Dural Arteriovenous Fistula Research Articles

NIMG-38. DIAGNOSIS AND TREATMENT OF BRAIN TUMORS USING METHIONINE PET

Abstract INTRODUCTION The usefulness of methionine PET examination in diagnosing brain tumors is widely recognized, and it is a frequently used examination method for distinguishing primary tumors from non-neoplastic lesions and recurrent lesions from radiation necrosis. In addition, during surgery, it has the property of being taken up by actively dividing tumor cells, which is useful for identifying the extent of resection. Method: Methionine PET examination was performed in 228 consecutive cases in our department from January 2021 to April 2023, and medical records and genetic analysis data were retrospectively analyzed. RESULTS Of the 228 cases, 146 cases provided useful data for clinical practice, such as the diagnosis of tumors and the differentiation of recurrent tumors from necrosis. On the other hand, there were 9 cases in which the pathological diagnosis of the resected specimen was “tumor” despite the lack of significant methionine accumulation. The details were astrocytoma, cavernous hemangioma, spinal ependymoma, etc. On the other hand, 26 cases were finally diagnosed as “non-neoplastic disease”. Of these, 13 cases had methionine accumulation. The details of the cases that were finally diagnosed as “non-neoplastic disease” were multiple sclerosis, cerebral infarction, dural arteriovenous fistula, inflammatory disease, etc. There were 12 cases in which a diagnosis of “neoplastic disease” was not revealed after methionine PET examination, and the patient was continuously observed. None of these 12 cases had an acute or malignant course. CONCLUSION Although methionine PET is considered useful for diagnosing neoplastic disease, there are cases in which there is no uptake, especially in astrocytoma, and a certain number of cases in which uptake was observed even in non-neoplastic diseases, so caution is required. In addition, in terms of treatment, it is possible to aim to improve surgical accuracy by integrating methionine PET images with intraoperative MRI and intraoperative molecular analysis techniques, and we report an example of this.

Utility of the turn-back supporting technique using a steerable intermediate catheter: illustrative case.

Selective shunt occlusion (SSO) for intracranial dural arteriovenous fistulas (DAVFs) is a safe and effective method that directly intercepts the shunted pouch from the affected sinus with minimal materials. However, it can be challenging to obliterate the shunted pouch if the microcatheter is not supported adequately. A 68-year-old woman presented with tinnitus and was diagnosed with multiple shunted DAVFs in the right transverse-sigmoid sinus (TSS) and the superior sagittal sinus (SSS). Although the entire sinus packing of the right TSS was performed, a follow-up angiography 7 months later revealed significant cerebral venous reflux due to occlusion of the left TSS and an increasing residual shunt flow in the venous pouch at the confluence of the SSS. A guiding catheter was introduced into the isolated sinus transvenously. Then, a steerable intermediate catheter (SIC) was manually steered into a hairpin shape and hooked on near the pouch prior to navigating a microcatheter into the fistula point. Finally, the fistula pouch was completely obliterated using only two coils under the adequate support of the turned-back intermediate catheter. The turn-back supporting technique using an SIC was useful in achieving SSO for DAVFs, providing both adequate support and guidance for the coaxial microcatheter. https://thejns.org/doi/10.3171/CASE24467.

Brainstem hemorrhage associated with venous hypertensive myelopathy without dural arteriovenous fistula: illustrative case.

Venous hypertensive myelopathy (VHM), formerly known as "Foix-Alajouanine syndrome," is a spinal cord dysfunction caused by impaired perfusion of the spinal cord. Most cases are attributed to spinal dural arteriovenous fistulas (dAVFs), but there are scattered reports of VHM without concomitant dAVF. Furthermore, no cases of VHM associated with intracranial hemorrhage exist. A 68-year-old man with a history of hypertension presented with a sudden headache, proximal paresis of the left upper extremity, impaired pain and temperature sensation in the right upper extremity, dysphagia, and dysarthria. Computed tomography scans showed intraparenchymal hemorrhage in the left medulla oblongata and a linear, continuous high-density area extending from the medulla oblongata to the cervical spinal cord. Magnetic resonance images showed cervical spondylosis at the C5-6 and C6-7 levels, with high signal intensity changes from the medulla oblongata to the lower cervical cord on T2-weighted images. Cerebral angiography showed no abnormal vessels. Conservative treatment gradually improved symptoms and the high signal intensity areas. This case highlights intracranial hemorrhage occurring from extracranial causes and the possibility of VHM due to cervical spondylosis. When hemorrhagic lesions of the craniovertebral junction or spinal parenchymal lesions are encountered, the underlying pathology should be investigated thoroughly and systematically. https://thejns.org/doi/10.3171/CASE24441.

