Embolization techniques of spontaneous direct carotid-cavernous fistulae: a single-center experience.

PURPOSE: Spontaneous direct carotid-cavernous fistula (CCF) are usually caused by a ruptured carotid cavernous aneurysm. We studied treatment of spontaneous direct CCFs in a single-center cohort of a high-volume tertiary referral center, reporting anatomical details, technical approaches of treatment, and outcomes. METHODS: Adult patients with a spontaneous direct CCF treated between 2010-2022 with follow-up MRI and/or DSA imaging available were retrospectively analyzed. We studied age, sex, clinical presentation, angiographic findings, treatment techniques, outcomes, and complications. RESULTS: Out of 80 patients with CCFs, twelve patients were treated for a non-traumatic direct CCF (15%) in 13 sessions. Median age was 65 years. Two patients had an underlying connective tissue disorder. In 10 cases, the direct CCF was caused by a ruptured cavernous carotid aneurysm. The direct CCFs were treated by endovascular transarterial embolization (10 cases), transvenous embolization (1 case), or surgery (1 case). Selective closure of the shunt was possible in 10 patients. Two patients were treated with parent vessel occlusion (PVO; one endovascular; one surgical, with bypass). Complications occurred in 2 / 12 patients (17%), with permanent morbidity in two patients (17%): trigeminal neuralgia after PVO and new infarct after surgical PVO and bypass. Selective closure of CCF resulted in no morbidity. There was no mortality in our series. CONCLUSION: Spontaneous direct CCFs are caused by rupture of a cavernous carotid aneurysm in most cases. Selective closure of the shunt, usually feasible transarterially with coils, achieves good results. Reconstructive endovascular techniques are preferred to minimize treatment related neurological complications.

Current Concepts in Intracranial Interstitial Fluid Transport and the Glymphatic System: Part I-Anatomy and Physiology.

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.

Current Concepts in Intracranial Interstitial Fluid Transport and the Glymphatic System: Part II-Imaging Techniques and Clinical Applications.

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.

Standards of Practice in Acute Ischemic Stroke Intervention International Recommendations.

After five positive randomized controlled trials showed benefit of mechanical thrombectomy in the management of acute ischemic stroke with emergent large-vessel occlusion, a multi-society meeting was organized during the 17th Congress of the World Federation of Interventional and Therapeutic Neuroradiology in October 2017 in Budapest, Hungary. This multi-society meeting was dedicated to establish standards of practice in acute ischemic stroke intervention aiming for a consensus on the minimum requirements for centers providing such treatment. In an ideal situation, all patients would be treated at a center offering a full spectrum of neuroendovascular care (a level 1 center). However, for geographical reasons, some patients are unable to reach such a center in a reasonable period of time. With this in mind, the group paid special attention to define recommendations on the prerequisites of organizing stroke centers providing medical thrombectomy for acute ischemic stroke, but not for other neurovascular diseases (level 2 centers). Finally, some centers will have a stroke unit and offer intravenous thrombolysis, but not any endovascular stroke therapy (level 3 centers). Together, these level 1, 2, and 3 centers form a complete stroke system of care. The multi-society group provides recommendations and a framework for the development of medical thrombectomy services worldwide.

Novel Technique Using Cyanoacrylate and Local Hemostatic Agents in the Management of High-Risk Exodontia Bleeding in a Patient With a Large Facial Arteriovenous Malformation.

PURPOSE: This report describes a case of a 32-year-old woman who had been diagnosed with a facial arteriovenous malformation during childhood. Because this patient possessed a major risk of perioperative hemorrhage, the use of several local hemostatic measures was thoroughly explored before routine exodontia. MATERIALS AND METHODS: Selective embolization of the right superior thyroid artery was performed intraoperatively and a novel hemostatic technique using a combination of a packing of Gelfoam wrapped in Surgicel was placed within the extraction sites and sealed with SwiftSet. RESULTS: Local hemostasis was achieved with a novel technique using a combination of cyanoacrylate and local hemostatic agents despite aggressive hemorrhaging after routine exodontia. CONCLUSION: By exploiting the local properties of these agents, local hemostasis can be achieved with this novel technique even in the most challenging cases of vascular anomalies.

