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BackgroundPediatric spinal arteriovenous shunts (SAVS) are rare lesions with heterogeneous pathogenesis and clinical manifestations.ObjectiveTo evaluate the clinical characteristics, angioarchitecture, and technical/clinical outcomes in SAVS through a large single-center cohort analysis and meta-analysis of individual patient data.MethodsA retrospective institutional database identified children (aged 0–21 years) who underwent digital subtraction spinal angiography (DSA) for SAVS between January 1996 and July 2021. Clinical data were recorded to evaluate angioarchitecture, generate modified Aminoff-Logue gait disturbance scores (AL) and McCormick grades (MC), and assess outcomes. We then performed a systematic literature review following PRISMA-IPD (Preferred Reporting Items for Systematic Reviews and Meta-Analyses for individual patient data) guidelines, extracting similar data on individual patients for meta-analysis.ResultsThe cohort consisted of 28 children (M:F=11:17) with 32 SAVS lesions, with a mean age of 12.8±1.1 years at diagnosis. At presentation, SAVS were most highly concentrated in the cervical region (40.6%). Children had a median AL=2 and MC=2, with thoracolumbar AVS carrying the greatest disability. Among treated cases, complete obliteration was achieved in 48% of cases and median AL scores and MC grades both improved by one point. Systematic literature review identified 161 children (M:F=96:65) with 166 SAVS lesions with a mean age of 8.7±0.4 years. Among studies describing symptom chronicity, 37/51 (72.5%) of children presented acutely. At presentation, children had a median AL=4 and MC=3, with thoracolumbar AVS carrying the highest MC grades. After intervention, median AL and MC both improved by one point.ConclusionsThis study provides epidemiologic information on the location, onset, and presentation of the full spectrum of pediatric SAVS, highlighting the role of targeted treatment of high-risk features.

BackgroundNo randomized trial of intracranial aneurysm coiling has compared long-term efficacy of polymer-modified coils to bare metal coils (BMCs). We report 5-year results comparing Matrix2 coils to BMCs. The primary objective was to compare the rates of target aneurysm recurrence (TAR) at 12 months. Secondary objectives included angiographic outcomes at TAR or 12 months and TAR at 5 years.MethodsA total of 626 patients were randomized to BMCs or Matrix2 coils. Detailed methods and 1-year results have been published previously.ResultsOf 580 patients eligible for 5-year follow-up, 431 (74.3%) completed follow-up or reached TAR. Matrix2 coils were non-inferior to BMCs (P=0.8) but did not confer any benefit. Core lab reported post-treatment residual aneurysm filling (Raymond III) correlated with TAR (PConclusionsAfter 5 years Matrix2 coils were non-inferior to BMCs but no benefit was demonstrated. Post-treatment residual angiographic aneurysm filling (Raymond III) is strongly associated with TAR (P

The pharyngo-tympano-stapedial middle meningeal artery (PTS-MMA) variant has been described in one case report and never in the setting of arterial supply to a dural arteriovenous fistula, to our knowledge. We report the case of a middle-aged patient with severe, daily headache who presented to our institution for angiography and treatment. CT angiography and MRI demonstrated an enlarged left middle meningeal artery coursing to a large venous varix in the falcotentorial region. Dural arteriovenous fistula was confirmed by subsequent cerebral angiography. Endovascular treatment was performed but without complete obliteration of the fistula. Follow-up angiography demonstrated parasitized arterial supply from a right middle meningeal artery arising from the proximal cervical internal carotid artery coursing through the middle ear consistent with a PTS-MMA variant. The fistula was then treated surgically without recurrence at the 6-month follow-up.

BackgroundPercutaneous sclerotherapy is an effective treatment for lymphatic malformations (LM) of the head and neck in adults. The purpose of this study was to examine the indications and efficacy of sclerotherapy for head/neck LM in the neonate and infant population.MethodsWe retrospectively reviewed patients treated with percutaneous sclerotherapy for LM of the head/neck at age ≤12 months at a single vascular anomalies clinic. The clinical, anatomic, and technical aspects of each treatment, complications, and post-treatment clinical and imaging outcomes were analyzed.Results22 patients underwent 36 treatments during the first year of life. Median age at first treatment was 6.2 months (range 2–320 days). Severe airway compromise was the most frequent indication for treatment (31.8%). Sclerosants included doxycycline (80.5%), sodium tetradecyl sulfate (55.5%), bleomycin (11.1%) and ethanol (2.8%). There were no immediate procedure-related complications; sclerosant-related laboratory complications included transient metabolic acidosis (8.3%) and hemolytic anemia (5.5%). Median follow-up was 3.7 years (IQR 0.6–4.8). 47.6% of patients showed >75% lesion size reduction and 19.0% showed minimal response (ConclusionsPercutaneous sclerotherapy is a safe and effective treatment for symptomatic LM of the head and neck in neonates and infants. Treatment strategy and management of recurrent symptoms requires consensus from an experienced, multidisciplinary team.

Although enthusiasm for transradial access for neurointerventional procedures has grown, a unique set of considerations bear emphasis to preserve safety and minimize complications. In the first part of this review series, we will review important anatomical considerations for safe and easy neuroendovascular procedures from a transradial approach. These include normal and variant radial artery anatomy, the anatomic snuffbox, as well as axillary, brachial, and great vessel arterial anatomy that is imperative for the neuroendovascular surgeon to be intimately familiar prior to pursuing transradial access procedures. In the next part of the review series, we will focus on safety and complications specific to a transradial approach.

Percutaneous sclerotherapy is an effective technique for treating lymphatic malformations of the head and neck, with clinical success rates exceeding 84%.1 Sodium tetradecyl, which damages lipid membranes and stimulates free radical-induced local damage, and doxycycline, which inhibits angiogenesis, have emerged as the safest and most effective of several available sclerosants.2–4 Although severe periprocedural morbidity is rare, temporary local complications are reported in 14% and skin necrosis or scarring in up to 0.8–5.8% of sclerotherapy procedures.5 As these lesions are frequently located in the face and/or neck, even minor complications can be disfiguring and must be avoided. This technical video describes a ‘dual-agent’ approach for percutaneous sclerotherapy of macrocystic lymphatic malformations using sodium tetradecyl as a ‘primer’ followed by doxycycline as a definitive sclerosant (video 1). This technique emphasizes meticulous backtable preparation and effective use of ultrasound and fluoroscopy to minimize complications.Video 1

