Cranial Dural Arteriovenous Fistulas Research Articles

Feasibility, safety, and efficacy of endovascular treatment of anterior cranial fossa dural arteriovenous fistulas: a systematic review and meta-analysis with a subanalysis for Onyx.

Dural Arteriovenous Fistulas (dAVFs) of the anterior cranial fossa (ACF) are uncommon but carry a high risk of hemorrhage and pose substantial treatment challenges. Recent advancements in endovascular treatment (EVT), including the introduction of novel liquid embolic agents, have markedly bolstered EVT's role in managing ACF-dAVFs, with notable series published in the last five years. We aimed to assess the feasibility, safety, and efficacy of EVT for ACF-dAVFs. We searched Medline, Scopus, Web of Science, and Cochrane Library databases following PRISMA guidelines. Eligible studies included those with ≥ 5 patients undergoing embolization of ACF-dAVFs, detailing both angiographic and clinical outcomes. We used single proportion analysis with 95% confidence intervals under a random-effects model, I2 to assess heterogeneity, and Baujat and sensitivity analysis to address high heterogeneity. Publication bias was assessed by funnel-plot analysis and Egger's test. Outcomes included complete occlusion following embolization, unsuccessful endovascular embolization attempts, incomplete occlusion following embolization, symptom resolution or clinical improvement following embolization, recurrence; procedure-related complications, morbidity, and mortality. Additionally, a subanalysis for studies exclusively utilizing Onyx™ embolic system was done. Eighteen studies comprising 231 ACF-dAVF were included. Unsuccessful endovascular embolization attempts rate was 2%. Complete occlusion rate was 85%, with 4% of complications. Incomplete occlusion rate was 10%. Successfully embolized patients experienced either symptom resolution or clinical improvement in 94% of cases. Morbidity and mortality rates were 1% and 0%, respectively. Onyx subanalyses showed an overall rate of 0% for unsuccessful attempts, 95% for complete occlusion, and 5% for incomplete occlusion. Symptom resolution or clinical improvement was 98% and recurrence rate was 0%. EVT for ACF-dAVF is highly feasible, effective, and safe, with a low rate of complications, morbidity, and mortality. The subanalyses focusing on Onyx embolizations revealed superior efficacy and safety outcomes compared to the findings of the primary analyses involving all included studies.

Multicenter US clinical experience with the Scepter Mini balloon catheter.

Distal navigability and imprecise delivery of embolic agents are two limitations encountered during liquid embolization of cerebrospinal lesions. The dual-lumen Scepter Mini balloon (SMB) microcatheter was introduced to overcome these conventional microcatheters' limitations with few small single-center reports suggesting favorable results. A series of consecutive patients undergoing SMB-assisted endovascular embolization were extracted from prospectively maintained registries in seven North-American centers (November 2019 to September 2022). Fifty-four patients undergoing 55 embolization procedures utilizing SMB were included (median age 58.5; 48.1% females). Cranial dural arteriovenous fistula embolization was the most common indication (54.5%) followed by cranial arteriovenous malformation (27.3%). Staged/pre-operative embolization was done in 36.4% of cases; and 83.6% of procedures using Onyx-18. Most procedures utilized a transarterial approach (89.1%), and SMB-induced arterial-flow arrest concurrently with transvenous embolization was used in 10.9% of procedures. Femoral access/triaxial setups were utilized in the majority of procedures (65.5% and 60%, respectively). The median vessel diameter where the balloon was inflated of 1.8 mm, with a median of 1.5 cc of injected embolic material per procedure. Technical failures occurred in 5.5% of cases requiring aborting/replacement with other devices without clinical sequelae in any of the patients, with SMB-related procedural complications of 3.6% without clinical sequelae. Radiographic imaging follow-up was available in 76.9% of the patients (median follow-up 3.8 months), with complete occlusion (100%) or >50% occlusion in 92.5% of the cases, and unplanned retreatments in 1.8%. The SMB microcatheter is a useful new adjunctive device for balloon-assisted embolization of cerebrospinal lesions with a high technical success rate, favorable outcomes, and a reasonable safety profile.

Middle cranial fossa non-cavernous sinus dural arteriovenous fistulas: 20years of experience.