Venous vascular malformation of the floor of mouth masquerading as a dermoid tumor.

Venous vascular malformations (VVMs) are described as abnormal post-capillary lesions which exhibit low flow. These are typically malleable and may grow with endocrine fluctuations. A VVM that mimics the classic appearance of dermoid tumor on imaging has never been reported. We encountered a 43-year-old woman with intermittent dysphagia relating to a firm submandibular mass. Physical exam and cross-sectional imaging revealed features consistent with variant dermoid cyst. However, catheter angiography eventually demonstrated a VVM which possessed vessels of variable size and partial thrombosis. We report the case and propose that catheter angiography remains important in cases where vascular malformation is considered.

Clinical, radiological, and flow-related risk factors for growth of untreated, unruptured intracranial aneurysms.

BACKGROUND AND PURPOSE: Unruptured intracranial aneurysms are frequently followed to monitor aneurysm growth. We studied the yield of follow-up imaging and analyzed risk factors for aneurysm growth. METHODS: We included patients with untreated, unruptured intracranial aneurysms and ≥6 months of follow-up imaging from 2 large prospectively collected databases. We assessed the proportion of patients with aneurysm growth and performed univariable and multivariable Cox regression analyses to calculate hazard ratios with corresponding 95% confidence intervals (CI) for clinical and radiological risk factors for aneurysm growth. We repeated these analyses for the subset of small (<7 mm) aneurysms. RESULTS: Fifty-seven (12%) of 468 aneurysms in 363 patients grew during a median follow-up of 2.1 years (total follow-up, 1372 patient-years). In multivariable analysis, hazard ratios for aneurysm growth were as follows: 1.1 (95% CI, 1.0-1.2) per each additional mm of initial aneurysm size; 2.7 (95% CI, 1.2-6.4) for dome > neck ratio; 2.1 (95% CI, 0.9-4.9) for location in the posterior circulation; and 2.0 (95% CI, 0.8-4.8) for multilobarity. In the subset of aneurysms <7 mm, 37 of 403 (9%) enlarged. In multivariable analysis, hazard ratios for aneurysm growth were 1.1 (95% CI, 0.8-1.5) per each additional mm of initial aneurysm size, 2.2 (95% CI, 1.0-4.8) for smoking, 2.9 (95% CI, 1.0-8.5) for multilobarity, 2.4 (95% CI, 1.0-5.8) for dome/neck ratio, and 2.0 (95% CI, 0.6-7.0) for location in the posterior circulation. CONCLUSIONS: Initial aneurysm size, dome/neck ratio, and multilobarity are risk factors for aneurysm growth. Cessation of smoking is pivotal because smoking is a modifiable risk factor for growth of small aneurysms.

Hemorrhage rates from brain arteriovenous malformation in patients with hereditary hemorrhagic telangiectasia.

BACKGROUND AND PURPOSE: Hereditary hemorrhagic telangiectasia (HHT) is a systemic disease characterized by mucocutaneous telangiectasias, epistaxis, and arteriovenous malformations (AVMs). Intracranial hemorrhage (ICH) rates in this population are not well described. We report ICH rates and characteristics in HHT patients with brain AVMs (HHT-BAVMs). METHODS: We studied the first 153 HHT-BAVM patients with follow-up data enrolled in the Brain Vascular Malformation Consortium HHT Project. We estimated ICH rates after BAVM diagnosis. RESULTS: The majority of patients were women (58%) and white (98%). The mean age at BAVM diagnosis was 31±19 years (range, 0-70), with 61% of cases diagnosed on asymptomatic screening. Overall, 14% presented with ICH; among symptomatic cases, 37% presented ruptured. During 493 patient-years of follow-up, 5 ICH events occurred yielding a rate of 1.02% per year (95% confidence interval, 0.42-2.44%). ICH-free survival differed significantly by ICH presentation (P=0.003); ruptured cases had a higher ICH rate (10.07%; 95% confidence interval, 3.25-31.21%) than unruptured cases (0.43%; 95% confidence interval, 0.11-1.73%). CONCLUSIONS: Patients with HHT-BAVM who present with hemorrhage are at a higher risk for rehemorrhage compared with patients with BAVM detected presymptomatically.