BackgroundDural arteriovenous fistulas (AVF) of the foramen magnum region (FMR) are technically challenging lesions to treat. Transvenous (TV), transarterial (TA), and surgical approaches have been described, but the optimum treatment strategy is not defined.ObjectiveTo report treatment strategies and outcomes for FMR-AVF at a single, high-volume referral center.MethodsA retrospective review from January 2010 to August 2020 identified patients with FMR-AVF at a single referral center. Angiographic features, treatment (observation, endovascular, surgical), and follow-up of angiographic and clinical results were recorded. The technical aspects of TV embolization are then presented in detail.Results29 FMR-AVF were identified in 28 patients. Of these, 24/29 (82.8%) were treated and 5/29 (17.2%) were observed. Treatment was endovascular in 21/24 (87.5%), combined (endovascular+surgical) in 2/24 (8.3%), and surgical in 1/24 (4.2%). Endovascular treatments were 76.2% TV, 14.3% TA, and 9.5% combined TV/TA. Sufficient follow-up data were available for 20/28 (71.4%) with mean follow-up of 16.8 months. No AVF recurrence was seen for TA/TV, combined endovascular/surgical, or surgical groups, and there was one recurrence (7.1%) in the TV group. Symptomatic improvement was seen in all groups: TV (71.4% complete, 28.6% partial), TA (66.7% complete, 33.3% no follow-up), TV+TA (100% partial), endovascular/surgical (100% complete), and surgical (100% partial). Minor non-neurologic complications included 1/14 (7.1%) in the TV group and 1/3 (33.3%) in the TA/TV group.ConclusionEndovascular treatment is safe and effective for most FMR-AVF. TV embolization has a high cure rate with few complications.

Although enthusiasm for transradial access for neurointerventional procedures has grown, a unique set of considerations bear emphasis to preserve safety and minimize complications. In the first part of this review series, we reviewed anatomical considerations for safe and easy neuroendovascular procedures from a transradial approach. In this second part of the review series, we aim to (1) summarize evidence for safety of the transradial approach, and (2) explain complications and their management.

ObjectiveTo evaluate the safety and effectiveness of the Flow Redirection Endoluminal Device (FRED) flow diverter in support of an application for Food and Drug Administration approval in the USA.Methods145 patients were enrolled in a prospective, single-arm multicenter trial. Patients with aneurysms of unfavorable morphology for traditional endovascular therapies (large, wide-necked, fusiform, etc) were included. The trial was designed to demonstrate non-inferiority in both safety and effectiveness, comparing trial results with performance goals (PGs) established from peer-reviewed published literature. The primary safety endpoint was death or major stroke (National Institutes of Health Stroke Scale score ≥4 points) within 30 days of the procedure, or any major ipsilateral stroke or neurological death within the first year. The primary effectiveness endpoint was complete occlusion of the target aneurysm with ≤50% stenosis of the parent artery at 12 months after treatment, and in which an alternative treatment of the target intracranial aneurysm had not been performed.Results145 patients underwent attempted placement of a FRED device, and one or more devices were placed in all 145 patients. 135/145 (93%) had a single device placed. Core laboratory adjudication deemed 106 (73.1%) of the aneurysms large or giant. A safety endpoint was experienced by 9/145 (6.2%) patients, successfully achieving the safety PG of 46% aneurysm occlusion was also achieved, with the effectiveness endpoint being met in 80/139 (57.6%)ConclusionAs compared with historically derived performance benchmarks, the FRED flow diverter is both safe and effective for the treatment of appropriately selected intracranial aneurysms.Clinical registration numberNCT01801007

IntroductionIndirect cavernous carotid fistulae (ICCFs) can present with insidious, non-specific symptoms and prove difficult to diagnose. This study evaluates associations among ICCF symptoms and angiographic findings.MethodsA retrospective analysis was performed of prospectively maintained records at four medical centers to identify patients with ICCFs evaluated with angiography. Patient demographics, symptoms, and angiographic findings were tabulated. Univariate and multivariate analyses were conducted to identify associations among these variables.ResultsRecords sufficient for review existed for 267 patients evaluated with angiography. Patients were most commonly women, in the sixth or seventh decade of life, and had symptoms for months before a definitive diagnosis. The most common symptoms included proptosis, diplopia, cranial nerve palsy, and chemosis. Cortical venous reflux was most common in patients with chemosis, orbital pain, or bruit. Intracranial hemorrhage was associated with cortical reflux and bilateral inferior petrosal sinus occlusion. Patients with loss of symptoms demonstrated higher rates of inferior petrosal sinus occlusion and a trend towards rupture.ConclusionA high index of suspicion is needed to promptly diagnose patients with ICCFs. High risk features are more common in the setting of chemosis, orbital pain, bruit, or spontaneous loss of symptoms. Patients with such symptoms warrant expedited angiographic evaluation.

Background and purpose Retinoblastoma (RB) is a rare malignancy affecting the pediatric population. Intravenous chemotherapy is the longstanding delivery method, although intra-arterial (IA) chemotherapy is gaining popularity given the reduced side effects compared with systemic chemotherapy administration. Given the sensitivity of the target organ, patient age, and secondary tumor susceptibility, a premium has been placed on minimizing procedural related radiation exposure. Materials and methods To reduce patient x-ray dose during the IA infusion procedure, customized surgical methods and fluoroscopic techniques were employed. The routine fluoroscopic settings were changed from the standard 7.5 pulses/s and dose level to the detector of 36 nGy/pulse, to a pulse rate of 4 pulses/s and detector dose to 23 nGy/pulse. The angiographic dose indicators (reference point air kerma (K a ) and fluoroscopy time) for a cohort of 10 consecutive patients (12 eyes, 30 infusions) were analyzed. An additional four cases (five eyes, five infusions) were analyzed using dosimeters placed at anatomic locations to reflect scalp, eye, and thyroid dose. Results The mean K a per treated eye was 20.1±11.9 mGy with a mean fluoroscopic time of 8.5±4.6 min. Dosimetric measurements demonstrated minimal dose to the lens (0.18±0.10 mGy). Measured entrance skin doses varied from 0.7 to 7.0 mGy and were 73.4±19.7% less than the indicated Ka value. Conclusions Ophthalmic arterial melphalan infusion is a safe and effective means to treat RB. Modification to contemporary fluoroscopic systems combined with parsimonious fluoroscopy can minimize radiation exposure.

