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Background: The selection of patients with large-vessel occlusion (LVO) stroke for endovascular treatment (EVT) depends on patient characteristics and procedural metrics. The relation of these variables to functional outcome after EVT has been assessed in numerous datasets from both randomized controlled trials (RCT) and real-world registries, but whether differences in their case mix modulate outcome prediction is unknown. Methods: We leveraged data from individual patients with anterior LVO stroke treated with EVT from completed RCTs from the Virtual International Stroke Trials Archive ( N = 479) and from the German Stroke Registry ( N = 4079). Cohorts were compared regarding (i) patient characteristics and procedural pre-EVT metrics, (ii) these variables’ relation to functional outcome, and (iii) the performance of derived outcome prediction models. Relation to outcome (functional dependence defined by a modified Rankin Scale score of 3–6 at 90 days) was analyzed by logistic regression models and a machine learning algorithm. Results: Ten out of 11 analyzed baseline variables differed between the RCT and real-world cohort: RCT patients were younger, had higher admission NIHSS scores, and received thrombolysis more often (all p Conclusions: RCT and real-world cohorts considerably differ in patient characteristics, individual outcome predictor strength, and overall outcome prediction model performance.

Acute stroke is a widespread, debilitating disease. Fortunately, it also has one of the most effective therapeutic options available in medicine, endovascular treatment. Imaging plays a major role in the diagnosis of stroke and aids in appropriate therapy selection. Given the rapid accumulation of evidence for patient subgroups and concurrent broadening of therapeutic options and indications, it is important to recognize the benefits of certain imaging technologies for specific situations. An effective imaging protocol should: 1) be fast, 2) easily implementable, 3) produce reliable results, 4) have few contraindications, and 5) be safe, all with the goal of providing the patient the best chance of achieving a favorable outcome. In the following, we provide a review of the currently available imaging technologies, their advantages and disadvantages, as well as an overview of the future of stroke imaging. Finally, we offer a perspective.

Background Neurointerventionalists use in-vitro vascular models to train for worst-case scenarios and test new devices in a simulated use environment to predict clinical performance. According to the Food and Drug Administration (FDA), any neurovascular navigation device should be able to successfully navigate two 360-degree turns and two 180-degree turns at the distal portion of the anatomical model. Here, we present a device benchmarking vascular model that complies with FDA recommendations. Methods Our vascular model was assembled from quantitative characterization of 49 patients who underwent CT angiography either for acute ischemic stroke caused by large vessel occlusion or for aneurysm treatment. Following complete characterization of these data, the vascular segments were 3D reconstructed from CT angiograms of 6 selected patients that presented with challenging anatomy. The curvature and total rotational angle were calculated for each segment and the anatomical parts that complied with FDA recommendations were fused together into a single in-vitro model. Results The model was constructed containing two common carotid branches arising from a type two aortic arch and the dimensions of the overall model exceeded the recommendations of the FDA. Two experienced neurointerventionalists tested the model for navigation difficulty using several devices on an in-vitro perfusion system and concluded that the model provided a realistic, challenging scenario. Conclusions This model provides a first prototype designed according to FDA recommendations of cumulative angle while also integrating an aggregation of actual patient-specific anatomy. The availability of this clinically relevant benchmark model presents a potential standardized approach for neurovascular device testing.

Background Preventing errors and complications in neurointervention is crucial, particularly in the treatment of unruptured intracranial aneurysms (UIAs), where the natural history is generally benign, and the margin of treatment benefit small. We aimed to investigate how neurointerventionalists perceive the importance and frequency of errors and the resulting complications in endovascular UIA treatment, and which steps could be taken to prevent them. Methods An international multidisciplinary survey was conducted among neurointerventionalists. Participants provided their demographic characteristics and neurointerventional treatment volume. They were asked about their perceptions on the importance and frequency of different errors in endovascular UIA treatment, and which solutions they thought to be most effective in preventing these errors. Results Two-hundred-thirty-three neurointerventionalists from 38 countries participated in the survey. Participants identified errors in technical execution as the most common source of complications in endovascular UIA treatment (40.4% thought these errors constituted a relatively or very large proportion of all complication sources), closely followed by errors in decision-making/indication (32.2%) and errors related to management of unexpected events (28.4%). Simulation training was thought to be most effective in reducing technical errors, while cognitive errors were believed to be best minimized by abandoning challenging procedures, more honest discussion of complications and better standardization of procedure steps. Conclusion Neurointerventionalists perceived both technical and cognitive errors to be important sources of complications in endovascular UIA treatment. Simulation training, a cultural change, higher acceptance of bail-out strategies and better standardization of procedures were perceived to be most effective in preventing these.