Natural history and management of basilar trunk artery aneurysms.

BACKGROUND AND PURPOSE: Basilar trunk aneurysms (BTAs), defined as aneurysms distal to the basilar origin and proximal to the origin of the superior cerebellar artery, are rare and challenging to manage. We describe the natural history and management in a consecutive series of BTAs. METHODS: Between 2000 and 2013, 2522 patients with 3238 aneurysms were referred to our institution for aneurysm management. A retrospective review of this database was conducted to identify all patients with BTAs. RESULTS: In total, 52 patients had a BTA. Mean age was 56 (SD±18) years. Median clinical follow-up was 33 (interquartile range, 8-86) months, and imaging follow-up was 26 (interquartile range, 2-80.5) months. BTAs were classified into 4 causal subtypes: acute dissecting aneurysms, segmental fusiform ectasia, mural bleeding ectasia, and saccular aneurysms. Multiple aneurysms were more frequently noticed among the 13 saccular aneurysms when compared with overall population (P=0.021). There was preponderance of segmental ectasia or mural bleeding ectasia (P=0.045) in patients presenting with transit ischemic attack/stroke or mass effect. Six patients with segmental and 4 with mural bleeding ectasia demonstrated increasing size of their aneurysm, with 2 having subarachnoid hemorrhage caused by aneurysm rupture. None of the fusiform aneurysms that remained stable bled. CONCLUSIONS: BTAs natural histories may differ depending on subtype of aneurysm. Saccular aneurysms likely represent an underlying predisposition to aneurysm development because more than half of these cases were associated with multiple intracranial aneurysms. Intervention should be considered in segmental ectasia and chronic dissecting aneurysms, which demonstrate increase in size over time as there is an increased risk of subarachnoid hemorrhage.

PHASES Score for Prediction of Intracranial Aneurysm Growth.

BACKGROUND AND PURPOSE: Growth of an intracranial aneurysm occurs in around 10% of patients at 2-year follow-up imaging and may be associated with aneurysm rupture. We investigated whether PHASES, a score providing absolute risks of aneurysm rupture based on 6 easily retrievable risk factors, also predicts aneurysm growth. METHODS: In a multicenter cohort of patients with unruptured intracranial aneurysms and follow-up imaging with computed tomography angiography or magnetic resonance angiography, we performed univariable and multivariable Cox regression analyses for the predictors of the PHASES score at baseline, with aneurysm growth as outcome. We calculated hazard ratios and corresponding 95% confidence intervals (CI), with the PHASES score as continuous variable and after division into quartiles. RESULTS: We included 557 patients with 734 unruptured aneurysms. Eighty-nine (12%) aneurysms in 87 patients showed growth during a median follow-up of 2.7 patient-years (range 0.5-10.8). Per point increase in PHASES score, hazard ratio for aneurysm growth was 1.32 (95% CI, 1.22-1.43). With the lowest quartile of the PHASES score (0-1) as reference, hazard ratios were for the second (PHASES 2-3) 1.07 (95% CI, 0.49-2.32), the third (PHASES 4) 2.29 (95% CI, 1.05-4.95), and the fourth quartile (PHASES 5-14) 2.85 (95% CI, 1.43-5.67). CONCLUSIONS: Higher PHASES scores were associated with an increased risk of aneurysm growth. Because higher PHASES scores also predict aneurysm rupture, our findings suggest that aneurysm growth can be used as surrogate outcome measure of aneurysm rupture in follow-up studies on risk prediction or interventions aimed to reduce the risk of rupture.

Clinical characteristics and preferential location of intracranial mirror aneurysms: a comparison with non-mirror multiple and single aneurysms.