Segmental arterial mediolysis (SAM) is a rare, non-inflammatory, non-atherosclerotic vasculopathy typically affecting the abdominal arteries although it may also affect the great vessels and cerebral vasculature. Diseased vessels manifest with aneurysms and/or dissections, often presenting clinically with catastrophic thromboembolic injury and less frequently with subarachnoid hemorrhage (SAH). The etiology of SAM remains indeterminate although there is evidence it may be an endogenous pathological response to vasospasm. The SAM literature is reviewed and a case of SAH related to a ruptured dissecting-type vertebral artery aneurysm is described. In addition to furthering awareness of SAM, this unique case offers insight into the acute phase of the disease and the potential role of vasospastic induction.

Background and purposeThe proper role of endovascular treatment of cervicocerebral atherosclerosis is unclear. Posterior circulation disease has not been investigated as extensively as disease in the anterior circulation. In this study, we characterized the rates of technical success, transient ischemic attack, stroke, and death or disability, for both acute and elective endovascular treatment of atherosclerosis in the vertebrobasilar system.MethodsWe identified patients with atherosclerosis of the vertebrobasilar circulation who underwent endovascular intervention at our hospital through retrospective medical record review, and evaluated the association between lesion and treatment features and subsequent stroke, death, or disability at 30 days and 1 year.ResultsWe identified 136 lesions in 122 patients, including 13 interventions for acute strokes. Technical success was achieved in 123 of 136 cases (90.4%). Elective procedures had higher rates of technical success (6.5% vs 15.4%, p=0.21) and better clinical outcomes. In multivariate analysis, intracranial lesions were associated with more disability (modified Rankin Scale score >2) at 30 days (OR 7.1, p=0.01) and 1 year (OR 10, p=0.03). Patients with non-hypoperfusion related symptoms had fewer strokes at follow-up at 1 year when treated after an asymptomatic interval of >10 days compared with those treated within 10 days of the presenting symptoms (OR 0.2, p=0.03). Statin treatment prior to intervention was associated with favorable outcomes across several examined endpoints. Preoperative antiplatelet treatment was associated with lower rates of disability at 30 days and 1 year (OR 0.1, pConclusionsEndovascular treatment of symptomatic vertebrobasilar atherosclerosis can be performed safely and with good outcomes. Technical results were better for those with extracranial disease while clinical outcomes were more favorable in those patients with non-progressive symptoms in the subacute period and those receiving statin therapy.

Introduction/purpose To best achieve complete occlusion of aneurysms treated with flow diverters (FDs), devices must be accurately sized to precisely match the parent vessel diameter. Appropriately sized FDs will have maximal coverage over the aneurysm neck and will be more likely to induce thrombosis. Catheterization for diagnostic angiography can cause vasospasm that may affect vessel measurements. This study evaluates the effects of intra-arterial infusion of a calcium channel blocker (CCB) on angiographic measurements in patients treated with FDs, investigating the impact on the final diameter of the expanded stent following deployment and subsequent occlusion. Materials and methods Retrospective analysis was performed of prospectively maintained procedure records to identify patients with aneurysms treated with FDs. In all patients, pre-treatment measurements were recorded for vessel diameter of the distal and proximal landing zones, as well as maximum and minimum diameters between these segments. Post-treatment measurements of the stent itself following deployment were recorded at the distal and proximal ends in addition to maximum and minimum diameters. When CCB was infused prior to treatment, post-infusion pre-treatment measurements were recorded. All measurements were performed after calibrating to a catheter included on the image. Rates of occlusion and time to confirmed occlusion were noted for all patients. Independent-sample 2 tailed T-tests were performed to assess for differences in pre- and post-treatment measurements, rates of occlusion, and time to confirmed occlusion between groups with and without CCB infusion. Results 21 FDs were deployed to treat 19 aneurysms in 18 patients. CCB infusion was performed prior to deployment of 9 devices. The change in measurements noted after CCB infusion are summarized in Table 1. No significant difference was noted between groups for pre- and post-treatment measurement changes. Subsequent aneurysm occlusion was more likely to occur in the CCB infusion group (100% vs. 44.4%, p Conclusion Optimization of device sizing is important to increase FD density over the aneurysm neck and promote thrombosis. To improve accuracy of measurements of parent vessels prior to device selection, CCB infusion can reduce the effects of mild vasospasm. In this study, subsequent aneurysm occlusion was more likely to occur following FD treatment when device size selection was based on measurements performed following CCB infusion. Disclosures M. Alexander: None. R. Darflinger: None. F. Settecase: None. A. Nicholson: None. D. Cooke: None. M. Amans: None. S. Hetts: None. C. Dowd: None. R. Higashida: None. V. Halbach: None.

BackgroundIntracranial atherosclerotic disease (ICAD) causes substantial morbidity and mortality. Treatment decisions have most commonly been driven by the degree of luminal stenosis. This study compares ICAD lesion stability features with percentage stenosis for associations with adverse outcomes following treatment with stents.Materials and methodsRetrospective analysis was performed of prospectively maintained procedure logs. Lesions were classified by symptom type as hypoperfusion, non-hypoperfusion, or indeterminate, and pretreatment asymptomatic intervals were noted. Hypoperfusion lesions and indeterminate or non-hypoperfusion lesions with ≥14 days of asymptomatic interval were classified as stable. Percentage stenosis was calculated and compared against these other symptom features for value in predicting technical complication, ischemic stroke, disability, or death at 90 days and 2 years using univariate and multivariate analysis.Results130 lesions were treated in 124 patients. The only statistically significant percent stenosis finding was lesions with 60–99% stenosis were less likely to have technical complications. In univariate analysis, stroke at 2 years was less common with hypoperfusion and stable lesions. In multivariate analysis, only hypoperfusion status was associated with lower stroke rates at 2 years.ConclusionsLesion stability features, particularly non-hypoperfusion symptomatology, outperform percentage stenosis in predicting outcomes following treatment of ICAD with stents. Further examination is needed to better classify the natural history of ICAD and more precisely classify lesion stability.

A neonate with congestive heart failure at birth due to a nearly holohemispheric pial arteriovenous malformation is described. This occurred despite a normal second trimester prenatal sonogram. Successful treatment of heart failure was achieved by embolization alone. This case demonstrates that hemodynamically significant lesions may arise later or enlarge more rapidly in utero than previously thought.