Background Some patients with ischemic stroke have poor outcomes despite small infarcts after endovascular thrombectomy, while others with large infarcts sometimes fare better. Aims We explored factors associated with such discrepancies between post-treatment infarct volume (PIV) and functional outcome. Methods We identified patients with small PIV (volume ≤ 25th percentile) and large PIV (volume ≥ 75th percentile) on 24–48-h CT/MRI in the ESCAPE randomized-controlled trial. Demographics, comorbidities, baseline, and 24–48-h stroke severity (NIHSS), stroke location, treatment type, post-stroke complications, and other outcome scales like Barthel Index, and EQ-5D were compared between “discrepant cases” – those with 90-day modified Rankin Scale(mRS) ≤ 2 despite large PIV or mRS ≥ 3 despite small PIV – and “non-discrepant cases”. Multi-variable logistic regression was used to identify pre-treatment and post-treatment factors associated with small-PIV/mRS ≥ 3 and large-PIV/mRS ≤ 2. Sensitivity analyses used different definitions of small/large PIV and good/poor outcome. Results Among 315 patients, median PIV was 21 mL; 27/79 (34.2%) patients with PIV ≤ 7 mL (25th percentile) had mRS ≥ 3; 12/80 (15.0%) with PIV ≥ 72 mL (75th percentile) had mRS ≤ 2. Discrepant cases did not differ by CT versus MRI-based PIV ascertainment, or right versus left-hemisphere involvement ( p = 0.39, p = 0.81, respectively, for PIV ≤ 7 mL/mRS ≥ 3). Pre-treatment factors independently associated with small-PIV/mRS ≥ 3 included older age ( p = 0.010), cancer, and vascular risk-factors; post-treatment factors included 48-h NIHSS ( p = 0.007) and post-stroke complications ( p = 0.026). Absence of vascular risk-factors ( p = 0.004), CT-based lentiform nucleus sparing ( p = 0.002), lower 24-hour NIHSS ( p = 0.001), and absence of complications ( p = 0.013) were associated with large-PIV/mRS ≤ 2. Sensitivity analyses yielded similar results. Conclusions Discrepancies between functional ability and PIV are likely explained by differences in age, comorbidities, and post-stroke complications, emphasizing the need for high-quality post-thrombectomy stroke care. Clinical trial registration https://clinicaltrials.gov/ct2/show/NCT01778335 .

Rationale Following endovascular treatment, poor clinical outcomes are more frequent if the initial infarct core or volume of irreversible brain damage is large. Clinical outcomes may be improved using neuroprotective agents that reduce stroke volume and improve recovery. Aim The aim of the REPERFUSE NA1 was to replicate the preclinical neuroprotection study that significantly reduced infarct volume in a primate model of ischemia reperfusion. Specifically, REPERFUSE NA1 will determine if administration of the neuroprotectant NA1 prior to endovascular therapy can significantly reduce early (Day 2 subtract Day 1 diffusion-weighted imaging volume) and delayed secondary infarct (90-day whole brain atrophy plus FLAIR volume—Day 1 diffusion-weighted imaging volume) growth, as measured by magnetic resonance imaging. Methods and design REPERFUSE-NA1 is a magnetic resonance imaging observational substudy of ESCAPE-NA1 (ClinicalTrialGov NCT02930018). A total of 150 acute stroke patients will be recruited (including 20% attrition) that have been randomized to either NA1 or placebo in the ESCAPE-NA1 trial. Study outcomes Primary—Early infarct growth measured using diffusion-weighted imaging will be at least 30% smaller in patients receiving NA1 compared to placebo. Secondary—Delayed secondary stroke injury at 90 days will be significantly reduced in patients receiving NA1 compared to placebo, as well as delayed secondary growth at 90 days. Conclusion REPERFUSE-NA1 will demonstrate the effect of NA1 neuroprotection on reducing the early and delayed stroke injury after reperfusion treatment.