Transarterial embolization of petrosal dural arteriovenous fistula (dAVF): Feasible and successful in the post-Onyx era

Background: Intracranial dural arteriovenous fistula (dAVF) is a rare arteriovenous malformation with potentially severe complications. This study investigates the efficacy and safety of transarterial embolization (TAE) in treating petrous dAVFs through a retrospective analysis and literature review. Case Description: A retrospective analysis of six patients with petrous dAVFs treated with TAE was conducted, accompanied by a systematic literature review to evaluate treatment outcomes. Data collection included patient characteristics, clinical presentation, Borden–Shucart and Cognard classifications, treatment specifics, and overall outcomes. TAE, particularly utilizing Onyx, demonstrated favorable outcomes in our six patients. Regarding literature review results, 102 articles were identified through PubMed Mesh tool search, but only five were included after careful evaluation. In addition, one article was manually added after searching for the remaining articles. Combining our six cases with literature findings, 79.8% (n = 75) of patients undergoing TAE achieved a cure with the technique, though Onyx was reported in only 13.9% (n = 13) of TAE cases. Complications were observed in 11.7% (n = 11) of TAE cases. Conclusion: Our presented cases and literature review suggest that the TAE of dAVFs is feasible and curative for selected cases of petrous dAVFs. However, the complexity of these lesions and the availability of other treatment modalities should be taken into consideration to optimize cure rates and patient outcomes.

Dural arteriovenous fistula associated with medullary ependymoma: an unusual association

Dural arteriovenous fistula associated with medullary ependymoma: an unusual association

Magnetic resonance imaging changes in spinal arteriovenous fistulae treated by endovascular means: are they reliable to predict complete cure of the fistula?

Regression or disappearance of MRI abnormalities is usually observed after treatment of spinal dural arteriovenous fistulae (sDAVF). To assess the correlation between spinal MRI (sMRI) changes with sDAVF exclusion and clinical outcome. Imaging data of patients treated with endovascular embolization for sDAVF between 2007 and 2023 were retrospectively analyzed. Spinal cord edema and perimedullary flow voids at baseline and 3-months' follow-up were compared between patients with and without sDAVF persistent occlusion and clinical improvement on the Aminoff and Logue Scale. Twenty-five patients were included in this study. At 3-months' follow-up, regression of spinal cord edema was significantly associated with sDAVF persistent occlusion (P=0.038). The combination of edema and flow voids regression was significantly associated with higher odds of a cured sDAVF (P<0.001) and clinical improvement (P<0.01). Improvement in the combination of the above-mentioned sMRI signs presented high sensitivity (100% (95% CI 78.20%-100%)) and negative predictive value (100% (95% CI 47.82%-100%)) for the detection of sDAVF cure compared with the criterion standard (digital subtraction angiography (DSA)). Patients with both spinal cord edema and flow voids regression at 3 months were more likely to present with a persistent occlusion of sDAVF and clinical improvement after endovascular embolization. Patients without sMRI improvement should be referred for DSA to seek recurrence of sDAVF.

Comparative microanatomy and histology of spinal and cerebral veins: Implications for dural arteriovenous fistula clinical presentations

Cranial dural arteriovenous fistulas (DAVFs) that display cortical venous drainage are at risk of hemorrhage, unlike spinal DAVFs, which seldom bleed. The underlying mechanism for this difference is poorly understood. We hypothesized that cerebral veins are more fragile than spinal veins due to differences in histologic compositions. Thus, spinal and cerebral veins from five formalin-fixed human cadavers were examined through macroscopic and histological analysis, using hematoxylin, eosin and safran (HES), and orcein stains to compare them. Twenty-four cerebral veins and thirteen spinal veins were analyzed. The mean diameter of the cerebral veins was 1.02 ± 0.59 mm, while that of spinal veins was 0.52 ± 0.26 mm (p = 0.003). The mean thickness of cerebral veins was similar to their spinal counterparts (0.09 ± 0.07 mm vs 0.06 ± 0.02 mm; p = 0.12). The mean diameter-to-thickness ratio was 13.76 ± 6.05 mm for cerebral veins and 10.06 ± 7.23 mm for spinal veins (p = 0.023). In most of the analyzed vessels, the venous wall was composed of endothelial cells resting on layers of smooth muscle, separated by elastica lamina. Cerebral and spinal veins exhibit distinct calibers while maintaining comparable wall thicknesses, resulting in a greater diameter-to-thickness ratio for cerebral veins compared to spinal veins. This difference may after their resistance to pressure. Furthermore, variations in the transparietal pressure gradient between cranial and spinal subarachnoid space, along with differences in arterial blood flow through the fistulous veins, might contribute to the observed differences in clinical presentation.

