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OBJECTIVE Spinal dural arteriovenous fistulas (SDAVFs) typically represent abnormal shunts between a radiculomeningeal artery and radicular vein, with the point of fistulization classically directly underneath the pedicle of the vertebral body, at the dural sleeve of the nerve root. However, SDAVFs can also develop in atypical locations or have more than one arterial feeder, which is a variant of SDAVF. The aim of this study was to describe the incidence and multidisciplinary treatment of variant SDAVFs in a single-center case series. METHODS Following institutional review board approval, the authors retrospectively analyzed their prospectively maintained database of patients with SDAVFs who presented between 2008 and 2020. For all patients, spinal digital subtraction angiograms were reviewed and variant SDAVFs were identified. Variant types of SDAVFs were defined as cases in which the fistulous point was not located underneath the pedicle. Patient demographics, angiographic features, clinical outcomes, and treatment modalities were assessed. RESULTS Of 59 patients with SDAVFs treated at the authors’ institution, 4 patients (6.8%) were identified as having a variant location of the shunt zone, pinpointed on the dura mater at the intervertebral level, further posteriorly within the spinal canal. In 3 cases (75%), a so-called bimetameric arterial supply was demonstrated. CONCLUSIONS Recognition of the variant type of SDAVF is crucial for management, as correct localization of the fistulous point and bimetameric supply are critical for successful surgical disconnection, preventing delay in achieving definitive treatment.

Purpose Differentiation of radiation necrosis from tumor progression in brain metastases treated with stereotactic radiosurgery (SRS) is challenging. For this, we assessed the performance of the centrally restricted diffusion sign. Methods Patients with brain metastases treated with SRS who underwent a subsequent intervention (biopsy/resection) for a ring-enhancing lesion on preoperative MRI between 2000 and 2020 were included. Excluded were lesions containing increased susceptibility limiting assessment of DWI. Two neuroradiologists classified the location of the diffusion restriction with respect to the post-contrast T1 images as centrally within the ring-enhancement (the centrally restricted diffusion sign), peripherally correlating to the rim of contrast enhancement, both locations, or none. Measures of diagnostic accuracy and 95% CI were calculated for the centrally restricted diffusion sign. Cohen's kappa was calculated to identify the interobserver agreement. Results Fifty-nine patients (36 female; mean age 59, range 40 to 80) were included, 36 with tumor progression and 23 with radiation necrosis based on histopathology. Primary tumors included 34 lung, 12 breast, 5 melanoma, 3 colorectal, 2 esophagus, 1 head and neck, 1 endometrium, and 1 thyroid. The centrally restricted diffusion sign was seen in 19/23 radiation necrosis cases (sensitivity 83% (95% CI 63 to 93%), specificity 64% (95% CI 48 to 78%), PPV 59% (95% CI 42 to 74%), NPV 85% (95% CI 68 to 94%)) and 13/36 tumor progression cases (difference p Conclusion We found a low probability of radiation necrosis in the absence of the centrally restricted diffusion sign.

The glymphatic system is a recently discovered network unique to the central nervous system that allows for dynamic exchange of interstitial fluid (ISF) and cerebrospinal fluid (CSF). As detailed in part I, ISF and CSF transport along paravascular channels of the penetrating arteries and possibly veins allow essential clearance of neurotoxic solutes from the interstitium to the CSF efflux pathways. Imaging tests to investigate this neurophysiologic function, although challenging, are being developed and are reviewed herein. These include direct visualization of CSF transport using postcontrast imaging techniques following intravenous or intrathecal administration of contrast material and indirect glymphatic assessment with detection of enlarged perivascular spaces. Application of MRI techniques, including intravoxel incoherent motion, diffusion tensor imaging, and chemical exchange saturation transfer, is also discussed, as are methods for imaging dural lymphatic channels involved with CSF efflux. Subsequently, glymphatic function is considered in the context of proteinopathies associated with neurodegenerative diseases and traumatic brain injury, cytotoxic edema following acute ischemic stroke, and chronic hydrocephalus after subarachnoid hemorrhage. These examples highlight the substantial role of the glymphatic system in neurophysiology and the development of certain neuropathologic abnormalities, stressing the importance of its consideration when interpreting neuroimaging investigations. © RSNA, 2021.

Normal physiologic function of organs requires a circulation of interstitial fluid to deliver nutrients and clear cellular waste products. Lymphatic vessels serve as collectors of this fluid in most organs; however, these vessels are absent in the central nervous system. How the central nervous system maintains tight control of extracellular conditions has been a fundamental question in neuroscience until recent discovery of the glial-lymphatic, or glymphatic, system was made this past decade. Networks of paravascular channels surrounding pial and parenchymal arteries and veins were found that extend into the walls of capillaries to allow fluid transport and exchange between the interstitial and cerebrospinal fluid spaces. The currently understood anatomy and physiology of the glymphatic system is reviewed, with the paravascular space presented as an intrinsic component of healthy pial and parenchymal cerebral blood vessels. Glymphatic system behavior in animal models of health and disease, and its enhanced function during sleep, are discussed. The evolving understanding of glymphatic system characteristics is then used to provide a current interpretation of its physiology that can be helpful for radiologists when interpreting neuroimaging investigations.

Epilepsies are a group of common neurological disorders with a substantial genetic basis. Despite this, the molecular diagnosis of epilepsies remains challenging due to its heterogeneity. Studies utilizing whole-genome sequencing may provide additional insights into genetic causes of epilepsies of unknown aetiology. Whole-genome sequencing was used to evaluate a cohort of adults with unexplained developmental and epileptic encephalopathies (n = 30), for whom prior genetic tests, including whole-exome sequencing in some cases, were negative or inconclusive. Rare single nucleotide variants, insertions/deletions, copy number variants and tandem repeat expansions were analysed. Seven pathogenic or likely pathogenic single nucleotide variants, and two pathogenic deleterious copy number variants were identified in nine patients (32.1% of the cohort). One of the copy number variants, identified in a patient with Lennox–Gastaut syndrome, was too small to be detected by chromosomal microarray techniques. We also identified two tandem repeat expansions with clinical implications in two other patients with Lennox–Gastaut syndrome: a CGG repeat expansion in the 5′untranslated region of DIP2B, and a CTG expansion in ATXN8OS (previously implicated in spinocerebellar ataxia type 8). Three patients had KCNA2 pathogenic variants. One of them died of sudden unexpected death in epilepsy. The other two patients had, in addition to a KCNA2 variant, a second de novo variant impacting potential epilepsy-relevant genes (KCNIP4 and UBR5). Overall, whole-genome sequencing provided a genetic explanation in 32.1% of the total cohort. This is also the first report of coding and non-coding tandem repeat expansions identified in patients with Lennox–Gastaut syndrome. This study demonstrates that using whole-genome sequencing, the examination of multiple types of rare genetic variation, including those found in the non-coding region of the genome, can help resolve unexplained epilepsies., Using whole-genome sequencing, Qaiser et al. identified rare genetic variants in a cohort of adults with unexplained developmental and epileptic encephalopathies (n = 30), for whom prior genetic tests were inconclusive. This is also the first report of coding and non-coding tandem repeat expansions identified in patients with Lennox–Gastaut Syndrome., Graphical Abstract Graphical Abstract

We appreciated the response by Fonseca et al1 to our article “Tumefactive Primary Central Nervous System Vasculitis: Imaging Findings of a Rare and Underrecognized Neuroinflammatory Disease”[2][1] on the importance of the “T1 shinethrough effect” on gadolinium-enhanced SWI (Gd-SWI).[3][2] Gd

Duplication of the internal maxillary artery (IMAX) results from a failed regression of either the embryological superficial or deep ring and is reported to be exceedingly rare. We present a patient with this rare anatomical variant who was treated by endovascular technique in the clinical context of an acute oropharyngeal hemorrhage.

