Most Promising Approaches to Improve Brain AVM Management: ARISE I Consensus Recommendations.

Brain arteriovenous malformations (bAVMs) are complex, and rare arteriovenous shunts that present with a wide range of signs and symptoms, with intracerebral hemorrhage being the most severe. Despite prior societal position statements, there is no consensus on the management of these lesions. ARISE (Aneurysm/bAVM/cSDH Roundtable Discussion With Industry and Stroke Experts) was convened to discuss evidence-based approaches and enhance our understanding of these complex lesions. ARISE identified the need to develop scales to predict the risk of rupture of bAVMs, and the use of common data elements to perform prospective registries and clinical studies. Additionally, the group underscored the need for comprehensive patient management with specialized centers with expertise in cranial and spinal microsurgery, neurological endovascular surgery, and stereotactic radiosurgery. The collection of prospective multicenter data and gross specimens was deemed essential for improving bAVM characterization, genetic evaluation, and phenotyping. Finally, bAVMs should be managed within a multidisciplinary framework, with clinical studies and research conducted collaboratively across multiple centers, harnessing the collective expertise and centralization of resources.

Combined Treatment of High-Flow Scalp Arteriovenous Malformations.

INTRODUCTION: Appropriate treatment of scalp arteriovenous malformations (SAVMs) remains largely unclear given the rarity of reported cases. This single-institution case series presents consecutive patients with extracranial SAVMs and long-term follow up.The primary aim of this study was to review treatment decisions, evaluate clinical outcomes, and compare our experience to available literature in order to better understand SAVMs and improve future outcomes. MATERIALS AND METHODS: A retrospective review of consecutive patients with extracranial SAVMs between January 2015 and December 2019 was performed. Treatment factors of interest included embolization method, embolic agents, and decision to proceed with surgical resection. Relevant clinical outcomes included recurrence rates, cure rates, and complications. RESULTS: Seven patients were included in the present series. Satisfactory outcomes were ultimately achieved for all 7 patients using embolization with or without combined surgical resection. Embolizations performed in combination with resection were curative in 4 of 4 cases (100%). Embolizations performed without resection were curative in 0 of 4 cases (0%), satisfactory in 2 of 4 cases (50%), and unsatisfactory in 2 of 4 cases (50%). DISCUSSION: All SAVM patients in this series were treated satisfactorily using embolization with or without operative resection. This study strongly suggests that embolization combined with surgical resection during the same admission yields the best treatment outcomes for SAVMs, specifically demonstrating lower rates of recurrence and embolization-related complications. Decisions on whether or not to proceed with resection should be made by the interventional radiologist, the plastic surgeon, and the patient together.

High Output Cardiovascular Physiology and Outcomes in Fetal Diagnosis of Vein of Galen Malformation.

Vein of Galen aneurysmal malformation (VGAM) is a rare anomaly associated with poor outcomes from high output cardiac failure and neurologic complications. Studies addressing fetal cardiovascular status and outcomes in this population are limited. A single-center retrospective review was conducted on patients with a prenatal diagnosis of VGAM who underwent a fetal echocardiogram between January 2015 and July 2019. Fetal echocardiographic data, brain magnetic resonance imaging (MRI) findings and outcomes were collected. Nine fetuses [median gestational age at echocardiogram 34 (1.1) weeks] were included. All patients had superior vena cava dilation and reversal of diastolic flow in the transverse aortic arch. Median cardiothoracic (CT) ratio was 0.39 (0.09). Right ventricular (RV) and left ventricular (LV) dysfunction was present in 66% and 11% fetuses, respectively. Four out of five patients that underwent postnatal endovascular neurosurgical interventions at our center were alive at follow-up (mean 2.7 years). Of the non-survivors (n = 5), 3 received comfort care because of severe brain damage and died in the neonatal period. Non-survivors more commonly had > mild tricuspid regurgitation (TR) (40% vs. 25%) and > mild RV dilation (60% vs. 25%). Combined cardiac index (CCI) was higher in non-survivors when compared to survivors (672.7 vs. 530.2 ml/kg/min, p = 0.016). Fetuses with significant parenchymal damage on brain MRI tended to have a higher CCI than those without (979.8 vs. 605.0 ml/kg/min, p = 0.047). RV dysfunction, TR and elevated CCI are more commonly seen in non-survivors with VGAM. A higher CCI is seen in those deemed untreatable due to significant parenchymal volume loss. Future multicenter studies are needed to assess for prenatal prediction of outcomes in this high-risk population.

