Intracranial Dural Arteriovenous Fistulas Research Articles

Dural arteriovenous fistulas without cortical venous drainage: presentation, treatment, and outcomes.

Current evidence suggests that intracranial dural arteriovenous fistulas (dAVFs) without cortical venous drainage (CVD) have a benign clinical course. However, no large study has evaluated the safety and efficacy of current treatments and their impact over the natural history of dAVFs without CVD. The authors conducted an analysis of the retrospectively collected multicenter Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) database. Patient demographics and presenting symptoms, angiographic features of the dAVFs, and treatment outcomes of patients with Borden type I dAVFs were reviewed. Clinical and radiological follow-up information was assessed to determine rates of new intracranial hemorrhage (ICH) or nonhemorrhagic neurological deficit (NHND), worsening of venous hyperdynamic symptoms (VHSs), angiographic recurrence, and progression or spontaneous regression of dAVFs over time. A total of 342 patients/Borden type I dAVFs were identified. The mean patient age was 58.1 ± 15.6 years, and 62% were women. The mean follow-up time was 37.7 ± 54.3 months. Of 230 (67.3%) treated dAVFs, 178 (77%) underwent mainly endovascular embolization, 11 (4.7%) radiosurgery alone, and 4 (1.7%) open surgery as the primary modality. After the first embolization, most dAVFs (47.2%) achieved only partial reduction in early venous filling. Multiple complementary interventions increased complete obliteration rates from 37.9% after first embolization to 46.7% after two or more embolizations, and 55.2% after combined radiosurgery and open surgery. Immediate postprocedural complications occurred in 35 dAVFs (15.2%) and 6 (2.6%) with permanent sequelae. Of 127 completely obliterated dAVFs by any therapeutic modality, 2 (1.6%) showed angiographic recurrence/recanalization at a mean of 34.2 months after treatment. Progression to Borden-Shucart type II or III was documented in 2.2% of patients and subsequent development of a new dAVF in 1.6%. Partial spontaneous regression was found in 22 (21.4%) of 103 nontreated dAVFs. Multivariate Cox regression analysis demonstrated that older age, NHND, or severe venous-hyperdynamic symptoms at presentation and infratentorial location were associated with worse prognosis. Kaplan-Meier curves showed no significant difference for stable/improved symptoms survival probability in treated versus nontreated dAVFs. However, estimated survival times showed better trends for treated dAVFs compared with nontreated dAVFs (288.1 months vs 151.1 months, log-rank p = 0.28). This difference was statistically significant for treated dAVFs with 100% occlusion (394 months, log-rank p < 0.001). Current therapeutic modalities for management of dAVFs without CVD may provide better symptom control when complete angiographic occlusion is achieved.

Intervention for unruptured high-grade intracranial dural arteriovenous fistulas: a multicenter study.

The risk-to-benefit profile of treating an unruptured high-grade dural arteriovenous fistula (dAVF) is not clearly defined. The aim of this multicenter retrospective cohort study was to compare the outcomes of different interventions with observation for unruptured high-grade dAVFs. The authors retrospectively reviewed dAVF patients from 12 institutions participating in the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR). Patients with unruptured high-grade (Borden type II or III) dAVFs were included and categorized into four groups (observation, embolization, surgery, and stereotactic radiosurgery [SRS]) based on the initial management. The primary outcome was defined as the modified Rankin Scale (mRS) score at final follow-up. Secondary outcomes were good outcome (mRS scores 0-2) at final follow-up, symptomatic improvement, all-cause mortality, and dAVF obliteration. The outcomes of each intervention group were compared against those of the observation group as a reference, with adjustment for differences in baseline characteristics. The study included 415 dAVF patients, accounting for 29, 324, 43, and 19 in the observation, embolization, surgery, and SRS groups, respectively. The mean radiological and clinical follow-up durations were 21 and 25 months, respectively. Functional outcomes were similar for embolization, surgery, and SRS compared with observation. With observation as a reference, obliteration rates were higher after embolization (adjusted OR [aOR] 7.147, p = 0.010) and surgery (aOR 33.803, p < 0.001) and all-cause mortality was lower after embolization (imputed, aOR 0.171, p = 0.040). Hemorrhage rates per 1000 patient-years were 101 for observation versus 9, 22, and 0 for embolization (p = 0.022), surgery (p = 0.245), and SRS (p = 0.077), respectively. Nonhemorrhagic neurological deficit rates were similar between each intervention group versus observation. Embolization and surgery for unruptured high-grade dAVFs afforded a greater likelihood of obliteration than did observation. Embolization also reduced the risk of death and dAVF-associated hemorrhage compared with conservative management over a modest follow-up period. These findings support embolization as the first-line treatment of choice for appropriately selected unruptured Borden type II and III dAVFs.