Spontaneous intracranial hypotension is caused by loss of CSF at the level of the spine. The most frequent symptom of this disorder is orthostatic headache, with the headache worsening in the upright position and subsiding after lying down. Neuroimaging has a crucial role in diagnosing and monitoring spontaneous intracranial hypotension, because it provides objective (albeit often subtle) data despite the variable clinical syndromes and often normal lumbar puncture opening pressure associated with this disorder. Spine imaging aims to classify and localise the site of CSF leakage as either (1) a ventral dural leak, (2) a leaking spinal nerve root diverticulum, or (3) a direct CSF-venous fistula. Searching for a CSF leak can be very difficult; the entire spine must be scrutinised for a dural breach often the size of a pin. Precisely locating the site of CSF leakage is fundamental to successful treatment, which includes a targeted epidural patch and surgical closure when conservative measures do not provide long-term relief. Increased awareness of spontaneous intracranial hypotension among clinicians highlights the need for dedicated diagnostic and therapeutic guidelines.

BackgroundVertebrobasilar dolichoectasia (VBDE) is a rare type of non-saccular intracranial aneurysm, with poor natural history and limited effective treatment options. Visualizing neurovascular microanatomy in patients with VBDE has not been previously reported, but may yield insight into the pathology, and provide important information for treatment planning.ObjectiveTo carry out a retrospective analysis of ultra-high resolution cone-beam computed tomography (UHR-CBCT) in patients with fusiform basilar aneurysms, visualizing neurovascular microanatomy of the posterior circulation with a special focus on the pontine perforators.MethodsUHR-CBCT was performed in seven patients (mean age 59 years; two female) with a VBDE, and in 14 control patients with unrelated conditions.ResultsThe mean maximum diameter of the fusiform vessel segment was 28 mm (range 19–36 mm), and the mean length of the segment was 39 mm (range 15–50 mm). In all patients with VBDE, UHR-CBCT demonstrated an absence of perforating arteries in the fusiform arterial segment and a mean of 3.7 perforators arising from the unaffected vessel segment. The network of interconnected superficial circumferential pontine arteries (brainstem vasocorona) were draping around the aneurysm sac. In controls, a mean of 3.6, 2.5, and 1.2 perforators were demonstrated arising from the distal, mid-, and proximal basilar artery, respectively.ConclusionsThe absence of pontine perforators in the fusiform vessel segment of VBDE is counterbalanced by recruitment of collateral flow from pontine perforators arising from the unaffected segment of the basilar artery, as well as collaterals arising from the anterior inferior cerebellar artery/posterior inferior cerebellar artery and superior cerebellar artery. These alternative routes supply the superficial brainstem arteries (brainstem vasocorona) and sustain brainstem viability. Our findings might have implications for further treatment planning.

Robotic-assisted technology has been used as a tool to enhance open and minimally invasive surgeries as well as percutaneous coronary and peripheral vascular interventions. It offers many potential benefits, including increased procedural and technical accuracy as well as reduced radiation dose during fluoroscopic procedures. It also offers the potential for truly “remote” procedures. Despite these benefits, robotic technology has not yet been used in the neuroendovascular field, aside from diagnostic cerebral angiography. Here, we report the first robotic-assisted, therapeutic, neuroendovascular intervention performed in a human. This was a stent-assisted coiling procedure to treat a large basilar aneurysm. All intracranial steps, including stent placement and coil deployment, were performed with assistance from the CorPath© GRX Robotic System (Corindus, a Siemens Healthineers Company, Waltham, MA, USA). This represents a major milestone in the treatment of neurovascular disease and opens the doors for the development of remote robotic neuroendovascular procedures.

Background and purposeComputational fluid dynamics (CFD) can provide valuable information regarding intracranial hemodynamics. Patient-specific models can be segmented from various imaging modalities, which may influence the geometric output and thus hemodynamic results. This study aims to compare CFD results from aneurysm models segmented from three-dimensional rotational angiography (3D-RA) versus novel four-dimensional CT angiography (4D-CTA).MethodsFourteen patients with 16 cerebral aneurysms underwent novel 4D-CTA followed by 3D-RA. Endoluminal geometries were segmented from each modality using an identical workflow, blinded to the other modality, to produce 28 'original' models. Each was then minimally edited a second time to match length of branches, producing 28 additional 'matched' models. CFD simulations were performed using estimated flow rates for 'original' models (representing real-world experience) and patient-specific flow rates from 4D-CTA for 'matched' models (to control for influence of modality alone).ResultsOverall, geometric and hemodynamic results were consistent between models segmented from 3D-RA and 4D-CTA, with correlations improving after matching to control for operator-introduced variability. Despite smaller 4D-CTA parent artery diameters (3.49±0.97 mm vs 3.78±0.92 mm for 3D-RA; p=0.005) and sac volumes (157 (37–750 mm3) vs 173 (53–770 mm3) for 3D-RA; p=0.0002), sac averages of time-averaged wall shear stress (TAWSS), oscillatory shear (OSI), and high frequency fluctuations (measured by spectral power index, SPI) were well correlated between 3D-RA and 4D-CTA 'matched' control models (TAWSS, R2=0.91; OSI, R2=0.79; SPI, R2=0.90).ConclusionsOur study shows that CFD performed using 4D-CTA models produces reliable geometric and hemodynamic information in the intracranial circulation. 4D-CTA may be considered as a follow-up imaging tool for hemodynamic assessment of cerebral aneurysms.