Dilated Superior Ophthalmic Vein: Clinical and Radiographic Features of 113 Cases.

PURPOSE: Dilated superior ophthalmic vein (SOV) is an uncommon radiographic finding. The authors review the presentation, etiology, radiography, and visual implications of 113 patients with dilated SOV. METHODS: An observational case series and multicenter retrospective chart review were conducted. There were 113 patients with a dilated SOV. Outcome measures included patient demographics, clinical features, radiographic findings, diagnosis, and treatment, and treatment outcomes were assessed. RESULTS: Cases included 75 women (66%) and 38 men (34%) with a mean age of 49 ± 24 years (range, 0.4-90 years). Diagnoses fell under 6 categories: vascular malformation (n = 92, 81%), venous thrombosis (n = 11, 10%), inflammatory (n = 6, 5%), traumatic hemorrhage (n = 2, 2%), lymphoproliferative (n = 1, 1%), and infectious (n = 1, 1%). Imaging modalities utilized included MRI (n = 98, 87%), digital subtraction angiography (n = 77, 68%), CT (n = 29, 26%), and ultrasonography (n = 4, 4%). Disease status at last follow up included no evidence of disease (n = 57, 50%), alive with persistent disease (n = 53, 47%), and expired from disease (n = 3, 3%). Treatment and management was tailored to the underlying disease process with a mean follow up of 18 months (range, 1 day to 180 months). Visual impairment observed at presentation and last follow up across all cases was 26% and 22%, respectively. CONCLUSION: Dilated SOV is a rare radiographic finding resulting from a wide spectrum of etiologies with clinical implications ranging from benign to sight- and life-threatening. Dilated SOV is most often found with dural-cavernous fistula or carotid-cavernous fistula, orbital or facial arteriovenous malformation, and venous thrombosis. Recognition of this finding and management of the underlying condition is critical.

Oral Surgical Procedures Performed Safely in Patients With Head and Neck Arteriovenous Malformations: A Retrospective Case Series of 12 Patients.

PURPOSE: This case series describes patients with head and neck arteriovenous malformations who underwent oral and maxillofacial surgical procedures combined with interventional radiology techniques to minimize blood loss. MATERIALS AND METHODS: Twelve patients underwent femoral cerebral angiography to visualize the extent of vascular malformation. Before the surgical procedures, surgical sites were devascularized by direct injection of hemostatic or embolic agents. Direct puncture sclerotherapy at the base of surgical sites was performed using Surgiflo or n-butylcyanoacrylate glue. Surgical procedures were carried out in routine fashion. A hemostatic packing of FloSeal, Gelfoam, and Avitene was adapted to the surgical sites. RESULTS: Direct puncture sclerotherapy with Surgiflo or n-butylcyanoacrylate glue resulted in minimal blood loss intraoperatively. Local application of the FloSeal, Gelfoam, and Avitene packing sustained hemostasis and produced excellent healing postoperatively. CONCLUSION: Patients with arteriovenous malformations can safely undergo routine oral and maxillofacial surgical procedures with minimal blood loss when appropriate endovascular techniques and local hemostatic measures are used by the interventional radiologist and oral and maxillofacial surgeon.

Safety and efficacy using a detachable tip microcatheter in the embolization of pediatric arteriovenous malformations.

