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Brain arteriovenous malformation (AVM) is a rare congenital disorder affecting young adults with an incidence of 0.94 per 100,000 population. Intracranial digital subtraction angiography has to be done in all patients and grading of AVM is done as per Spetzler-Martin grading. We report a rare case of left basal ganglia large AVM treated by endovascular embolization. Our experience with endovascular embolization using Onyx is successful in the treatment of large brain AVM. Endovascular embolization with Onyx is safe and feasible in deeply located large AVMs of the brain. Our patient has postoperatively recovered completely without any neurological deficit. [ABSTRACT FROM AUTHOR]

Background and importanceArteriovenous malformations (AVMs) are complex vascular anomalies that pose significant risks, including intracranial hemorrhage and neurological deficits. Surgical resection is the preferred treatment, requiring precise intraoperative imaging to ensure complete removal while preserving critical structures. This case report presents the first combined use of hyperspectral imaging (HSI) and indocyanine green video angiography (ICG VA) to visualize perfusion during brain AVM surgery, highlighting the potential benefits of these advanced imaging techniques.Case descriptionA 66-year-old male presented with chronic headaches but no neurological deficits. MRI revealed a superficial AVM in the left frontal lobe within the superior frontal sulcus, measuring approximately 2.4 cm. The AVM was fed by feeders from the pericallosal artery, callosomarginal artery, and middle cerebral artery (MCA) branches, with drainage through a dilated cortical vein into the superior sagittal sinus. Preoperative embolization of two MCA feeding branches was performed, followed by microsurgical resection with ICG VA and HSI.ConclusionsThis case report demonstrates the successful application of HSI and ICG VA in brain AVM surgery. The combined use of these technologies provided comprehensive intraoperative assessment, enhancing surgical precision and safety. The integration of HSI offers non-invasive, contrast-agent-free imaging, potentially improving outcomes by enabling detailed perfusion mapping. Future studies should explore the broader applications of these imaging modalities in neurovascular practice.

Background: Stereotactic radiosurgery (SRS) is a current therapeutic option for treatment of arteriovenous malformations (AVMs) located in deep or eloquent brain regions. Obliteration usually occurs in a delayed fashion, with an expected latency of 3–5 years. Here, we assess how AVM flow correlates with volume before and after SRS treatment. Methods: Patients with supratentorial AVM treated with SRS at our institution between 2012–2022 were retrospectively reviewed. Patients were included if Quantitative Magnetic Resonance Angiography (QMRA) study was performed at baseline and at least at the first follow-up. Correlation between AVM flow and volume before and after treatment was evaluated. AVM flow and volume were additionally assessed for obliteration using the non-parametric receiver operating characteristic (ROC) curve. Results: Twelve patients with radiologic follow-up imaging were included. Eight patients presented AVM rupture, one of which occurred after radiosurgical treatment. Three patients underwent embolization prior SRS. Mean AVM initial volume was 3.8 cc (0.1–12.4 cc), mean initial flow 174 ml/min (11–604 ml/min), both variables showed progressive reduction at follow-up (range 3–57 months); and flow decreased with volume reduction (p < 0.001). Area under the ROC was 0.914 for both AVM flow and volume with obliteration (p = 0.019). Conclusions: AVM flow significantly decreased after SRS treatment, reflecting volume reduction. Baseline AVM flow and volume both predicted obliteration. QMRA provides additional non-invasive information to monitor patients after radiosurgical treatment. [ABSTRACT FROM AUTHOR]

The most common manifestation of brain arteriovenous malformations (BAVM) is intracranial hemorrhage. The incidence of ruptured BAVM is 3.5 per 100,000 people per year. The mortality rate of ruptured BAVM within 1 month after diagnosis was 12.7%. Spontaneous thrombosis occurs in less than 1.5% of ruptured BAVMs. This phenomenon was still elusive. Up until now, the gold standard of imaging examination has been cerebral digital subtraction angiography (DSA), whose sensitivity and specificity reach 100%. We reported the spontaneous thrombosis of a ruptured deep BAVM. An 18-year-old woman presented with severe headache and vomiting. The patient also complained of seizures. There was no body weakness, skewed face, or slurred speech. Cerebral computed tomography (CT) showed extensive hemorrhage in the ventricular system and subarachnoid space. Cerebral DSA showed a left subcortical BAVM and was found to have spontaneous thrombosis 3 weeks later when the patient was about to be embolized. Spontaneous thrombosis of ruptured BAVM may occur after intracranial hemorrhage. In this patient, spontaneous thrombosis occurred within 3 weeks.

Pediatric brain arteriovenous malformations are a major cause of morbidity and mortality, with the harmful effects of this disease compounded by the additional disability-years experienced by children with ruptured or other symptomatic arteriovenous malformations. In addition to the risks shared with their adult counterparts, pediatric patients frequently experience recurrence following radiographic cure, which presents an additional source of morbidity and mortality. Therefore, there is a need to synthesize potential mechanisms contributing to the elevated recurrence risk in the pediatric population and discuss how these translate to practical considerations for managing these patients. [ABSTRACT FROM AUTHOR]

Abstract Background Endovascular approaches have been widely applied in patients with brain arterio-venous malformations (AVM). However, little is known regarding the risk factors for complications or predictors of procedure success. Herein, we report our experience regarding the outcomes of endovascular embolization of posterior fossa AVM, focusing on how angioarchitectural and hemodynamic characteristics of the AVM affect the post-intervention outcomes. 17 patients diagnosed with posterior cranial fossa AVM were enrolled and scheduled for endovascular interventions by Onyx or Histoacryl. Results Most patients had a single session (58.8%), while 29.4% had two sessions, 11.7% had three sessions. Total nidus obliteration was achieved in 52.9% of cases, while 35.3% and 11.8% of them had subtotal and partial occlusion, respectively. Postprocedural hematoma was encountered in 17.6% of cases. All preprocedural demographic characteristics did not have a significant impact on occlusion outcomes. However, some angioarchitecture criteria were associated with partial occlusion including large size, superficial or mixed drainage. No significant association was noted between patients criteria and the incidence of complications. Conclusion Endovascular interventions could be curative for brain AVM, with an accepted periprocedural morbidity rate. Proper knowledge of the angioarchitectural characteristics of these lesions could help us to predict lesions that carry high risk for complications or high chance for cure.