INTRODUCTION: The purpose of our study was to compare the clinical characteristics and preferential localization of aneurysms in three patient groups: single aneurysm, non-mirror multiple aneurysms, and mirror aneurysms. METHODS: We retrospectively reviewed the clinical and radiological data of 2223 consecutive patients harboring 3068 aneurysms registered at the Toronto Western Hospital between May 1994 and November 2010. The patients were divided into single, non-mirror multiple, or mirror aneurysm groups. Expected incidences of mirror aneurysms at each location were calculated on the basis of the single aneurysm incidences at each location. RESULTS: Patients with mirror aneurysms (n = 197) did not differ from patients with non-mirror multiple aneurysms (n = 392) in having female predominance (81.7 vs. 76.3 %) or a family history of intracranial aneurysm (20.5 vs. 17.6 %). When compared with expected incidences at each location, mirror aneurysms were more frequently found at the cavernous internal carotid artery (30 vs. 11.5 %) (p < 0.0001). Mirror aneurysms involving the posterior circulation were less frequent (6.7 %) than aneurysms in the single (19.6 %) or non-mirror multiple aneurysm groups (18.9 %) (p < 0.05). CONCLUSION: Patients with mirror aneurysms had similar clinical characteristics to non-mirror multiple aneurysm patients. Mirror aneurysms showed a predilection for the cavernous carotid artery, whereas they were comparatively rare in the posterior circulation.

Imaging diagnosis and the role of endovascular embolization treatment for vascular intraspinal tumors.

Intraspinal tumors comprise a large spectrum of neoplasms, including hemangioblastomas, paragangliomas, and meningiomas. These tumors have several common characteristic imaging features, such as highly vascular mass appearance in angiography, hypointense rim and serpentine flow voids in MRI, and intense enhancement after intravenous contrast administration. Due to their rich vascularity, these tumors represent a special challenge for surgical treatment. More recently, the surgical treatment of intraspinal vascular tumors has benefited from the combination of endovascular techniques used to better delineate these lesions and to promote preoperative reduction of volume and tissue blood flow. Endovascular embolization has been proven to be a safe procedure that facilitates the resection of these tumors; hence, it has been proposed as part of the standard of care in their management.

Clinical features and outcomes of spinal cord arteriovenous malformations: comparison between nidus and fistulous types.

BACKGROUND AND PURPOSE: As a result of the rarity of spinal cord arteriovenous malformations (AVM), there are only a few series available that describe clinical features, outcome after treatment, and natural history of these lesions. In this article, we aim to describe our experience with both nidus- and fistulous-type spinal cord AVMs. METHODS: Forty-four consecutive patients with spinal cord AVMs were retrospectively reviewed. There were 26 patients with a nidus-type and 18 patients with a fistulous-type AVM. Treatments were performed with embolization (n=23), surgery (n=13), combined embolization-surgery (n=3), or conservative management (n=5). Clinical features, radiological findings, treatment results, and clinical outcomes were assessed. RESULTS: Patients with nidus-type AVMs were younger at presentation and more often presented with hemorrhage, with a higher proportion of hematomyelia than fistulous-type AVMs (P<0.05). Progression of clinical presentation from hemorrhage to congestive myelopathy during follow-up was noted in 5 patients, all of which had AVMs of the nidus type. Complete obliteration could be achieved more often in the fistulous type (72%) than in the nidus type (27%). Improved or stable clinical status at last follow-up was noted in 100% of fistulous-type and 77% of nidus-type patients. Long-term clinical deterioration was noted in 6 of 26 patients with nidus-type (23%) AVMs and was related to recurrent bleeding (n=3) or progressive venous congestion (n=3). Overall rebleed rate after presentation with hemorrhage was 7 in 145.5 patient-years (4.8%/y) if the lesion was not treated, 3 in 102 patient-years (2.9%/y) after partial treatment, and 0 in 47.5 patient-years (0%) after complete treatment. CONCLUSIONS: Nidus and fistulous spinal cord AVMs have different clinical features and obliteration rates, which may affect their long-term prognosis.

Natural history and outcome after treatment of unruptured intradural fusiform aneurysms.