Background The role of catheter angiography in the diagnosis and management of traumatic cerebrovascular injury has evolved rapidly with advances in CT and MR angiography and continued development of endovascular techniques. Objective To identify the modern spectrum of traumatic arterial injury encountered during catheter neuroangiography and to examine current patterns of endovascular treatment. Methods Records of trauma patients undergoing catheter neuroangiography over a 4 year period at two high volume centers were retrospectively reviewed. The sample comprised 100 separate arterial lesions that were classified according to mechanism, location, acuity, and endovascular treatment. Follow-up imaging and clinical notes were reviewed to identify procedural complications. Results Of 100 arterial lesions, 81% were related to blunt trauma. Distribution of lesions by location was 42% intracranial, 39% cervical, and 19% extracranial. The most common injuries were pseudoaneurysm (38%), fistula (29%), and dissection (19%). In total, 41% of lesions underwent endovascular treatment, with trends favoring treatment of non-acute, penetrating, non-cervical, and high grade lesions. Therapy involved coil embolization for 89% of treated lesions. There were a total of two immediate neurovascular complications and one delayed neurovascular complication; one of these resulted in a permanent neurological deficit. Conclusions Our experience in a large cohort of patients suggests that a relatively high proportion of traumatic arterial lesions identified by catheter angiography are treated by endovascular means, with a low rate of immediate and delayed neurovascular complications.

Introduction/purpose Numerous processes can cause pulsatile tinnitus (PT), some of which are potentially life threatening. This case series describes a cause of PT – prominent condylar veins – that has undergone little investigation to date. This report characterizes angiographic findings in patients with prominent condylar veins and means to localize symptoms to these structures using dynamic angiography with head positioning and venous balloon test occlusion. Materials and methods Retrospective analysis was performed under IRB approved protocol for 43 consecutive PT patients referred for diagnostic angiography at a major academic medical center between January 2013 and December 2015. Rates of different etiologies of PT among patients in this group were noted. In addition to standard diagnostic cervicocerebral angiography, dynamic angiography with head turning was conducted. The effects of provocative maneuvers were measured using time-resolved flow analysis known (iFlow, Siemens Healthcare, Erlangen Germany). Results 5 (11.6%) patients were found to have prominent condylar veins. 16 (37.2%) had a dAVF, 4 (9.3%) had a venous diverticulum, and 9 (20.9%) had no angiographic abnormality detected. The findings of the five patients with prominent condylar veins are summarized in the table. Representative images are provided in the figure. Conclusion Prominent flow in condylar veins should be considered among the numerous causes of PT. This may be a frequent cause of these symptoms in patients who previously would have had no identifiable cause Further investigation is warranted with respect to this cause of PT and PT in general. Disclosures M. Alexander: None. K. Meisel: None. V. Halbach: None. R. Darflinger: None. A. Nicholson: None. F. Settecase: None. D. Cooke: None. R. Higashida: None. C. Dowd: None. S. Hetts: None. M. Amans: None.

Retinoblastoma is a rare and curable malignancy affecting the pediatric population. For advanced stage intraocular retinoblastoma, enucleation remains the primary treatment modality, although the use of laser photocoagulation, cryotherapy, radiotherapy and chemotherapy are frequently used, particularly in the setting of bilateral disease. Intravenous chemotherapy is the long-standing method of delivery, but local administration (subtenon, intravitreal or intra-arterial) is gaining in popularity because of the reduced side effects related to systemic administration. Of these newer methods, intra-arterial infusion has demonstrated technical feasibility, few procedural complications and robust tumor response. A case is described where a collateral supply to the affected ophthalmic artery was via the zygomatico-orbital branch of the ipsilateral superficial temporal artery. Melphalan infusion was performed via this pathway without incident.

Pial arteriovenous fistulas (AVFs) are a rare, although clinically significant, vascular anomaly affecting the pediatric population. There are few retrospective case series describing their epidemiological, clinical and radiographic characteristics as well as technical elements of treatment. Combined transarterial and transvenous embolization of a 12 month old female with a multi-hole pial AVF is described. The patient underwent treatment in a staged fashion and without neurological complication.

Hemorrhage represents the most feared complication of cerebral arteriovenous malformations (AVMs) in both untreated patients and those treated with gamma knife radiosurgery. Radiosurgery does not immediately lead to obliteration of the malformation, which often does not occur until years following treatment. Post-obliteration hemorrhage is rare, occurring months to years after radiosurgery, and has been associated with residual or recurrent AVM despite prior apparent nidus elimination. Three cases are reported of delayed intracranial hemorrhage in patients with cerebral AVMs treated with radiosurgery in which no residual AVM was found on catheter angiography at the time of delayed post-treatment hemorrhage. That the pathophysiology of these hemorrhages involves progressive venous outflow occlusion is speculated and the possible mechanistic link to subsequent vascular rupture is discussed.

Introduction/purpose The intracranial arterial vasculature is known to have an abundance of variability, especially in and around the Circle of Willis. A functional absence of the anterior communicating artery (ACom), an artery that connects the paired A1 segment anterior cerebral arteries (ACAs), is a common variation. This usually manifests with normal, bilaterally symmetric ACAs with paired A1 segments, A2 segments, and so on. In rare cases, the A1 segments can join to form a singular A2 segment, resulting in what is termed an “azygous” ACA. This variation has been reported in 0.4–1% of the population, and is similar to the standard arterial anatomy in lower primates. In humans, azygous configuration of the ACA has been associated with other midline abnormalities such as dysgenesis of the corpus collosum, lobar holoprosencephaly, and septooptic dysplasia, as well as arteriovenous malformations and (anecdotally, at least) aneurysms. Materials and methods In our practice, we see the azygous ACA configuration extremely uncommonly. We performed a retrospective review of all neurointerventional angiographic procedures performed in our department during a 10 year period, comprising over 20,000 angiograms and embolizations. Patients were identified as having an azygous configuration ACA through a search of the medical records, which were reviewed with the angiogram report (and images, where available). Results Among this set of patients, we found a total of 45 patients (0.225%) with azygous ACA configuration. Of these 45 patients, 14 (31.1%) had an associated aneurysm, either at the A1 confluence, or the origin of the pericallosal artery. Four of these aneurysms (28.5%) presented with rupture, with the remainder discovered on workup of other aneurysms, or incidentally during other imaging procedures. Half of the ruptured aneurysms were treated with endovascular coiling and half were treated with surgical clipping, all with technically excellent results. An additional 4 unruptured azygous ACA-associated aneurysms received treatment during this time (2 via coiling and 2 via surgical clipping), also with excellent results. Two of our patients with an azygous ACA were also found to have brain AVMs, one of whom also had an azygous ACA-associated aneurysm. The remaining 6 patients with azygous ACA-associated aneurysms were untreated and demonstrated no aneurysm growth or other high-risk features and have remained clinically stable. Conclusion Azygous configuration of the A2 segment anterior cerebral artery is an uncommonly seen anatomic variant, and our experience is similar to the published occurrence rates (0.2% at our institution). This finding has been associated with several conditions and, in our experience, is very commonly associated with aneurysms of the ACA (31%), with 28.5% of these aneurysms presenting with rupture. When an azygous configuration of the ACA is identified it is important to take care in studying the ACA thoroughly to look for associated aneurysms. Disclosures A. Nicholson: None. D. Cooke: None. M. Amans: None. F. Settecase: None. S. Hetts: None. C. Dowd: None. R. Higashida: None. V. Halbach: None.