Abstract Endovascular embolization techniques are showing an extraordinary potential to treat patients suffering from complex neurovascular malformations. The embolization with liquid embolic agents via Onyx is a prominent approach to treat arteriovenous malformation (AVM). However, intraoperative reflux of the liquid agents can be very challenging and, thus, is impairing full success of endovascular treatment. A possible technique to prevent intraoperative endovascular reflux is the pressure-cooker technique (PCT) utilizing coils to build a wedge proximal to the AVM. Few modifications of the PCT have been developed in the recent years to improve effectiveness of embolization procedure. Hereby, we present a novel PCT modification utilizing extra-soft Kaneka coils and glue to build well-fitting wedges. After the application of extremely soft bare coils with high trackability, flexibility and crossability, liquid agents can be injected with reduced reflux. We think the pressure-cooker technique with extra-soft Kaneka coils enables more efficient embolization in even farther, tinier and more tortuous target vessels. This technical note presents two illustrative patient cases with treatment-refractory, high-grade cerebral arteriovenous malformations which were successfully treated via embolization with PCT in which the plug was formed with Kaneka coils.

In this review article, we aim to provide a summary of the discoveries and developments that were instrumental in the evolution of the Neurointerventional field. We begin with developments in the advent of Diagnostic Cerebral Angiography and progress to cerebral aneurysm treatment, embolization in AVMs and ischemic stroke treatment. In the process we discuss many persons who were key in the development and maturation of the field. A pivotal aspect to rapid growth in the field has been the multidisciplinary involvement of the different neuroscience specialties and therefore we close out our discussion with excitement about ongoing and future developments in the field with a focus on treatments in the non-cerebrovascular disease realm. [ABSTRACT FROM AUTHOR]

Background: Endovascular approaches have been widely applied in patients with brain arterio-venous malformations (AVM). However, little is known regarding the risk factors for complications or predictors of procedure success. Herein, we report our experience regarding the outcomes of endovascular embolization of posterior fossa AVM, focusing on how angioarchitectural and hemodynamic characteristics of the AVM affect the post-intervention outcomes. 17 patients diagnosed with posterior cranial fossa AVM were enrolled and scheduled for endovascular interventions by Onyx or Histoacryl. Results: Most patients had a single session (58.8%), while 29.4% had two sessions, 11.7% had three sessions. Total nidus obliteration was achieved in 52.9% of cases, while 35.3% and 11.8% of them had subtotal and partial occlusion, respectively. Postprocedural hematoma was encountered in 17.6% of cases. All preprocedural demographic characteristics did not have a significant impact on occlusion outcomes. However, some angioarchitecture criteria were associated with partial occlusion including large size, superficial or mixed drainage. No significant association was noted between patients criteria and the incidence of complications. Conclusion: Endovascular interventions could be curative for brain AVM, with an accepted periprocedural morbidity rate. Proper knowledge of the angioarchitectural characteristics of these lesions could help us to predict lesions that carry high risk for complications or high chance for cure. [ABSTRACT FROM AUTHOR]

Endovascular embolization techniques are showing an extraordinary potential to treat patients suffering from complex neurovascular malformations. The embolization with liquid embolic agents via Onyx is a prominent approach to treat arteriovenous malformation (AVM). However, intraoperative reflux of the liquid agents can be very challenging and, thus, is impairing full success of endovascular treatment. A possible technique to prevent intraoperative endovascular reflux is the pressure-cooker technique (PCT) utilizing coils to build a wedge proximal to the AVM. Few modifications of the PCT have been developed in the recent years to improve effectiveness of embolization procedure. Hereby, we present a novel PCT modification utilizing extra-soft Kaneka coils and glue to build well-fitting wedges. After the application of extremely soft bare coils with high trackability, flexibility and crossability, liquid agents can be injected with reduced reflux. We think the pressure-cooker technique with extra-soft Kaneka coils enables more efficient embolization in even farther, tinier and more tortuous target vessels. This technical note presents two illustrative patient cases with treatment-refractory, high-grade cerebral arteriovenous malformations which were successfully treated via embolization with PCT in which the plug was formed with Kaneka coils. [ABSTRACT FROM AUTHOR]

Eloquent brain creates a challenge when resecting brain arteriovenous malformations (bAVMs). Here the authors present their technique of using subcortical motor mapping as an adjunct to increase safety during resection of a high-grade bAVM involving somatosensory cortex as well as cortical spinal tracts and visual tracts. After a bilateral craniotomy, they use direct cortical stimulation of the left motor cortex and subcortical stimulation using a suction stimulator to dynamically map motor tracts during the resection. They get within 3 mm of the corticospinal tracts by stimulation. The video can be found here: https://stream.cadmore.media/r10.3171/2024.10.FOCVID24107., Competing Interests: Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication.The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this publication., (© 2025, The Authors.)

Brain arteriovenous malformations are type of intracranial high-flow vascular malformation that can present with incidental finding in asymptomatic patients, seizures, headache, ischemic events due to vascular steal from normal brain, hemorrhage. Pulsatile tinnitus is the result of blood flow related sounds transmitted to the inner ear and coincides with heartbeat. AVMs are a rare cause of pulsatile tinnitus which contributes to less than 1% of published cases in the literature. We report a case of morbid tinnitus due to brain AVM which was resolved completely by endovascular embolization of the lesion. [ABSTRACT FROM AUTHOR]

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., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Institutional Ethics Committee, All India Institute of Medical Sciences, Jodhpur issued approval AIIMS/IEC/2018/782; dated December 22, 2018. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Mohan et al.)