Non-cavernous sinus (CS) dural arteriovenous fistulas (DAVFs) involving the sphenoid bone are rare entities that are easily confused with one another due to the complex structure and high variability of the venous system around the middle cranial fossa. We present a large retrospective study on middle cranial fossa non-CS DAVFs and review the literature on DAVF treatment in this location as well as relative anatomy. 15 patients had DAVFs involving the lesser sphenoid wing and 11 patients had DAVFs involving the greater sphenoid wing. Six patients presented with intracranial hemorrhage or subarachnoid hemorrhage (23.1%, 6/26). The most common symptoms were eye symptoms (38.5%, 10/26). Nineteen patients were treated with trans-arterial embolization (TAE) using liquid embolic agents and two patients were treated with transvenous embolization (TVE) using Onyx or in combination with coils. Surgical disconnection of the drainage veins was performed in five patients, with three cases experiencing unsuccessful TAE. Anatomic cure was achieved in 92.3% of the patients (24/26). Twelve patients had DSA and clinical follow-up from 3 to 27months. There was one recurrence (8.3%) of the fistula in the patient two months after the initial complete occlusion. The majority of patients can be cured endovascularly. Laterocavernous sinus DAVFs may not be embolized by transvenous approach via the cavernous sinus because there is often no connection between them in most patients. A small percentage of patients may require surgical ligation to be cured.

Performance of ear canal sound measurements in detecting dural arteriovenous fistulas.

Patients with pulsatile tinnitus (PT) are often referred for digital subtraction angiography (DSA) to exclude cranial dural arteriovenous fistula (DAVF). Because DSA is not without risk, the authors studied the sensitivity and specificity of an automated detection algorithm that analyses external ear canal sound measurements to evaluate the presence of DAVF in PT patients. Between 2015 and 2021, external ear canal sound measurements of 72 PT patients were collected prospectively at our tertiary tinnitus clinic preceding referral of these patients to the neurosurgical department for counseling about DSA. The measurements were analyzed with an algorithm that objectifies a pulsatile sound as a PT coherence index (PTCI) per frequency band. Ultimately, DSA was performed in 49 PT patients. DAVF was revealed in 15 patients (31%). PTCI cutoff values of 0.7 (at 250 Hz) and 0.6 (at 1000 Hz) resulted in sensitivity of 100% (78%-100%) and specificities of 62% (44%-78%) and 68% (49%-83%), respectively, for detecting DAVF on DSA. Analysis of external ear canal sound measurements in PT patients showed 100% sensitivity for detecting DAVF on DSA. This analysis can potentially be used as a screening tool to help clinicians and PT patients to decide on the necessity of DSA. Retrospectively, the use of sound measurement in our cohort would have narrowed the indication for DSA to 23 of 49 cases (47%) without missing a DAVF.

Letter to the Editor. Aggressive cranial dural arteriovenous fistulas: higher obliteration and recurrence rates?

Letter to the Editor. Aggressive cranial dural arteriovenous fistulas: higher obliteration and recurrence rates?

Copolymer liquid embolization of dural arteriovenous fistulas: A 20-year single-center experience.

Dural arteriovenous fistulas (DAVFs) with cortical venous drainage (CVD) carry significant risks of cerebral ischemia and intracranial hemorrhage. Endovascular treatment (EVT) using Onyx, a copolymer-based liquid embolic material, has become the preferred approach. However, the optimal treatment strategy for anterior cranial fossa DAVFs remains debated. This retrospective study analyzed outcomes of EVT for DAVFs in a single center from 2002 to 2023. Patient data including demographics, clinical status, angiographic findings, embolization techniques, and outcomes were recorded. The results of the anterior fossa malformations were analyzed separately afterward. A total of 195 DAVFs were included in the study. The most common presenting symptom was hemorrhage (41%), most fistulas were located in the transverse and sigmoid sinus region (48%), and the majority of DAVFs had direct CVD (78%). Transarterial embolization with Onyx was the preferred treatment strategy in majority of cases (92%). Overall, 94% of patients showed improvement or stability on the modified Rankin Scale. Two patients died due to rebleeding after partial DAVF embolization. Onyx demonstrated higher immediate complete occlusion rate compared to other embolic materials (88% vs. 35%). Overall, 91% of fistulas were closed at the last follow-up. Ten anterior fossa DAVFs were treated, resulting in clinical improvement and complete occlusion in all cases. Based on the results of our study, we believe that a cure of DAVFs, including those in the anterior fossa, can be achieved in more than 90% of cases through transarterial Onyx embolization, given long-term clinical experience.