Purpose To evaluate the ability of intravenous (IV) and intraarterial (IA) MR perfusion to characterize meningioma blood supply. Materials and methods Institutional review board approval and informed consent were obtained for this prospective, HIPAA-compliant study. Studies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Twelve patients underwent IV and IA T2* dynamic susceptibility contrast MR perfusion immediately prior to x-ray-guided meningioma embolization. DSA was used to characterize regional arterial supply to the tumor as ECA dural, ICA dural or pial. MR perfusion data ROIs were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM), and time to 50% and 60% signal recovery (TSR50–60%). One-sided t-tests were used to analyze ROI data. Results Arterial supply was ECA dural (n = 11), ICA dural (n = 4) or pial (n = 3) based on DSA. No differences in IA MR perfusion peak height (p = 0.66), FWHM (p = 0.78), TSR50% (p = 0.41), and TSR60% (p = 0.55) were found between ECA and ICA dural ROIs. ICA and ECA dural ROIs were combined and compared to pial ROIs. Pial ROIs demonstrated shorter FWHM (t = 7.9s vs. 16.9s, p = 0.025), TSR50% (t = 5.2s vs. 12.6s, p = 0.043), and TSR60% (t = 6.5s vs. 16.4s, p = 0.046). There was no difference in peak height. For IV MR perfusion, no differences were found between ECA and ICA dural ROIs and dural and pial ROIs. Conclusions IA MR perfusion measures can identify ICA-derived pial supply not amenable to embolization, although IV MR perfusion imaging may not be sensitive enough. Disclosures S. Hetts: 1; C; NIH-NIBIB, NIH-NCI, Siemens, Penumbra, Stryker, MicroVention Terumo. 2; C; Silk Road Medical, Medina Medical, Stryker, Penumbra. 4; C; ChemoFilter, Medina Medical. 5; C; UCSF. M. Lum: None. A. Martin: None. D. Cooke: None. P. Lillaney: None. M. Amans: None. F. Settecase: None. A. Nicholson: None. C. Dowd: None. V. Halbach: None. R. Higashida: None. M. McDermott: None. D. Saloner: 1; C; NIH-NCI.

Background Embolic agents for embolization of cerebral arteriovenous malformations (AVMs) currently include n-BCA, Onyx, particles, and detachable coils. Ethanol sclerotherapy is seldom used in the treatment of cerebral AVMs due to safety concerns. 1,2 In some circumstances, however, such as when limited reflux of an embolic agent is permissible, the use of ethanol may be preferable. In this retrospective case series, we report on patients with brain AVMs presenting with acute hemorrhage at our institution in whom ethanol was used to successfully treat a feeding artery aneurysms or intranidal aneurysms. Methods A keyword search of our neurointerventional database identified 10 patients with cerebral AVM feeding artery aneurysms or intranidal aneurysms treated using ethanol sclerotherapy between 2005 and 2014. Neuroimaging, angiograms, operative reports and electronic medical records were reviewed. Results 13 feeding artery or intranidal aneurysms were identified in 10 patients, of which 12 were treated with intraarterial ethanol sclerotherapy (Table 1). One of the 13 aneurysms was not treated due to risk of non-target embolization of calcarine artery branches. All patients presented with acute intracranial hemorrhage. Dehydrated ethanol 60–80% (70% ethanol was used in 7 of the 10 patients) was delivered slowly under roadmap-mask guidance directly into the artery supplying the aneurysm. Post-therapy angiography to assess for aneurysm occlusion was performed 10–20 min after ethanol injection. Volume of ethanol injected ranged from 2–22 cc (median 3.75 cc) (Table 1). Complete occlusion of the aneurysm was seen in 11/12 treated aneurysms (92%) (Figure 1). Follow-up was available in 9/10 patients (mean follow-up was 1.3 years). None required more than one treatment session and there were no recurrences. A complication was encountered in one patient, who developed hemiparesis and aphasia due to non-target embolization of posterolateral choroidal artery branches to normal brain. No deaths were attributed to ethanol sclerotherapy. Conclusion In a subset of ruptured cerebral AVMs in which other embolic agents cannot be safely used, ethanol sclerotherapy of feeding artery or nidal aneurysms can be performed with a high degree of technical success and a low rate of permanent neurologic complication. References Yakes WF, Krauth L, Ecklund J, et al . Ethanol endovascular management of brain arteriovenous malformations: initial results. Neurosurgery 1997; 40 (6):1145–52; discussion 52–4 Wong GA, Armstrong DC, Robertson JM. Cardiovascular collapse during ethanol sclerotherapy in a pediatric patient. Paediatric Anaesthesia 2006;16(3):343–6 Disclosures F. Settecase: None. M. Amans: None. A. Nicholson: None. S. Hetts: None. D. Cooke: None. C. Dowd: None. R. Higashida: None. V. Halbach: None.