Due to advances in interventional techniques, the transvenous approach may present an effective treatment option for embolization of brain arteriovenous malformations (AVMs). Contrary to the transarterial method, the transvenous approach can only be utilized in a specific subset of patients and is not suitable as a standard procedure for all AVM lesions. While this technique can be helpful in certain patients, careful patient selection to ensure patient safety and favorable clinical outcomes is important. However, especially in high-flow AVMs, targeted deposition of embolic materials through a transvenous access can be challenging. Therefore, a temporary flow arrest may prove helpful. Transient cardiac arrest by use of adenosine has been applied in cerebrovascular surgery but is not common for endovascular embolization. Adenosine-induced arrest and systemic hypotension may be a feasible, safe method to reduce flow and help endovascular transvenous embolization of certain AVMs. Our study evaluated the efficiency and safety of adenosine-induced circulatory arrest for transvenous embolization of cerebral AVMs. [ABSTRACT FROM AUTHOR]

Brain arteriovenous malformations (bAVM) arise as congenital or sporadic focal lesions with a significant risk for intracerebral hemorrhage (ICH). A wide range of interindividual differences is present in the onset, progression, and severity of bAVM. A growing body of gene expression and polymorphism‐based research studies support the involvement of localized inflammation in bAVM disease progression and rupture. In this review article, we analyze the altered responses of neural, vascular, and immune cell types that contribute to the inflammatory process, which exacerbates the pathophysiological progression of vascular dysmorphogenesis in bAVM lesions. The cumulative effect of inflammation in bAVM development is orchestrated by various genetic moderators and inflammatory mediators. We also discuss the potential therapies for the treatment of brain AVM by targeting the inflammatory processes and mediators. Elucidating the precise role of inflammation in the bAVM growth and hemorrhage would open novel avenues for noninvasive and effectual causal therapy that may complement the current therapeutic strategies. [ABSTRACT FROM AUTHOR]

Brain arteriovenous malformations (BAVMs) are an important cause of intracranial hemorrhage (ICH) in young adults. A small percent of BAVMs is due to hereditary hemorrhagic telangiectasia 1 and 2 (HHT1 and 2), which are caused by mutations in two genes involved in TGF-β signaling: endoglin (ENG) and activin-like kinase 1 (ALK1). The BAVM phenotype is an incomplete penetrant in HHT patients, and the mechanism is unknown. We tested the hypothesis that a "response-to-injury" triggers abnormal vascular (dysplasia) development, using Eng and Alk1 haploinsufficient mice. Adeno-associated virus (AAV) expressing vascular endothelial growth factor (VEGF) was used to mimic the injury conditions. VEGF overexpression caused a similar degree of angiogenesis in the brain of all groups, except that the cortex of Alk1(+/-) mice had a 33% higher capillary density than other groups. There were different levels of cerebrovascular dysplasia in haploinsufficient mice (Eng(+/)>Alk1(+/-)), which simulates the relative penetrance of BAVM in HHT patients (HHT1>HHT2). Few dysplastic capillaries were observed in AAV-LacZ-injected mice. Our data indicate that both angiogenic stimulation and genetic alteration are necessary for the development of dysplasia, suggesting that anti-angiogenic therapies might be adapted to slow the progression of the disease and decrease the risk of spontaneous ICH.

Brain arteriovenous malformations (AVMs) are dynamic lesions. Unlike the recruitment of additional vessels and the growth of the nidus over time, which are well reported in the literature, spontaneous regression is much less frequent. Only a handful of cases reporting recanalization of spontaneously regressed AVMs have been published. AVMs that undergo spontaneous regression typically share structural and historical features, including previous hemorrhage, a small nidus, superficial venous drainage, and a single draining vein. Structural features and hemodynamic changes may predispose brain AVMs to spontaneous regression, and angiogenic processes are hypothesized to contribute to recanalization and hemorrhage. We present the case of a 37-year-old female who had been diagnosed 12 years ago with an unruptured Spetzler-Martin grade 3 AVM in the left medial occipital lobe after a history of progressively worsening migraines. The AVM was monitored for 1 year, but the patient was lost to follow-up until 11 years later, when the AVM nidus was found to be significantly smaller in size. One month later, the patient presented with acute intraparenchymal hemorrhage due to rupture of the AVM, which was then surgically resected. Our case is the second reported case of rupture of a spontaneously regressed AVM and the first reported case of this outcome with no history of previous hemorrhage. Close monitoring of brain AVMs may be warranted for longer periods of time than previously recommended. [ABSTRACT FROM AUTHOR]

Intracerebral hemorrhage, seizures, neurologic deficits, and cognitive impairments due to brain AVM in childhood are incriminating for brain and executive function with sequelae for further social life. Long-term follow-up data on brain AVM in young patients are rare, making it difficult to compare and evaluate treatment risks and outcomes. We studied young patients with brain AVM who were referred to our institution between 2005 and 2012 and for whom follow-up data were available. We stratified the patients into those with ruptured AVM (rAVM) and unruptured AVM (uAVM) and compared treated and nontreated patients. Differences in outcome and social participation were assessed. A total of 29 young patients with brain AVM, median age 16 years, were included in our study with complete follow-up data of over 5 years (mean, 6 years). In 18 (62.1%) patients rAVM and in 11 (37.9%) patients uAVM were found. Twenty (69%) patients received treatment (rAVM 70% vs. uAVM 30%). Among treatment methods, microsurgery was most frequently used (rAVM 33.3% vs. uAVM 36.4%). In rAVM, 16 of 18 (88.9%) patients returned to work or school, and in uAVM, 11 (100%) patients did so. Concerning cognitive problems, no statistically significant difference was found in the 2 groups comparing treated and nontreated patients (P > 0.05). A favorable outcome was achieved in 13 (72.2%) patients with rAVM and in 11 (100%) patients with uAVM. Favorable outcome was achieved in the majority of patients. The rate of neurologic improvement and participation in social life was very high in the 2 groups. [ABSTRACT FROM AUTHOR]