PURPOSE: The treatment of deep-seeded pediatric brain arteriovenous malformations (AVMs) remains a challenging task. We describe our experience using a new detachable tip microcatheter in the embolization of brain arteriovenous malformations, pial arteriovenous fistulas, and vein of Galen malformations. We describe the safety and efficacy using a new detachable tip microcatheter in the treatment of pediatric deep brain arteriovenous malformations, pial malformations, and vein of Galen malformations. METHODS: During a period of 9 months from March 2013 through January 2014, 11 pediatric patients in 14 procedures with 27 total injections were selected for treatment with a detachable tip under Food and Drug Administration (FDA) compassionate use exemption and were admitted to our department for treatment of their brain AVM using a liquid embolic agent and a detachable tip microcatheter. The ages of the patients ranged from 3 months to 18 years old. RESULTS: Of the 27 total injections done, the tip detached in seven cases. For the 16 n-BCA injections, the tip detached six times (37.5 %), and for the 11 Onyx injections, the tip detached one time (9 %). There were no cases of premature microcatheter detachment during normal vessel navigation. CONCLUSIONS: The introduction of these detachable tip microcatheters allows for a safe and relaxed injection that permits a true circumferential occlusion, and may further permit filling a larger amount of angioarchitecture without the risk of distal migration, or vessel damage during the usual rapid removal of non detachable micocatheters.

Vein of Galen Malformations.

Significant efforts have been made over the last few decades to improve the diagnosis and management of patients with vein of Galen malformations (VOGMs). The mainstays of treatment remain focused on primary endovascular management by staged transarterial embolizations with adjunctive use of transvenous embolization, medical therapy, and neurosurgical intervention for symptom control in select patients. Innovation in endovascular technology and techniques as well as promising new genomic research elucidating potential therapeutic targets hold significant promise for the future of VOGM treatment.

The effect of carotid endarterectomy on cerebral blood flow and cognitive function.

BACKGROUND: The effect of carotid endarterectomy on cognitive function is not fully understood. This study aims to characterize changes in cerebral blood flow after carotid endarterectomy and to determine if patients with improvement in cerebral blood flow have improved cognitive function after endarterectomy. METHODS: Cerebral blood flow was measured preoperatively and 1 month postoperatively using phase contrast magnetic resonance angiography. Preoperative flow impairment was defined as ipsilateral flow at least 20% less than contralateral flow. Improvement in flow was defined as an absolute increase of at least 0.10 in flow ratio from pre- to postoperative assessments. Patients underwent cognitive testing preoperatively and at 1, 6, and 12 months postoperatively. RESULTS: Twenty-four patients with unilateral carotid stenosis were enrolled from 3 sites. Preoperative internal carotid artery (ICA) and middle cerebral artery (MCA) flow impairment was observed in 50% and 22% of patients, respectively. Patients with preoperative flow impairment had an average of 0.25 and 0.16 absolute improvement in flow ratio in the ICA and MCA vessels, respectively; this was statistically significant for patients with baseline ICA flow impairment (P < .01). One hundred percent of patients with improvement in MCA flow had a significant improvement in attention compared to 56% of patients without MCA flow improvement (P = .06). Clinically significant improvements in all 4 cognitive domains were observed at 1 year (P < .01). CONCLUSIONS: Patients with baseline impairment of MCA blood flow were more likely to experience improvement in flow after revascularization. Improvement in MCA blood flow was associated with greater cognitive improvement in attention and executive functioning.

Onyx embolization using dual-lumen balloon catheter: initial experience and technical note.

INTRODUCTION: Onyx as an embolization agent for the management of vascular malformation is well established. We report our initial experience with dimethyl-sulphoxide (DMSO) compatible double lumen balloon catheters used for Onyx embolization. METHODS AND TECHNIQUE: Between December 2011 and March 2013, we treated 22 patients aged between 1.5 to 70years with two types of DMSO compatible dual-lumen balloon catheters (Scepter C and Ascent) to treat dural arteriovenous fistulas, brain arteriovenous malformation (AVM) with dural feeders, mandibular, facial, lingual, vertebral and paravertebral AVMs. The catheter has good navigability, compliant balloon on inflation formed a "plug" that has more resistance than Onyx plug enhancing better penetration. During injection, the balloon remained stable without spontaneous deflation or rupture and withstood the pressure build-up well. The retrieval of the catheter in most cases took less than a minute (19/28) while in five, it was less than five minutes and in the remaining four, it was longer that includes a trapped catheter on prolonged attempted retrieval resulted in an epidural hematoma, requiring emergent surgical evacuation. The fluoroscopy time is reduced, as we do not form a proximal onyx plug, the injection time is shorter along with easy and instantaneous removal of the catheter after balloon deflation in most cases. CONCLUSION: Dual-lumen balloon catheter Onyx embolization is a safe and effective technique. Currently, an important tool to circumvent some of the shortcomings associated with Onyx embolization. The catheter has good navigability, the balloon has stability, tolerance, enhances penetrability. It is easy to retrieve the microcatheter. With the experience gained, and with more compliant balloon catheters available, this technique can be applied to cerebral vessels in near future.