The GestSure system is an Food and Drugs Administration (FDA)-registered depth-sensing infrared device initially developed for touchless image navigation during open surgery. The goal of this study was to explore the feasibility of this technology with medical students, residents, fellows and staff neurointerventionalists, using cases of intracranial aneurysm coiling. This was a prospective cohort study of operative performance using standard keyboard and mouse against a gestural interface. A total of four medical students, six residents, six fellows and five staff neurointerventionalists were involved in the training and subsequent testing. Training involved description and demonstration of a set of gestures optimized for 3D software functions. Cases were selected from the set of patients who underwent endovascular aneurysm coiling at the Toronto Western Hospital. For the overall group 15/21 (71.4%) individuals learned the left anterior oblique 30 degrees (LAO30) task within 20 cases, 17/21 (80.9%) learned the aneurysm neck task within 20 cases, 16/21 (76.2%) learned the parent vessel task and 14/21 (66%) learned the neck and parent vessel (anatomical) tasks. Staff were more consistent (i.e. smallest standard deviation) amongst the groups compared to medical students and residents; however, it was noted that a significant learning effect was observed in participants across every level of medical and angiographic expertise. Touchless angiography suite control with a gestural interface is feasible for the manipulation of angiographic images for neuroendovascular procedures. Learning to use the system was rapid across any level of medical training but greatest for staff neurointerventionalists.

Background Certain cavernous sinus (CS) dural arteriovenous fistulas (DAVFs) are difficult to access through transarterial or transvenous routes and may necessitate access through direct transorbital puncture of the superior ophthalmic vein (SOV) or the CS. However, to be successful, the accurate design of the puncture route and guidance are crucial. This study aimed to report our preliminary clinical experience using cone-beam computed tomography (CT) with real-time fluoroscopic overlays for image guidance during transorbital needle puncture. Methods Between December 2017 and July 2018, 3 patients with CS DAVFs were treated via a transorbital puncture to establish access to the CS under the guidance of XperGuide planning software either via direct CS puncture or through the SOV. The guidance trajectory was superimposed onto the real-time fluoroscopic image during needle puncture. Once access was established, the CS DAVFs were treated with a combination of liquid embolic materials and coils. Results Image guidance aided to avoid at-risk structures and treatment resulted in all cases in complete obliteration of the CS DAVFs as verified by control angiography without peri- or postprocedural complications. Conclusions Endovascular embolization of CS DAVFs via direct transorbital puncture aided by image guidance provided an alternative option when more conventional approaches are deemed not possible.

Distal intracranial occlusions can sometimes cause significant neurological deficits. Endovascular thrombectomy in these vessels may improve outcome but carry a higher risk of haemorrhagic complications due to the small calibre and tortuosity of the target vessel. We report two cases of isolated M2/3 artery occlusion causing dense hemiplegia that was successfully treated with stent retrieval thrombectomy. A “semi-deployment technique” of a 3 mm stentriever was employed at the M2/3 bifurcation of the middle cerebral artery. Partial stent unsheathing allowed adequate clot engagement while avoiding excessive tension by the stent metal struts along the tortuous course of a distal vessel. Complete revascularization was achieved after first-pass of the stent retriever without complication, resulting in good clinical outcome in both cases. The described semi-deployment technique reduces the radial and tractional force exerted by the stentreiver on small branches, and may reduce the risk of vessel laceration or dissection in distal vessel thrombectomy.

Background Permeability-surface product is a predictor of blood–brain barrier disruption, a condition that may be related to higher likelihoods of hemorrhagic transformations in acute stroke. Purpose To investigate whether permeability-surface product can be used as a parameter for predicting outcome after mechanical thrombectomy in patients with anterior circulation acute ischemic stroke. Material and Methods We retrospectively identified patients with acute middle cerebral artery stroke who underwent successful mechanical thrombectomy between November 2009 and July 2015. Multiple parameters (including age) and CT perfusion-related parameters (including permeability-surface product) were compared between patients with favorable (modified Rankin Scale [mRS] = 0–2) and unfavorable (mRS > 2) outcome. Results Thirty patients were included, 50% having favorable and 50% having unfavorable outcome. Younger age was significantly associated with favorable outcome ( P Conclusions No significant difference was observed between patients with and without favorable outcome after mechanical thrombectomy for either permeability-surface product value or permeability-surface product ratio. Although permeability-surface product is a good predictor of blood–brain barrier disruption, this study revealed no evidence that either permeability-surface product value or permeability-surface product ratio is associated with future change in the penumbra.

BackgroundPreliminary clinical studies on the safety and efficacy of the pipeline embolization device (PED) for the treatment of small/medium aneurysms have demonstrated high occlusion rates with low complications.ObjectiveTo evaluate the safety and effectiveness of the PED for treatment of wide necked small and medium intracranial aneurysms.MethodsPREMIER is a prospective, multicenter, single arm trial. Patients were treated with the PED for unruptured wide necked aneurysms, measuring ≤12 mm along the internal carotid artery or vertebral artery, between July 2014 and November 2015. At 1 year post-procedure, the primary effectiveness endpoint was complete occlusion (Raymond grade 1) without major parent vessel stenosis (≤50%) or retreatment, and the primary safety endpoint was major stroke in the territory supplied by the treated artery or neurologic death.ResultsA total of 141 patients were treated with PEDs (mean age 54.6±11.3 years, 87.9% (124/141) women). Mean aneurysm size was 5.0±1.92 mm, and 84.4% (119/141) measured ConclusionsTreatment of wide necked small/medium aneurysms with the PED results in high rates of complete occlusion without significant parent vessel stenosis and low rates of permanent neurologic complications.Trial registrationNCT02186561.

Introduction Stent thrombosis (ST) is a known complication after intracranial stent implantation. The pathophysiology of ST is multifactorial, and standardized treatments for ST remain uncertain. Case Description A patient harboring an unruptured aneurysm of the posterior communicating segment of the left internal carotid artery was treated with stent-assisted coil embolization while on dual antiaggregation therapy. Despite adherence to medication, ST occurred 8 days after the intervention. Following tirofiban infusion, the thrombus dissolved and clinical symptoms improved. However, after tirofiban was stopped, the patient experienced again ischemic symptoms. The patient underwent high-flow extracranial-to-intracranial bypass with good patency of the graft and resolution of symptoms. Conclusions In case of refractory ST, high-flow extracranial-to-intracranial bypass proved to be in this case a feasible and effective rescue option.

OBJECTIVEThe goal of this study was to describe changes in the angioarchitecture of brain arteriovenous malformations (bAVMs) between acute and delayed cerebral digital subtraction angiography (DSA) obtained after hemorrhage, and to examine bAVM characteristics predicting change.METHODSThis is a retrospective study of a prospective institutional bAVM database. The authors included all patients with ruptured bAVMs who had DSA in both acute and delayed phases, with no interval treatment of their bAVM, between January 2000 and April 2017. The authors evaluated the existence or absence of angioarchitectural changes. Demographic data, radiological characteristics of hemorrhages, and angioarchitectural features of the bAVMs of the two patients’ groups were analyzed. Univariate and multivariate logistic analyses were performed to identify predictors of angioarchitectural change.RESULTSA total of 42 patients were included in the series. Seventeen (40.5%) patients had angioarchitectural changes including bAVM only visible on the delayed DSA study (n = 8), spontaneous thrombosis of the AVM (n = 3), or alteration of the size or the opacification of the nidus (n = 6). The factors associated with angioarchitectural changes were a small nidus (3.8 ± 7.9 ml vs 6.1 ± 9.5 ml, p = 0.046), a superficial location (94.1% vs 5.9%, p = 0.016), and a single superficial draining vein (58.8% vs 24.0%, p = 0.029).CONCLUSIONSAngioarchitectural changes can be seen in 40% of ruptured bAVMs between the acute- and delayed-phase DSA. A small nidus, a superficial location, and a single superficial draining vein were statistically associated with the occurrence of angioarchitectural changes. These changes included either enlargement or spontaneous occlusion of the bAVM, as well as subsequent diagnosis of a bAVM following an initial negative DSA study.