Background Since 2015, endovascular therapy has been established as a standard of care for acute stroke. This has caused major challenges regarding the organization of systems of care, which have to meet the increasing demand for thrombectomies. This study aims to evaluate how endovascular therapy decisions made by European and North American physicians under their current local resources differ from those made under assumed ideal conditions. Methods In an international, multidisciplinary survey, physicians involved in acute stroke care were asked to give their treatment decisions to 10 out of 22 randomly assigned stroke case-scenarios. Participants stated (a) their treatment approach under assumed ideal conditions (without any external limitations) and (b) the treatment they would pursue under their current local resources. Resources gaps (ideal minus current endovascular therapy rates) were calculated for different countries/states/provinces and correlated to economic and healthcare key metrics (gross domestic product-per-capita, public or private health insurance coverage, etc.). Results A total of 607 physicians, among them 218 from North America and 136 from 25 European countries, responded to the survey. Resources gaps in the majority of North American states/provinces and European countries were small (Discussion and conclusion In the majority of North American states/provinces and European countries covered in this study, the discrepancy between endovascular therapy decisions under current local resources and assumed ideal conditions seems to be small, even in countries with a limited economic status and healthcare infrastructure.

Background Telerobotic endovascular therapy (EVT) has the potential to decrease time to treatment and expand existing networks of care to more rural populations. It is currently unclear how its implementation would impact existing stroke networks. Methods Conditional probability models were generated to predict the probability of excellent outcome for patients with suspected large vessel occlusion (LVO). A baseline stroke network was created for California using existing intravenous thrombolysis (IVT) centers and comprehensive stroke centers (CSCs) capable of IVT and EVT. Optimal transport decisions and catchment areas were generated for the baseline model and three hypothetical scenarios through conversion of IVT centers at various distances from a CSC into centers capable of telerobotic EVT [i.e., hospitals ≥15 and Results Telerobotic EVT centers decreased median travel time for LVO patients in all three scenarios. The estimated number of robotically treated LVOs per year in Scenarios 1, 2, and 3 were 2,172, 740, and 212, respectively. Scenario 1 (15–50 miles) was the most sensitive to robotic time delay and success rate, but all three scenarios were more sensitive to decreases in procedural success rate compared to time delay. Conclusions Telerobotic EVT has the potential to improve care for stroke patients outside of major urban centers. Compared to procedural time delays in robotic EVT, a decrease in procedural success rate would not be well tolerated.

BackgroundEndovascular treatment is recommended in clinical practice in Japan. However, its utilization and comprehensiveness are less well described.AimsTo report endovascular treatment utilization and overall geographical coverage in Japan and to analyze regional differences in the number of endovascular treatments, specialists, and endovascular treatment-capable hospitals.MethodsA national survey of members of the Japanese Society for NeuroEndovascular Therapy (JSNET) was conducted in 2017 and 2018. The total number of endovascular treatment cases per year was estimated, and the number of endovascular treatment cases per 100,000 people was calculated using the 2015 census. The distribution of treatment hospitals and JSNET specialists was mapped and the population coverage rate was determined.ResultsThe total number of endovascular treatment cases in Japan increased by 34.5% from 2016 (7702) to 2017 (10,360). The number of endovascular treatment-capable hospitals in Japan increased from 597 in 2016 to 693 in 2017, with an average annual caseload of 14.9 in 2017. The number of JSNET specialists per hospital decreased from 1.81 in 2016 to 1.76 in 2017 because of the increase in endovascular treatment-capable hospitals. Only 50 (7.2%) hospitals had > 40 endovascular treatment cases annually. The majority (97.7%) of the Japanese population lives within a 60-min drive of any endovascular treatment-capable hospital. However, only 70.4% live within a 60-min drive of a high-volume center (>40 cases annually).ConclusionsUtilization of endovascular treatment in Japan is increasing; however, the number of cases per hospital remains low, as is the number of specialists per endovascular treatment-capable hospital. Increased number of specialists and centralization of endovascular treatment services may improve patient outcomes.

