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Endoglin (ENG) mutation causes type 1 hereditary hemorrhagic telangiectasia (HHT1). HHT1 patients have arteriovenous malformations (AVMs) in multiple organs, including the brain. In mice, Eng deletion induced by R26RCreER or SM22αCre leads to AVM development in the brain and other organs. We hypothesized that an increase in Eng- negative ECs will enhance AVM severity. To increase EC Eng deletion, we used a codon-improved cre (icre), which is more potent in recombination of the floxed alleles than the wild-type (WT) cre. R26RCreER;Engf/f mice that have a Rosa promoter driving and tamoxifen (TM)-inducible WT cre expression globally, and PdgfbiCreER;Engf/f mice that have a Pdgfb promoter driving and TM-inducible icre expression in ECs were treated with three intra-peritoneal injections of TM (2.5 mg/25 g of body weight) to delete Eng globally or in the ECs. AAV-VEGF was stereotactically injected into the brain to induce brain focal angiogenesis and brain AVM. We found that icre caused more Eng deletion in the brain, indicated by a lower level of Eng proteins (p < 0.001) and fewer Eng-positive ECs (p = 0.01) than mice with WT cre. Mice with icre-mediated Eng deletion have more abnormal vessels (p = 0.02), CD68+ macrophages (p = 0.002), and hemorrhage (p = 0.04) and less vascular pericyte and smooth muscle coverage than mice with WT cre. In addition, arteriovenous shunts were detected in the intestines of icre mice, a phenotype that has not been detected in WT cre mice before. RNA-seq analysis showed that 8 out of the 10 top upregulated pathways identified by gene ontology (GO) analysis are related to inflammation. Therefore, the increase in Eng deletion in ECs exacerbates AVM severity, which is associated with enhanced inflammation. Strategies that can reduce Eng-negative ECs could be used to develop new therapies to reduce AVM severity for HHT1 patients.

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

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 longterm survival in brain AVM patients. [ABSTRACT FROM AUTHOR]

Pediatric intracranial arteriovenous malformation (AVM) patients are commonly admitted to the emergency room (ER). Increasing patient utilization of the ER has been associated with healthcare disparities and a trend of decreased efficiency. The aim of this study was to evaluate the trends of pediatric AVM ER admissions over recent years and identify factors associated with health care resource utilization and outcomes. The 2016–2019 National Inpatient Sample was queried for patients under the age of 18 admitted with AVM. Cases of admission through the ER were identified. Demographic and severity factors associated with ER admission were explored using comparative and regression statistics. Of 3875 pediatric patients with AVM admitted between 2016 and 2019, 1280 (33.0%) were admitted via the ER. Patients admitted via the ER were more likely to be in the lowest median income category (P < 0.001), on Medicaid insurance (P = 0.008), or in the South (P < 0.001) than patients admitted otherwise. There was increased severity and increased rates of intracranial hemorrhage (ICH) in patients admitted via the ER (P < 0.001). Finally, there were increasing trends in ER admissions and ICH throughout the years. ER admission of pediatric AVM patients with ICH is increasing and is associated with a distinct socioeconomic profile and increased healthcare resource utilization. These findings may reflect decreased access to more advanced diagnostic modalities, primary care, and other important resources. Identifying populations with barriers to care is likely an important component of policy aimed at decreasing the risk of severe disease presentation. [ABSTRACT FROM AUTHOR]

Objective: Gamma Knife radiosurgery (GKRS) is an effective and noninvasive treatment for high-risk arteriovenous malformations (AVMs). Since differences in GKRS outcomes by nidus type are unknown, this study evaluated GKRS feasibility and safety in patients with brain AVMs. Methods: This single-center retrospective study included patients with AVM who underwent GKRS between 2008 and 2021. Patients were divided into compact- and diffuse-type groups according to nidus characteristics. We excluded patients who performed GKRS and did not follow-up evaluation with magnetic resonance imaging or digital subtraction angiography within 36 months from the study. We used univariate and multivariate analyses to characterize associations of nidus type with obliteration rate and GKRS-related complications. Results: We enrolled 154 patients (mean age, 32.14±17.17 years; mean post-GKRS follow-up, 52.10±33.67 months) of whom 131 (85.1%) had compact- and 23 (14.9%) diffuse-type nidus AVMs. Of all AVMs, 89 (57.8%) were unruptured, and 65 (42.2%) had ruptured. The mean Spetzler-Martin AVM grades were 2.03±0.95 and 3.39±1.23 for the compact- and diffuse-type groups, respectively (p<0.001). During the follow-up period, AVM-related hemorrhages occurred in four individuals (2.6%), three of whom had compact nidi. Substantial radiation-induced changes and cyst formation were observed in 21 (13.6%) and one patient (0.6%), respectively. The AVM complete obliteration rate was 46.1% across both groups. Post-GKRS complication and complete obliteration rates were not significantly different between nidus types. For diffuse-type nidus AVMs, larger AVM size and volume (p<0.001), lower radiation dose (p<0.001), eloquent area location (p=0.015), and higher Spetzler-Martin grade (p<0.001) were observed. Conclusion: GKRS is a safe and feasible treatment for brain AVMs characterized by both diffuse- and compact-type nidi. [ABSTRACT FROM AUTHOR]