LIQUID - Treatment of high-grade dural arteriovenous fistulas with Squid liquid embolic agent: a prospective, observational multicenter study

BackgroundEndovascular embolization is a feasible treatment for cranial dural arteriovenous fistulas (DAVFs). New embolic agents aim to improve the success of DAVF embolization.ObjectiveTo assess the safety, efficacy, and short-term outcome...

RETRACTED: Head-Mounted Augmented Reality in the Planning of Cerebrovascular Neurosurgical Procedures: A Single-Center Initial Experience

Augmented reality (AR) technology has played an increasing role in cerebrovascular neurosurgery over the last 2decades. Hence, we aim to evaluate the technical and educational value of head-mounted AR in cerebrovascular procedures. This is a single-center retrospective study of patients who underwent open surgery for cranial and spinal cerebrovascular lesions between April and August 2022. In all cases, the Medivis Surgical AR platform and HoloLens 2 were used for preoperative and intraoperative (preincision) planning. Surgical plan adjustment due to the use of head-mounted AR and subjective educational value of the tool were recorded. A total of 33 patients and 35 cerebrovascular neurosurgical procedures were analyzed. Procedures included 12 intracranial aneurysm clippings, 6 brain and 1 spinal arteriovenous malformation resections, 2 cranial dural arteriovenous fistula obliterations, 3 carotid endarterectomies, two extracranial-intracranial direct bypasses, two encephaloduroangiosynostosis for Moyamoya disease, 1 biopsy of the superficial temporal artery, 2 microvascular decompressions, 2 cavernoma resections, 1 combined intracranial aneurysm clipping and encephaloduroangiosynostosis for Moyamoya disease, and 1 percutaneous feeder catheterization for arteriovenous malformation embolization. Minor changes in the surgical plan were recorded in 16 of 35 procedures (45.7%). Subjective educational value was scored as "very helpful" for cranial, spinal arteriovenous malformations, and carotid endarterectomies; "helpful" for intracranial aneurysm, dural arteriovenous fistulas, direct bypass, encephaloduroangiosynostosis, and superficial temporal artery-biopsy; and "not helpful" for cavernoma resection and microvascular decompression. Head-mounted AR can be used in cerebrovascular neurosurgery as an adjunctive tool that might influence surgical strategy, enable 3-dimensional understanding of complex anatomy, and provide great educational value in selected cases.

Letter: Stereotactic Radiosurgery for Dural Arteriovenous Fistulas: A Systematic Review and Meta-Analysis and International Stereotactic Radiosurgery Society Practice Guidelines.