New concept in neurovascular navigation: technical description and preclinical experience with the Bendit 17 and Bendit 21 microcatheters in a rabbit aneurysm model.

BACKGROUND: Endovascular treatment of intracranial vascular diseases, such as aneurysms, is often challenged by unfavorable vascular anatomy. The Bendit Steerable Microcatheter (Bendit Technologies, Tel Aviv, Israel) has bending and torqueing capabilities designed to improve navigation and stability during device delivery, with or without a guidewire. We describe our preclinical experience with the Bendit 17 and Bendit 21 microcatheters in a rabbit aneurysm model. METHODS: Bifurcation and side wall aneurysms were created surgically in six New Zealand rabbits. We attempted to navigate Bendit devices through the vasculature and enter the aneurysms without a guidewire. Various positions within the aneurysm were selectively explored. Angiographic imaging was used to visualize catheterization, navigation, vascular manipulations, and placement of coils, stents, and intrasaccular devices. RESULTS: We successfully navigated the Bendit microcatheters to all aneurysms without a guidewire. We successfully recanalized a nearly occluded carotid artery and navigated the Bendit through a braided stent. In contrast, we were unable to navigate a comparator device with a guidewire as effectively as the Bendit. Coils were introduced at different locations within the aneurysm and could be pushed, pulled, and repositioned with the Bendit tip. Finally, we used the Bendit to deliver intrasaccular devices designed for terminal aneurysms to treat side wall aneurysms. CONCLUSIONS: Bendit's bending and torqueing abilities, combined with its stability in the bent position, enable quick navigation and optimal deployment of devices. Clinical studies are necessary to determine whether these navigation advantages lead to more efficient treatment of intracranial and peripheral aneurysms.

Infantile dural sinus malformation: curative embolization in two stages with the Scepter mini balloon microcatheter.

Endovascular embolization is the mainstay for treatment of infantile dural sinus malformations.1 2 Distal access and flow control are limiting factors in controlled embolization.3-6 The Scepter mini catheter (Microvention, Aliso Viejo, California, USA) is a low-profile, dual-lumen balloon microcatheter designed to provide navigability in small-caliber, tortuous intracranial vessels. In this technical video, we demonstrate the staged embolization of a dural sinus malformation with multiple arteriovenous fistulae using the Scepter mini catheter (video 1). In the newborn patient, embolizations were performed through the parietal branches of the left and right middle meningeal arteries. The catheter easily navigated into the small feeding arteries. No neurological complications occurred due to the procedures. Post-embolization injections demonstrated significant flow reduction into the malformation. Three-month follow-up angiography illustrated resolution of the previously dilated left transverse sinus. Complete obliteration of the dural sinus malformation was achieved in the newborn patient. neurintsurg;15/1/97/V1F1V1Video 1Curative embolization in two stages with the Scepter mini balloon microcatheter. ΑP, anteroposterior; CCA, common carotid artery.

Evolution of transvenous embolization in vein of Galen malformation: case series and review of the literature.