Purpose Meningiomas often benefit from preoperative embolization in order to reduce operative blood loss and associated morbidity. Intraarterial (IA) administration of contrast directly into the external carotid artery (ECA) and internal carotid artery (ICA) branches supplying the tumor during the embolization procedure maps out the blood vessels supplying the tumor as well as evaluating which portions of the tumor are successfully devascularized prior to surgery. Whereas IA digital subtraction x-ray angiography (DSA) is the gold standard for embolization guidance, IA perfusion MRI may offer increased sensitivity to residual areas of vascularized tumor. Materials and Methods Studies were performed in a combined “XMR” suite wherein an x-ray angiography unit (Integris V5000, Philips Medical Systems) is coupled in-line to a 1.5 T MR scanner (Intera, Philips Medical Systems), allowing easy patient movement between the two imaging modalities during endovascular procedures. We evaluated 14 patients with selective IA T2* dynamic susceptibility contrast (DSC) perfusion MR during preoperative embolization. Eight of these patients were also evaluated with intraprocedural IA T1 weighted perfusion MR. IA perfusion was performed with dilute Gd injected initially into the external carotid and subsequently into the common carotid. The selected carotid artery was confirmed to be providing vascular supply to the tumor by prior angiographic evaluation. The portion of the tumor demonstrated to be associated with external or internal carotid supply, based on IA MR perfusion measures, were correlated with DSA obtained during each procedure. IA perfusion assessments were additionally compared to preoperative conventional MRI and IV T2* perfusion MR studies. Results Both T2* and T1 IA perfusion MR techniques were more sensitive than DSA at detecting vascularized tumor prior to or following embolization. The T1 technique was subject to less susceptibility artifact, and thus performed better than the T2* technique at the skull base and near aerated paranasal sinuses. Both IA MR perfusion techniques demonstrated tighter arterial input functions than the IV MRI perfusion technique due to contrast administration directly into cervicocerebral arteries. Similarly, time enhancement curves for the IA MR perfusion methods demonstrated reduced mean transit time and lack of a recirculation peak as comparted to the IV MR perfusion method. IA MR perfusion methods were good at differentiating ECA from ICA supply to individual tumors. However, vascular variants such as anterior falx artery or ethmoidal artery tumor supply arising from the ophthalmic artery (ICA branches outside the blood brain barrier) presented interpretive challenges for MRI but were readily apparent on DSA. Conclusion IA MR perfusion techniques appear to be a useful adjunct to DSA in determining tumor vascularity and the source of that blood supply during DSA guided preoperative embolization procedures.

Introduction Intracranial atherosclerotic disease (ICAD) is often stratified by degree of stenosis. Additional features such as patient demographics and symptom characteristics also affect lesion behavior and response to treatment. This study compares stratification by degree of narrowing to these additional features. Materials and methods Retrospective analysis was performed on patients at 4 hospitals with ICAD causing stroke or transient ischemic attack (TIA) treated with stents. Patient demographics, lesion features, symptom characteristics, treatment success, and post-treatment outcomes such as technical complication, transient ischemic attack, stroke, or death were noted. Symptom characteristics were divided by aetiology as hypoperfusion, non-hypoperfusion, or indeterminate. Univariate logistic regression was performed for nominal variable types, and decision trees were constructed using recursive partitioning for continuous variables. Results Chi-square univariate logistic regression analysis demonstrated significant correlation of female gender with stroke at 30 days (x 2 [1, n = 130] = 5.106, p = 0.024). At point of last clinical contact, TIA was associated with an indeterminate symptom aetiology as opposed to identifiable hypoperfusion or non-hypoperfusion aetiology (x2 [1, n = 130] = 5.556, p = 0.018), as was initial presentation with TIA rather than stroke (x 2 [1, n = 130] = 6.458, p = 0.011). When comparing non-hypoperfusion and indeterminate symptom etiologies against clearly identifiable hypoperfusion aetiology, the non-hypoperfusion group was more likely to have a stroke by point of last contact (x 2 [1, n = 130] = 7.664, p = 0.006). Stroke outcome was also associated with lesion stenosis >95% (x 2 [1, n = 130] = 5.709, p = 0.017). Recursive partitioning analysis confirmed the above-described results and identified age >76.6 years as associated with symptomatic technical complications (x 2 [1, n = 130] = 0.047). Conclusion Degree of atherosclerotic stenosis is commonly used to stratify lesions when assessing suitability for treatment. This study identified stronger prognostic value in lesion features, specifically pathophysiologic features of presenting symptoms, and patient age and sex. Further research is needed to develop more robust models to predict natural history and potential response to endovascular treatment for ICAD. Disclosures M. Alexander: None. D. Cooke: None. P. Meyers: None. M. Amans: None. J. Narvid: None. C. Dowd: None. V. Halbach: None. R. Higashida: None. S. Hetts: None.

Purpose Although many intracranial dural arteriovenous fistulas (DAVFs) are straightforward to treat, de novo and rapidly progressive (“runaway” or “malignant”) DAVFs are more complex, often requiring multiple treatment sessions with suboptimal results. As these are rare entities, we sought to review our experience in the treatment of de novo and progressive DAVFs in order to better understand predictors of disease progression. Materials and methods Under an IRB-approved protocol, 29 patients with multiple, recurrent, de novo , or progressive DAVFs were identified from our hospital’s neurointerventional radiology database of 578 patients treated for intracranial DAVFs between 1986 and 2012. One patient with acute traumatic carotid cavernous fistulas was excluded. Patient demographics, clinical presentation, lesion angioarchitecture, treatment approaches, and clinical outcomes were categorized and assessed. Categorical variables were analyzed with odds ratios and 2-sided Fisher’s exact tests. Results We compared 28 patients with multiple, recurrent, de novo , or progressive DAVFs to 550 DAVF patients without such features. Whereas 18/28 (64%) of patients with multiple, recurrent, de novo , or progressive DAVFs were female, 283/550 (51%) without such features were female (OR 1.7, 95% CI: 0.73–4.2, p = 0.24). Mean age at presentation in the multiple, recurrent, de novo , or progressive DAVF group was 42 ± 23 years (range 2 months to 77 years) compared to 52 ± 20 years (range 1 day to 87 years) for the entire DAVF cohort. The most common presenting signs and symptoms the 28 patients treated for multiple, recurrent, de novo , or progressive DAVFs were headache (50%), cranial neuropathy (46%), tinnitus (36%), visual changes (32%), and intracranial haemorrhage (29%). 59 DAVFs were identified in these 28 patients. Location of fistulas included transverse/sigmoid sinus in 18 (64%), superior sagittal sinus in 8 (29%), torcula in 6 (21%), cavernous sinus in 5 (18%), marginal sinus in 5 (18%), and petrosal sinus in 2 patients (7%). Eight patients had DAVFs in other intracranial locations. Number of interventions per patient ranged from 2 to 19 (mean 5.5, median 4.5). All 28 patients were treated endovascularly; 15 (54%) were also treated with surgery. Embolic agents included coils in 25 patients (89%), ethanol in 23 (82%), polyvinyl alcohol in 21 (75%), N-butyl cyanoacrylate in 10 (36%), and Onyx in 5 (18%). 153 transarterial, transvenous, and surgical interventions were performed. The time between diagnosis of DAVF and last imaging ranged from 10 days to 21 years. At last follow up, 10 patients (36%) had no symptoms or residual DAVFs, 15 patients (54%) had neurological symptoms and/or residual DAVFs, and 3 patients (11%) had died due to intracranial haemorrhage or refractory elevations in intracranial pressure related to intracranial venous hypertension. A total of 19/28 patients had de novo or rapidly progressive DAVFs (68%) with all 3 deaths occurring in that group. No deaths were recorded in the other 9 patients with only recurrent or multiple DAVFs. Conclusion De novo or rapidly progressive DAVFs constituted 3% of all intracranial DAVF cases treated at our institution. Among these patients, despite aggressive endovascular and surgical care, a minority followed a malignant clinical course. Disclosures S. Hetts: 1; C; NIH-NIBIB, NIH-NCI, Siemens, Covidien. 2; C; Stryker, Penumbra, Medina Medical, Silk Road Medical. 4; C; Medina Medical, ChemoFilter, DriftCoast. T. Tsai: None. D. Cooke: 1; C; Siemens. 4; C; Viket. M. Amans: None. J. Narvid: None. C. Dowd: None. R. Higashida: None. V. Halbach: None.