To the Editor: We read with interest the article by Singh et al1 synthesizing the modern literature around the use of stereotactic radiosurgery (SRS) in the treatment of cranial dural arteriovenous fistulas (DAVFs). Neurointervention has disrupted the established treatment paradigm for many neurosurgical conditions. From intracranial aneurysms and large vessel occlusions to hydrocephalus, neuroendovascular surgery favorably altered the natural history and reduced the treatment-related morbidity of these and other disease processes. This has changed the mindset of clinicians who treat patients with cerebrovascular disease. For instance, a patient with an unruptured wide-necked aneurysm may be better served with an endovascular treatment that leaves a small neck remnant than with clip reconstruction that affords complete occlusion but requires a considerably more invasive surgical approach. Endovascular therapy has, in a generally safe and minimally invasive fashion, lowered the clinical risk of many pathologies without affording complete cure. In light of the available literature, a similar shift in mindset may be warranted regarding SRS for the treatment of cranial DAVFs. Just as SRS met with initial skepticism regarding its efficacy for vestibular schwannomas,2 neurointerventionalists and cerebrovascular surgeons have been slow to embrace its utility for DAVFs.3 In recent years, mounting evidence has emerged to support the efficacy of SRS as more than just a salvage therapy after failed endovascular embolization of DAVFs.4,5 In light of this, a recent systematic review and meta-analysis by Singh et al1 on behalf of the International Stereotactic Radiosurgery Society has summarized the DAVF SRS outcomes and provided some practice guidelines. In their analysis of 705 SRS-treated patients with DAVF in 21 studies, the authors reported complete occlusion and symptomatic cure rates of nearly 70% and 80%, respectively.1 In comparison, a recent meta-analysis of transarterial DAVF embolization using ethylene vinyl alcohol copolymer (Onyx; Medtronic Neurovascular) reported a complete occlusion rate of 82%.6 A multicenter retrospective analysis of the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) database reported a complete obliteration rate of 55% after initial Onyx embolization.7 In this CONDOR study, the final obliteration rate with Onyx was less than 70%, even after all treatments. Surgical DAVF series typically report a higher obliteration rates than endovascular series, but many of these surgical cases have failed endovascular therapy, and operative morbidity and mortality rates up to 17% have been reported.3,8,9 The rates of post-SRS hemorrhage and permanent neurological deficits reported by Singh et al1 in their meta-analysis were 1.1% and 1.3%, respectively. By comparison, the risk of permanent neurological deficit after DAVF embolization was 4% in the meta-analysis by Sadeh-Gonike et al6 and 16.1% in the CONDOR database.7 In a separate analysis of unruptured high-grade DAVFs from CONDOR, post-treatment hemorrhage rates in the observation, endovascular, surgical, and SRS groups were 6.9%. 1.6%, 2.3%, and 0%, respectively.4 Although there were relatively few patients in the SRS group (n = 19), the risk of post-treatment hemorrhage seems to be similar among the various therapeutic modalities for unruptured DAVFs. DAVFs can be rewarding lesions to address for neurointerventionalists, as they provide a satisfying combination of technical skill, anatomic knowledge, and innovative approaches (ie, transvenous, direct puncture, combined surgical and endovascular). However, these cases can require hours of radiation exposure for the patient over potentially multiple embolization sessions, and there is a modest risk of DAVF recurrence even after initial angiographic cure. Based on analyses of the CONDOR database, obliteration of a low-grade DAVF after a single embolization session was achieved in <40% of cases,10 and the rate of recurrent arteriovenous shunting after angiographic cure (which required a mean of >2 embolization sessions) was 7%.11 Based on these findings, SRS may warrant consideration as a first-line treatment for unruptured DAVFs.1 If patients understand the potential risks associated with the latency period between treatment and efficacy, SRS should be discussed with unruptured patients with DAVF as a viable and reasonable alternative to embolization and surgical ligation. Definitive evidence from randomized comparative trials among the various treatment strategies for DAVFs is unlikely to be forthcoming for such a rare condition. Therefore, we will continue to rely on large multicenter databases, such as CONDOR, for our best available evidence regarding management outcomes and complications in contemporary neurovascular practice. The practice guidelines put forth by the ISRS underscore the favorable risk to benefit profile of SRS for appropriately selected DAVFs.

Natural history, angiographic presentation and outcomes of anterior cranial fossa dural arteriovenous fistulas

BackgroundAnterior cranial fossa dural arteriovenous fistulas (ACF-dAVFs) are aggressive vascular lesions. The pattern of venous drainage is the most important determinant of symptoms. Due to the absence of a venous...

Microsurgical treatment of cranial and spinal dural arteriovenous fistulas for acute occlusion: a single institution’s experience

ABSTRACT Objectives To determine the success rate of primary microsurgical treatment of both cranial and spinal dural arteriovenous fistulas (cdAVFs and sdAVFs). Methods Data of 40 consecutive patients (mean age, 64.5 years; range, 35–88 years) who underwent microsurgical treatment for a diagnosed cdAVF/sdAVF at a single academic institution were retrospectively obtained. General patient information, such as age on the day of surgery and sex, patient charts, admission protocols, operating reports, and discharge protocols were reviewed. Outcomes, including modified Rankin Scale (mRS) scores and the rate of complete occlusion confirmed by a postoperative angiography were analyzed. Results The overall post-treatment occlusion rate was 100% in sdAVFs and 92% in cdAVFs. The most common presentation of cdAVFs was intracerebral hemorrhage (67%), followed by headache (53%) and vertigo (33%). The main symptoms of sdAVFs were sensory deficits, paresis, gait abnormalities, and incontinence. Additional endovascular treatment after primary surgery was needed in seven (47%) patients with cdAVF and one patient (4%) with sdAVF. All sdAVFs were classified as Cognard grade V, while six (40%) cdAVFs were Cognard grade III, eight (54%) were grade IV and one (6%) was grade V. Complications included cerebrospinal fluid (CSF) fistulas, CSF circulation disorders, meningitis, and epidural and intracerebral hemorrhages. Furthermore, sdAVF showed higher rates of clinical improvement than cdAVF (56% vs. 47%). Discussion Microsurgery resulted in complete occlusion in most cases of sdAVFs. However, additional endovascular treatment was necessary in nearly 50% of patients with cdAVF. Therefore, combined treatment in cranial cdAVF seems to be the desired strategy.

