to 210.86 ± 59.67 AI/s (p < 0.001).

CONCLUSIONS

ICG-VA integrated with FLOW 800 is an available method for determining the velocity of superficial drainage veins. Whether the color of the superficial drainage veins on the cortical surface returns to normal can determine whether the lesion is completely resected and can reduce the possibility of residual postoperative lesions.

Compactness index: a radiosurgery outcome predictor for patients with unruptured brain arteriovenous malformations

OBJECTIVE

The goal of the study was to define and quantify brain arteriovenous malformation (bAVM) compactness and to assess its effect on outcomes after Gamma Knife radiosurgery (GKRS) for unruptured bAVMs.

METHODS

Unsupervised machine learning with fuzzy c-means clustering was used to differentiate the tissue constituents of bAVMs on T2-weighted MR images. The percentages of vessel, brain, and CSF were quantified. The proposed compactness index, defined as the ratio of vasculature tissue to brain tissue, categorized bAVM morphology into compact, intermediate, and diffuse types according to the tertiles of this index. The outcomes of interest were complete obliteration and radiation-induced changes (RICs).

RESULTS

A total of 209 unruptured bAVMs treated with GKRS were retrospectively included. The median imaging and clinical follow-up periods were 49.2 and 72.3 months, respectively. One hundred seventy-three bAVMs (82.8%) achieved complete obliteration after a median latency period of 43.3 months. The rates of RIC and permanent RIC were 76.1% and 3.8%, respectively. Post-GKRS hemorrhage occurred in 14 patients (6.7%), resulting in an annual bleeding risk of 1.0%. Compact bAVM, smaller bAVM volume, and exclusively superficial venous drainage were independent predictors of complete obliteration. Diffuse bAVM morphology, larger bAVM volume, and higher margin dose were independently associated with RICs.

CONCLUSIONS

The compactness index quantitatively describes the compactness of unruptured bAVMs. Moreover, compact bAVMs may have a higher obliteration rate and a smaller risk of RICs than diffuse bAVMs. This finding could help guide decision-making regarding GKRS treatment for patients with unruptured bAVMs.

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.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The impact of embolization on radiosurgery obliteration rates for brain arteriovenous malformations: a systematic review and meta-analysis

There exists no consensus in the literature regarding the impact of pre-stereotactic radiosurgery (SRS) embolization on obliteration rates and clinical outcome after radiosurgery treatment of intracranial arteriovenous malformations (AVM). We performed a systematic review of four databases and included studies with at least 10 patients evaluating obliteration rates of intracranial AVMs treated with SRS alone (SRS cohort) and combined pre-SRS embolization followed by SRS (E + SRS cohort). Meta-analytic results were pooled together via random-effects models. A total of 43 studies, with 7103 patients, were included in our analysis. Among our included patients, complete obliteration was achieved in 51.5% (964/1871) of patients in the E + SRS cohort as compared to 61.5% (3217/5231) of patients in the SRS cohort. Meta-analysis of the pooled data revealed that obliteration was significantly lower in the E + SRS cohort (pooled OR = 0.64, 95% CI = 0.54-0.75, p < 0.0001). The use of pre-SRS embolization was significantly associated with lower AVM obliteration rates when compared to treatment with SRS alone. Our analysis seeks to provide a macroscopic insight into the complex interaction between pre-SRS embolization and brain AVM obliteration rates and prognosis. Pre-SRS embolization may still be beneficial in select patients, and further studies are needed to identify patients who benefit from neoadjuvant AVM embolization.

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.