Background and purpose The natural history of perimedullary arteriovenous fistulae (PMAVFs), also known as type IV spinal cord AV fistulae, is incompletely understood. Both open surgical and endovascular approaches have been described as treatment modalities for this disease. The goal of this study was to evaluate the long term outcome of patients with PMAVFs treated at a single tertiary care institution. Materials and methods We conducted a retrospective study on 32 patients with PMAVFs, evaluated between 1983 and 2009. Data were gathered by reviewing outpatient clinic notes, operative and radiological reports, and spinal angiograms. The PMAVFs were categorized into one of three types based on the angiographic imaging criteria. Pretreatment and post-treatment ambulation and micturition symptoms were quantified using the Aminoff and Logue scale (ALS). Results 30 patients underwent corrective procedures, four by embolization alone, 11 by surgery alone and 15 patients received a combination of the two. 28 patients underwent follow-up spinal angiography, with residual shunting noted in six patients. Mean follow-up period was 54 months (range 1–228). Analysis of the ALS scores revealed that treatment of PMAVFs, independent of modality, resulted in significant improvement in ambulation, but inconsistent changes in micturition. In addition, residual fistula at the time of follow-up angiogram was associated with worsened neurologic status or lack of improvement. Outcome analysis based on fistula type showed dramatic improvement in ALS ambulation scores (62%) for type 3 fistulae compared with type 1 and 2 (26%, 27%, respectively). Conclusion Significant improvement in ambulation, but not micturition, was observed following treatment. Residual fistula on follow-up angiography was associated with progressive worsening or lack of improvement in neurologic function. Patients with type 3 fistulae were shown to benefit most from treatment, with marked improvement in post-treatment ambulation scores. As endovascular and surgical techniques continue to evolve, further studies are warranted.

Purpose The use of ethylene-vinyl alcohol copolymer (EVOH, Onyx) for liquid embolisation of cranial vascular lesions has occasionally resulted in microcatheter fragments unintentionally remaining in situ in patients following endovascular procedures. Undergoing subsequent diagnostic MRI examinations poses a safety concern due to potential radiofrequency (RF) heating mediated by the metallic braid incorporated into the microcatheter. We sought to assess heating of a microcatheter commonly used to deliver Onyx in a phantom. Methods A 1.9F nitinol braided microcatheter (eV3 Echelon™-14, Irvine, CA) was embedded in a polyacrylamide phantom with five fluoroptic temperature probes placed along the length of the microcatheter and an additional background sensor. The phantom was scanned using a fast spin echo (FSE) sequence at average specific absorption rate (SAR) levels from 0.25 to 4.0 W/kg. Further scanning was performed using 2-minute clinical scans: T1 FSE, T2 FSE, DWI, T2 FLAIR, 3D-SPGR and b-SSFP. The scan that produced the most heating was repeated over a 15-minute acquisition. The experiments were then repeated with catheter fragment lengths of 9cm, 18cm, 36cm and 72cm. Experiments were performed on both 1.5T (Philips Achieva, Cleveland, OH) and 3T (GE Discovery 750w, Milwaukee, WI) clinical scanners. Results The maximal heating for the nitinol braided catheter immersed 93cm occurred at 20cm proximal to the tip using the T1 FSE sequence at 1.5 T. Maximal heating at 3T occurred using the b-SSFP sequence at the same position. The maximal temperature rise during a 2-minute scan was 0.84C at 1.5T and 0.45C at 3T. Figure 1 shows the temperature changes along different points on the catheter during a 15-minute T1 FSE sequence at 1.5T. The same scans for fragment lengths of 9cm, 18cm, 36cm and 72cm produced maximal temperature (C) rises of 0.68, 0.80, 1.70 and 1.07 at 1.5T, respectively. The temperature changes during a 15-min b-SSFP sequence at 3T for these fragment lengths were 0.66, 0.83, 1.07 and 0.72, respectively. Conclusions Heating of nitinol braided microcatheters occurred during diagnostic MR scanning and was a function of SAR level and geometric considerations. SAR and time limitations are proposed for patients with this microcatheter entrapped in their vasculature. Although the catheter displayed higher heating levels at 1.5T relative to 3T at a given SAR, it should be noted that there are most likely differences between the SAR models on the two scanner interfaces. Furthermore, the 3T scanner used for this study had a wider diameter bore. Disclosures A. Losey: None. P. Lillaney: None. A. Martin: None. V. Halbach: None. D. Cooke: None. C. Dowd: None. R. Higashida: None. D. Saloner: None. M. Wilson: None. M. Saeed: None. S. Hetts: None.