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Brain arteriovenous malformations (AVM) present complex treatment decisions, particularly for low-grade AVM where surgical resection is often considered the standard. This case report emphasizes the importance of patient preferences and cultural considerations in selecting endovascular embolization over traditional surgical approaches for Spetzler-Martin Grade I AVM management, highlighting the evolving practice of patient-centered care in neurointervention. A 30-year-old male presented with recurrent seizures, characterized by a sudden onset of headache followed by speech arrest, without any preceding medical history of neurological deficits. Initial physical examination revealed no focal neurological deficits. Non-contrast computed tomography, magnetic resonance imaging, and magnetic resonance angiography suggested an AVM involving the cortical-subcortical regions of the left frontal lobe, measuring approximately 1.7 × 2.6 × 1.5 cm, fed by the left middle cerebral artery M3 segment, and draining into the superior sagittal sinus. Spetzler-Martin Grade I classification was confirmed via digital subtraction angiography. Given the patient's strong preference against invasive procedures, driven by personal and cultural beliefs, endovascular embolization was selected as the treatment strategy. Post-embolization, the patient showed marked symptomatic improvement with no evidence of residual AVM on follow-up imaging, and no postprocedure complications were reported. This case highlights the importance of considering patient preferences in AVM treatment planning, illustrating that endovascular embolization can be an effective and less invasive alternative to surgery in selected patients, reinforcing the need for personalized, patient-centered approaches in neurointerventional care.

Background: Cerebral arteriovenous malformations (AVMs) are complex, heterogeneous, uncommon lesions that carry a high risk of intracranial hemorrhage with subsequent disability. Aim: To evaluate the outcome of patients with cerebral AVMs treated in our center, King Faisal Specialized Hospital and Research Center (KFSH&RC) Saudi Arabia with SRS using the CyberKnife. Methods: Medical records of patients treated in the above-mentioned way in the period between 2009-2021 were retrospectively evaluated. Results: A total of 51 patients were included in this study. The median age at diagnosis was 31 (3-77) years. Neurological alteration and intracranial hemorrhage were the most common presentations in 24 (47.1%) patients. The mean maximum AVM nidus diameter and volume were 2.9 cm and 5.9 cc respectively. All the patients received SRS using CyberKnife with a median marginal dose of 20 (14-21) Gy over a single fraction. Volume staged treatment was applied in 4 (7.8%) patients. After a median follow-up of 37 (2-170) months, all patients were alive with successful obliteration of the AVM nidus occurring in 31 (60.8%) patients after a median latency period of 27 (4-68.9) months in those who achieved complete obliteration. No patients developed post-SRS hemorrhage and 11 (21.6%) patients developed post-SRS radiological radiation-induced changes of which only 3 (27.3%) patients were symptomatic (in the form of uncontrolled seizures). only SRS dose > 19 Gy was significantly correlated with the obliteration rate, as 79.3% of patients who received SRS dose > 19 Gy achieved obliteration vs 36.4 % only in those who received dose Conclusion: SRS treatment using CyberKnife is effective management for patients with cerebral AVMs without an increase in the incidence of post-SRS hemorrhage, stroke, or death.

We present a case of successful embolization of an anterior chest wall arteriovenous malformation (AVM) in a 24-year-old male patient. This report aims to highlight the efficacy and safety of using the liquid embolic agent (onyx) as well as the combined approaches (trans-femoral and trans-radial) in managing rare complex chest wall AVMs.