DNA methylation signatures on vascular differentiation genes are aberrant in vessels of human cerebral arteriovenous malformation nidus

Arteriovenous malformation (AVM) is a tangle of arteries and veins, rupture of which can result in catastrophic hemorrhage in vulnerable sites such as the brain. Cerebral AVM is associated with a high mortality rate in humans. The causative factor or the stimulus at the artery-venous junction and the molecular basis of the development and progression of cerebral AVM remain unknown. While it is known that aberrant hemodynamic forces in the artery-vein junction contribute to the development of AVMs, the mechanistic pathways are unclear. Given that various environmental stimuli modulate epigenetic modifications on the chromatin of cells, we speculated that misregulated DNA methylome could lead to cerebral AVM development. To identify the aberrant epigenetic signatures, we used AVM nidus tissues and analyzed the global DNA methylome using the Infinium DNA methylome array. We observed significant alterations of DNA methylation in the genes associated with the vascular developmental pathway. Further, we validated the DNA hypermethylation by DNA bisulfite sequencing analysis of selected genes from human cerebral AVM nidus. Taken together, we provide the first experimental evidence for aberrant epigenetic signatures on the genes of vascular development pathway, in human cerebral AVM nidus.

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.

Linac-based stereotactic radiosurgery for brain arteriovenous malformations

PURPOSE

Linac stereotactic radiosurgery (SRS) is gaining popularity as a form of radiation treatment for cerebral arteriovenous malformations (AVMs) since the theory of combined radiosurgical and endovascular treatment poses much uncertainty and due to significant technical progress for SRS. This study focuses on how to evaluate obliteration and re-bleeding rates, and to determine factors and adverse effects influencing obliteration after linac-based SRS for cerebral AVMs.

MATERIAL AND METHODS

From a statistical record of 71 patients, 31 had partial embolisation, five surgery and 29 had no prior treatment. Using Kaplan-Meier survival and life table analyses, actuarial obliteration and annual bleeding hazard rates were calculated after SRS.

RESULTS

After a follow up of 1, 2 and 3 years the actual obliteration rates were 22, 59 and 66%, respectively whereby it was noted that prior embolization had no effect on the obliteration rate. Annual bleeding hazard rates were further analyzed after stereotactic radiosurgery to be 2.1% and 1.4% for the first and second year respectively. Asymptomatic abnormalities were detected after imaging in 33.9% of patients. A dose of less than 18 Gy significantly reduced the obliteration probability.

CONCLUSION

SRS is a therapeutic option for intracerebral AVM. In general, there is a low rate of morbidity and a high probability of nidus obliteration.

Surgical management outcomes of intracranial arteriovenous malformations after preoperative embolization: a systematic review and meta-analysis

OBJECTIVE

Preoperative embolization for brain arteriovenous malformations (AVMs) has been shown to mitigate morbidity for high-risk AVMs, chiefly by reducing lesional blood flow before resection. However, associated risks include postembolization AVM rupture, and the effect of preoperative embolization on outcome remains uncertain. We performed a meta-analysis of the literature on preoperative embolization for microsurgically treated AVMs.

METHODS

A systematic review and meta-analysis were conducted of all English-language publications reporting clinical outcomes after combined embolization and surgical resection for AVMs. Single- and 2-arm analyses were performed using random-effects modeling.

RESULTS

Thirty-six studies with 2108 patients were included in this analysis. Most patients (90.6%) who underwent embolization had at least a 50% obliteration of AVMs on posttreatment preoperative angiography, with a mean rate of obliteration of approximately 80% (range 28.8-100%). Among patients who had combined treatment, 3.4% (95% confidence interval [CI] 2.1-4.6%) experienced embolization-related hemorrhagic complications before surgery. Both treatment groups achieved excellent postsurgical complete resection rates (odds ratio [OR] 1.05; 95% CI 0.60-1.85). Neither the clinical outcome (OR 1.42; 95% CI 0.84-2.40) nor the total number of hemorrhagic complications (OR 1.84; 95% CI 0.88-3.85) was significantly different between the treatment groups.