Reversible cognitive impairment and parkinsonism with leukoencephalopathy due to cranial dural arteriovenous fistula

Parkinsonism and rapid cognitive impairment may have many causes, but only a few have specific treatment. Cranial dural arteriovenous fistula (DAVF) represents 10-15% of intracranial arteriovenous malformations. Clinical manifestations depend on location and venous drainage. It is common the presence of pulsatile tinnitus, bruits and headache or headache and papilledema. Progressive cognitive decline is an unusual presentation due to bilateral thalamic edema or cortical venous hypertension. Endovascular or surgical treatment can reverse disease symptoms.We present a 74-year old man with rapidly progressive cognitive impairment and parkinsonism and a subsequent diagnosis of dural arteriovenous fistula (DAVF). Brain MRI revealed diffuse leukoencephalopathy probably attributable to elevated venous pressure. He was treated with partial embolization with Onix and left transverse sinus angioplasty. Following the procedure, there was a substantial reduction of venous pressure signs and remarkable clinical and imaging improvement, persisting at two years follow-up. This case represents an unusual presentation of DAVF. It is important to suspect the diagnosis of DAVF in cases with rapidly evolving cognitive impairment, parkinsonism and leukoencephalopathy as it can be reversible with early treatment.

Anterior cranial fossa osseous arteriovenous fistula of the crista galli with bone erosion: patient series

BACKGROUNDAlthough an anterior cranial fossa dural arteriovenous fistula (ACFdAVF) is thought to have a fistula on the dura near the olfactory groove, the detailed angioarchitecture remains unreported.OBSERVATIONSIn case 1, a 65-year-old man was found to have an asymptomatic ACFAVF. His computed tomography angiography (CTA)-maximum intensity projection (MIP) showed the shunt point in the crista galli (CG), with the intradural drainer penetrating the destroyed bone of the CG. In case 2, a 78-year-old man had a past history of intracerebral hemorrhage and was found to have an ACFAVF. The rotational angiography (RA)-MIP showed the intraosseous fistula in the CG with the drainer passing through a tiny bone defect of the CG. In case 3, a 35-year-old man was investigated for epilepsy. The RA-MIP showed an osseous arteriovenous fistula (AVF) in the anterior cranial base, with the drainer penetrating the skull osteolytic site. In case 4, a 73-year-old woman was found to have an asymptomatic ACFAVF. Her RA-MIP showed the osseous AVF with the drainer penetrating the CG with bone erosion.LESSSONSAll patients were diagnosed with anterior cranial fossa osseous AVF rather than dAVF, with bone erosion in the CG. These findings should be noted at the time of diagnosis and treatment.

Risk of Early Versus Later Rebleeding From Dural Arteriovenous Fistulas With Cortical Venous Drainage.

Background:Cranial dural arteriovenous fistulas with cortical venous drainage are rare lesions that can present with hemorrhage. A high rate of rebleeding in the early period following hemorrhage has been reported, but published long-term rates are much lower. No study has examined how risk of rebleeding changes over time. Our objective was to quantify the relative incidence of rebleeding in the early and later periods following hemorrhage.Methods:Patients with dural arteriovenous fistula and cortical venous drainage presenting with hemorrhage were identified from the multinational CONDOR (Consortium for Dural Fistula Outcomes Research) database. Natural history follow-up was defined as time from hemorrhage to first treatment, rebleed, or last follow-up. Rebleeding in the first 2 weeks and first year were compared using incidence rate ratio and difference.Results:Of 1077 patients, 250 met the inclusion criteria and had 95 cumulative person-years natural history follow-up. The overall annualized rebleed rate was 7.3% (95% CI, 3.2–14.5). The incidence rate of rebleeding in the first 2 weeks was 0.0011 per person-day; an early rebleed risk of 1.6% in the first 14 days (95% CI, 0.3–5.1). For the remainder of the first year, the incidence rate was 0.00015 per person-day; a rebleed rate of 5.3% (CI, 1.7–12.4) over 1 year. The incidence rate ratio was 7.3 (95% CI, 1.4–37.7; P, 0.026).Conclusions:The risk of rebleeding of a dural arteriovenous fistula with cortical venous drainage presenting with hemorrhage is increased in the first 2 weeks justifying early treatment. However, the magnitude of this increase may be considerably lower than previously thought. Treatment within 5 days was associated with a low rate of rebleeding and appears an appropriate timeframe.

