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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., (Crown Copyright © 2021. Published by Elsevier Inc. All rights reserved.)

Background: Cerebral cavernous malformations (CCM) can cause intracerebral hemorrhage. The lesions themselves are frequently associated with perifocal hemosiderin deposits caused by repetitive microhemorrhages. Main indications for a surgical treatment are recurrent symptomatic hemorrhages or cavernoma-related epilepsy. After surgical resection, follow-up magnetic resonance imaging (MRI) is usually performed to confirm 1) the complete resection of the CCM and, especially in cases of cavernoma-related epilepsy, 2) the complete resection of the hemosiderin deposits., Methods: This prospective study evaluates the value of early postoperative MRI (within 72 hours) regarding the detection of CCM or hemosiderin remnants compared with a standard 3-6 months postoperative MRI control in 61 CCM cases., Results: Sensitivity of early postoperative MRI for CCM remnant detection was 66.67% (95% confidence interval [CI], 9.43%-99.16%), specificity was 76.74% (95% CI, 61.37%-88.24%), positive predictive value was 16.67% (95% CI, 2.09%-48.41%), and negative predictive value was 97.06% (95% CI, 84.67%-99.93%). Because of the high number of patients who could not be evaluated because of imaging artifacts, sensitivity and specificity analysis was not performed for early postoperative MRI using T2*/susceptibility-weighted imaging to assess hemosiderin remnants. Sensitivity of early postoperative MRI for hemosiderin remnant detection using T2-weighted sequences was 85.71% (95% CI, 63.66%-96.95%), specificity was 66.67% (95% CI, 44.68%-84.37%), positive predictive value was 69.23% (95% CI, 55.45%-80.27%), and negative predictive value was 84.21% (95% CI, 64.31%-94.04%)., Conclusions: Our data suggest that early postoperative MRI after CCM surgery is often hampered by imaging artifacts creating false-positive results and therefore ineligible for a resection control. However, reliability of a negative result on early postoperative T2-weighted MRI is relatively high regarding both CCM and hemosiderin remnants., (Copyright © 2017 Elsevier Inc. All rights reserved.)