Arteriovenous malformations (AVMs) are complex vascular lesions most commonly found in the brain and infrequently found in the head and neck. AVMs are characterized by a tangle of blood vessels called a nidus, which shunts blood from an artery directly to a draining vein. Various treatments are available, including surgical resection and endovascular embolization. Here, we report the case of a 32-year-old male patient who complained of painful pulsating left neck swelling with dysphagia for 1 year, which turned out to be an AVM alongside the left thyroid gland. The AVM was treated by embolization using Onyx in 2 sessions. The patient has been free of symptoms since the treatment.

Abstract Background Clinically, arteriovenous malformations in the buttocks (bAVMs) are extremely rare. Our study aimed to evaluate the efficacy and safety of ethanol embolotherapy in managing bAVMs. Results A total of 32 patients with bAVMs (14 females and 18 males) from 2012 to 2021 were included in this study. All patients underwent complete clinical and imaging examinations. Further, the AVMs lesions were analyzed according to Schöbinger staging and Yakes classification. Each patient had undergone a multistage ethanol embolization. The amelioration of clinical symptoms and devascularization on angiography were evaluated at regular follow-ups. In the present cohort, the 11–20 age group had the most patients (15/32; 46.88%). A total of 124 embolization procedures were performed (average 3.88 procedures per patient), and the average dose of absolute ethanol was 18.96 mL per procedure. Thirteen patients with dominant draining veins underwent additional coil deployment before ethanol embolization (13/32; 40.63%). During follow-ups, clinical improvement was found in 23 of 27 who presented with a pulsating mass (85.19%), 17 of 20 with abnormal local skin temperature (85%), 5 of 6 with bleeding (83.33%), and 5 of 5 patients treated for pain (100%). More than 75% angiographic devascularization was achieved in 18 patients (18/32; 56.25%). Finally, 12 out of 13 patients (92.31%) reduced from Schöbinger Stage III to a lower grade, and ten patients exhibited a complete response (10/32; 31.23%). There was a single serious complication of local necrosis, while neither paranesthesia nor infection was observed postoperatively. Conclusions Ethanol embolization assisted with coils can treat bAVMs effectively and safely. The Yakes classification contributed to the optimal ethanol embolotherapy of bAVMs.

Abstract Background Osler-Weber-Rendu syndrome (OWRS) is an autosomal dominant disease with recurrent epistaxis, mucocutaneous telangiectasias, and arteriovenous malformations. Its clinical presentation ranges from simple skin lesions to life-threatening complications. When the diagnosis of the disease is delayed, it can be mortal and have high morbidity. This case is presented because OWRS is rare, and although she has all the features of the disease, she was diagnosed in the geriatric age group. Case presentation A 72-year-old female patient who applied to the emergency department with the complaint of melena was diagnosed with upper gastrointestinal system bleeding. Gastroscopy revealed angiodysplasia in the bulb. Colonoscopy was normal. She had telangiectasias on her face, maxilla, nose, tongue and lips. She also had recurrent epistaxis and a family history. Thorax CT showed aneurysmatic vascular malformations in the lung. Abdominal MRI revealed vascular malformations in the liver. Brain MRI was normal. The patient was diagnosed with OWRS according to the Curaçao diagnostic criteria because of telangiectasia in the mouth, nose, and face, angiodysplasia in the gastric bulb, aneurysmatic vascular dilatation in the lung, vascular pathologies in the liver, and a history of epistaxis and telangiectasia in the patient’s family members. Conclusion This patient is presented because OWRS is rare, and although she has all the features of the disease, she was diagnosed in the geriatric age group. Clinicians should be aware of this rare disease. Especially in the elderly, when angiodysplasia causing gastrointestinal bleeding is detected, it should be considered in the differential diagnosis that this may be an OWSR case.