Angiographically occult spinal dural arteriovenous fistula diagnosed by exploratory surgery with intraoperative ultrasound: illustrative case.

A 78-year-old male presented with progressive myelopathic symptoms. The clinical course and imaging findings raised a high suspicion for venous hypertensive myelopathy due to a spinal dural arteriovenous fistula (SDAVF). Magnetic resonance angiography and four complete spinal angiograms did not reveal the presence of an SDAVF. Despite multiple negative angiograms, intraoperative ultrasound revealed abnormal cord edema and arterialized pulsatile vessels, confirming the presence of an SDAVF. The fistula was found and cauterized, which resulted in a decrease in the caliber of the dilated veins and an observed reduction of spinal cord stiffness posttreatment. The patient exhibited gradual improvement in neurological function. Retrospective analysis of the multiple complete spinal angiograms failed to reveal an anomaly at the treated level or any other level. This case underscores the diagnostic utility of intraoperative Doppler ultrasound and the importance of maintaining a high index of suspicion for SDAVF in cases with consistent clinical characteristics and a lack of alternative diagnoses, even with negative spinal angiography. https://thejns.org/doi/10.3171/CASE24438.

Arterial spin labeling could detect the occlusion of inferior petrosal sinus for cavernous sinus dural AVF

Abstract Several reports indicate that arterial spin labeling (ASL) magnetic resonance imaging (MRI) is useful for the diagnosis, identification of cortical venous reflux, and assessment of therapeutic effect in dural arteriovenous fistula (dAVF). However, there is no reports indicating the utility of ASL in the identification of venous sinus obstruction. We herein report the case of a 72-year-old woman presented with diplopia and right trigeminal neuralgia due to bilateral CS-dAVF. Digital subtraction angiography (DSA) showed temporal occlusion of the inferior petrosal sinus (IPS) and ASL indicated hyperintense signal in the IPS. The ASL signal could indicate venous stasis soon after the occlusion based on the serial changes of IPS patency and occlusion observed in the Digital subtraction angiography.

Transarterial embolization for anterior cranial fossa dural arteriovenous fistula based on multi-modal three-dimensional imaging

Background: Dural arteriovenous fistula (DAVF) in the anterior cranial fossa (ACF) is known to show a high risk of intracranial hemorrhage. Recently, multi-modal fusion imaging with computed tomography angiography, computed tomography venography, and three-dimensional (3D) rotation angiography have been used preoperatively to ensure anatomical safety. We report on endovascular treatment as a first-line approach for ACFDAVF based on the understanding of vascular anatomy obtained from multi-modal fusion imaging. Methods: All patients with ACF-DAVF treated endovascularly as a first-line approach were included in this study. Analyses took into account complications (particularly visual function), immediate angiographic outcomes, and follow-up findings in consecutive patients with ACF-DAVF treated with interventional treatment based on multi-modal fusion imaging. Results: Five patients with ACF-DAVF underwent six sessions of transarterial embolization (TAE) in our institution. The five male patients (mean age, 74.5 years; range, 60–84 years) were treated with liquid embolic agents (Onyx, four procedures; n-butyl 2-cyanoacrylate, two procedures). No difference was seen between preoperative image evaluation and image evaluation during the endovascular procedure, and in all cases, a microcatheter was navigated into a target artery assumed from preoperative multi-modal imaging, allowing treatment completion in a single procedure. In all cases, the shunt disappeared completely and visual function after procedure was maintained. At the last follow-up, all patients showed a modified Rankin scale score of 0 or 1 with no recurrences. Conclusion: Multi-modal fusion imaging facilitates a 3D understanding of the vascular anatomy, allowing TAE as the first-line treatment for ACF-DAVF.