The natural history of intradural spinal cord arteriovenous shunts is unknown. We performed an observational study in a consecutive patient cohort with symptomatic intradural spinal cord arteriovenous shunts who were admitted to three institutes to investigate the clinical course of this complex disease, which would provide valuable evidence to inform clinical decision-making. The clinical course of patients with symptomatic intradural spinal cord arteriovenous shunts from initial presentation to occurrence of clinical deterioration, initiation of treatment, or last follow-up was analysed. Patients with at least 1 month of observation were included in this study. Clinical onset and deterioration patterns were divided into acute and gradual. Annual and cumulative rates of clinical deterioration as well as their risk factors were analysed using Kaplan-Meier life table analysis and Cox proportional hazards model. To assess risks and benefits of treatment, post-treatment clinical courses were further assessed. Four hundred and sixty-six patients with a mean observational period of 36.9 ± 58.8 months were included; 56.7% of patients presented with acute onset, of whom 77.3% experienced spontaneous recovery. Age of onset older than 28 years, initial modified Aminoff and Logue scale of >3, mid-thoracic lesions and non-ventral lesions were independent predictors of failure for spontaneous recovery. The annual risk of general, acute and gradual clinical deterioration after onset was 30.7%, 9.9% and 17.7%, respectively. Risk of deterioration was highest in the early period after initial onset. Acute onset was the only independent risk factor [hazard ratio 1.957 (95% confidence interval, CI 1.324–2.894); P = 0.0008] of acute deterioration and gradual onset was the strongest predictor [hazard ratio 2.350 (95% CI 1.711–3.229); P < 0.0001] of the gradual deterioration among all the stratifying factors. After invasive treatment, complete obliteration was achieved in 37.9% of patients (138 of 364) and improved or stable clinical status was noted in 80.8% of patients. Forty-two patients (11.5%) experienced permanent complications. Overall post-treatment deterioration rate was 8.4%/year, and 5.3%/year if permanent complications were excluded. The natural history of symptomatic spinal cord arteriovenous shunts is poor, especially in the early period after onset, and early intervention is thus recommended. Initial onset pattern significantly affects the natural history of the lesion, which prompts a differentiated treatment strategy.

BackgroundFemoral access is the traditional approach for endovascular carotid artery stenting. Radial access is increasingly used as an alternative approach due to its known anatomical advantages in patients with unfavorable aortic arch morphology via the femoral approach and its excellent access site safety profile. Our objective was to analyze procedural success using radial access for carotid artery stenting as reported in the literature.MethodsThree online databases were systematically searched following PRISMA guidelines for studies (n ≥20) using radial artery access for carotid artery stenting (1999–2018). Random-effects meta-analysis was used to pool the procedural success (successful stent placement with no requirement for crossover to femoral access), mortality, and complication rates associated with radial access.ResultsSeven eligible studies reported procedural success outcomes with a pooled meta-analysis rate of 90.8% (657/723; 95% CI 86.7% to 94.2%; I2=53.1%). Asymptomatic radial artery occlusion occurred in 5.9% (95% CI 4.1% to 8.0%; I2=0%) and forearm hematoma in 1.4% (95% CI 0.4% to 2.9%; I2=0%). Risk of minor stroke/transient ischemic attack was 1.9% (95% CI 0.6% to 3.8%; I2=42.3%) and major stroke was 1.0% (95% CI 0.4% to 1.8%; I2=0%). There were three deaths across the seven studies (0.6%; 95% CI 0.2% to 1.3%; I2=0%). The meta-analysis was limited by statistically significant heterogeneity for the primary outcome of procedural success.ConclusionRadial access for carotid artery stenting has a high procedural success rate with low rates of mortality, access site complications, and cerebrovascular complications. The potential benefits of this approach in patients with unfavorable aortic arch access should be explored in a prospective randomized trial.

Background and Purpose— Intracranial atherosclerosis (ICAS) is an important cause of large vessel occlusion and poses unique challenges for emergent endovascular thrombectomy. The risk factor profile and therapeutic outcomes of patients with ICAS-related occlusions (ICAS-O) are unclear. We performed a systematic review and meta-analysis of studies reporting the clinical features and thrombectomy outcomes of large vessel occlusion stroke secondary to underlying ICAS (ICAS-O) versus those of other causes (non–ICAS-O). Methods— A literature search on thrombectomy for ICAS-O was performed. Random-effect meta-analysis was used to analyze the prevalence of stroke risk factors and outcomes of thrombectomy between ICAS-O and non–ICAS-O groups. Results— A total of 1967 patients (496 ICAS-O and 1471 non–ICAS-O) were included. The ICAS-O group had significantly higher prevalence of hypertension (odds ratio [OR] 1.46; 95% CI, 1.10–1.93), diabetes mellitus (OR, 1.68; 95% CI, 1.29–2.20), dyslipidemia (OR, 1.94; 95% CI, 1.04–3.62), smoking history (OR, 2.11; 95% CI, 1.40–3.17) but less atrial fibrillation (OR, 0.20; 95% CI, 0.13–0.31) than the non–ICAS-O group. About thrombectomy outcomes, ICAS-O had higher intraprocedural reocclusion rate (OR, 23.7; 95% CI, 6.96–80.7), need for rescue balloon angioplasty (OR, 9.49; 95% CI, 4.11–21.9), rescue intracranial stenting (OR, 14.9; 95% CI, 7.64–29.2), and longer puncture-to-reperfusion time (80.8 versus 55.5 minutes, mean difference 21.3; 95% CI, 11.3–31.3). There was no statistical difference in the rate of final recanalization (modified Thrombolysis in Cerebral Infarction score of 2b/3; OR, 0.67; 95% CI, 0.36–1.27), symptomatic intracerebral hemorrhage (OR, 0.79; 95% CI, 0.50–1.24), good functional outcome (modified Rankin Scale score of 0–2; OR, 1.16; 95% CI, 0.85–1.58), and mortality (OR, 0.94; 95% CI, 0.64–1.39) between ICAS-O and non–ICAS-O. Conclusions— Patients with ICAS-O display a unique risk factor profile and technical challenges for endovascular reperfusion therapy. Intraprocedural reocclusion occurs in one-third of patients with ICAS-O. Intraarterial glycoprotein IIb/IIIa inhibitors infusion, balloon angioplasty, and intracranial stenting may be viable rescue treatment to achieve revascularization, resulting in comparable outcomes to non–ICAS-O.