Background: Cerebral arteriovenous malformations (AVMs) are complex, heterogeneous, uncommon lesions that carry a high risk of intracranial hemorrhage with subsequent disability. Aim: To evaluate the outcome of patients with cerebral AVMs treated in our center, King Faisal Specialized Hospital and Research Center (KFSH&RC) Saudi Arabia with SRS using the CyberKnife. Methods: Medical records of patients treated in the above-mentioned way in the period between 2009-2021 were retrospectively evaluated. Results: A total of 51 patients were included in this study. The median age at diagnosis was 31 (3-77) years. Neurological alteration and intracranial hemorrhage were the most common presentations in 24 (47.1%) patients. The mean maximum AVM nidus diameter and volume were 2.9 cm and 5.9 cc respectively. All the patients received SRS using CyberKnife with a median marginal dose of 20 (14-21) Gy over a single fraction. Volume staged treatment was applied in 4 (7.8%) patients. After a median follow-up of 37 (2-170) months, all patients were alive with successful obliteration of the AVM nidus occurring in 31 (60.8%) patients after a median latency period of 27 (4-68.9) months in those who achieved complete obliteration. No patients developed post-SRS hemorrhage and 11 (21.6%) patients developed post-SRS radiological radiation-induced changes of which only 3 (27.3%) patients were symptomatic (in the form of uncontrolled seizures). only SRS dose > 19 Gy was significantly correlated with the obliteration rate, as 79.3% of patients who received SRS dose > 19 Gy achieved obliteration vs 36.4 % only in those who received dose <19 Gy, p value 0.002. Conclusion: SRS treatment using CyberKnife is effective management for patients with cerebral AVMs without an increase in the incidence of post-SRS hemorrhage, stroke, or death. [ABSTRACT FROM AUTHOR]

Background: Clinically, arteriovenous malformations in the buttocks (bAVMs) are extremely rare. Our study aimed to evaluate the efficacy and safety of ethanol embolotherapy in managing bAVMs. Results: A total of 32 patients with bAVMs (14 females and 18 males) from 2012 to 2021 were included in this study. All patients underwent complete clinical and imaging examinations. Further, the AVMs lesions were analyzed according to Schöbinger staging and Yakes classification. Each patient had undergone a multistage ethanol embolization. The amelioration of clinical symptoms and devascularization on angiography were evaluated at regular follow-ups. In the present cohort, the 11–20 age group had the most patients (15/32; 46.88%). A total of 124 embolization procedures were performed (average 3.88 procedures per patient), and the average dose of absolute ethanol was 18.96 mL per procedure. Thirteen patients with dominant draining veins underwent additional coil deployment before ethanol embolization (13/32; 40.63%). During follow-ups, clinical improvement was found in 23 of 27 who presented with a pulsating mass (85.19%), 17 of 20 with abnormal local skin temperature (85%), 5 of 6 with bleeding (83.33%), and 5 of 5 patients treated for pain (100%). More than 75% angiographic devascularization was achieved in 18 patients (18/32; 56.25%). Finally, 12 out of 13 patients (92.31%) reduced from Schöbinger Stage III to a lower grade, and ten patients exhibited a complete response (10/32; 31.23%). There was a single serious complication of local necrosis, while neither paranesthesia nor infection was observed postoperatively. Conclusions: Ethanol embolization assisted with coils can treat bAVMs effectively and safely. The Yakes classification contributed to the optimal ethanol embolotherapy of bAVMs. [ABSTRACT FROM AUTHOR]

Intracranial vascular malformations typically encountered by pediatric neurosurgeons include arteriovenous malformations, vein of Galen malformations and cavernous malformations. While these remain amongst some of the most challenging lesions faced by patients and caregivers, the past decade has produced marked advances in the understanding of the pathophysiology of these conditions, with concomitant innovations in treatment. This article will highlight present and future perspectives relevant to these diseases, with a focus on an emerging approach utilizing disease-specific mutations to develop a novel taxonomy for these conditions. [ABSTRACT FROM AUTHOR]

Pediatric intracranial arteriovenous malformations (AVMs) are challenging lesions managed by pediatric neurosurgeons. The high risk of hemorrhage and neurologic injury is compounded by the unique anatomy of each malformation that requires individualizing treatment options. This article reviews the current status of pediatric AVM epidemiology, pathophysiology and clinical care, with a specific focus on the rationale and methodology of surgical resection. [ABSTRACT FROM AUTHOR]

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

Vascular anomalies are vascular lesions that are present from childhood. They are classified into tumours or malformations based on clinical and histological features. Benign infantile haemangiomas are the most common vascular tumour and have a predictable self-limiting course. Rarer vascular tumours exist, and some may cause platelet consumption. Management is usually conservative, with active treatment reserved for functional or cosmetic complications (ulceration, or obstruction and distortion of vital structures). Oral propranolol is useful for troublesome lesions. Vascular malformations are structural anomalies of vascular morphogenesis present at birth without cellular proliferation that, in general, grow with the patient. They are sub-classified by vessel type as 'low flow' (capillary, lymphatic and venous) and 'high flow' (arteriovenous) or lesions with a combination of vessel type. They become problematic under certain circumstances, usually puberty and also pregnancy. The most troublesome are extensive lesions, especially venous and arteriovenous. Their effects may be cosmetic, those of a space-occupying lesion, infection, bleeding, pain or coagulopathy. Venous lesions cause consumptive coagulopathy, sometimes with life-threatening risks. Treatment options include medication and symptom control with antibiotics, analgesia, control of menses, compression garments and intervention with laser (capillary type), sclerotherapy, embolization and/or surgical excision. Patients with complex lesions are best managed by a multidisciplinary team and all surgical sub-specialties may be involved. [ABSTRACT FROM AUTHOR]