Background Angiolipomas are mesenchymal tumors composed of mature adipocytes with abnormal vascular elements. They are most commonly found in subcutaneous tissues of the trunk and are rarely seen at craniospinal axes. Case Description We present an untypical case of frontal lobe angiolipoma manifested with seizures and initially described as an arteriovenous malformation. Conclusion MRI with fat-suppression sequence plays key role in angiolipomas diagnostics. [ABSTRACT FROM AUTHOR]

Background: The treatment of brain arteriovenous malformations (BAVMs) is still contrarily discussed. Despite the debatable results of the ARUBA trial, most BAVMs still require treatment depending on the Spetzler-Martin (SM) grading. Since size is measurable and venous drainage is visible, the determination of eloquence is comparably crucial but not fully objective. The present bicentric cohort study aims to examine the influence of preoperative navigated transcranial magnetic stimulation (nTMS) motor and language mapping data on decision-making for or against surgical treatment of BAVMs.Methods: The influence of data from nTMS on decision-making for or against treatment of BAVMs was examined by confirming/falsifying presumed motor or language eloquence.Results: The results of nTMS mappings changed the SM grading in nine cases. In six cases, the SM grading changed to a lower grade (= falsified eloquence); in three cases, the SM grading changed to a higher grade due to nTMS mappings (= unexpected eloquence). Out of all 34 cases, indication for surgery was supported by nTMS mappings in 15 cases (7 motors, 8 languages). In six cases, the decision against surgery was made based on nTMS mappings (three motors, three languages).Conclusion: In 21 of 34 cases (62%), nTMS was a supportive argument. We could show that nTMS motor and language data can be used for a more objective decision-making regarding the treatment of BAVMs and for a more detailed SM grading regarding the rating of eloquence. [ABSTRACT FROM AUTHOR]

Brain arteriovenous malformations (AVMs) are lesions thought to be primarily congenital in origin, consisting of fistulous connections of abnormal arteries and veins, without normal intervening capillary beds and no cerebral parenchyma between vessels. In the pediatric population, AVMs represent the most common cause of spontaneous intracranial hemorrhage (ICH), with a high recurrent bleeding risk. The aim of this paper is to report 2 cases of ruptured lobar AVMs in children, presenting with spontaneous ICH. Due to the patients’ neurological status, the only imaging examination performed preoperatively was a CT scan, showing intraparenchymal hemorrhage. Thus, there was no MRI/angiographic examination to prove the existence of a brain AVM prior to the surgical interventions. Also, the cerebral angiography performed after the surgery showed, in both patients, no signs of residual vascular malformations. Therefore, the diagnosis of AVM was certified by macroscopic and microscopic pathological findings, with no brain imaging suggestive of a vascular malformation.

The treatment of brain arteriovenous malformations (bAVM) continues to be challenging even with radiosurgery chosen as the first treatment option in selected cases. The correct definition of the radiosurgical target is one of the most important factors for the obliteration of these malformations. The current imaging protocol usually provides images in two dimensions, which makes it difficult to completely understand the anatomical complexity of the lesions. This case report proposes a realistic 3D model as a tool for better delineation of arteriovenous malformations submitted to radiosurgery. A 32-year-old woman presented to the clinic for evaluation of a bAVM detected on imaging studies post stroke associated with intraventricular hemorrhage in April 2011. Angiography revealed an bAVM in the right insular lobe with feeding vessels from the medial lenticulostriate artery. The medical team decided to pursue interventional endovascular treatment in sessions, final one in December 2018 (four sessions in total). The last digital subtraction angiography (DSA) demonstrated 90% of occlusion but still a nidus that received an arterial supply from the branches of the right posterior cerebral artery. The patient was counseled to treat the medial and deep portions of the AVM with radiosurgery. During the CT scan a AngioCT (DICOM files, slices 1,5 mm) was recalled and used for 3D printing. One bAVM printing model was previously obtained. For prototype generation, file format stereolithography (*.stl) were obtained from the combination of CT scan and AngioCT of the patient from the software Materialise Mimics Research™. We adopted that magenta color for patent blood vessels and white resin for embolized vessels. Utilizing all of this information a single target was designed in two steps by the same neurosurgeon. Initially, a bAVM volume (V1) using just the protocol images (CT, MRI and DSA) was created. After this, other contouring (V2) was designed using the CT, MRI, DSA plus the 3D model like a real image to understand the lesion and two different plans were created. In the first one (V1) the volume was 16.17 cm3 while the second (V2) was 13.85 cm3. The difference between the two volumes (V1 – V2) was 2.32 cm3 that represents 14.34% of the V1 volume (V1-V2/V1). The treatment was performed in June 2019 using V2 as a target, receiving a radiation dose of 15Gy. At this moment, she is being followed with control images without complaint. [ABSTRACT FROM AUTHOR]