BackgroundFlow diverters are a breakthrough treatment for large and giant intracranial aneurysms but carry a risk of periprocedural death or major stroke. Pipeline Flex is a second-generation device that is thought to have lower complication rates because of improvements in the delivery system as well as increased operator experience. Our objective was to analyze the risk of periprocedural death or major complications using Pipeline Flex for unruptured intracranial aneurysms.MethodsA systematic search of three databases was performed for studies of ≥10 treatments using Pipeline Flex for unruptured intracranial aneurysms (2014–2019) using PRISMA guidelines. Random effects meta-analysis was used to pool the rates of periprocedural (ResultsWe included eight studies reporting 901 treatments in 879 patients. Periprocedural mortality (2=0%). Rate of major complications (death, major ischemic stroke, or symptomatic intracranial hemorrhage) was 1.8% (14/901; 95% CI 1.0% to 2.7%; I2=0%). Aneurysm size ≥10 mm was a statistically significant predictor of a major complication (OR 6.4; 95% CI 2.0 to 20.7; p=0.002). Risk of a major complication in aneurysms 2=0%). The meta-analysis was limited by the predominance of anterior circulation aneurysms.ConclusionTreatment of unruptured intracranial aneurysms using the Pipeline Flex flow diverter has a low periprocedural risk of death (0.8%) or major complication (1.8%). The risk of a major complication is significantly higher for large/giant aneurysms (4.4%) and is very low for aneurysms

Purpose Blood velocity and flow rate information may be helpful for a wide variety of applications, but it often requires separate acquisitions. The dynamic information combined with the high spatial resolution of four-dimensional computed tomography angiography (4D-CTA) offers the possibility to quantify blood flow simultaneous to vascular anatomy. Methods A 4D-CTA clinical protocol with a novel dedicated postprocessing were validated in vitro in a patient-specific model, and tested in a pilot study of six patients. Blood flow was assessed in both internal carotid (ICAs) and vertebral (VAs) arteries by analyzing spatial displacement of contrast agent in the form of time-intensity curves (TICs). Unlike previous approaches, it does not require any a priori assumptions about TIC shape, but rather computes mean velocity and flow rates from the spatial displacement of the TICs along the automatically segmented vessels. Results In vitro experiments showed good agreement between 4D-CTA and flowmeter measurements under steady and pulsatile flow conditions. In vivo measurements exhibited large interpatient variability of the TIC shapes, from which blood flow rates could nevertheless be successfully measured in all patients and investigated vessels. On average, measured flow rates were 3.2 ± 0.7 ml/s (in ICAs) and 1.3 ± 0.8 ml/s (in VAs) consistent with previous reference standards. Contrary to our novel approach, which considered the full TIC shape, application of previous time-to-peak analyses based on idealized TIC shapes showed limited reliability. Conclusions We demonstrate the high potential of 4D-CTA for assessing blood velocity and flow rate in addition to anatomical evaluation. The wide variety of TIC shapes encountered in vivo highlights the importance of an adaptive TIC analysis as proposed in the present work.

Background and objectivePulsatile tinnitus (PT) can be debilitating and lead to significant morbidity. Cerebral venous sinus lesions, such as venous sinus stenosis, diverticula, and high-riding jugular bulb, are uncommon causes of PT, for which there is no standard treatment. Endovascular interventions have shown promising results for PT secondary to idiopathic intracranial hypertension, and may be a valid therapeutic option for isolated venous PT.MethodsWe conducted a systematic literature review on the outcome and safety of endovascular treatment for patients with isolated, debilitating venous PT. The venous lesion characteristics, endovascular techniques, complications, and clinical outcomes were assessed. In addition, an illustrative case of endovascular stenting for PT caused by venous sinus stenosis was included.ResultsA total of 41 patients (90.2% female) from 26 papers were included. The median age was 46 years (IQR 23; range 25–72 years). Focal venous sinus stenosis (20 patients) and sinus diverticula (14 patients) were the most common culprit lesions. Endovascular treatment included venous sinus stenting in 35 patients, 11 of whom had adjuvant coil embolization, and coil embolization alone in six patients. Complete resolution of the tinnitus was achieved in 95.1% of patients. There was one complication of cerebellar infarct, and no procedure-related mortality.ConclusionsIn patients with debilitating PT secondary to venous sinus lesions, endovascular treatment by stenting and/or coil embolization appears to be safe and effective. Prospective randomized studies with objective outcome assessments are needed to confirm the treatment benefits.

Flow modification has caused a paradigm shift in the management of intracranial aneurysms. Since the FDA approval of the Pipeline Embolization Device (Medtronic, Dublin, Ireland) in 2011, it has grown to become the modality of choice for a range of carefully selected lesions, previously not amenable to conventional endovascular techniques. While the vast majority of flow-diverting stents operate from within the parent artery (ie, endoluminal stents), providing a scaffold for endothelial cells growth at the aneurysmal neck while inducing intra-aneurysmal thrombosis, a smaller subset of endosaccular flow disruptors act from within the lesions themselves. To date, these devices have been used mostly in Europe, while only utilized on a trial basis in North America. To the best of our knowledge, there has been no dedicated review of these devices. We therefore sought to present a comprehensive review of currently available endosaccular flow disruptors along with high-resolution schematics, presented with up-to-date available literature discussing their technical indications, procedural safety, and reported outcomes.

OBJECTIVEFlow diversion for posterior circulation aneurysms performed using the Pipeline embolization device (PED) constitutes an increasingly common off-label use for otherwise untreatable aneurysms. The safety and efficacy of this treatment modality has not been assessed in a multicenter study.METHODSA retrospective review of prospectively maintained databases at 8 academic institutions was performed for the years 2009 to 2016 to identify patients with posterior circulation aneurysms treated with PED placement.RESULTSA total of 129 consecutive patients underwent 129 procedures to treat 131 aneurysms; 29 dissecting, 53 fusiform, and 49 saccular lesions were included. At a median follow-up of 11 months, complete and near-complete occlusion was recorded in 78.1%. Dissecting aneurysms had the highest occlusion rate and fusiform the lowest. Major complications were most frequent in fusiform aneurysms, whereas minor complications occurred most commonly in saccular aneurysms. In patients with saccular aneurysms, clopidogrel responders had a lower complication rate than did clopidogrel nonresponders. The majority of dissecting aneurysms were treated in the immediate or acute phase following subarachnoid hemorrhage, a circumstance that contributed to the highest mortality rate in those aneurysms.CONCLUSIONSIn the largest series to date, fusiform aneurysms were found to have the lowest occlusion rate and the highest frequency of major complications. Dissecting aneurysms, frequently treated in the setting of subarachnoid hemorrhage, occluded most often and had a low complication rate. Saccular aneurysms were associated with predominantly minor complications, particularly in clopidogrel nonresponders.