BACKGROUND: Treatment of vein of Galen malformations (VOGMs) has improved greatly since the inception of endovascular treatment. Transvenous embolization (TVE) is an attractive option to achieve complete obliteration. OBJECTIVE: To review the literature on TVE of VOGM and then analyze our practice's unique experience and evolving treatment strategies over 30 years. METHODS: A retrospective review of our clinical database for patients with the diagnosis of VOGM treated between January 2004 and August 2021 was performed. A literature review of 49 relevant articles was also carried out. RESULTS: TVE in VOGM has evolved with initial introduction as a transtorcular (TT) approach, which then lost favor to transarterial embolization (TAE). TAE has been considered the more favorable approach in most high-volume centers. In more recent times, the transvenous embolization (TVE) approach has been revisited as a last treatment to achieve a cure after a series of TAE treatments. We presently favor beginning treatment with staged TAE to reduce flow to the lesion and, importantly, shrink the draining vein. This then allows for the performance of TVE with the Chapot pressure cooker technique (CPCT) with coils and liquid embolic embolization. CONCLUSIONS: TT TVE itself carries a high degree of risk and is most highly associated with long-term morbidities and mortality. Traditional transfemoral/transjugular TVE approaches are safe and effective in simple fistulas with a small venous pouch; however, we believe that the CPCT is the safest technique as a last-stage treatment for its security in avoiding reflux and obtaining occlusion of the small perforators.

Clinical experience with the Bendit steerable microcatheter: a new paradigm for endovascular treatment.

BACKGROUND: Vessel tortuosity poses a challenge during endovascular treatment of neurovascular lesions. Bendit Technologies (Petah Tikva, Israel) has developed flexible, steerable microcatheters designed with unique bending and torquing capabilities. OBJECTIVE: To describe our first-in-human trial of Bendit21. METHODS: Bendit21 was used in our exploratory, prospective, multicenter, open-label, single-arm clinical study, and in two compassionate use cases. Procedures were conducted at four centers in Austria, Germany, Israel, and the United States between May 2021 and March 2022, in patients with neurovascular conditions. The primary endpoints were device-related safety events, successful navigation through the neurovasculature, and, when intended, successful delivery of contrast or therapy. RESULTS: Two patients with giant aneurysms were treated successfully under compassionate use approval. The clinical study included 25 patients (mean age: 63.4±11.8 years; 32.0% female). Fourteen patients (56.0%) had aneurysms, two had arteriovenous malformations/fistulas (8.0%), one had a stroke (4.0%), four (16.0%) had intracranial stenosis, and four (16.0%) had other conditions. Bendit21 was used without a guidewire in 12/25 (48.0%) procedures. Bendit21 was successfully navigated through the vasculature without delays or spasms in all cases (100%). Contrast was delivered as intended in 7/7 (100%) cases. Therapeutic devices were delivered successfully with Bendit as intended in 14/18 (77.8%) cases; four deficiencies occurred in three patients with aneurysms, in whom delivery of coils, an intrasaccular device, or a flow diverter was attempted. There were no device-related safety events or mortalities. CONCLUSIONS: Our initial clinical experience with the Bendit21 microcatheter demonstrates its usefulness in achieving technical success in patients with challenging neurovascular conditions.

Percutaneous sclerotherapy of microcystic lymphatic malformations: the use of an innovative gravity-dependent technique.

BACKGROUND: In the last few decades there has been development of innovative therapies for the treatment of craniofacial lymphatic malformations. Percutaneous sclerotherapy has demonstrated efficacy in the management of macrocystic lymphatic lesions, but it is less suitable for microcystic lesions given their size. The gravity-dependent technique is a novel augmentation of standard percutaneous sclerotherapy: the technique enables a sclerosing agent to permeate the small microchannels seen in microcystic lesions that would otherwise be difficult to treat. METHODS: Between 2005 and 2021, 124 patients with microcystic or mixed lymphatic malformations were treated using a novel gravity-dependent sclerotherapy technique. Bleomycin at a maximum dose of 15 IU per session was used as the main sclerosing agent. Fluoroscopy and ultrasound were used to ensure proper positioning of the catheter prior to injecting the sclerosing agent. The response to treatment was assessed clinically and with cross-sectional imaging. RESULTS: Nearly all cases showed significant improvement after the gravity-dependent technique. There have been no permanent complications from sclerotherapy treatment. There was a mild transient adverse effect from bleomycin in one case of erythema and tenderness that lasted several weeks then ameliorated. CONCLUSIONS: The gravity-dependent sclerotherapy technique is a suitable treatment option for microcystic lymphatic malformations.

Transvenous balloon-assisted approach to anterior fossa dural arteriovenous fistula using retrograde pressure cooker technique.