Abstract #2 LATAM Experience: Cost Effectiveness of Endovascular Stroke Therapy. Analysis From a Colombian Healthcare Perspective

Foramen magnum dural arteriovenous fistulas (DAVF) with perimedullary venous drainage represent a small minority of intracranial DAVF, and only a number of small series with limited cases have been reported. The purpose of this retrospective study is to summarize experience of transarterial Onyx embolisation in the treatment of these lesions, with emphasis on the balloon-augmented technique.Five consecutive patients with DAVF at the foramen magnum were treated by transarterial embolisation using the Onyx system. Their symptoms included myelopathy (n = 4) and SAH (n = 1). Suppliers were from the vertebral artery (VA) (n = 4), occipital artery (OA) (n = 4), and ascending pharyngeal artery (APA) (n = 2), with drainage to the perimedullary veins. After catheterization of the dilated supplier, the fistulous connections, proximal draining veins and appropriate distal segment of the feeders of these DAVF were transarterial embolized using Onyx-18. In three patients, balloon-augmented technique was used to assist embolisation. The technical feasibility of the procedure, angiographic results, and clinical outcome were evaluated.In every case, complete obliteration was achieved. Neither intraprocedural vessel rupture nor other procedure-related complications occurred. The results remained stable in all patients on follow-up angiograms (mean, 7.2 months). At the last clinical follow-up (mean, 17.6 months), two patients showed complete resolution of the initial symptoms, and three patients showed significant improvement.We found that Onyx embolisation is a feasible and safe alternative to open surgery in the treatment of selective DAVF at the foramen magnum. The balloon-augmented technique widens indications for transarterial Onyx packing of these lesions, and improved safety of the procedure.

Endovascular Treatment of Medial Tentorial Dural Arteriovenous Fistula Through the Dural Branch of the Pial Artery.

Background: Tentorial dural arteriovenous fistula is a rare subtype of intracranial dural arteriovenous fistula (DAVF) with a deteriorating natural course, which may be attributed to its pial angioarchitecture. TDAVF often harbors feeders arising from pial arteries (FPAs). Reports have revealed that, if these feeders are not obliterated early, the restricted venous outflow during the embolization process may cause upstream congestion in the fragile pial network, which increases the risk of hemorrhagic complications. Because most reported cases of TDAVF were embolized through feeders from non-pial arteries (FNPAs), little is known of the feasibility of direct embolization through FPAs.Methods: We present three patients with medial TDAVFs that were embolized through the dural branches of the posterior cerebral and superior cerebellar arteries. Findings from brain magnetic resonance imaging, computed tomography, angiography, and clinical outcomes are described. Furthermore, we performed a review of the literature on TDAVFs with FPAs.Results: The fistulas were completely obliterated in two patients; both recovered well with no procedure-related complications. The fistula was nearly obliterated in one patient, who developed left superior cerebellum and midbrain infarct due to the reflux of the embolizer into the left superior cerebellar artery. Including our cases, eight cases of TDAVFs with direct embolization through the FPAs have been reported, and ischemic complications occurred in three (37.5%).Conclusions: Advancing microcatheter tips as close to the fistula point as possible and remaining highly aware of potential embolizer flow back into the pial artery are key factors in achieving successful embolization. Balloon-assisted embolization may be an option for treating TDAVFs with FPAs in the future.