Tortuous conjunctival vessels and central retinal vein occlusion in spontaneous dural arteriovenous fistula.

Tortuous conjunctival vessels and central retinal vein occlusion in spontaneous dural arteriovenous fistula.

Dural arteriovenous fistulas at the craniocervical junction: a systematic review and meta-analysis.

The management for craniocervical junction dural arteriovenous fistulas (CCJ-DAVFs) remains controversial and clinically challenging. We systemically summarized the clinical and angiographic outcomes of microsurgery, embolization, and conservative management. Relevant articles were retrieved from PubMed, Scopus, Web of Science, and Cochrane, following PRISMA guidelines. A systematic review and meta-analysis were conducted on the clinical characteristics, management approaches, and clinical and angiographic outcomes. We included 13 articles (166 patients). The weighted mean age was 58.9 years (95%CI: 53.2-64.5), 58.8 years (95%CI: 48.4-69.2), and 63.8 years (95%CI: 60.1-67.5), in microsurgery, embolization, and conservative groups respectively, with an overall male sex predominance (microsurgery [n = 51/77, 66.2%], embolization [n = 44/56, 78.6%], and conservative management [n = 6/8, 75.0%]). Patients were managed with microsurgery (n = 80/172, 46.5%), embolization (n = 79/172, 45.9%), and conservative treatment (n = 13/172, 7.6%). Foramen magnum was the most common location (microsurgery [n = 34/77, 44.2%], embolization [n = 31/56, 55.4%], and conservative treatment [n = 3/8, 37.5%]). Vertebral artery was the primary feeder (microsurgery [n = 58/84, 69.1%], embolization [n = 41/86, 47.6%], and conservative treatment [n = 4/7, 57.1%]). Complete fistula obliteration rates were 74.1% (95%CI:52.3-88.2%) in the microsurgery group and 54.9% (95%CI:30.7-77.0%) in the embolization group. Complications rates were 16.2% (95%CI:6.7-34.5%) in the embolization group, 11.6% (95%CI:3.8-30.4%) in the microsurgery group, and 7.7% (95%CI:1.1-39.1%) in the conservative group. Different rates of good clinical outcomes were observed [microsurgery: 66.4% (95%CI:48.1-80.8%), embolization: 51.9% (95%CI:30.8-72.4%), and conservative: 11.6% (95%CI:4.4-27.4%)]. In patients with CCJ-DAVFs, each management approach has its own merits based on the fistula and patient characteristics.

Posterior short ciliary arteries ischemia following embolization of anterior ethmoid artery to treat dural arteriovenous fistulas: a case report

BackgroundThe Onyx™ Liquid Embolic System is a non-adhesive liquid embolic agent, which has been proved by the US FDA for embolization of lesions in the peripheral and neurovasculature since 2005. We reported a case of ischemic optic neuropathy after using Onyx-18 to embolize the anterior ethmoid arteries that feeding dural arteriovenous fistulas (DAVF).Case presentationA 57-year-old Asian male presented with anterior cranial fossa DAVF underwent embolotherapy by delivering Onyx-18 through a microcatheter into the anterior ethmoid arteries under angiography guidance. The interventional procedure was successful and no clear evidence was found pointing to untargeted occlusive embolus. But after the surgery the patient experienced delayed painless vision loss in the right eye (RE). The fundoscopy showed unilateral papilledema with pale optic disc in RE, accompanied by significant edema and thickening in the retinal nerve fiber layer (RNFL) of macula. The fundus fluorescence angiography showed that most of the optic disc in RE had postponed or absent fluorescence filling. Visual evoked potential (VEP) confirmed that the amplitude of the P100 component was decreased in RE without significant prolongation of the latency. The patient was diagnosed with anterior ischemic optic neuropathy, but immediate pulse steroid therapy failed to rescue his vision.ConclusionPreoperative evaluation of the patient’s hemodynamic status and fundus examination are essential for assessing the risk of ischemic ocular complications, and the non-adhesive liquid embolic agent Onyx-18 should be used cautiously during endovascular embolization of intracranial artery.