Background and purpose Recent studies suggest that thrombus imaging characteristics such as Hounsfield unit (HU) and perviousness assessed on noncontrast computed tomography (NCCT) and CT angiography (CTA) can predict successful recanalization. We assessed whether these thrombus imaging characteristics could predict successful first-pass recanalization. Methods We retrospectively reviewed cases of mechanical thrombectomy over a three-year period in which patients received a multiphase CTA and were treated with a stent retriever on first pass. Thrombus attenuation, thrombus enhancement on arterial- and delayed-phase CTA and percentage washout were calculated and their association with first-pass recanalization, successful recanalization and distal embolic complications was studied. Results Fifty-two mechanical thrombectomy patients were included. First-pass recanalization was achieved in 59.6% and complete revascularization (Thrombolysis in Cerebral Infarction scale 2b/3) was achieved in 84.6%. There was no correlation between first-pass recanalization with thrombus density on NCCT ( p = 0.94), percentage enhancement on arterial ( p = 0.61) and delayed-phase CTA ( p = 0.23) or thrombus length ( p = 0.16). There was no correlation between number of passes and either thrombus density on NCCT ( p = 0.91) or percentage enhancement on arterial- ( p = 0.79) and delayed-phase ( p = 0.14) CTA or thrombus length ( p = 0.34). Clot length was significantly higher in patients with distal embolic complications than in those without (18.5 ± 7.9 vs 11.4 ± 6.6 mm, p = 0.005). Conclusions Our data suggest that thrombus imaging characteristics on multiphase CTA cannot predict first-pass recanalization or successful revascularization in acute ischemic stroke patients treated with stent retrievers. Longer clot length was associated with higher risk of distal embolic complications.

Objective Intracranial dural arteriovenous fistulas (DAVFs) can manifest with a reversible form of dementia and parkinsonism that may be related to medullary venous hypertension and impaired cortical venous drainage. We report a consecutive case series of patients with DAVFs who presented with cognitive decline and report angioarchitecture and outcomes of treatment. Methods From a prospectively collected database of 389 cranial DAVFs, we identified patients who presented with progressive dementia. Data collected included demographic characteristics, other presenting symptoms, fistula location and type, preoperative and postoperative imaging findings, and treatment outcomes. Descriptive statistics were reported. Results Of 389 patients with DAVF, 6 patients with progressive dementia (1.4%) were identified. All patients were male. Mean patient age was 68.6 years. Four patients had superior sagittal sinus DAVFs, 1 patient had a tentorial DAVF, and 1 patient had a transverse sinus DAVF. All patients had evidence of medullary venous hypertension on imaging with either reflux and arterialization of the transmedullary veins or venous congestion of the transmedullary veins. All patients underwent endovascular treatment and had reversal of dementia-related symptoms after a mean follow-up of 6.2 months. Conclusions Cognitive decline is a rare but reversible manifestation of DAVFs that have impaired venous drainage of the transmedullary veins and associated medullary venous hypertension.

Background and Purpose: The aim of this study was to investigate the efficacy of thrombus density on noninvasive computed tomography (CT) neuroimaging for predicting thrombus pathology and patient outcome after mechanical thrombectomy in acute ischemic stroke. Materials and Methods: This retrospective chart and imaging review included patients that were treated by mechanical thrombectomy at Siriraj Hospital according to the American Heart Association/American Stroke Association guidelines for the early management of patients with acute ischemic stroke from March 2010 to February 2015 study period. Preintervention noncontrast CT (NCCT), CT angiography (CTA), and/or contrast-enhanced CT (CECT) images were interpreted using CT densitometry. Pathology results were classified as white, red, or mixed thrombi. The result of treatment was evaluated by the modified Rankin Scale at 90 days after treatment. Results: From 97 included patients – 97 NCCT images, 48 CTA images, 48 CECT images, and 54 pathologic results of cerebral thrombi were included in the final analysis. Mean clot Hounsfield unit values on NCCT, CTA, and CECT were significantly different between red and white thrombus (P = 0.001 on NCCT, P = 0.03 on CTA, and P = 0.001 on CECT), and between red and mixed thrombus (P = 0.043 on NCCT and P = 0.002 on CTA). However, no significant difference was observed between white thrombus and mixed thrombus (P = 0.09 on NCCT, P = 1.00 on CTA, and P = 0.054 on CECT). There was no significant correlation between type of cerebral thrombus or clot density and the result of treatment. Conclusion: Thrombus density on CT was found to be a significant predictor of thrombus pathology; however, no significant association was observed between thrombus type or clot density and patient outcome after mechanical thrombectomy.

Hereditary hemorrhagic telangiectasia (HHT) is generally considered a disorder of endothelial dysfunction, characterized by the development of multiple systemic arteriovenous malformations (AVMs), including within the brain. However, there have recently been a number of reports correlating HHT with malformations of cortical development, of which polymicrogyria is the most common type. Here we present 7 new cases demonstrating polymicrogyria in HHT, 6 of which demonstrate a brain AVM (bAVM) in close spatial proximity, with the aim of providing a common origin for the association. Upon reviewing patient genetics and imaging data and comparing with previously reported findings, we form 2 new conclusions: (1) polymicrogyria in HHT appears exclusively associated with a subset of mutations in the transmembrane protein endoglin that is involved with blood flow–related mechanotransduction signaling during angiogenesis and (2) the polymicrogyria is characteristically unilateral, typically focal, and correlates with vascular regions experiencing low fluid shear stress during corticogenesis in utero. Integrating these with findings in the literature from genetics and molecular biology experiments, we propose a theory suggesting haploinsufficient endoglin mutations, especially those that are dominant-negative, may predispose focal, aberrant hypersprouting angiogenesis during corticogenesis that leads to the production of polymicrogyria. This hypoxic insult may further serve as the revealing trigger for later development of a spatially coincident bAVM. This hypothesis suggests an essential role for endoglin-mediated hemodynamic mechanotransduction in normal corticogenesis.