Intracranial Dural Arteriovenous Fistulas with Cortical Venous Drainage: Radiosurgery as an Effective Alternative Treatment

To evaluate the clinical and radiological outcome of Gamma Knife radiosurgery (GKS) in treatment of intracranial dural arteriovenous fistula (DAVF) with cortical venous drainage (CVD) and compare it with the outcome of endovascular therapy. Patients who underwent GKS or endovascular therapy for intracranial DAVF with CVD over 10 years (January 2007 to December 2016) at the All India Institute of Medical Sciences, New Delhi, were included. Demographics, clinical presentation, imaging details, and follow-up clinical status were reviewed retrospectively. Clinical follow-up was conducted once every 6 months. Radiological follow-up using digital subtraction angiography was performed at a mean 24 months after intervention. Patients with clinical follow-up of <1 year were excluded from the study. The study included 35 patients (26 in embolization group and 9 in GKS group) who had intracranial DAVF with CVD were included in the study. Clinical improvement was seen in 77.78% of the patients who received GKS and 57.7% of the patients who underwent embolization (P= 0.431). Complete obliteration of DAVF was seen in 55.56% of the patients in the GKS group and 57.7% of the patients in the embolization group (P= 1). GKS was at least as effective as embolization in terms of clinical and radiological outcome in treatment of intracranial DAVF with CVD. Contrary to popular perception, GKS should be considered as an effective first-line treatment alternative of intracranial DAVF with CVD.

Extracranial Dural Arteriovenous Fistula as a Cause of Mastoid Mass: A Case Report

Introduction: Dural arteriovenous fistulas account for 10 to 15% of intracranial arteriovenous malformations. They are defined as malformations to short-circuits between dural and extracranial arteries with dural venous sinuses. Its presentation is in frequent and its management is a challenge in low- and middle-income countries where there are difficulties in accessing high quality technological tools. Case: We present the case of an unusual dural arteriovenous fistula involving the mastoid region and draining into the external jugular vein and through emissary veins into the superior longitudinal sinus, which was treated transarterially. Conclusion: Endovascular management of intracranial dural arteriovenous fistulas can be a challenge. Endovascular treatment includes a transarterial or transvenous approach from the femoral artery or vein. There is little evidence on this subject, so it is necessary to carry out more studies to determine risk factors, intervention effects and medium- and long-term outcomes.

Diagnostic Accuracy of 3D Contrast-Enhanced T1 High Resolution Isotropic Volume Excitation MRI for Non-Cavernous Intracranial Dural Arteriovenous Fistula

Objective: To determine the accuracy of 3D contrast-enhanced THRIVE MRI in diagnosis of non-cavernous intracranial dural AVF compared with DSA. Materials and Methods: Thirty-three patients including fourteen dural AVF cases and nineteen control subjects, were included in the present study. They underwent 3D contrast-enhanced THRIVE MRI by 3T, contrast-enhanced MRA, and DSA. Two independent readers reviewed 3D contrast-enhanced THRIVE images for the presence of transosseous arterial feeders, low signal intensity curvilinear structures in the dural venous sinus, shaggy dural sinus, and cortical venous dilatation. Diagnostic performance values were calculated for 3D contrast-enhanced THRIVE MRI. Results: The 3D contrast-enhanced THRIVE MRI identified 23 from 29 locations of dural AVFs. The overall accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 91.4%, 79.3%, 93.5%, 67.6% and 96.3%, respectively. Shaggy dural sinus and dilated cortical veins were found in 78.6% and 85.7%, respectively. Conclusion: The 3D contrast-enhanced THRIVE MRI is a valuable tool for diagnosis of dural AVF as well as exclusion of dural AVF due to high sensitivity and specificity. Keywords: Dural arteriovenous fistula; Dural AVF; 3D contrast-enhanced THRIVE MRI

A multicenter prospective registry of Borden type I dural arteriovenous fistula: results of a 3-year follow-up study

PurposeAlthough intracranial dural arteriovenous fistula (DAVF) without retrograde leptomeningeal venous drainage (Borden type I) is reported to have a benign nature, no study has prospectively determined its clinical course. Here, we report a 3-year prospective observational study of Borden type I DAVF.MethodsFrom April 2013 to March 2016, consecutive patients with DAVF were screened at 13 study institutions. We collected data on baseline characteristics, clinical symptoms, angiography, and neuroimaging. Patients with Borden type I DAVF received conservative care while palliative intervention was considered when the neurological symptoms were intolerable, and were followed at 6, 12, 24, and 36 months after inclusion.ResultsDuring the study period, 110 patients with intracranial DAVF were screened and 28 patients with Borden type I DAVF were prospectively followed. None of the patients had conversion to higher type of Borden classification or intracranial hemorrhage during follow-up. Five patients showed spontaneous improvement or disappearance of neurological symptoms (5/28, 17.9%), and 5 patients showed a spontaneous decrease or disappearance of shunt flow on imaging during follow-up (5/28, 17.9%). Stenosis or occlusion of the draining sinuses on initial angiography was significantly associated with shunt flow reduction during follow-up (80.0% vs 21.7%, p = 0.02).ConclusionIn this 3-year prospective study, patients with Borden type I DAVF showed benign clinical course; none of these patients experienced conversion to higher type of Borden classification or intracranial hemorrhage. The restrictive changes of the draining sinuses at initial diagnosis might be an imaging biomarker for future shunt flow reduction.