Background A proportion of patients presenting with acute small ischemic strokes have poor functional outcomes, even following rapid recanalization treatment. Aims Infarct growth may occur even after successful recanalization and could represent an appropriate endpoint for future stroke therapy trials. Methods Magnetic resonance diffusion-weighted imaging lesion volumes were obtained at 5 h (initial posttreatment) and 24 h (follow-up) after acute stroke treatment for n = 33 in ischemic stroke patients. Sample sizes per arm (90% power, 30% effect size) for diffusion-weighted imaging lesion growth between initial and 24 h, early change in the National Institutes of Health Stroke Scale between pre- and 24 h, National Institutes of Health Stroke Scale at 24 h, and diffusion-weighted imaging lesion volume at 24 h were estimated to power a placebo-controlled stroke therapy trial. Results For patients with poor recanalization (modified thrombolysis in cerebral infarction Conclusion Despite best efforts to recanalize the ischemic brain, early diffusion-weighted imaging lesion growth still occurs. Treatment trials in stroke should consider early diffusion-weighted imaging lesion growth as a surrogate outcome measure to significantly reduce sample sizes.

The modified Rankin Scale (mRS) at 90 days after stroke onset has become the preferred outcome measure in acute stroke trials, including recent trials of interventional therapies. Reporting the range of modified Rankin Scale scores as a paired horizontal stacked bar graph (colloquially known as “Grotta bars”) has become the conventional method of visualizing modified Rankin Scale results. Grotta bars readily illustrate the levels of the ordinal modified Rankin Scale in which benefit may have occurred. However, complementing the available graphical information by including additional features to convey statistical significance may be advantageous. We propose a modification of the horizontal stacked bar graph with illustrative examples. In this suggested modification, the line joining the segments of the bar graph (e.g. modified Rankin Scale 1–2 in treatment arm to modified Rankin Scale 1–2 in control arm) is given a color and thickness based on the p-value of the result at that level (in this example, the p-value of modified Rankin Scale 0–1 vs. 2–6)—a thick green line for p-values

Background and purpose Ischemic stroke patients must be transferred to comprehensive stroke centers for endovascular treatment, but this transfer can be interpreted post hoc as “futile” if patients do not ultimately undergo the procedure or have a poor outcome. We posit that transfer decisions must instead be evaluated in terms of appropriateness at the time of decision-making. Methods We propose a classification schema for Appropriateness of Transfer for Endovascular Thrombectomy based on patient, logistic, and center characteristics. Results The classification outline characteristics of patients that are 1. Appropriate for transfer for endovascular treatment; 2. Inappropriate for transfer; and 3. Appropriate for transfer for higher level of care. Conclusions Appropriate transfer decisions for endovascular treatment are significant for patient outcomes. A more nuanced understanding of transfer decision-making and a classification for such transfers can help minimize inappropriate transfers in acute stroke.

Background The number needed to treat is a commonly used statistical term in modern neurointerventional practice. It represents the number of patients that need to be treated for one patient to benefit from an intervention. Given its growing popularity in reflecting study results, understanding the basics behind this statistic is of practical value to the neurointerventionalist. Methods Here, we review the basic theory and calculation of the number needed to treat, its application to stroke interventions, and its limitations. In addition, we demonstrate several simple methods of calculating the number needed to treat utilizing recent thrombectomy trial results. By presenting the number needed to treat as a universal metric, we provide a comprehensive comparative of the number needed to treat for key stroke therapies, including mechanical thrombectomy, tissue plasminogen activator, carotid endarterectomy, and prevention with antiplatelet and statin drugs. Conclusions In comparison with available stroke therapies, mechanical thrombectomy stands out as the most effective acute intervention in patients with emergent large-vessel occlusions. Understanding how the number needed to treat is derived and its implications helps provide perspective to clinical trial data, identify health-care resource priorities, and improve communication with patients, health-care providers, and additional key stakeholders.