Safety and efficacy of newer liquid embolic agents squid and PHIL in endovascular embolization of cerebral arteriovenous malformations and dural arteriovenous fistulas: A systematic review and meta-analysis

Safety and efficacy of newer liquid embolic agents squid and PHIL in endovascular embolization of cerebral arteriovenous malformations and dural arteriovenous fistulas: A systematic review and meta-analysis

Ruptured venous aneurysm associated with a dural arteriovenous fistula: Two case reports

BACKGROUND In general, venous aneurysm associated with dural arteriovenous fistula (dAVF) is considered to be developed under long standing venous hypertension and manifested as venous ectasia of draining vein itself. However, discrete saccular shaped venous aneurysm without angiographic evidence of venous hypertension arising from the draining vein, like cerebral arterial aneurysm, is quite rare and its pathomechanism remains unclear in patients with dAVF. CASE SUMMARY In this report, we present two cases of ruptured saccular venous aneurysms associated with dAVF without venous hypertension or venous ectasia. In both cases, significant curve or stenosis is observed in draining vein, which is located in just distal portion of the venous aneurysms. These aneurysms were successfully treated with a transarterial embolization. Underlying mechanism of venous aneurysms in these cases is discussed. CONCLUSION Although there is little doubt that hemodynamic stress has a critical role in the development of venous aneurysms in patients with dAVF, preceding venous hypertension or venous ectasia is not necessary for development and enlargement of venous aneurysms. Considering the significant risk of rupture, a careful review of draining vein features including tortuosity or stenosis is needed, especially in venous aneurysms without evidence of venous hypertension.

Endoluminal Visualization of Dural Arteriovenous Fistula using Virtual Angioscopy

BackgroundVirtual Angioscopy (VA) has been used for vessel investigation and treatment planning in fields such as vascular surgery. To our knowledge, the utilization of VA in neurointerventional cases has not been demonstrated. Methods2 cases of dural arteriovenous fistula (dAVF) where virtual angioscopy was utilized were reviewed. Results2 cases of dAVF are reported where virtual angioscopic images were derived from 3D volume rendered (VR) images. The endoluminal visualization of the fistula served as additional tool that helped anatomic understanding and treatment planning. ConclusionThese cases demonstrate the utility of VA in endoluminal visualization of dural arteriovenous fistula that may aid in treatment planning considerations.

Classification, angioarchitecture and treatment outcomes of medullary bridging vein-draining dural arteriovenous fistulas in the foramen magnum region: a multicenter study.

This study aimed to classify medullary bridging vein-draining dural arteriovenous fistulas (MBV-DAVFs) located around the foramen magnum (FM) according to their location and characterize their angioarchitecture and treatment outcomes. Patients with MBV-DAVFs diagnosed between January 2013 and October 2022 were included. MBV-DAVFs were classified into four groups. Jugular vein-bridging vein (JV-BV) DAVF: located in proximity to jugular fossa, Anterior condylar vein (ACV)-BV DAVF: proximity to anterior condylar canal, Marginal sinus (MS)-BV DAVF: lateral surface of FM and Suboccipital cavernous sinus (SCS)-BV DAVF: proximity to dural penetration of vertebral artery. Twenty patients were included, three JV-BV, four ACV-BV, three MS-BV and ten SCS-BV DAVFs, respectively. All groups showed male predominance. There were significant differences in main feeders between JV (jugular branch of ascending pharyngeal artery) and SCS group (C1 dural branch). Pial feeders from anterior spinal artery (ASA) or lateral spinal artery (LSA) were visualized in four SCS and one MS group. Drainage pattern did not differ between groups. Transarterial embolization (TAE) was performed in three, two, one and two cases and complete obliteration was obtained in 100%, 50%, 100% and 0% in JV, ACS, MS and SCS group, respectively. Successful interventions without major complications were finally obtained in 100%, 75%, 100%, and 40% in JV, ACS, MS and SCS group, respectively. JV-BV DAVFs were successfully treated using TAE alone. SCS-BV DAVFs were mainly fed by small C1 dural branches of vertebral artery often with pial feeders from ASA or LSA, and difficultly treated by TAE alone.

Dural arteriovenous fistula may be occluded through recanalization of impaired venous sinuses.