Progressive myelopathy due to treatable intracranial dural arterovenous fistulae

Intracranial dural arteriovenous fistulae (DAVF) can rarely have a perimedullary venous drainage (Cognard Type V) resulting in an aggressive but potentially treatable and reversible myelopathy. Early diagnosis is often challenging.

Successful surgical management of a tentorial dural arteriovenous fistula causing spinal cord myelopathy

Intracranial dural arteriovenous fistulas account for 10 to 15% of all intracranial arteriovenous malformations. Tentorial dural arteriovenous fistulas with spinal medullary venous drainage causing spinal cord myelopathy have been rarely reported in the literature. We describe a case using a temporo-pterional approach for the surgical treatment of a tentorial artery dural arteriovenous fistula causing spinal cord myelopathy.

Alterations in Resting-State Functional MRI Connectivity Related to Cognitive Changes in Intracranial Dural Arteriovenous Fistulas Before and After Embolization Treatment.

Cognitive decline is a non-hemorrhagic, major complication of intracranial dural arteriovenous fistula (DAVF), thought to be primarily related to venous hypertension. However, imaging features to predict cognitive decline are scanty in the literature. To evaluate functional connectivity (FC) changes of resting-state networks (RSNs) in DAVF before and after treatment and its relation to cognitive impairment. Prospective. DAVF subjects were screened for inclusion. Pre-embolization (N=33, mean age 45.9 years, 29 males), 1 month post-embolization (N=20, mean age 42.7 years, 19 males), and healthy controls (HC, N=33, mean age 45.09 years, 27 males). 3.0 T, resting-state functional magnetic resonance imaging (MRI), three-dimensional (3D) T1, T2 fast spin echo (FSE), diffusion weighted imaging (DWI), susceptibility weighted imaging (SWI), fluid-attenuated inversion recovery, and time of flight. Data quality assessment was performed. FC analysis was done using group independent component analysis (ICA) and seed to voxel analysis. Neuropsychology (NP) scores of patients were compared with HC and correlated with FC changes. Voxel-wise parametric T-statistics for F-test was executed in FC analysis (p-FDR corrected <0.05). NP scores between DAVF group and HC group were compared using one-way analysis of variance with post hoc Bonferroni correction (P < 0.05). Both RSNs analysis methods showed reduced FC at the precuneus-posterior cingulate cortex (PC-PCC) of default mode network (DMN), anterior cingulate cortex (ACC) of the salience network (SN), and possible compensatory increased connectivity at the frontoparietal (FPN) and dorsal attention (DAN) networks. DAVF with low NP scores showed reduced FC at DMN and SN and minimal to absent connectivity at FPN and DAN. At post-embolization 1-month follow-up, improvement in FC at PC-PCC of DMN and ACC of SN were noted. RS-fMRI in DAVF displayed FC changes that may be related to cognitive decline and its subsequent reversibility after treatment. FC changes at DMN, SN, FPN, and DAN were linked to cognitive decline and the corresponding NP scores. 2 TECHNICAL EFFICACY: Stage 2.

The impact of software-based metal artifact reduction on the liquid embolic agent Onyx in cone-beam CT: a systematic in vitro and in vivo study

BackgroundOnyx is frequently used for endovascular embolization of intracranial arteriovenous malformations (AVMs) and dural arteriovenous fistulas (dAVFs). One drawback of using Onyx is the generation of artifacts in cone-beam CT...