Background Gamma Knife radiosurgery (GKRS) is an option in the treatment of pediatric arteriovenous malformations (AVMs), especially for AVMs in eloquent locations or patients with good functional status. Prior studies have indicated that lower target volumes and higher prescription doses are associated with improved obliteration rates. Certain angiographic features including maximal diameter, diffuse border, and venous drainage patterns have also been shown to have n influence on rate of obliteration after GKRS.1 2 3 Methods We retrospectively reviewed all pediatric patients age ≤18 treated with GKRS for an AVM between 2000 and 2010 at our institution. Angiographic features based on pre-treatment angiography were prospectively recorded in a standardized manner and scored by experienced neuroradiologists. Results Between 2000 and 2010, 41 children (23 boys and 18 girls) underwent GKRS for an AVM. Follow-up information was available for 39 patients with 3-year angiographic follow-up in 22. Mean age at time of treatment was 13.5±3.5 years. Two patients had a Spetzler-Martin grade (SMG) II, 23 had grade III, 12 had grade IV, and 4 had grade V. The mean target volume for GKRS was 9.2±10.2 cm3 while the median prescription dose of radiation was 18Gy (range 16–20 Gy). 13 patients underwent staged GKRS. Among the 22 patients with 3-year angiographic follow-up, complete obliteration was observed in 9 (40.9%), while 12 (54.5%) showed a partial response. Only one patient had no response. Prescription dose was significantly correlated to angiographic response (p=0.046, logistic regression), with a dose ≥18 Gy being associated with a 75% complete obliteration rate compared to 27.2% in patients treated with 1), and fewer draining veins reaching a sinus (1 vs >1). Factors that did not have an influence on response rate included diffuse borders of AVM, having only deep venous drainage, venous ectasia, venous reflux, presence of any aneurysm, embolization prior to GKRS, and arterial inflow through anterior vs. posterior circulation. Conclusion There is a growing literature that GKRS is an effective treatment for pediatric AVMs. Our study finds that in addition to AVM volume and prescription dose, certain angioarchitectural features play a role in the rate of obliteration after treatment with GKRS. Smaller AVMs with fewer draining veins and fewer draining veins reaching a sinus had favorable outcomes. Competing interests None. References 1. Chang et al. J Neurosurg 2000;93(Suppl 3):96–101. 2. Kano et al. J Neurosurg Pediatrics 2012;9:1–10. 3. Yeon et al. Childs Nerv Syst 2011;27:1109–19.

Background and Purpose Children with brain AVMs are more likely than adults to present with hemorrhage. Prior studies have also demonstrated that AVMs in children are more frequently located deep within the brain than in adults. We sought to determine in greater detail which angioarchitectural features differ between children and adults with brain AVMs. Methods Under an IRB approved protocol, an institutional brain AVM database collected prospectively since 2001 was queried. Only patients with nidal AVMs were included for analysis; those with vein of Galen malformations, dural AV fistulas, or non-Galenic pial AV fistulas were excluded. Demographic and angioarchitecture information was abstracted and analyzed with Cox univariate and multivariable models. Results Children were more likely to present with AVM hemorrhage than adults (Abstract O-023 table 1). There was an over-representation of Hispanic children as compared to adults when patients were identified by self-reported or parent-reported ethnicity. Although the size of AVM nidus did not differ significantly between children and adults, the location and venous drainage did differ (Abstract O-023 table 2). Several angioarchitectural features did not differ significantly in their frequency between children and adults, including: AVM side, cerebellar hemispheric location, presence of arterial aneurysms not related to shunt flow, dural arterial supply, pial to pial arterial collaterialization, moyamoya-like changes, sharp vs diffuse AVM nidal border, nidal aneurysms, number of draining veins, and venous sinus thrombosis. There were non-significant trends toward increasing venous stenosis (p=0.061) and venous reflux (p=0.084) being more frequent in adults as compared to children. Children were more likely to have exclusively deep venous drainage than adults (p Conclusions Although children with brain AVMs were more likely to come to clinical attention due to hemorrhage than their adult counterparts at our institution, high risk features such as venous stenosis and feeding artery aneurysms were underrepresented in those children. AVMs and their draining veins were also more likely to be located deep within the brain in children, raising the possibility that centrally-located AVMs may arise earlier in development or be more likely to come to clinical attention early in life. Competing interests S Hetts: Silk Road Medical. H Kim: None. D Cooke: None. J English: Silk Road Medical. N Gupta: None. C Stout: None. W Kim: None. C Dowd: None. V Halbach: None. R Higashida: None. M Lawton: None. W Young: None.

Background and purpose Cerebral vasospasm (CV) following aneurysmal subarachnoid hemorrhage (SAH) is a significant cause of morbidity and mortality. We review our experiences using percutaneous transluminal angioplasty (PTA) and intra-arterial (IA) verapamil infusion for treating medically refractory cases. Materials and methods Retrospective review of SAH patients admitted from July 2003 to January 2008. Results Of 546 patients admitted with SAH, 231 patients (42%) developed symptomatic CV and 189 patients (35%) required endovascular therapy. A total of 346 endovascular sessions were performed consisting of a single angioplasty, 286 IA verapamil infusions and 59 combined therapies. PTA was performed on 151 vessel segments and IA verapamil infused in 720 vessel segments. IA verapamil doses ranged from 2.0 to 30.0 mg per vessel segment and 3.0 to 55.0 mg per treatment session. Repeat treatments were necessary in 182 patients (96%) for persistent, recurrent or worsening CV. There were six treatment related complications (1.7%) of which two (0.6%) resulted in clinical worsening. No deaths were attributable to endovascular therapy. At follow-up, 115 patients (61%) had a good outcome and 55 patients (29%) had a poor outcome. Sixteen patients died from causes related to SAH while three died from other medical complications. Conclusion Endovascular treatments are an integral part of managing patients with medically refractory CV. In our experience, PTA and IA verapamil are safe with a very low complication rate but further studies are required to determine appropriate patient selection and treatment efficacy.

Introduction and purpose Traumatic intracranial aneurysms are rare and represent fewer than 1% of all intracranial aneurysms. They may develop as the result of blunt or penetrating head trauma and are associated with a significant mortality of up to 50%. Traumatic aneurysms typically involve the anterior circulation or the internal carotid artery at the level of the skull base. They rarely involve the posterior circulation. We present three pediatric patients with traumatic aneurysms in the posterior circulation and describe their clinical presentation, angiographic findings and clinical outcome after being treated by endovascular technique. Materials and methods We retrospectively reviewed the angiographic and clinical findings in three pediatric patients, aged 12 years and younger, with traumatic pseudoaneurysms occurring in the posterior circulation in a variety of locations: one in the basilar artery, one in the posterior cerebral artery and one in the superior cerebellar artery. Results Three patients with three posterior circulation pseudoaneurysms (two male patients and one female patient; aged 3–12 years) were admitted during the past 2 years. All three patients underwent endovascular coil embolization. No complications were noted from these procedures. All patients improved clinically after treatment. Conclusions Contemporary endovascular techniques can be used effectively to treat posterior circulation pseudoaneurysms in the pediatric population. Treatment efficacy may be improved if there are bony confines around the aneurysm or if therapy takes place in the subacute period, when the wall of the pseudoaneurysm has matured and stabilized.