To investigate the effect and safety of recanalization of stenosed or occluded venous sinuses for dural arteriovenous fistulas (DAVFs) and possible mechanism of DAVF formation, patients with DAVF accompanied by venous sinus stenosis or occlusion treated with balloon angioplasty and/or stenting were retrospectively enrolled. The clinical data, treatment outcomes and complications were analyzed. In 7 patients enrolled, the DAVF was Cognard IIa grade in 3 (42.9% or 3/7) and IIa + b in 4 (57.1% or 4/7) patients, including complex DAVFs in 2 (28.6% or 2/7). The angioplasty procedure was successful in all (100%) patients, including complete cure in 3 (42.9% or 3/7) patients with the initial Cognard grade IIa, transformation from Cognard grade IIa + b to I in 2 (28.6% or 2/7) patients, and unchanged Cognard grade IIa + b in 2 (28.6% or 2/7) patients. The symptoms were all improved. At 3-month angiographic follow-up, 5 (71.4% or 5/7) cases were cured, whereas 2 cases still had grade I fistulas but no clinical symptoms. Staged embolization in 2 patients resulted in significant symptom improvement. At the last follow-up of a median 4 years, no clinical symptoms were present in 5 (71.4% or 5/7) patients, intermittent headache in 1 (14.3% or 1/7), and death from trauma in 1 (14.3% or 1/7). In conclusion, endovascular recanalization of occluded or stenosed venous sinuses using balloon angioplasty and stenting is able to induce occlusion of DAVFs and is a safe and efficient treatment approach for DAVFs which are possibly caused by significant pressure increase.

Microsurgical Treatment of Intracranial Dural Arteriovenous Fistulas: A Collaborative Investigation From the Multicenter Consortium for Dural Arteriovenous Fistula Outcomes Research.

First-line therapy for most intracranial dural arteriovenous fistulas (dAVFs) is endovascular embolization, but some require microsurgical ligation due to limited endovascular accessibility, anticipated lower cure rates, or unacceptable risk profiles. We investigated the most common surgically treated dAVF locations and the approaches and outcomes of each. The Consortium for Dural Arteriovenous Fistula Outcomes Research database was retrospectively reviewed. Patients who underwent dAVF microsurgical ligation were included. Patient demographics, angiographic information, surgical details, and postoperative outcomes were collected. The 5 most common surgically treated dAVF locations were analyzed about used surgical approaches and postoperative outcomes. Univariate analyses were performed with statistical significance set at a threshold of P < .05. In total, 248 patients in the Consortium for Dural Arteriovenous Fistula Outcomes Research database met inclusion criteria. The 5 most common surgically treated dAVF locations were tentorial, anterior cranial fossa (ACF), transverse-sigmoid sinus (TSS), convexity/superior sagittal sinus (SSS), and torcular. Most tentorial dAVFs were approached using a suboccipital, lateral supracerebellar infratentorial approach (39.3%); extended retrosigmoid approach (ERS) (25%); or posterior subtemporal approach (19.6%). All ACF dAVFs used a subfrontal approach; 5.3% also included an anterior interhemispheric approach. Most TSS dAVFs were ligated via ERS (31.3%) or subtemporal (31.3%) approaches. All convexity/SSS dAVFs used an interhemispheric approach. All torcular dAVFs used the suboccipital, lateral supracerebellar infratentorial approach, with 10.5% undergoing simultaneous ERS craniotomy. Angiographic occlusion rates after microsurgery were 85.5%, 100%, 75.8%, 79.2%, and 73.7% for tentorial, ACF, TSS, convexity/SSS, and torcular dAVFs, respectively (P = .02); the permanent neurological complication rates were 1.8%, 2.6%, 9.1%, 0%, and 0% (P = .31). There were no statistically significant differences in development of complications (P = .08) or Modified Rankin Scale at the last follow-up (P = .11) by fistula location. Although endovascular embolization is the first-line treatment for most intracranial dAVFs, surgical ligation is an important alternative. ACF and tentorial fistulas particularly demonstrate high rates of postoperative obliteration.

Recognition of dural to pial supply in high-grade dural arteriovenous fistula: A technical note.

High-grade dural arteriovenous fistulas (DAVFs) are known to demonstrate classical dural supply and can demonstrate pre-existing dural supply and 'pure' arterial supply from pial branches. The latter two are examples of congenital versus acquired pial to dural shunting, respectively. We describe the recognition of dural to pial supply during combined transarterial and transvenous embolization of a high-grade DAVF with holocephalic venous reflux, stressing the importance of careful assessment of this condition with micro catheter injections.