Congenital vascular malformations (CVMs) are the result of an aberrant development during embryogenesis. Although these lesions are present at birth, they are not always visible yet. Once symptomatic, patients suffer from pain, bleeding, ulcers, infections or lymphatic leakage, depending on the subtype of vessels involved. Treatment includes conservative management, surgery, sclerotherapy, embolization and pharmacological therapy. The clinical presentation varies widely and treatment can be challenging due to the rarity of the disease and potential difficulties of treatment. This review gives an overview of the historical developments in diagnosis and classification and exposes the key elements of innovations in the past decades on the identification of genetic mutations and personalized treatment. These advances in the field and a multidisciplinary approach are highly valuable in the optimization of clinical care aimed at both curing or stabilizing the CVM and pursuing physical and psychosocial wellbeing. [ABSTRACT FROM AUTHOR]

Background: Osler-Weber-Rendu syndrome (OWRS) is an autosomal dominant disease with recurrent epistaxis, mucocutaneous telangiectasias, and arteriovenous malformations. Its clinical presentation ranges from simple skin lesions to life-threatening complications. When the diagnosis of the disease is delayed, it can be mortal and have high morbidity. This case is presented because OWRS is rare, and although she has all the features of the disease, she was diagnosed in the geriatric age group. Case presentation: A 72-year-old female patient who applied to the emergency department with the complaint of melena was diagnosed with upper gastrointestinal system bleeding. Gastroscopy revealed angiodysplasia in the bulb. Colonoscopy was normal. She had telangiectasias on her face, maxilla, nose, tongue and lips. She also had recurrent epistaxis and a family history. Thorax CT showed aneurysmatic vascular malformations in the lung. Abdominal MRI revealed vascular malformations in the liver. Brain MRI was normal. The patient was diagnosed with OWRS according to the Curaçao diagnostic criteria because of telangiectasia in the mouth, nose, and face, angiodysplasia in the gastric bulb, aneurysmatic vascular dilatation in the lung, vascular pathologies in the liver, and a history of epistaxis and telangiectasia in the patient's family members. Conclusion: This patient is presented because OWRS is rare, and although she has all the features of the disease, she was diagnosed in the geriatric age group. Clinicians should be aware of this rare disease. Especially in the elderly, when angiodysplasia causing gastrointestinal bleeding is detected, it should be considered in the differential diagnosis that this may be an OWSR case. [ABSTRACT FROM AUTHOR]

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

Objective: To analyze the outcomes of hypofractionated stereotactic radiotherapy (HFSRT) for Spetzler Martin grades 4 and 5 arteriovenous malformations (AVMs) in a pediatric population. Methods: Fourteen patients with Spetzler Martin (SM) grades IV and V large AVMs who underwent HFSRT between January 2013 and July 2019 were retrospectively reviewed. All patients received HFSRT at a dose of 30–36 Gy in 5 to 6 fractions. They were followed up annually with clinical and imaging assessments to evaluate obliteration rates. Results: The median age at presentation was 15 years (range 8–21 years). Ten (71%) were SM grade 4 AVMs and the rest were SM grade 5 AVMs. The majority presented with headache (8 [57%]), and 3 (21%) presented with bleeding. The median nidus volume was 39.4 cc (IQR, 31.4–52.4). Two (14%) patients had infratentorial AVMs. All of them had deep venous drainage. The median clinical follow-up duration was 75 months (range 31–107 months). There was complete obliteration of the nidus in 3 (21%) patients with a median time to obliteration of 39 months. HFSRT resulted in a reduction of the AVM volume to 12 cc or less in nearly 70% of patients. None of the patients experienced re-bleeding. 79% reported an improvement in their symptoms. Conclusion: HFSRT is a highly effective treatment for high-grade AVMs in children, which can result in either complete elimination or significant reduction of the nidus volume or make it suitable for additional treatment, such as single-session stereotactic radiosurgery (SRS). [ABSTRACT FROM AUTHOR]