Rationale Endovascular treatment has been shown to restore blood flow effectively. Second-generation medical devices such as stent retrievers are now showing overwhelming efficacy in clinical trials, particularly in conjunction with intravenous recombinant tissue plasminogen activator. Aims and Design This statistical analysis plan utilizing a novel, sequential approach describes a prospective, individual patient data analysis of endovascular therapy in conjunction with intravenous recombinant tissue plasminogen activator agreed upon by the Thrombectomy and Tissue Plasminogen Activator Collaborative Group. Study outcomes This protocol will specify the primary outcome for efficacy, as ‘favorable’ outcome defined by the ordinal distribution of the modified Rankin Scale measured at three-months poststroke, but with modified Rankin Scales 5 and 6 collapsed into a single category. The primary analysis will aim to answer the questions: ‘what is the treatment effect of endovascular therapy with intravenous recombinant tissue plasminogen activator compared to intravenous tissue plasmi-nogen activator alone on full scale modified Rankin Scale at 3 months?’ and ‘to what extent do key patient characteristics influence the treatment effect of endovascular therapy?’. Key secondary outcomes include effect of endovascular therapy on death within 90 days; analyses of modified Rankin Scale using dichotomized methods; and effects of endovascular therapy on symptomatic intracranial hemorrhage. Several secondary analyses will be considered as well as expanding patient cohorts to intravenous recombinant tissue plasminogen activator-ineligible patients, should data allow. Discussion This collaborative meta-analysis of individual participant data from randomized trials of endovascular therapy vs. control in conjunction with intravenous thrombolysis will demonstrate the efficacy and generalizability of endovascular therapy with intravenous thrombolysis as a concomitant medication.

ESCAPE is a prospective, multicenter, randomized clinical trial that will enroll subjects with the following main inclusion criteria: less than 12 h from symptom onset, age > 18, baseline NIHSS >5, ASPECTS score of >5 and CTA evidence of carotid T/L or M1 segment MCA occlusion, and at least moderate collaterals by CTA. The trial will determine if endovascular treatment will result in higher rates of favorable outcome compared with standard medical therapy alone. Patient populations that are eligible include those receiving IV tPA, tPA ineligible and unwitnessed onset or wake up strokes with 12 h of last seen normal. The primary end-point, based on intention-to-treat criteria is the distribution of modified Rankin Scale scores at 90 days assessed using a proportional odds model. The projected maximum sample size is 500 subjects. Randomization is stratified under a minimization process using age, gender, baseline NIHSS, baseline ASPECTS (8–10 vs. 6–7), IV tPA treatment and occlusion location (ICA vs. MCA) as covariates. The study will have one formal interim analysis after 300 subjects have been accrued. Secondary end-points at 90 days include the following: mRS 0–1; mRS 0–2; Barthel 95–100, EuroQOL and a cognitive battery. Safety outcomes are symptomatic ICH, major bleeding, contrast nephropathy, total radiation dose, malignant MCA infarction, hemicraniectomy and mortality at 90 days.

We aimed to evaluate how predefined candidate cerebral perfusion parameters correlate with collateral circulation status and to assess their capacity to predict infarct growth in patients with acute ischemic stroke (AIS) eligible for endovascular therapy. Patients enrolled in the SWIFT PRIME trial with baseline computed tomography perfusion (CTP) scans were included. RAPID software was used to calculate mean relative cerebral blood volume (rCBV) in hypoperfused regions, and hypoperfusion index ratio (HIR). Blind assessments of collaterals were performed using CT angiography in the whole sample and cerebral angiogram in the endovascular group. Reperfusion was assessed on 27-h CTP; infarct volume was assessed on 27-h magnetic resonance imaging/CT scans. Logistic and rank linear regression models were conducted. We included 158 patients. High rCBV ( p = 0.03) and low HIR ( p = 0.03) were associated with good collaterals. A positive association was found between rCBV and better collateral grades on cerebral angiography ( p = 0.01). Baseline and 27-h follow-up CTP were available for 115 patients, of whom 74 (64%) achieved successful reperfusion. Lower rCBV predicted a higher infarct growth in successfully reperfused patients ( p = 0.038) and in the endovascular treatment group ( p = 0.049). Finally, rCBV and HIR may serve as markers of collateral circulation in AIS patients prior to endovascular therapy.

