Symptomatic Unruptured Arteriovenous Malformations: Focal Edema, Thrombosis, and Vessel Wall Enhancement: A Retrospective Cohort Study.

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

Deep venous communication in vein of Galen malformations: incidence, Imaging, and Implications for treatment.

BACKGROUND: Failure to appreciate deep venous drainage pathways is a major cause of severe complications in the endovascular treatment of vein of Galen aneurysmal malformations (VOGMs). OBJECTIVE: To report deep venous drainage patterns in patients with VOGM, emphasizing the internal cerebral veins, and to describe the challenges in evaluating these. METHODS: Patients with VOGM presenting to our institute between 2000 and 2018 were retrospectively analyzed. Patients with complete and good quality imaging datasets were included in the study. Three neuroradiologists with expertise in the subject independently analyzed the deep venous drainage patterns on multi-sequence MRI and digital subtraction angiography. Follow-up imaging studies were analyzed for alterations in deep venous drainage patterns that occurred following endovascular treatment. Descriptive statistics were used to report findings. RESULTS: Twenty-three patients had optimal quality MRI imaging and 25 had optimal quality DSA imaging available. In 14/23 (61%) patients, internal cerebral vein (ICV) communication could be reliably identified on MRI and in 8/25 (32%) patients on DSA. Deep venous communication with the VOGM was demonstrated in 8/26 (30.8%) patients. One (3.8%) patient demonstrated ICV communication with the VOGM only on postoperative imaging, while in 2 (8%) patients the ICV drainage route changed from VOGM to alternative pathways after the procedure. Other variant pathways included lateral mesencephalic vein, superior or inferior sagittal sinus, anterior mesencephalic vein, tentorial sinus, deep Sylvian vein, and superior vermian vein. CONCLUSION: ICV communication with the VOGM is not uncommon and requires dedicated preprocedural imaging to identify it. However, there are significant challenges in assessing this communication in the presence of high-flow fistulae, vessel tortuosity and size, and contrast limitations in this population.

First clinical experience with the new Surpass Evolve flow diverter: technical and clinical considerations.

OBJECTIVE: To describe the results in patients treated with the Surpass Evolve (SE) device, the new generation of Surpass flow diverters. METHODS: Twenty-five consecutive patients (20 women, average age 58 years), with anterior or posterior circulation aneurysms treated with SEs in two early-user centers, were included. Device properties and related technical properties, imaging and clinical follow-up data, and intraprocedural, early (<30 days) and delayed (>30 days) neurological complications, further divided into minor (silent/non-permanent) and major (permanent) complications, were recorded and analyzed. RESULTS: Twenty-nine SEs were successfully implanted in all subjects to treat 26 aneurysms using an 0.027" microcatheter with an average of 1.2 stents per patient. No intraprocedural thromboembolic or hemorrhagic complications were seen. At clinical follow-up, 24/25 (96%) patients had a modified Rankin Score of 0-2. Mortality was 0%. Imaging follow-up, available in 22/25 (88%) patients (median follow-up time 4 months), showed a complete aneurysm occlusion in 13/23 (57%) imaged lesions. Minor, transitory neurological deficits were recorded in 5/25 (20%) patients. One (4%) major complication was seen in one patient (4%) with a left-sided hemispheric stroke on postprocedural day 4 due to an acute stent thrombosis. CONCLUSIONS: Preliminary experience in patients demonstrates a good performance of the SE. This newly designed implant maintains the engineering characteristics of Surpass flow diverters, including precise placement due to its lower foreshortening and a high mesh density, yet can be deployed through a significantly lower-profile delivery system.

Procedural success with radial access for carotid artery stenting: systematic review and meta-analysis.

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

Periprocedural complications of second-generation flow diverter treatment using Pipeline Flex for unruptured intracranial aneurysms: a systematic review and meta-analysis.

BACKGROUND: Flow diverters are a breakthrough treatment for large and giant intracranial aneurysms but carry a risk of periprocedural death or major stroke. Pipeline Flex is a second-generation device that is thought to have lower complication rates because of improvements in the delivery system as well as increased operator experience. Our objective was to analyze the risk of periprocedural death or major complications using Pipeline Flex for unruptured intracranial aneurysms. METHODS: A systematic search of three databases was performed for studies of ≥10 treatments using Pipeline Flex for unruptured intracranial aneurysms (2014-2019) using PRISMA guidelines. Random effects meta-analysis was used to pool the rates of periprocedural (<30 days) death, major ischemic stroke, symptomatic intracranial hemorrhage, and minor stroke/transient ischemic attack. RESULTS: We included eight studies reporting 901 treatments in 879 patients. Periprocedural mortality (<30 days) was 0.8% (5/901; 95% CI 0.4% to 1.5%; I2=0%). Rate of major complications (death, major ischemic stroke, or symptomatic intracranial hemorrhage) was 1.8% (14/901; 95% CI 1.0% to 2.7%; I2=0%). Aneurysm size ≥10 mm was a statistically significant predictor of a major complication (OR 6.4; 95% CI 2.0 to 20.7; p=0.002). Risk of a major complication in aneurysms <10 mm was 0.9% (95% CI 0.3% to 1.7%; I2=0%). The meta-analysis was limited by the predominance of anterior circulation aneurysms. CONCLUSION: Treatment of unruptured intracranial aneurysms using the Pipeline Flex flow diverter has a low periprocedural risk of death (0.8%) or major complication (1.8%). The risk of a major complication is significantly higher for large/giant aneurysms (4.4%) and is very low for aneurysms <10 mm (0.9%).

SPECT-CT/VQ versus CTPA for diagnosing pulmonary embolus and other lung pathology: Pre-existing lung disease should not be a contraindication.

INTRODUCTION: Single Photon Emission Computed Tomography-Ventilation-Perfusion (SPECT-VQ) with low-dose CT (SPECT-CT/VQ) has equivalent diagnostic accuracy to CTPA for diagnosing pulmonary embolus (PE) while using lower radiation doses, but is underutilized owing to perceived inaccuracy of scintigraphy in the setting of pre-existing lung disease. This study assesses the accuracy of SPECT-CT/VQ compared with CTPA for the diagnosis of PE, including in patients with pre-existing lung disease. METHODS: Retrospective non-inferiority cohort study of all patients who underwent SPECT-CT/VQ scanning at St Vincent's Hospital, NSW, from June 2012 to November 2013, who also had a CTPA within the same admission and <72 h apart (n = 102). RESULTS: SPECT-CT/VQ had 100% sensitivity and 94.4% specificity when compared with CTPA. Of the 102 patients, 14 were lung transplant patients, and 27 had other pre-existing lung disease (41/102, 40.2%), with SPECT-CT/VQ having a sensitivity of 100% and specificity of 97.2% in this patient group. Non-inferiority of SPECT-CT/VQ was demonstrated at a significance level of 0.005. CONCLUSION: SPECT-CT/VQ has high sensitivity and specificity for diagnosing PE compared with CTPA, even among patients with pre-existing lung disease, with lower radiation doses.