Background Flow diversion for basilar apex aneurysms has rarely been reported. Objective To assess flow diversion for basilar apex aneurysms in a multicenter cohort. Methods Retrospective review of prospectively maintained databases at 8 academic institutions was performed from 2009 to 2016 to identify patients with basilar apex aneurysms treated with flow diversion. Clinical and radiographic data were analyzed. Results Sixteen consecutive patients (median age 54.5 yr) underwent 18 procedures to treat 16 basilar apex aneurysms with either the Pipeline Embolization Device (Medtronic Inc, Dublin, Ireland) or Flow Redirection Endoluminal Device (Microvention, Tustin, California). Five aneurysms (31.3%) were treated in the setting of subarachnoid hemorrhage. Seven aneurysms (43.8%) were treated with flow diversion alone, while 9 (56.2%) underwent flow diversion and adjunctive coiling. At a median follow-up of 6 mo, complete (100%) and near-complete (90%-99%) occlusion was noted in 11 (68.8%) aneurysms. Incomplete occlusion occurred more commonly in patients treated with flow diversion alone compared to those with adjunctive coiling. Patients with partial occlusion were significantly younger. Retreatment with an additional flow diverter and adjunctive coiling occurred in 2 aneurysms with wide necks. There was 1 mortality in a patient (6.3%) who experienced posterior cerebral artery and cerebellar strokes as well as subarachnoid hemorrhage after the placement of a flow diverter. Minor complications occurred in 2 patients (12.5%). Conclusion Flow diversion for the treatment of basilar apex aneurysms results in acceptable occlusion rates in highly selected cases. Both primary flow diversion and rescue after failed clipping or coiling resulted in a modified Rankin Scale score that was either equal or better than at presentation and the technology represents a viable alternative or adjunctive option.

BackgroundThe use of robotics in medicine may enable increased technical accuracy, reduced procedural time and radiation exposure, and remote completion of procedures. We have previously described the first-in-human, robotic-assisted cerebral aneurysm treatment using the CorPath GRX Robotic System. In this report we discuss our early experiences and outcomes using this robotic device for endovascular treatment of intracranial aneurysms using stent-assisted coil embolization and flow diversion.MethodsThe patient and disease characteristics, procedural details, and follow-up imaging and clinical outcomes of consecutive patients undergoing robotically-assisted intracranial aneurysm embolization between November 2019 and February 2020 are presented.ResultsSix patients underwent robotically-assisted embolization of intracranial aneurysms. Four of the patients were treated with a neck-bridging stent (with or without coiling) and two patients were treated with a flow-diverting stent. Two patients were treated in the subacute period of subarachnoid hemorrhage and four patients were treated electively. All of the procedures could be completed robotically and there was no need for unplanned manual intervention. The technical success rate of the procedures was 100%. There was no morbidity or mortality associated with the procedures. One year follow-up imaging showed that four aneurysms were completely obliterated (Raymond-Roy Occlusion Classification (RROC) class I) and the remaining two were occluded with a residual neck (RROC class II).ConclusionsThe Corpath GRX Robotic System demonstrated a precise control over the microcatheter, wire and stent during aneurysm treatment. Robotic neuro-procedures seem to be safe and effective and demonstrate stable occlusion results in the midterm follow-up.

Brain arteriovenous malformations (AVMs) are characterized by shunting between pial arteries and cortical or deep veins, with the presence of an intervening nidus of tortuous blood vessels. These lesions present a therapeutic challenge, because their natural history entails a risk of intracranial hemorrhage, but treatment may cause significant morbidity. In this article, imaging features of AVMs on MR imaging and catheter angiography are reviewed to stratify the risk of hemorrhage and guide appropriate management. The angioarchitecture of AVMs may evolve over time, spontaneously or in response to treatment, necessitating ongoing imaging surveillance.

Background Focal brain edema in unruptured brain arteriovenous malformations (AVMs) is rare and associated with venous outflow abnormalities and aneurysm growth. These patients have an increased rate of progressive neurologic symptoms, as well as a potentially increased risk of hemorrhage. In this study, we aim to assess in further detail the relationship between perifocal edema and enhancement of the vessel wall in symptomatic patients with an unruptured brain AVM. Methods A single-center retrospective cohort study of all patients presenting with an unruptured AVM at Toronto Western Hospital from 2009 to 2019 was performed. Patients were included for review if they had focal edema surrounding an AVM on magnetic resonance imaging (MRI) and a contrast-enhanced MRI scan. Associated digital subtraction angiography studies were reviewed. Results A total of 122 patients presented with an unruptured AVM. Twelve symptomatic patients presented with focal edema surrounding the AVM. Six patients had focal edema and contrast-enhanced MRI performed. All 6 demonstrated luminal thrombosis at the level of the brain edema on MRI. Moreover, the vessel wall demonstrated enhancement at the level of the luminal thrombus in all. Conclusions Vessel wall enhancement, perifocal edema, and luminal thrombosis demonstrated in all patients with unruptured AVM points towards a common mechanism. We suspect an interplay between vascular hypoxia, the innate immune system, and thrombosis formation. Current research in the field of immunothrombosis supports this theory. Unravelling the mechanisms involved is important because it might guide therapy for patients with an unruptured AVM towards noninvasive options.

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 the multimodal treatment approach to isolated sinus DAVFs in a large single-center cohort.MethodsRetrospective analysis of adult patients with an isolated sinus DAVF treated at our institution between 2004 and 2020 was performed. Cases were analyzed for demographics, clinical presentation, angiographic findings, treatment techniques, angiographic and clinical outcomes, and complications.ResultsOf 317 patients with DAVFs, 20 (6.3%) with an isolated sinus DAVF underwent treatment. Transarterial embolization was performed through the middle meningeal artery in 9 of 12 procedures, with a success rate of 66.7%. Transarterial glue embolization proved successful in two of five procedures (40%) and Onyx in six of seven procedures (85.7%). Transvenous embolization (TVE) with navigation via the occlusion into the isolated sinus was successful in seven out of nine procedures (77.8%). All three open TVE and one pure open surgical procedure gained complete closure of the fistula. There were two major complications. Complete occlusion of the fistula was eventually obtained in all cases (100%).ConclusionsIsolated sinus DAVFs are always aggressive and require a multimodal approach to guarantee closure of the shunt. Transarterial treatment with Onyx achieves good results. Transvenous treatment appears equally successful, navigating into the occluded segment across the occlusion or via burr hole as backup.

Background: Accurate and reliable models of intracranial hemorrhage (ICH) risk in the untreated course of brain arteriovenous malformation (BAVM) patients are needed to help weigh the risk-benefit of treatment. We present preliminary estimates of rates and risk factors for ICH or death in the Multicenter AVM Research Study (MARS), which is the largest individual patient data meta-analysis (IPDMA) of cohort studies of unruptured BAVM. Methods: Longitudinal data from 9 cohorts comprising 2,839 unruptured BAVM at time of diagnosis were included: UCSF (n=557), Macquarie (n=462), Kaiser Permanente Northern California (n=354), Columbia (n=335), Barrow Neurological Institute (n=324), Tiantan Hospital (n=303), Mayo Clinic-Rochester (n=244), Scottish Intracranial Vascular Malformation Study (n=194), and Toronto Western Hospital (n=66). Clinical and angiographic data were collected using standardized definitions across cohorts. Cox proportional hazards analysis of time-to-event (ICH or death) in the untreated course after diagnosis was performed, censoring at first treatment or last visit. Baseline hazard rates were stratified by cohort to account for different rates and follow-up times. Results: The combined cohort was 49% female, 72% white race, and 17% Hispanic ethnicity; mean age at diagnosis was 37±17 years and mean follow-up was 3.4±7.0 years. The most common presenting symptom was seizures (43%). Mean AVM size was 3.5±1.9 cm and 46% were Spetzler-Martin grade I-II. Overall, 123 ICH and 131 deaths occurred over 9,608 person-years (PY) for an event rate of 2.64 per 100 PY [95% CI: 2.34-2.99]. Cox regression analyses adjusting for age at diagnosis (HR=1.67 [1.54, 1.82], P Conclusion: Our current model identified increasing age, exclusively deep venous drainage, and cerebellar location as risk factors for ICH or death in the untreated course of unruptured bAVM patients. Review of imaging data, multiple imputation of missing angioarchitectural data, and additional data from pending cohorts will provide greater power to search for additional risk factors in this ongoing IPDMA.