Microsurgery as first-line treatment in acute hemorrhagic cranial dural arteriovenous fistulas (dAVFs) and ruptured intracranial aneurysms—anachronism or duty?

Microsurgery as first-line treatment in acute hemorrhagic cranial dural arteriovenous fistulas (dAVFs) and ruptured intracranial aneurysms—anachronism or duty?

Transarterial Embolization of Ethmoidal Dural Arteriovenous Fistula: 2-Dimensional Video.

Cranial dural arteriovenous fistulae (dAVF) are rare cerebrovascular lesions characterized by direct arteriovenous shunting within the dural leaflets, with stark heterogeneity in angioarchitecture among different patients.1,2 It is, therefore, crucial to personalize treatment strategies to unique patients and their specific lesion. The authors describe an ethmoidal dAVF in an elderly female patient with arterial supply from the ophthalmic arteries and the contralateral middle meningeal artery. This, together with recent advances in microcatheter technology and the controllability of modern liquid embolic agents, opened up a route for transarterial embolization, obviating the need to course through the ophthalmic artery or the need for open surgery.3 Onyx is Food and Drug Administration-approved for treatment of arteriovenous malformations and can be used off-label for treatment of dAVF, as described here. This video demonstrates the technical nuances and safety considerations of transarterial liquid embolization through the middle meningeal artery while providing an overview of alternative treatment approaches for ethmoidal dAVFs. The patient consented to the procedure.

Recurrence after cure in cranial dural arteriovenous fistulas: a collaborative effort by the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR).

Cranial dural arteriovenous fistulas (dAVFs) are often treated with endovascular therapy, but occasionally a multimodality approach including surgery and/or radiosurgery is utilized. Recurrence after an initial angiographic cure has been reported, with estimated rates ranging from 2% to 14.3%, but few risk factors have been identified. The objective of this study was to identify risk factors associated with recurrence of dAVF after putative cure. The Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) data were retrospectively reviewed. All patients with angiographic cure after treatment and subsequent angiographic follow-up were included. The primary outcome was recurrence, with risk factor analysis. Secondary outcomes included clinical outcomes, morbidity, and mortality associated with recurrence. Risk factor analysis was performed comparing the group of patients who experienced recurrence with those with durable cure (regardless of multiple recurrences). Time-to-event analysis was performed using all collective recurrence events (multiple per patients in some cases). Of the 1077 patients included in the primary CONDOR data set, 457 met inclusion criteria. A total of 32 patients (7%) experienced 34 events of recurrence at a mean of 368.7 days (median 192 days). The recurrence rate was 4.5% overall. Kaplan-Meier analysis predicted long-term recurrence rates approaching 11% at 3 years. Grade III dAVFs treated with endovascular therapy were statistically significantly more likely to experience recurrence than those treated surgically (13.3% vs 0%, p = 0.0001). Tentorial location, cortical venous drainage, and deep cerebral venous drainage were all risk factors for recurrence. Endovascular intervention and radiosurgery were associated with recurrence. Six recurrences were symptomatic, including 2 with hemorrhage, 3 with nonhemorrhagic neurological deficit, and 1 with progressive flow-related symptoms (decreased vision). Recurrence of dAVFs after putative cure can occur after endovascular treatment. Risk factors include tentorial location, cortical venous drainage, and deep cerebral drainage. Multimodality therapy can be used to achieve cure after recurrence. A delayed long-term angiographic evaluation (at least 1 year from cure) may be warranted, especially in cases with risk factors for recurrence.

Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR): rationale, design, and initial characterization of patient cohort.