Selective brain cooling is a promising advent for reducing final infarct volume and improving outcomes in ischemic stroke victims. Despite the robust body of evidence from animal studies, evidence supporting the use of selective hypothermia in stroke patients is lacking. A recent study provided promising results on the safety and possible efficacy of selective brain hypothermia via intraarterial infusion of cooled saline. Better understanding of the patients’ population that may attain benefit from this approach will be informative. Details of infarct progression using perfusion imaging will also help understand the mechanism of effect of selective hypothermia to inform future trials.

Introduction Endovascular treatment of acute ischemic stroke is more effective when performed quickly. In this report, we describe quality interventions to ensure fast endovascular treatment times in the ESCAPE (Endovascular Treatment for Small Core and Anterior circulation Proximal Occlusion with Emphasis on Minimizing CT to Recanalization Times) trial. Methods An “audit and feedback” intervention using webinar and letter was used to improve treatment time over the course of the trial. The time metrics were computed tomography-to-groin-puncture (target Results There were 165 patients enrolled into the endovascular arm from 22 sites. The computed tomography-to-groin-puncture time dropped from 57 to 47 min (p = 0.14) while computed tomography-to-reperfusion time dropped from 89 to 81 min (p = 0.48). Over the course of the trial, the absolute treatment benefit increased by 7.8% (p Conclusions An “audit and feedback” intervention throughout the conduct of the ESCAPE trial was a feasible way to ensure fast treatment times. Quality improvement processes should continue as standard practice beyond the trial to encourage good patient selection and the best clinical outcomes.

Background There is an increasing trend to treating proximal vessel occlusions with intravenous–inter-arterial (IV-IA) thrombolysis. The best dose of IV tissue plasminogen activator (tPA) remains undetermined. We compared the combination of full-dose IV recombinant tissue plasminogen activator (rtPA) and IA thrombolytic therapy to IA therapy. Methods Between 2002 and 2009, we reviewed our computed tomographic angiography database for patients who received full-dose intravenous rtPA and endovascular therapy or endovascular therapy alone for acute ischaemic stroke treatment. Details of demographics, risk factors, endovascular procedure, and symptomatic intracranial haemorrhage were noted. Modified Rankin Scale ≤2 at three-months was used as good outcome. Recanalization was defined as Thrombolysis in Myocardial Ischaemia 2–3 flow on angiography. Results Among 157 patients, 104 patients received IV-IA treatment and 53 patients underwent direct IA therapy. There was a higher recanalization rate with IV-IA therapy compared with IA alone (71% vs. 60%, P < 0·21) which was driven by early recanalization after IV rtPA. Mortality and independent outcome were comparable between the two groups. Symptomatic intracranial haemorrhage occurred in 8% of patients (12% in the IA group, 7% in the IV-IA group) but was more frequent as the intensity of intervention increased from device alone to thrombolytic drug alone to device plus thrombolytic drug(s). Recanalization was a strong predictor of reduced mortality risk ratio (RR) 0·48 confidence interval95 0·27–0·84) and favourable outcome (RR 2·14 confidence interval95 1·3–3·5). Conclusions Combined IV-IA therapy with full-dose intravenous rtPA was safe and results in good recanalization rates without excess symptomatic intracranial haemorrhage. Testing of full-dose IV tPA followed by endovascular treatment in the IMS3 trial is justified.