Endovascular embolization is the first-line therapy for dural arteriovenous fistulas (dAVFs). Transarterial embolization (TAE) may be limited by poor anatomical access. Transvenous embolization avoids this, but carries a risk of hemorrhage, venous redirection, and neurologic deterioration. Dual-lumen balloon microcatheters like the Scepter Mini (Microvention, Aliso Viejo, CA, USA) provide flow arrest and prevent reflux during TAE with liquid embolic agents (LEAs), but use in the distensible veins may be challenging. In this video, we use a Scepter Mini in a transvenous approach to a Cognard type IV anterior ethmoidal dAVF as a safe alternative to surgery, transvenous pressure cooker, and trans-ophthalmic TAE (video 1). The Scepter Mini was navigated transvenously to the anterior superior sagittal sinus. LEA was injected with excellent penetration to the venous pouch and further penetration into the network of tortuous feeders. No neurologic complications were experienced, and follow-up angiogram 9 months later demonstrated cure of the dAVF. Video 2 describes procedural considerations in transvenous approaches, steps of the procedure, and includes references1-10 which are relevant to this topic.neurintsurg;jnis-2023-020530v1/V1F1V1Video 1 neurintsurg;jnis-2023-020530v1/V2F2V2Video 2 .

Use of a mini balloon microcatheter to facilitate penetration of fine vascular networks and curative embolization in vein of Galen malformations.

Background Patients with vein of Galen malformations (VOGMs) can develop fine angiogenic networks with fistulous connections to the precursor of the vein of Galen. In these cases, transarterial embolization (TAE) with liquid embolic agents (LEAs) is challenging due to reflux in the pedicle leading to the network, causing poor penetration. Transvenous approaches carry a risk of hemorrhage from pathologic vasculature. Dual-lumen balloon microcatheters like the Scepter Mini (Microvention, Aliso Viejo, CA) improve distal pedicle access, preventing reflux.Objective Here, we report on the use of the Scepter Mini for TAE of angiogenic VOGM.Methods A single-institution retrospective chart review identified all VOGMs treated with Scepter Mini microcatheters. Clinical data, angioarchitecture, and technical parameters were reviewed.Results 17 Scepter Mini catheters were used in 12 embolization procedures of 7 patients with VOGM at a median age of 2.1 years. Patients presented with hydrocephalus (100%) and gross motor and speech delays (57.1%). Networks developed extra-axially into the subependymal zone fed by posterior choroidal, posterior cerebral, and thalamoperforator arteries. Posterior choroidal branches (n=7/17, 41.2%) were most frequently catheterized to achieve distal access to the network. Embolization with Onyx-18 and significant network penetration occurred in 17/17 uses. Near tip entrapment with LEA cast displacement occurred in 1/17 uses. Another patient experienced postprocedural intraventricular hemorrhage requiring a third ventriculostomy without permanent neurologic deficit.Conclusion The Scepter Mini provided excellent distal access with penetration to the fistula and extra-axial network reduction with few complications. The Scepter Mini provides a means for successful treatment of technically challenging angiogenic VOGM.

Genetic dysregulation of an endothelial Ras signaling network in vein of Galen malformations.

To elucidate the pathogenesis of vein of Galen malformations (VOGMs), the most common and severe congenital brain arteriovenous malformation, we performed an integrated analysis of 310 VOGM proband-family exomes and 336,326 human cerebrovasculature single-cell transcriptomes. We found the Ras suppressor p120 RasGAP ( RASA1 ) harbored a genome-wide significant burden of loss-of-function de novo variants (p=4.79×10 -7 ). Rare, damaging transmitted variants were enriched in Ephrin receptor-B4 ( EPHB4 ) (p=1.22×10 -5 ), which cooperates with p120 RasGAP to limit Ras activation. Other probands had pathogenic variants in ACVRL1 , NOTCH1 , ITGB1 , and PTPN11 . ACVRL1 variants were also identified in a multi-generational VOGM pedigree. Integrative genomics defined developing endothelial cells as a key spatio-temporal locus of VOGM pathophysiology. Mice expressing a VOGM-specific EPHB4 kinase-domain missense variant exhibited constitutive endothelial Ras/ERK/MAPK activation and impaired hierarchical development of angiogenesis-regulated arterial-capillary-venous networks, but only when carrying a "second-hit" allele. These results illuminate human arterio-venous development and VOGM pathobiology and have clinical implications.