CONCLUSIONS

In this meta-analysis, preoperative embolization appears to have substantially reduced the lesional volume with active AV shunting before AVM resection. Anecdotally, preoperative embolization facilitates safe and efficient resection; however, differences in outcomes were not significant. The decision to pursue preoperative embolization remains a nuanced decision based on individual lesion anatomy and treatment team experience.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Curative Embolization of Small Brain Arteriovenous Malformations by Ethyl Vinyl Alcohol Copolymer: A Systematic Review and Meta-Analysis

The right choice in treating small (Spetzler-Ponce grade A) brain arteriovenous malformations (AVMs) is a matter of debate with varying views from neurology, neurosurgery, and interventional neuroradiology points of view. The Spetzler-Martin 1 and 2 brain AVMs, especially those in eloquent and deep areas that are difficult to access by micro-neurosurgery, are most suitable for a complete cure by endovascular embolization with ethyl vinyl alcohol (EVOH)-based agents.

A literature search was done with keywords such as endovascular embolization of small brain AVM. Data from 13 articles are included in the study based on predetermined inclusion and exclusion criteria.

Meta-analysis for the complete cure rate was done, publication bias was removed, and regression analysis showed a 76% cure rate with a 95% confidence interval (CI). Major complications were hemorrhage and neurological deficit, which ranged from 0-20% and 0-16% with a mean proportion of 0.11 and 0.09, respectively. Long-term (3-6 months) follow-up data showed 0-4% recurrence at three months, 0-8% recurrence at six months, and 2-10% permanent disability. The mortality rate ranged from 3% to 4%. Three illustrative cases with data from the author’s institute are included in the article. To conclude, endovascular embolization for small brain AVMs is a satisfactory treatment modality, however, prospective registries and randomized controlled trials involving embolization versus neurosurgery and/or stereotactic radiosurgery (SRS) may validate the role of embolization in small brain AVMs as curative treatment.

Understanding burden of proof and equipoise in the design of pragmatic clinical trials: An example from a trial on brain arteriovenous malformations

BACKGROUND AND PURPOSE

The burden of proof principle is rarely discussed and poorly understood, but central to the proper design of pragmatic clinical trials. A better understanding of the principle could play an important role in the re-introduction of scientific methods within practice and in revising fundamental problems with the current research-care separation.

METHODS

We analyze the design of the ARUBA trial on the management of unruptured brain arteriovenous malformations. We also review how the concept of clinical equipoise was introduced to address a misconceived problem of research ethics.

RESULTS

The ARUBA trial hypothesis in favour of conservative management of brain arteriovenous malformations failed to take into account the fact that the burden of proof was on surgery, endovascular treatment or radiation therapy. Thus, results remained inconclusive and other trials are needed. The equipoise notion fails to take into account that the burden of proof is on unvalidated medical or surgical interventions, if we want to provide outcome-based medical care that patients can trust.

CONCLUSION

The burden of proof principle is essential to properly design pragmatic trials. This principle also explains why in certain circumstances optimal care is a randomized care trial.

Stereotactic radiosurgery for ruptured versus unruptured intracranial arteriovenous malformations

Background:

There are a limited data examining the effects of prior hemorrhage on outcomes after stereotactic radiosurgery (SRS). The goal of this study was to identify risk factors for arteriovenous malformation (AVM) rupture and compare outcomes, including post-SRS hemorrhage, between patients presenting with ruptured and unruptured AVMs.

Methods:

A retrospective review of consecutive patients undergoing SRS for intracranial AVMs between 2009 and 2019 at our institution was conducted. Chi-square and multivariable logistic regression analyses were utilized to identify patient and AVM factors associated with AVM rupture at presentation and outcomes after SRS including the development of recurrent hemorrhage in both ruptured and unruptured groups.

Results:

Of 210 consecutive patients with intracranial AVMs treated with SRS, 73 patients (34.8%) presented with AVM rupture. Factors associated with AVM rupture included smaller AVM diameter, deep venous drainage, cerebellar location, and the presence of intranidal aneurysms (P < 0.05). In 188 patients with adequate follow-up time (mean 42.7 months), the overall post-SRS hemorrhage rate was 8.5% and was not significantly different between ruptured and unruptured groups (10.3 vs. 7.5%, P = 0.51). There were no significant differences in obliteration rate, time to obliteration, or adverse effects requiring surgery or steroids between unruptured and ruptured groups.