Cranial dural arteriovenous fistulas (dAVFs) are rare lesions, hampering efforts to understand them and improve their care. To address this challenge, investigators with an established record of dAVF investigation formed an international, multicenter consortium aimed at better elucidating dAVF pathophysiology, imaging characteristics, natural history, and patient outcomes. This report describes the design of the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) and includes characterization of the 1077-patient cohort. Potential collaborators with established interest in the field were identified via systematic review of the literature. To ensure uniformity of data collection, a quality control process was instituted. Data were retrospectively obtained. CONDOR comprises 14 centers in the United States, the United Kingdom, the Netherlands, and Japan that have pooled their data from 1077 dAVF patients seen between 1990 and 2017. The cohort includes 359 patients (33%) with Borden type I dAVFs, 175 (16%) with Borden type II fistulas, and 529 (49%) with Borden type III fistulas. Overall, 852 patients (79%) presented with fistula-related symptoms: 427 (40%) presented with nonaggressive symptoms such as tinnitus or orbital phenomena, 258 (24%) presented with intracranial hemorrhage, and 167 (16%) presented with nonhemorrhagic neurological deficits. A smaller proportion (224 patients, 21%), whose dAVFs were discovered incidentally, were asymptomatic. Many patients (85%, 911/1077) underwent treatment via endovascular embolization (55%, 587/1077), surgery (10%, 103/1077), radiosurgery (3%, 36/1077), or multimodal therapy (17%, 184/1077). The overall angiographic cure rate was 83% (758/911 treated), and treatment-related permanent neurological morbidity was 2% (27/1467 total procedures). The median time from diagnosis to follow-up was 380 days (IQR 120-1038.5 days). With more than 1000 patients, the CONDOR registry represents the largest registry of cranial dAVF patient data in the world. These unique, well-annotated data will enable multiple future analyses to be performed to better understand dAVFs and their management.

Contemporary Management of Cranial Dural Arteriovenous Fistulas

Cranial dural arteriovenous fistulas (dAVFs) are rare acquired neurovascular disorders that have the potential to profoundly alter the local and global cerebral venous drainage. Factors such as location, angioarchitecture, degree of shunting, and mode of presentation all appear to have some bearing on the natural history of dAVFs, which can vary from almost entirely benign to life-threatening. Accurate and evidence-based risk stratification is, therefore, key to informing important management decisions. The treatment strategies are nuanced and, for an already rare entity, can vary tremendously from 1 fistula to another. It is only through a thorough understanding of their behavior and the treatment options available that we will be able to deliver tailored treatment to the correct dAVF and the correct patient. We aimed to provide an up-to-date summary of the reported data on the natural history and predictors of aggressive behavior for cranial dAVFs ingeneral, followed by site-specific management considerations.

Risk Factors of Aggressive Clinical Presentation in Patients with Angiographically Aggressive Cranial Dural Arteriovenous Fistulas.

Compared to nonaggressive cranial dural arteriovenous fistulae (cDAVF), aggressive cDAVF carries leptomeningeal venous drainage (LVD) and has approximately 15% annual risk of hemorrhagic and non-hemorrhagic aggressive neurological presentations. In terms of aggressive clinical presentations, the previous classification does not adequately differentiate the higher risk group from the lower risk group. Herein, we retrospectively collected a series of patients with aggressive cDAVF and explored the risk factors for differentiating the higher-risk group from the lower-risk group with aggressive clinical presentations. We retrospectively collected patients with aggressive cDAVF from March 2011 to March 2019. The risk of aggressive clinical presentation was recorded. Risk factors were included in the analysis for aggressive clinical presentations. From March 2011 to March 2019, 37 patients had aggressive cDAVF. Among them, 24 presented with aggressive clinical presentation (20, hemorrhagic presentation; four, non-hemorrhagic presentation). In patients presenting with hemorrhage, four patients experienced early rebleeding after diagnosis. In the univariate analysis, risk location, directness of LVD, exclusiveness of LVD, and venous strain were significantly different in patients with aggressive clinical presentation. In the multivariate analysis, exclusiveness of LVD and venous strain were observed, with a significant difference between patients with aggressive clinical presentation and those with benign clinical presentation. Among patients with angiographically aggressive cDAVFs, approximately 65% presented with aggressive clinical presentations in our series. Among all potential risk factors, patients with exclusiveness of LVD and venous strain have even higher risk and should be treated aggressively and urgently.