Stereotactic radiosurgery (SRS) has proven to be an effective strategy in the management of intracranial arteriovenous malformations (AVMs) in children and adults over the past three decades. Its application has resulted in lowering the morbidity and mortality associated with treatment of deep-seated AVMs. SRS has been used as a primary modality of therapy as well as in conjunction with embolization and microsurgery in the management of AVMs. The obliteration rate after SRS has been reported to range from 35% to 92%. Smaller AVMs receiving higher marginal doses have obliteration rates of 70% and more. The median follow-up reported in most series is approximately 36-40 months. The median time to obliteration has been reported to be approximately 24-36 months in most series. Radiation-induced neurological complications have been reported in less than 10% of patients, with a 1.5%-6% risk of developing a new permanent neurological deficit. The bleeding rate during the latency to obliteration has been reported to be approximately 5%. This review describes the experience reported in literature with respect to the indications, dosage, factors affecting obliteration rate of AVMs, and complications after SRS. [ABSTRACT FROM AUTHOR]

Haemorrhage is the most frequent revealing condition of brain arteriovenous malformations (bAVMs). We report a rare case of unruptured parietal bAVM revealed by spontaneous thrombosis of the main draining vein, responsible for a focal neurological deficit. The bAVM was embolized in emergency conditions; complete regression of the neurological symptoms was observed within five days after the embolization. Potential mechanisms of such spontaneous thrombosis of the bAVM’s main drainage pathway as well as an exhaustive review of the literature concerning this rare revealing condition are presented and discussed. [ABSTRACT FROM AUTHOR]

Objective: The assessment of hemorrhagic risk is of central importance in the management of pediatric brain arteriovenous malformations (AVMs). A recently published scoring system, the R2eD AVM (race, exclusive deep location or not, AVM size < 3 or ≥ 3, venous drainage exclusively deep or not, and monoarterial feeding or >1 arterial feeders) considers patient race and AVM location, size, venous drainage, and arterial supply and was successfully externally validated for use in adults to predict the risk of AVM hemorrhagic presentation. In this study the authors sought to externally validate the R2eD AVM score for prediction of hemorrhagic risk in the pediatric AVM population., Methods: A pediatric database at Boston Children's Hospital was retrospectively reviewed for all patients with a diagnosis of intracranial AVM. Exclusion criteria included age > 21 years, multiple AVMs, and incomplete clinical/radiographic data. Demographic data and R2eD AVM score calculations were collected for all patients. Univariate binary logistic regression and multivariate stepwise backward elimination models were used to determine factors associated with hemorrhagic presentation., Results: A total of 212 AVMs were identified in 212 patients with vascular anomalies from 1995 to 2021, and 144 patients met the inclusion criteria (74 [51.4%] male, 111 [77.1%] White), of whom 87 (60.4%) patients presented with rupture and 122 (84.7%) underwent resection. The mean age at surgery was 12 years (range 3 months to 20 years). The R2eD AVM scoring system was applied to each patient. The score components of size < 3 cm and exclusive deep venous drainage were significantly associated with rupture risk (p < 0.05). The complete model for the R2eD AVM score had an area under the curve of 0.671 (95% CI 0.586-0.757)., Conclusions: This study demonstrated poor external validity of the R2eD AVM score in predicting pediatric AVM rupture risk. The results suggest that future studies are warranted to determine a better scoring method to capture pediatric rupture risk, given the significant differences in clinical presentation in pediatric compared with adult AVM patients.

Brain arteriovenous malformations (AVMs) are lesions thought to be primarily congenital in origin, consisting of fistulous connections of abnormal arteries and veins, without normal intervening capillary beds and no cerebral parenchyma between vessels. In the pediatric population, AVMs represent the most common cause of spontaneous intracranial hemorrhage (ICH), with a high recurrent bleeding risk. The aim of this paper is to report 2 cases of ruptured lobar AVMs in children, presenting with spontaneous ICH. Due to the patients' neurological status, the only imaging examination performed preoperatively was a CT scan, showing intraparenchymal hemorrhage. Thus, there was no MRI/angiographic examination to prove the existence of a brain AVM prior to the surgical interventions. Also, the cerebral angiography performed after the surgery showed, in both patients, no signs of residual vascular malformations. Therefore, the diagnosis of AVM was certified by macroscopic and microscopic pathological findings, with no brain imaging suggestive of a vascular malformation. [ABSTRACT FROM AUTHOR]

Endovascular embolization is an important modality in the treatment of brain AVMs. Nowadays staged embolization is the method of choice for the prevention of perioperative hemorrhagic complications. Current theory suggests that simultaneous occlusion of more than 60% of AVM volume induces significant redistribution local blood flow. That, in turn, may lead to hemorrhage due to AVM rupture. Aside from angiographic findings, there is still no method that predicts the degree of safe partial embolization. Intraluminal measurement of flow velocity and pressure in the vicinity of the AVM nidus might allow detecting the changes in local hemodynamics. That can provide a valuable data and shed the light on the origin of vascular catastrophes. Ten patients underwent 12 embolization sessions with intraluminal flow velocity and pressure monitoring. The measurements were performed by dual-sensor guidewire. The ''Combomap'' (Volcano) system with Combowire microguidewires was chosen for measurements, as there is a documented experience of safe use of said guidewires in the cerebral vasculature. The findings observed during the study matched empirical data as well as the current physiological hypothesis of AVM hemorrhage. In conjunction with DSA runs, intraluminal flow velocity and pressure monitoring has the potential to become a valuable tool in AVM treatment. [ABSTRACT FROM AUTHOR]