Conclusion:

Smaller AVM size, deep venous drainage, and associated intranidal aneurysms were associated with rupture at presentation. AVM rupture at presentation was not associated with an increased risk of recurrent hemorrhage or other complication after SRS when compared to unruptured AVM presentation. Obliteration rates were similar between ruptured and unruptured groups.

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

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

Molecular feature of arterial remodeling in the brain arteriovenous malformation revealed by arteriovenous shunt rat model and RNA sequencing

PURPOSE

Morphological research suggested the feeding artery of brain arteriovenous malformation (bAVM) had vascular remodeling under the high blood flow; however, the underlying molecular mechanisms were unclear.

METHODS

We constructed 32 simplified AVM rat models in four groups: the control group (n = 6), 1-week high-blood-flow group (n = 9), 3-week high-blood-flow group (n = 7) and 6-week high-blood-flow group (n = 10). The circumference, blood velocity, blood flow, pressure, and wall shear of the feeding artery were measured or calculated. The arterial wall change was observed by Masson staining. RNA sequencing (RNA-seq) of feeding arteries was performed, followed by bioinformatics analysis to detect the potential molecular mechanism for bAVM artery remodeling under the high blood flow.

RESULTS

We observed hemodynamic injury and vascular remodeling on the feeding artery under the high blood flow. RNA-seq showed immune/inflammation infiltration and vascular smooth muscle cell (VSMC) phenotype transformation during remodeling. Weighted gene co-expression network analysis (WGCNA) and time series analysis further identified 27 key genes and pathways involved in remodeling. Upstream miRNA and molecular drugs were predicted targeting these key genes.

CONCLUSIONS

We depicted molecular change of bAVM arterial remodeling via RNA-seq in high-blood-flow rat models. Twenty-seven key genes may regulate immune/inflammation infiltration and VSMC phenotype transform in bAVM arterial remodeling.

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

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

Unruptured Arteriovenous Malformations in the Multidetector Computed Tomography Era: Frequency of Detection and Predictable Failures

Objectives:

While hemorrhage arising from ruptured arteriovenous malformations (AVMs) is usually evident on multidetector non-contrast computed tomography (NCCT), unruptured AVMs can be below the limits of detection. We performed a retrospective review of NCCT of patients with a proven diagnosis of unruptured AVM to determine if advances in CT technology have made them more apparent and what features predict their detection.

Material and Methods:

Twenty-five NCCTs met inclusion criteria of having angiography or MR proven AVM without hemorrhage, prior surgery, or other CNS disease. Demographic variables, clinical symptoms at presentation, abnormal CT imaging findings, attenuation of the superior sagittal sinus (SSS), and Spetzler-Martin grade of each AVM were recorded. We examined the relationship between AVM detection and SSS attenuation through Kruskal–Wallis test. Exploratory serial logistic principal components analysis was performed including demographics, symptoms, and CT features in the multivariate model.

Results:

About 80% of the NCCTs showed an abnormality while 20% were normal. All those with an identifiable abnormality showed hyperdensity (80%). Logistic regression models indicate that clustered associations between several CT features, primarily calcifications, hyperdensity, and vascular prominence significantly predicted Spetzler-Martin grade (likelihood ratio 7.7, P = 0.006). SSS attenuation was significantly lower in subjects with occult AVMs when compared to those with CT abnormalities (median 47 vs. 55 HU, P < 0.04).