There is no consensus on how the reliability and predictive ability of noncontrast computed tomography (NCCT) and computed tomography angiography source image (CTASI) change over time from acute ischemic stroke onset. We hypothesized that the reliability for detecting early ischemic changes (EIC) would be lower in early time periods and that changes identified on CTASI would be more reliable across examiners than changes identified on NCCT. To address this, we compared the relationships between CTASI, NCCT, and final infarct in patients with initial computed tomography (CT) imaging at different time points after stroke onset. Patients with acute ischemic stroke with proximal anterior circulation occlusions (internal carotid artery, middle carotid artery M1, proximal M2) from Calgary CT Angiography (CTA) database were studied. The cohort was categorized in four groups based on time from stroke onset to baseline NCCT/CTA: 0–90 mins ( n = 69), 91–180 mins ( n = 88), 181–360 mins ( n = 46), and >360 mins ( n = 58). Median scores of NCCT-Alberta Stroke Program Early CT Score (ASPECTS), CTASI ASPECTS, and follow-up ASPECTS among different time categories were compared. To determine reliability, a subsample of NCCT brain and CTASI were interpreted at separate sessions weeks apart by two neuroradiologists and two stroke neurologists in random order. Median and mean ASPECTS ratings on NCCT and CTASI were higher than final ASPECTS in each time category ( P < 0·001 for all comparisons). CTASI ASPECTS was lower than NCCT ASPECTS in each time category, and differences were significant at 0–90 mins and 91–180 mins ( P < 0·001). The least agreement among readers was in detection of EIC on NCCT brain in the ultra-early phase (

The role of embolisation in the treatment of small (< 3cm) brain arteriovenous malformations (AVMs) has not been elucidated. We reviewed our experience using embolisation in the treatment of small AVMs and correlated a proposed grading system based on the angioarchitecture to the percentage obliteration achieved by embolisation. Eighty-one small AVMs in 80 patients were embolised from 1984 to 1999. The age range was from 3 to 72 years. The AVMs were given a score from 0 to 6 based on the angioarchitecture. The assigned scores were as follows: nidus (fistula = 0, < 1 cm = 1, 1–3 cm = 2), type of feeding arteries (cortical = 0, perforator or choroidal = 1), number of feeding arteries (single = 0, multiple = 2) and number of draining veins (single = 0, multiple = 1). Angiographic results based on percentage obliteration were grouped into three categories: complete, 66–99%, and 0–65%. The goal of embolisation was cure in 27 AVMs, pre-surgical in 23, pre-radiosurgery in 26, and elimination of an aneurysm in five. Embolisation achieved complete obliteration in 22 (27%) of the 81 AVMs. In the AVMs where the goal was cure, 19 (70%) of 27 were completely obliterated. In the AVMs with angioarchitecture scores of 0–2, 12 (86%) of 14 were cured, with scores of 3–4, 8 (34%) of 24 were cured and with scores of 5–6, 2 (4%) of 44 were cured. Embolisation resulted in transient morbidity of 5.0%, permanent morbidity of 2.5%, and mortality of 1.2%. There were no complications in AVMs with scores of 0–2. Embolisation is an effective treatment of small AVMs when the angioarchitecture is favourable (scores 0–2). This includes pure fistulas and AVMs with a single, pial, feeding artery.

Spontaneous vertebrovertebral arteriovenous fistula (SWAVF) is a rare condition which often presents as a bruit. We reviewed the clinical and imaging records of 12 patients with 13 SVVAVF fistulae who were managed at our institution over the last 14 years. Two patients had predisposing conditions, neurofibromatosis in one and Ehlers-Danlos syndrome in the other. Nine of the patients presented with a bruit; one patient presented with a myelopathy and one with congestive cardiac failure. Six of the 13 fistulae were at C1 and five of these six were children. In seven of the fistulae there was retrograde flow in the distal vertebral artery. Eight patients underwent endovascular treatment. Six required both contralateral and ipsilateral vertebral artery approaches. Coils (two patients), balloons (three patients), or a combination of agents including liquid adhesives (three patients) were used. Preservation of the vertebral artery was possible in three of the eight patients. Angiographic obliteration was obtained in all eight patients. There were no significant procedure-related complications. Embolisation is the primary treatment of SVVAVF and can be performed successfully with low morbidity. Preservation of the vertebral artery, although desired, is often not possible.

We report a case of dural arteriovenous fistual (DAVF) with cortical venous reflux in whom disconnection of the refluxing cortical vein was achieved by using a retrograde transcortical venous approach through the cortical vein itself.

We describe a technique for performing clot angioplasty using a single lumen balloon catheter for thrombolytic administration, check injections of the distal circulation and for angioplasty. We believe this reduces both the time of the procedure and the risk of vessel rupture.