Background Vessel wall imaging (VWI) of cerebral aneurysms is a new tool to risk stratify unruptured aneurysms. We hypothesized that the degree and pattern of aneurysm wall enhancement may predict the regrowth of these aneurysms. The aim of this study was to identify patient risk factors and VWI parameters associated with aneurysm regrowth. Methods We retrospectively reviewed 71 saccular aneurysms and 75 follow-up VWI studies in patients who underwent the coil embolization procedure for unruptured saccular aneurysm. The relationship between VWI enhancement and aneurysm regrowth was analyzed by Pearson’s chi-square test. Diagnostic performance of VWI enhancement in the diagnosis of regrowth aneurysm was determined to compare with digital subtraction angiography (DSA), and contrast-enhanced magnetic resonance angiography (CE-MRA) or time-of-flight MRA (TOF-MRA). Inter-rater agreement was measured by Cohen’s kappa coefficient. Results Fourteen of 71 aneurysms (19.71%) were categorized into the aneurysm regrowth group, while aneurysm wall enhancement was found in 55 studies (73.33%). All wall enhancements were found in the aneurysm regrowth group, and no significant association was found between aneurysm regrowth and patient risk factors or VWI parameters. The diagnostic performance parameters of VWI relative to the DSA, and CE-MRA or TOF-MRA results were 100% sensitivity, 38.5% specificity, 30.4% positive predictive value, 100% negative predictive value, and 52% accuracy. Conclusions Wall enhancement of post-coil embolization of saccular aneurysm on VWI may be used as a screening imaging test to predict aneurysm regrowth, and may help to identify an unstable aneurysm, if the degree of enhancement increase or change of the pattern.

Background Delivery of most flow diverters (FD) requires larger, and thus stiffer microcatheters (0.021–0.027in.) which can pose challenges to intracranial navigation. The concomitant use of two microwires within one microcatheter, also known as the buddy-wire technique, may be helpful for navigation and support in challenging situations. Methods We analyzed all flow diverter procedures in our prospectively collected database. We recorded all patient-related, anatomical and procedural information. We performed univariate statistics and technical descriptions. Results In total, 208 consecutive patients treated with a FD at our institution between July 2014 and August 2020 were retrospectively analyzed. In 17 patients the buddy-wire technique was used (mean age 63 years, range 31–87 years: 16 female). Aneurysms were located at the petrous, cavernous, supraophthalmic internal carotid artery, and a proximal M2 branch in 2, 7, 7 and 1 patient(s), respectively. In all cases a 0.027in. microcatheter was used for device deployment. In 14 patients with a wide-necked aneurysm the buddy-wire provided additional support to advance the microcatheter and mitigated the ledge between the aneurysm neck and the parent artery or a side branch. In two giant cavernous aneurysms treated with telescoping FDs, the buddy-wire was used to re-enter the proximal end of the foreshortened FD. Conclusion The buddy-wire is a useful technique in FD procedures to prevent herniation of the microcatheter into the aneurysm sack, in wide-necked aneurysms to mitigate the ledge effect between the aneurysm neck and the parent artery where the microcatheter tip may get stuck, or to enable re-entry into a foreshortened FD.

Transdural blood supply (TDBS) to pial brain arteriovenous malformations (BAVM) is uncommon and believed to be related to vascular endothelial growth factor - induced angiogenesis. The aim of this study was to define the BAVM characteristics in relation to presence and volume of TDBS.BAVMs managed at our institution between January 2006 and December 2016 who subsequently underwent complete digital subtraction angiography (DSA) were included. They were classified based on presence of TDBS as well as volume of TDBS.Of the 641 BAVM patients managed during the recruitment period, 387 (391 BAVMs) had complete pretreatment DSAs. Forty-three (11.0 %, 10 ruptured) BAVMs exhibited TDBS. With TDBS group had a significantly greater proportion of large nidus (3.1 cm) than the Without TDBS group (85.1 % vs 19.5 %, p0.01) and were more frequently temporal (32.6 % vs 14.7 %, p0.01) and occipital (25.6 % vs 13.5 %, p0.05) in location. In unruptured BAVMs, the presence of headaches was significantly more prevalent when the malformation harboured TDBS compared to not (57.6 vs 34.8 %, p0.05). The annual rupture rate among unruptured BAVMs treated by conservative management was 4.7 % in the With TDBS (n = 12) group and 0% (n = 21) in BAVMs with TDBS that underwent treatment including surgery, endovascular therapy, or radiosurgery.BAVMs with TDBS are more likely to be associated with a large nidus and located in the temporal and occipital lobes. Headache is more frequently associated with the presence of TDBS. Rupture rate of unruptured BAVMS with TDBS can be effectively reduced following treatment.

There is limited data on the effectiveness of endovascular therapy (EVT) in stroke patients with active malignancy. In this study, we investigated the outcome of EVT for acute ischemic stroke for patients with active malignancy compared to those without malignancy.We selected patients who underwent EVT for acute ischemic stroke between January 2015 and July 2019. Patients were divided into two groups, those with active malignancy (oncology group - OG) and those without (non-oncology group, NOG).300 patients were included in this study. There were 19 EVT procedures (18 patients) in the OG and 285 procedures (282 patients) in the NOG. There was no difference in recanalization success rate (mTICI 2b3) between the groups: 94.7% versus 80.9% in OG and NOG respectively (p = 0.13). Success rate using the direct aspiration (ADAPT) technique of EVT was not different between compared groups (42.9% versus 67.7%; p = 0.18). However, when using smaller-caliber aspiration devices, ADAPT was less successful in OG (0.0% versus 64.7%, p 0.05). There was no difference in recanalization success rate of EVT when using a stent-retriever or combined technique. Patients in the OG had a less favorable functional outcome than in the NOG group (mRS 0-2 at 90-days post event: 22.2% versus 48.2%, p 0.05) CONCLUSION: The technical success rate of EVT in patients with active malignancy is similar to the general population of stroke patients. Interestingly, the success rate of EVT using the ADAPT technique was lower in the OG when using smaller caliber aspiration devices.