Conclusion:

Abnormal hyperdensity was evident in all detectable cases (80%) and multiple CT features were predictive of a higher Spetzler-Martin AVM grade. Moreover, SSS attenuation less than 50 HU was significantly correlated with a false-negative NCCT.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Optimal control problem arising in mathematical modeling of cerebral vascular pathology embolization

Arteriovenous malformation (AVM) of the brain is a congenital vascular abnormality, in which the arterial and venous blood pools are intertwined and directly connected. This dangerous disease causes a high risk of intracranial hemorrhage and disrupts brain functioning. The preferred method of AVM treating is embolization, which is the endovascular filling of abnormal AVM vessels with a special embolic agent. Despite the fact that this method is widely used in neurosurgery, in some cases its use is accompanied by perioperative AVM vessels rupture. In this regard, the aim of this work is to study the optimal scenarios for multi-stage AVM embolization from the effectiveness and safety of the procedure point of view. Mathematically, the joint movement of blood and embolic agent in the AVM body is described on the basis of a one-dimensional two-phase filtration model, which takes into account the redistribution of blood to surrounding healthy vessels. For the numerical solution of the resulting integro-differential system of equations, a monotonic modification of the CABARET scheme is used. To find optimal embolization scenarios, the optimal control problem with phase constraints arising from medicine is formulated. A modified particle swarm optimization method is used to solve this problem numerically. This technique is used to obtain optimal embolization scenarios on the basis of real patients clinical data collected during neurosurgical operations.

Correlation between angioarchitectural characteristics of brain arteriovenous malformations and clinical presentation of 183 patients

BACKGROUND

The correlation between angioarchitecture and clinical presentation of brain arteriovenous malformation (bAVM) remains a subject of debate.

OBJECTIVE

The main purpose of the present study was to assess the correlation between angioarchitectural characteristics of bAVM and clinical presentation.

METHODS

A retrospective review of all consecutive patients presenting a bAVM who underwent a cerebral angiography at Beneficencia Portuguesa Hospital in São Paulo between January 2006 and October 2016 was carried out. Patients were divided in five groups: group 1 - hemorrhage; group 2 - seizure; group 3 - headache; group 4 - progressive neurological deficits (PND); group 5 - incidental).

RESULTS

A total of 183 patients were included, with group 1 comprising 56 cases, group 2 49 cases, group 3 41 cases, group 4 28 cases, and group 5 9 cases. Regarding hemorrhage presentation, a statistical correlation was observed with female gender (P < 0.02), Spetzler-Martin 3B (P < .0015), and lesions with low flow (P < 0.04). A positive association was found between group 2 and age less than 36 years (P < 0.001), male sex (P < 0.018), presence of superficial lesions not classified as SM 3B (P < 0.002), presence of venous ectasia (p <0.03), and arterial steal phenomenon (P < 0.03). Group 4 was associated with older age (P < 0.01).

CONCLUSIONS

Angioarchitectural characteristics can be correlated with some clinical presentations as well as with some clinical data, making it possible to create predictive models to differentiate clinical presentations.

Preoperative Embolization With Fused CT Angiography and Tractography Facilitates Safe Resection of a Spetzler-Martin Grade IV Arteriovenous Malformation

Brain arteriovenous malformations (BAVMs) are high-flow vascular lesions that have a propensity to rupture resulting in high rates of morbidity and mortality. Microsurgical resection of BAVMs is the standard of care for high-risk, resectable lesions. Multiple imaging modalities aid in the surgical planning and resection of high-grade BAVMs, but all have hidden variables that would prove useful if available. We present a 20-year-old male with a ruptured BAVM with concern for the involvement of the corticospinal tract (CST) and basal ganglia. We describe the melding of computed tomography angiography (CTA) and diffusion tensor imaging (DTI) in addition to preoperative embolization to aid in the planning and resection of a lesion close to eloquent structures. Post-operative CTA and DTI showed a total resection of the lesion with retained CST white matter tracts, and the patient retained the functional ability of the contralateral limbs. The combination of CTA, brain DTI, and preoperative embolization provides a framework to improve the safety of resection of BAVMs that occur near eloquent brain networks.