Utility of silent magnetic resonance angiography in the evaluation and characterisation of intracranial dural arteriovenous fistula

To evaluate the utility of silent magnetic resonance angiography (MRA) in the diagnosis, characterisation, and therapeutic planning of intracranial dural arteriovenous fistula (DAVF). Twenty consecutive patients with DAVF were enrolled prospectively and were evaluated using silent MRA and digital subtraction angiography (DSA) as a part of routine work-up. The diagnosis and location of fistula, Borden and Cognard classification, entire arterial feeders, and venous drainage were analysed. A therapeutic strategy was formulated, and the accessible route and vessel were predicted, which was confirmed on endovascular treatment. Silent MRA was 100% sensitive and accurate for location and classification of fistulas. Silent MRA showed a sensitivity of 82% and 76.5% for entire arterial feeders and draining veins, which improved to a sensitivity of 90% and 94% when prominent feeders and immediate venous drainage was considered. Among the missed veins, thrombosed sinus, slow sinus flow, small calibre, reduced image quality were the causes. The therapeutic decision matched with DSA in all cases and silent MRA accurately identified the potential accessible feeder in 94% cases. Silent MRA is a promising MR technique that can provide both diagnostic and therapeutic information similar to that obtained from DSA.

Embolization strategies for intracranial dural arteriovenous fistulas with an isolated sinus: a single-center experience in 20 patients

BackgroundIntracranial dural arteriovenous fistulas (DAVFs) draining into an isolated sinus segment constitute a specific entity within the spectrum of cranial dural AV shunts, with under-reporting of their optimal treatment.ObjectiveTo describe...

Central Venous Occlusion in End-Stage Renal Failure—A Rare Mimic of Dural Arteriovenous Fistula (DAVF)

Intracerebral hemorrhage is a devastating form of stroke and is more common in patients with hypertension and renal disease. We present the case of a lady suffering from chronic kidney disease who presented with severe headache and aphasia. On evaluation, she was found to have an intraparenchymal hemorrhage in the left temporal lobe with prominent pial and dural veins suggestive of a dural arteriovenous fistula (DAVF). Subsequently, she was detected to have occlusion of the left brachiocephalic vein (LBCV), which resulted in venous hypertension and resulted in this rare complication. Angioplasty followed by stenting of the LBCV resulted in subsidence of her symptoms. We wish to highlight this unusual but treatable complication of limb AV fistula which can mimic intracranial DAVF.

Clinical outcomes of adjunct sinus stenting in dural arteriovenous fistulas

This study investigated the clinical outcomes and follow-up results of venous sinus stenting (VSS) for constrictive dural sinus restoration in patients with intracranial dural arteriovenous fistulas (DAVFs). We hypothesized that this treatment would have durable benefits in such patients. Patients who underwent VSS for DAVFs with cortical venous reflux between January 2008 and June 2020 were identified after aretrospective review (n=18). Clinical and endovascular treatment data and follow-up information were reviewed. The mean age of the 18patients was 59.9 years. Stents were implanted in 10 previously occluded sinuses and 9 stenotic sinuses in addition to endovascular embolization. One patient received bilateral VSS. Subdural hemorrhage occurred in one patient after recanalization for embolization, followed by uneventful stenting. In 17patients with clinical follow-up, the median follow-up time was 59.5 months (interquartile range 18 to 84months). Of these, sixteen patients had follow-up vascular imaging, revealing AVF obliteration in 6patients (38%) and stent patency in11 (69%). Retreatment was performed for8 (50%) patients. The mean follow-up modified Rankin scale score was 1.28. All patients had longstanding symptomatic improvement. Restoration of sinus flow in DAVFs with cortical venous reflux through VSS has an acceptable complication rate and long-term symptomatic control; however, retreatment is often required, and stent occlusion is not uncommon.

Results of transvenous embolization of intracranial dural arteriovenous fistula: a consecutive series of 136 patients with 142 fistulas.