The persistent primitive marginal sinus-observations in children with Vein of Galen malformation.

INTRODUCTION: Knowledge of venous anatomy and drainage in children with neurovascular diseases is crucial. The primitive marginal sinuses (PMS) are embryonic sinuses forming the later superior sagittal sinus. Their angiographic persistence has not been reported before. The purpose of this study is to demonstrate the angiographic characteristics in children with Vein of Galen malformation and to discuss their embryology and clinical significance. METHODS: We retrospectively reviewed digital subtraction angiography and magnetic resonance venography of 102 Vein of Galen malformations (VGM) from the database of two high-load centres for paediatric neurovascular diseases. RESULTS: We found 10 persistent PMS in 102 children indicating a frequency of 9.8 %. Illustrative cases are shown to demonstrate the vast spectrum of venous variability. The PMS becomes visualised in situations of high-flow arteriovenous shunt in children and can even disappear or remodel after successful shunt reduction or closure. CONCLUSION: Knowledge and recognition of the PMS are important for neurointerventionalists in endovascular treatment planning using the transvenous route and can help neurosurgeons in avoiding severe surgical complications.

Transvenous embolization of vein of galen aneurysmal malformations with coils as a final procedure for cure: A single-institution experience of 18 years.

INTRODUCTION: Staged, transarterial embolization (TAE) is currently considered the gold standard for the treatment of vein of Galen aneurysmal malformation (VGAM); however, as transarterial access becomes restricted, further staged TAE may become ineffective or carry an increased risk of hemorrhagic or ischemic stroke when attempting complete obliteration. OBJECTIVE: To describe the first consecutive, retrospective series of VGAM treated with transvenous embolization (TVE) with coils alone, as the final treatment in staged endovascular therapy, at a single institution between January 2004 and September 2021. RESULTS: A total of 10 patients with a median age of 5.5 (IQR: 9.25) years were treated with coiling TVE. Patients were treated with a median number of 5 (IQR: 2.75) TAEs prior to the final TVE treatment. Complete or near-complete immediate angiographic obliteration was achieved in eight patients. Immediate post-procedural (within 48 h) hemorrhagic complications were noted in two patients (20%), one of whom passed away while the second suffered from hemiparesis. Stereotactic radiosurgery was performed in two patients with incomplete obliteration after TVE. The median follow-up time after TVE was 17 (IQR: 9) months. At long-term follow up (17 months) for the remaining nine patients, all VGAMs were completely obliterated. Long-term clinical deterioration compared to pre-TVE was noticed in one case. CONCLUSION: Transvenous coil embolization is a technically feasible but risky option, as a final-stage treatment for cure of VGAMs with restricted trans-arterial access. Although TVE with coils remains an effective therapeutic modality, we recommend continuing investigation of safer TVE techniques to achieve cure.

De novo brain AVM following radiotherapy for cerebral cavernous malformation in a child: A 15-year clinical course.

Multiple de novo brain arteriovenous malformations (bAVM) have been reported in the literature, raising questions about the contended purely congenital nature of these lesions. We present the 15-year course of a pediatric patient, who initially presented at age 5 with a thalamic cavernous malformation and was treated with radiosurgery, and then subsequently developed a thalamic de novo bAVM immediately adjacent to the initial lesion location, discovered 2 years later. Treatment of the bAVM entailed two transarterial embolizations and one radiosurgery session which ultimately led to complete angiographic resolution. Finally, this patient's course was complicated by intraparenchymal hemorrhage and acute obstructive hydrocephalus, and further imaging revealed two newly formed cavernous malformations, also associated with the initial lesion's location, that have remained stable since their formation. This case likely represents the second-hit model for the formation of vascular malformations, as sparsely supported by the current literature. According to this, genetically aberrant, yet quiescent, brain areas might promote the de novo formation of vascular malformations after brain injury, including radiation.