Objective: Our study aimed to identify predictive factors for malignant post-treatment edema and hemorrhage in patients who underwent microsurgical treatment of arteriovenous malformation (AVM) in our institution., Methods: The study included 72 patients treated by microsurgery for cerebral symptomatic and/or ruptured AVM between 2010 and 2020. Six patients developed postprocedural malignant edema and hemorrhage (group M); the other 66 patients had no malignant edema and hemorrhage (group NM). In each patient, flow was assessed indirectly by summing the diameters of all feeding arteries to obtain an overall diameter (ODA), and similarly for draining veins (ODV). High-flow was defined as a delay between feeding artery injection and draining vein injection (DAV)<1 second on dynamic digital subtraction angiography. Univariate analysis was performed., Results: Mean ODA and ODV were respectively 11mm (±8.2) and 11mm (±5.3) in group M and 2.9mm (±1.4) and 3.7mm (±1.3) in group NM (P=0.001). High-flow AVM was demonstrated in 4 out of 5 patients (85%) in group M and in 14 out of 55 (25%) in group NM (P=0.02). Associated aneurysm was seen in 5 patients in group M (83%) and in 11 in group NM (17%) (P=0.001)., Conclusion: High-flow AVM may be associated with higher risk of postoperative edema and hemorrhage. Multidisciplinary discussion is mandatory in these cases, to define a pre-therapeutic plan for progressive staged vascular malformation occlusion., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Rationale and Objectives: For the evaluation of patients scheduled for the treatment of brain arteriovenous malformations (AVMs), accurate anatomical information is essential. The purpose of this study was to assess the usefulness of three-dimensional (3D) digital subtraction angiography (DSA)-magnetic resonance (MR) fusion imaging for the pretreatment evaluation of AVMs. Materials and Methods: The study population consisted of 11 consecutive patients (7 males, 4 females; age 10–72 years; mean 45 years) with brain AVMs. All prospectively underwent pretreatment MR imaging (MRI), MR angiography (MRA), and two-dimensional (2D) and 3D DSA. The 3D DSA and MR images were semiautomatically fused with fusion software on a workstation. In the delineation of AVM nidus, feeder, drainer, and relationship between AVM and the adjacent brain structures, two radiologists independently evaluated MRA and MRI, three-dimensional (3D) DSA, and MRI, and 3D DSA-MR fusion images using a 4-point scoring system. The referring neurosurgeons were asked whether the information provided by 3D DSA-MR fusion images was helpful for treatment decisions. Results: For all four items, the delineation was significantly better with the 3D DSA/MRI or 3D DSA-MR fusion images than the MRA/MRI images. Although the delineation for the nidus, feeder, and drainer were not significantly different between the 3D DSA/MRI and 3D DSA-MR fusion images, 3D DSA-MR fusion imaging were significantly better for the relationship between AVM and the adjacent brain structures than 3D DSA/MR imaging (P = .0047). The information provided by 3D DSA-MR fusion images was helpful for treatment decisions in all cases. Conclusion: 3D DSA-MR fusion images are useful for the pretreatment evaluation of brain AVMs. [ABSTRACT FROM AUTHOR]

Background: Brain arteriovenous malformations (bAVMs) represent a high risk for hemorrhagic stroke, leading to significant neurological morbidity and mortality in young adults. The etiopathogenesis of bAVM remains unclear. Research progress has been hampered by the lack of animal models. Hereditary Hemorrhagic Telangiectasia (HHT) patients with haploinsufficiency of endoglin (ENG, HHT1) or activin receptor-like kinase 1 (ALK1, HHT2) have a higher incidence of bAVM than the general population. We previously induced cerebrovascular dysplasia in the adult mouse that resembles human bAVM through Alk1 deletion plus vascular endothelial growth factor (VEGF) stimulation. We hypothesized that Eng deletion plus VEGF stimulation would induce a similar degree of cerebrovascular dysplasia as the Alk1-deleted brain. Methods: Ad-Cre (an adenoviral vector expressing Cre recombinase) and AAV-VEGF (an adeno-associated viral vector expressing VEGF) were co-injected into the basal ganglia of 8- to 10-week-old Eng2f/2f (exons 5 and 6 flanked by loxP sequences), Alk12f/2f (exons 4-6 flanked by loxP sequences) and wild-type (WT) mice. Vascular density, dysplasia index, and gene deletion efficiency were analyzed 8 weeks later. Results: AAV-VEGF induced a similar degree of angiogenesis in the brain with or without Alk1- or Eng-deletion. Abnormally patterned and dilated dysplastic vessels were found in the viral vector-injected region of Alk12f/2f and Eng2f/2f brain sections, but not in WT. Alk12f/2f mice had about 1.8-fold higher dysplasia index than Eng2f/2f mice (4.6 ± 1.9 vs. 2.5 ± 1.1, p < 0.05). However, after normalization of the dysplasia index with the gene deletion efficiency (Alk12f/2f: 16% and Eng2f/2f: 1%), we found that about 8-fold higher dysplasia was induced per copy of Eng deletion (2.5) than that of Alk1 deletion (0.3). ENG-negative endothelial cells were detected in the Ad-Cre-treated brain of Eng2f/2f mice, suggesting homozygous deletion of Eng in the cells. VEGF induced more severe vascular dysplasia in the Ad-Cre-treated brain of Eng2f/2f mice than that of Eng+/- mice. Conclusions: (1) Deletion of Eng induces more severe cerebrovascular dysplasia per copy than that of Alk1 upon VEGF stimulation. (2) Homozygous deletion of Eng with angiogenic stimulation may be a promising strategy for development of a bAVM mouse model. (3) The endothelial cells that have homozygous causal gene deletion in AVM could be crucial for lesion development. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Brain arteriovenous malformations (BAVMs) are an important cause of intracranial hemorrhage (ICH) in young adults. A small percent of BAVMs is due to hereditary hemorrhagic telangiectasia 1 and 2 (HHT1 and 2), which are caused by mutations in two genes involved in transforming growth factor-β signaling: endoglin (Eng), and activin-like kinase 1 (Alk1). The BAVM phenotype has incomplete penetrance in HHT patients, and the mechanism is unknown. We tested the hypothesis that a “response-to-injury” triggers abnormal vascular (dysplasia) development, using Eng and Alk1 haploinsufficient mice. Adeno-associated virus (AAV) expressing vascular endothelial growth factor (VEGF) was used to mimic the injury conditions. VEGF overexpression caused a similar degree of angiogenesis in the brain of all groups, except that the cortex of Alk1+/− mice had a 33% higher capillary density than other groups. There were different levels of cerebrovascular dysplasia observed in haploinsufficient mice (Eng+/− > Alk1+/−), which simulates the relative penetrance of BAVM in HHT patients (HHT1 > HHT2). Few dysplastic capillaries were observed in AAV-LacZ-injected mice. Our data indicate that both angiogenic stimulation and genetic alteration are necessary for the development of vascular dysplasia, suggesting that anti-angiogenic therapies might be adapted to slow the progression of the disease and decrease the risk of spontaneous ICH. [ABSTRACT FROM AUTHOR]