Intracranial dural arteriovenous fistula (DAVF) is mainly treated with an endovascular approach. Two major treatment advances include transvenous embolization (TVE) with coils in 1989 and, more recently, transarterial embolization with Onyx. The aim of this study was to present a large monocentric series of patients with DAVF treated with TVE. This series reports more than 20 years of experience and describes the evolution of the medical management of these patients, as well as current indications for this treatment at the authors' center. Consecutive patients treated for intracranial DAVFs with TVE from 1995 to 2018 were included. Clinical and imaging data were systematically collected. Univariate and multivariate analyses were performed to identify factors that were significantly associated with adverse clinical course or complications. In this study of 136 patients with 142 DAVFs treated with TVE, the occlusion rate was 90%. The median length of follow-up was 11 months. The rate of permanent complications was 5.1%, and the procedure-related mortality rate was 1.5%. Procedure-related mortality was associated with extension of thrombosis that was observed early in our experience. The introduction of a postoperative anticoagulation regimen has drastically decreased the occurrence of this complication. Other minor complications included cochleovestibular syndrome after embolization of lateral sinus DAVF and oculomotor nerve damage after embolization of cavernous sinus DAVF. TVE allows efficient occlusion of DAVF. It remains a valid option for DAVF located on a sinus that does not participate in normal venous drainage of the brain.

A case series of intracranial dural arteriovenous fistulae mimicking cervical myelitis: a diagnosis not to be missed

ObjectiveTo describe the diagnostic features of intracranial dural arteriovenous fistulae (DAVF) presenting with cervical cord or brainstem swelling.MethodsRetrospective case note and neuroimaging review of patients with angiographically confirmed DAVF diagnosed during January 2015–June 2020 at a tertiary neuroscience centre (Walton Centre NHS Foundation Trust, Liverpool, UK).ResultsSix intracranial DAVF causing cervical cord or brainstem oedema (all males aged 60–69 years) and 27 spinal DAVF (88% thoracolumbar) were detected over a 5.5-year period. Significantly more patients with intracranial DAVF received steroids for presumed inflammatory myelitis than those with spinal DAVF (5/6 vs 1/27, p = 0.0001, Fisher’s exact test). Several factors misled the treating clinicians: atypical rostral location of cord oedema (6/6); acute clinical deterioration (4/6); absence (3/6) or failure to recognise (3/6) subtle dilated perimedullary veins on MRI; intramedullary gadolinium enhancement (2/6); and elevated CSF protein (4/5). Acute deterioration followed steroid treatment in 4/5 patients. The following features may suggest DAVF rather than myelitis: older male patients (6/6), symptomatic progression over 4 or more weeks (6/6) and acellular CSF (5/5).ConclusionIntracranial DAVF are uncommon but often misdiagnosed and treated as myelitis, which can cause life-threatening deterioration. Neurologists must recognise suggestive features and consider angiography, especially in older male patients. Dilated perimedullary veins are an important clue to underlying DAVF, but may be invisible or easily missed on routine MRI sequences.

Impaired intrinsic functional connectivity among medial temporal lobe and sub-regions related to memory deficits in intracranial dural arteriovenous fistula.

The functional changes concerning memory deficits in dural arteriovenous fistula (dAVF) brain are inadequately understood. This study aimed to understand the functional connectivity alterations of brain regions widely affirmed for explicit and implicit memory functions in dAVF patients (DP) and look into the frequency effects of the altered functional networks. Resting-state functional magnetic resonance imaging (rsfMRI) analysis was done in the memory-associated regions of 30 DP and 30 healthy controls (HC). Frequency decomposition was used to determine potential frequency-dependent functional connectivity changes. They underwent neuropsychological tests and were correlated with changes in memory networks compared with HC. The results showed weaker functional connectivity among the medial temporal lobe and sub-regions in DP suggestive of dysfunction of explicit and implicit memory functions, which corroborated with the positive correlation between memory scores and hippocampal-parahippocampal connectivity of DP, along with a significant group difference of lower memory and cognitive performance in DP assessed by neuropsychological tests. A frequency-dependent study of the altered rsFC revealed lower functional connectivity strength and impaired neural coupling manifested at some sub-band frequencies indicative of disturbed cortical rhythm in DP. This pilot study gives insights into significant intrinsic functional connectivity changes in the memory regions of the dAVF brain. The results may have clinical implications in the choice of interventional management of dAVF and can impact clinical decision making for realizable prevention of progressive memory impairment and irreversible brain damage in such patients.

Commentary: Role of Surgical Intervention for Intracranial Dural Arteriovenous Fistulae With Cortical Drainage in an Endovascular Era: A Case Series.

Commentary: Role of Surgical Intervention for Intracranial Dural Arteriovenous Fistulae With Cortical Drainage in an Endovascular Era: A Case Series.