BACKGROUND AND PURPOSE: Management of unruptured fusiform intracranial aneurysms is controversial because of the paucity of natural history data. We studied their natural history and outcome after treatment. METHODS: We reviewed our neurovascular database from January 2000 to October 2013. Inclusion criteria were unruptured, intradural fusiform aneurysms with a diameter of <2.5 cm. Criteria were developed to define atherosclerotic aneurysms. For outcome assessment, we used the modified Ranking Scale and aneurysm measurements on serial imaging. Mann-Whittney (continuous) and Fisher exact (categorical) tests were used for risk factor analysis. RESULTS: For nonatherosclerotic aneurysms (96 patients; 193 person-years follow-up), 1 patient died (rupture) during follow-up (mortality, 0.51% per year) and 8 patients (10%) showed aneurysm progression (risk, 1.6% per year). Risk factors for progression were maximum diameter (>7 mm; odds ratio, 12; 95% confidence interval, 1.4-104) and symptomatic clinical presentation (odds ratio, 16; 95% confidence interval, 3.1-81.4). Of the 23 treated patients, 3 had died (mortality, 12.5%) and 3 had serious disability (modified Ranking Scale, ≥3; 12.5%). For the atherosclerotic aneurysms (25 patients; 97 person-years follow-up), 5 had died (mortality, 5.2% per year) and 13 of 20 (65%) had aneurysm progression (risk, 12% per year). When compared with patients with nonatherosclerotic aneurysms, case fatality (odds ratio, 19.2; 95% confidence interval, 2.1-172) and aneurysm progression (odds ratio, 17.8; 95% confidence interval, 5.3-56) were higher. CONCLUSIONS: Nonatherosclerotic fusiform intradural aneurysms have a low risk of adverse outcome within the first few years after diagnosis and remain stable unless symptomatic on presentation or >7 mm in maximum diameter. High risks of treatment should be balanced against this benign natural history. Atherosclerotic aneurysms have a worse natural history and may represent a different disease entity.

Management of dural carotid cavernous fistulas: a single-centre experience.

OBJECTIVES: To report the epidemiological features, clinical presentation, angiographic characteristics and therapeutic options, success and complication rates in patients with dural carotid cavernous fistulas (dural CCFs). METHODS: Retrospective evaluation of patients followed in our institution between January of 2005 and September of 2013. RESULTS: There were 38 patients, 76 % females, with an average age of 63 years. Ocular symptoms and signs were the most frequent clinical findings. Dural CCFs were Barrow type B in 8%, type C in 10% and type D in 82%. Cortical venous reflux was present in 50% of cases. Medical treatment was performed in 16% of patients, external ocular compression in 8%, transarterial embolisation in 13%, transvenous embolisation in 60% and radiosurgery in 3%. Clinical and angiographic follow-up data were available in 89% and 82% of patients with a mean follow-up time of 9 and 7 months, respectively. Clinical cure was achieved in 58% of patients and improvement in 24%. Anatomical cure was demonstrated in 68%. Transient worsening or new onset of ocular symptoms was observed in 29%. There was no permanent morbidity or mortality. CONCLUSIONS: In properly selected patients, endovascular embolisation, particularly by transvenous approach, represents a safe and effective treatment for dural CCFs. KEY POINTS: Dural carotid cavernous fistulas are more common in elderly women. Dural CCFs most commonly present with ocular symptoms and signs. Endovascular treatment is effective and safe in properly selected patients.

The accuracy and utility of contrast-enhanced MR angiography for localization of spinal dural arteriovenous fistulas: the Toronto experience.

OBJECTIVES: The purpose of this study was to determine the accuracy and utility of contrast-enhanced MR angiography (CE-MRA) in spinal dural arteriovenous fistulas (SDAVF). METHODS: A retrospective analysis from 1999-2012 identified 70 patients clinically suspected of harboring a SDAVF. Each patient underwent consecutive conventional MR-imaging, CE-MRA, and digital subtraction angiography (DSA). The presence or absence of serpentine flow voids, T2-weighted hyperintensity, and cord enhancement were evaluated, as well as location of the fistula as predicted by CE-MRA. DSA was used as the reference standard. RESULTS: Of the 70 cases, 53 were determined to be a SDAVF, 10 cases were shown to be other forms of vascular malformation, and 7 were DSA-negative. On MRI, all reported cases of SDAVF showed serpentine flow voids (100 %). T2-weighted hyperintensity was seen in 48 of 50 cases (96 %), extending to the conus in 41 of 48 cases (85 %). Cord enhancement was seen in 38 of 41 cases (93 %). CE-MRA correctly localized the SDAVF in 43 of the 53 cases (81 %). CONCLUSIONS: CE-MRA is a useful non-invasive examination for the detection and localization of SDAVF. CE-MRA facilitates but does not replace DSA as confirmation of location, fistula type, and arterial detail, which are required before treatment. KEY POINTS: • CE-MRA correctly localized the site of the SDAVF in over 80 % of cases. • CE-MRA facilitates diagnostic DSA and expedites the diagnostic process. • CE-MRA does not replace diagnostic DSA in SDAVF cases as confirmative test. • CE-MRA provides better understanding of missed or mislocalized SDAVF cases.