Summary ¶Background. To evaluate the angioarchitecture of cerebral arteriovenous malformations (cAVMs) with special regard to its influence on the risk of intracranial haemorrhage. Methods. Clinical and neuroradiological data of 171 patients with cAVMs, who were treated at our department, were analysed retrospectively. The angioarchitectonic data were obtained from angiographic series, cranial CT scans and MR images. A χ2 test was conducted to correlate the parameters and determine the P values. Findings. The following parameters correlate to an increased risk of haemorrhage: diameter of the nidus ≤2 cm (P<0.001), number of arterial feeders ≤2 (P<0.001), diameter of the main feeder ≤1 mm (P<0.0001), number of veins draining the nidus ≤2 (P<0.001), exclusive deep drainage (P<0.05), and low or middle flow-velocity (P<0.01). Specific angioarchitectonic features such as venous stenoses, varicose dilatation of the draining vein, arterial aneurysms of the feeding artery, arteriovenous fistula within the nidus, contralateral drainage and sinushypo/-aplasia did not alter the bleeding rate. Interpretation. Various angiographic features were correlated with the occurrance of intracranial haemorrhage in patients with cerebral AVMs. In addition to the well-known factors influencing the bleeding risk of cAVMs like size, pattern of venous drainage and location within the brain our data demonstrate the importance to look at the diameter of the main feeder and the number of draining veins showing a better correlation. [ABSTRACT FROM AUTHOR]

Summary. Background: The management of cerebral arteriovenous malformations needs effective treatments. So far, no study has shown that partial targeted embolization treatment (PTET) reduces the risk of intracranial hemorrhage with respect to the natural history of the malformation. Methods: The pre-treatment and post-treatment-initialization hemorrhage incidences of neuro-interventional patients were compared. Two hundred fifteen patient years from 519 patients were used to observe the short term course of the untreated disease. Five hundred patient years from 326 patients were used to observe hemorrhage after the start of treatment. The Kaplan-Meier estimator of hemorrhage free time under treatment was compared with results in the literature. Confounding influences resulting from selection processes or the disease parameters were studied. Results: The yearly hemorrhage incidence rate of all untreated patients was observed as 0.089 (95% CI [0.053, 0.138]). This rate was 0.052 (95% CI [0.019, 0.114]) in the subgroup of patients who underwent PTET later. In the same group the observed annual rate after the start of PTET was 0.036 (95% CI [0.021, 0.057]). Crawford's results about intracranial hemorrhage during the natural course show the lowest risk values compared to other published studies [3]. There was a significant difference between the Crawford's reference data and the ICH incidence after the start of PTET in the neuro-interventional population (p=0.037). The morbidity risk in treated patients was 5.3% for a transitory and 2% for a persisting neurological deficit. Mortality results were compared with those of Crawford. Conclusion: The neuro-interventional patients under study show a lower hemorrhage risk than the population studied by Crawford. A significant superiority with respect to hemorrhage risk is established two years after the start of the PTET treatment. [ABSTRACT FROM AUTHOR]

Objective: Epileptic seizures in patients with brain arteriovenous malformations (bAVMs) may be caused by hemodynamic alterations due to the complex angioarchitecture of bAVMs. In particular, an arterial steal phenomenon and venous outflow disruption may play an etiological role in seizure development but remain challenging to demonstrate quantitatively. Blood oxygenation level-dependent (BOLD) cerebrovascular reactivity (CVR) imaging is an emerging technique that can measure both arterial steal phenomenon (as a paradoxical BOLD signal decrease during a vasodilatory stimulus) and impaired perinidal BOLD-CVR (which has been found in the presence of venous congestion on conventional angiography in bAVM patients with epilepsy). By applying this innovative BOLD-CVR technique, the aim is to better study CVR patterns and their correlation with morphological features on conventional angiography in patients with bAVM with and without epilepsy., Methods: Twenty-two patients with unruptured and previously untreated bAVMs (8 with and 14 without epilepsy) were included in this case-control study. Quantitative CVR measurements were derived from BOLD functional MRI volumes using a novel standardized and precise hypercapnic stimulus (i.e., % BOLD/mm Hg CO2). In addition, 22 matched healthy controls underwent an identical BOLD-CVR study. Evaluation of venous congestion was performed on conventional angiography for all patients with bAVM., Results: Patients with bAVM-associated epilepsy showed impaired whole-brain BOLD-CVR compared to those in the nonepilepsy group, even after correction for AVM volume and AVM grade (epilepsy vs nonepilepsy group: 0.17 ± 0.07 vs 0.25 ± 0.07, p = 0.04). A BOLD-CVR-derived arterial steal phenomenon was observed in 2 patients with epilepsy (25%). Venous congestion was noted in 3 patients with epilepsy (38%) and in 1 patient without epilepsy (7%; p = 0.08)., Conclusions: These data suggest that whole-brain CVR impairment, and more pronounced hemodynamic alterations (i.e., arterial steal phenomenon and venous outflow restriction), may be more present in patients with bAVM-associated epilepsy. The association of impaired BOLD-CVR and bAVM-associated epilepsy will need further investigation in a larger patient cohort.