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.

Clinical and Anatomical Characteristics of Perforator Aneurysms of the Posterior Cerebral Artery: A Single-Center Experience.

INTRODUCTION: Posterior cerebral artery (PCA) aneurysms represent up to 1% of all cerebral aneurysms. P1-P2 perforator aneurysms are thought to be even less prevalent and often require complex treatment strategies due to their anatomical and morphological characteristics, with risk of a perforator infarct. We studied the treatment of P1-P2 perforator aneurysms in a single-center cohort from a high-volume tertiary center, reporting clinical and anatomical characteristics, treatment strategies, and outcomes. METHODS: A retrospective analysis of adult patients with a P1-P2 perforator aneurysm who presented at our institution between January 2000 and January 2023 was performed. The patients were analyzed for demographics, clinical presentation, imaging findings, treatment techniques, outcomes, and complications. Subgroup analyses between ruptured versus non-ruptured cases were included. RESULTS: Out of 2733 patients with a cerebral aneurysm, 14 patients (0.5%) presented with a P1-P2 perforator aneurysm. All six patients with a ruptured aneurysm were treated by endovascular coiling, of whom one patient (16.7%) required surgical clipping of a recurrence. One out of eight (12.5%) patients with unruptured aneurysms was treated by surgical clipping. P1-P2 perforator aneurysms predominantly affected middle-aged individuals (median 59.5 years), with 10/14 (71.4%) being female. Endovascular coiling was the primary treatment modality overall, yielding favorable technical outcomes, however, it was complicated by a perforator infarct in two patients (33.3%) without new permanent morbidity or mortality secondary to treatment. CONCLUSIONS: P1-P2 perforator aneurysms are a rare subtype of intracranial aneurysm. Endovascular coiling could present an effective treatment modality; however, care should be taken for ischemic complications in the dependent perforator territory. Larger studies are required to provide more insights.

Factors determining the success of endovascular treatments among patients with spinal dural arteriovenous fistulas.

INTRODUCTION: Despite improvements of embolization agents and techniques, endovascular treatment of spinal dural arteriovenous fistula (SDAVF) is still limited by inconsistent success. The aim of embolization is to occlude initial portion of the draining vein by liquid embolic materials. This study investigates factors that contribute to the success of embolization treatments among SDAVF patients. METHODS: We performed a retrospective analysis on consecutive SDAVF patients who received N-butyl cyanoacrylate (NBCA) glue embolization between January 1992 and June 2012. Univariable and multivariable logistic regression analyses were performed to calculate the probability of successful draining vein occlusion for variable procedure-related factors. RESULTS: We attempted endovascular approach as the first intention treatment in 66 out of 90 consecutive patients. Among them, a total of 43 NBCA glue injections were performed in 40 patients. Successful embolization was achieved in 24 patients (60 %). In multivariable analyses, antegrade flow during microcatheter test injection (OR 13.2, 95 % CI 1.7 to 105.4) and use of glue concentration ≥ 30 % (OR 0.1, 95 % CI 0.01 to 0.8) were detected as significant positive and negative predictors of successful venous penetration, respectively. With persistent antegrade flow, the success rates using a glue mixture of more than 30 % dropped significantly from 85.0 to 42.9 % (p = 0.049). If contrast stagnated during microcatheter injections, success rates were low regardless of glue concentrations. CONCLUSIONS: Presence of antegrade flow toward the draining vein and injection of NBCA glue less than 30 % are associated with higher chance of draining vein penetration and, therefore, successful endovascular SDAVF obliteration.