In brain arteriovenous malformations (AVMs), there is mismatched communication between arteries and veins, causing a nidal bed between them. This systematic review explores whether a magnetic resonance angiogram (MRA) can be used as a diagnostic imaging tool instead of a digital subtraction angiogram (DSA). Utilizing PubMed, Cochrane, and Google Scholar, as well as the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for article selection, a literature search was conducted over the past five years. Eleven studies were included, with a majority of the articles suggesting a potential for consideration. Arterial spin labeling (ASL) versus time-of-flight (TOF) scans was a comparison study, in addition to the study on pseudo-continuous arterial spin labeling (pc-ASL), which proved its high sensitivity in comparison with DSA scans. Other studies included quantitative magnetic resonance angiogram (Q-MRA) measuring the blood flow and susceptibility weighted imaging (SWI) modality. Although promising, digital subtraction angiogram (DSA) scans have diagnostic superiority. In addition, articles discussed follow-up magnetic resonance angiogram (MRA) scans after surgery. Overall, digital subtraction angiogram remains the gold standard due to its superior spatial resolution and hemodynamic properties; these are the key limitations of magnetic resonance studies. MRA has demonstrated its ability to reproduce high-quality diagnostic images for arteriovenous malformation (AVM) angioarchitecture; however, coupled with their limitations, not many studies with large sample sizes over longer periods have been conducted, and we urge more research into it., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Raman et al.)

The authors describe the angio-architecture of intracranial vascular malformations. Several patterns can be identified thanks to the intracranial superselective angiograms that can now be performed. Schematically, the following features can be seen: 1. Direct arterial supply, 2. Indirect arterial supply, 3. Flow-related arterial ectasia (aneurysm), 4. Dysplastic aneurysm, 5. Direct arteriovenous fistula, 6. Intralesional arterial ectasia (aneurysm), 7. Intralesional venous ectasia (aneurysm), 8. Venous ectasia. Each of these elementary arrangements are illustrated and their clinical significance outlined whenever possible. Finally, the dural AVM drainage into the cortical venous system serves as an almost experimental model for the appreciation of the role played by the venous congestive phenomenon in brain AVM symptoms. [ABSTRACT FROM AUTHOR]

A 71-year-old man, with a pial micro-arteriovenous malformation (pAVM) draining into the confluence of the vein of Trolard and the vein of Labbé was surgically removed, sparing these cortical veins. 4-months MR and angiographic controls showed a de novo dural arteriovenous fistula (dAVF) draining into the previously spared cortical veins. It was removed using intraoperative motor evoked potentials (MEP). This is the first case of iatrogenic dAVF developing on the same draining vein of a previously treated pAVM. De novo dAVFs are generally iatrogenic. This case suggests that the unresected venous drainage of an AVM might be the substratum for neo-angiogenetic processes; moreover inflammation related to surgery might be the trigger factor for the development of the dAVF. [ABSTRACT FROM AUTHOR]

The localization of arteriovenous malformations (AVMs) intraoperatively in the setting of an acute intracerebral hemorrhage (ICH) is crucial to avoid damage of delicate vascular structures that may even further exacerbate the bleed. Currently, surgical mapping using preoperative angiographic is the standard of practice. We report the use of intraoperative ultrasound for the diagnosis and localization of an AVM in the case of a 61-year-old female with reported iodine contrast allergy and previous severe reaction, in a setting with limited resources, without other imaging options or timely transfer to another facility readily available. Immediate surgical care was warranted to avoid further deterioration of the patient; intraoperative diagnosis and localization of the suspected underlying lesion were done using ultrasound. The ultrasound display showed tubular anechoic intertwined structures that demonstrated bidirectional flow, which is suggestive of an AVM. The intraoperative diagnosis allowed the surgeon to avoid an inadvertent approach to the vascular malformation nidus or vessels, which could have further complicated the case. We believe that intraoperative ultrasound may be valuable for the neurosurgeons today in many settings. Despite the fact that this case occurred in a scenario with limited resources and no other imaging method (such as magnetic resonance imaging (MRI), magnetic resonance angiography (MRA)) available, we advise readers not to rely solely on intraoperative ultrasound., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2019, Bertani et al.)

Background: Theoretical modeling allows investigations of cerebral arteriovenous malformation (AVM) hemodynamics, but current models are too simple and not clinically representative. We developed a more realistic AVM model based on graphics processing unit (GPU) computing, to replicate highly variable and complex nidus angioarchitectures with vessel counts in the thousands-orders of magnitude greater than current models., Methods: We constructed a theoretical electrical circuit AVM model with a nidus described by a stochastic block model (SBM) of 57 nodes and an average of 1000 plexiform and fistulous vessels. We sampled and individually simulated 10,000 distinct nidus morphologies from this SBM, constituting an ensemble simulation. We assigned appropriate biophysical values to all model vessels, and known values of mean intravascular pressure (P mean ) to extranidal vessels. We then used network analysis to calculate P mean and volumetric flow rate within each nidus vessel, and mapped these values onto a graphic representation of the nidus network. We derived an expression for nidus rupture risk and conducted a model parameter sensitivity analysis., Results: Simulations revealed a total intranidal volumetric blood flow ranging from 268 mL/min to 535 mL/min, with an average of 463 mL/min. The maximum percentage rupture risk among all vessels in the nidus ranged from 0% to 60%, with an average of 29%., Conclusion: This easy to implement biomathematical AVM model, allowed by parallel data processing using advanced GPU computing, will serve as a useful tool for theoretical investigations of AVM therapies and their hemodynamic sequelae., (Copyright © 2019 Elsevier Ltd. All rights reserved.)