Brain edema associated with unruptured brain arteriovenous malformations

Introduction  Brain edema in unruptured brain arteriovenous malformations (AVMs) is rare; this study examines (1) its frequency and clinical presentation, (2) imaging findings with emphasis on venous drainage abnormalities, and (3) implications of these findings on natural history and management. Methods  Presentation and imaging features of all unruptured brain AVMs were prospectively collected in our brain AVM database. Neurological findings, size, location, venous drainage pattern, presence of venous thrombosis, ectasia, or stenosis, and brain edema were specifically recorded. Treatment details of all patients with brain edema and their clinical and imaging follow-up were reviewed. Finally, a comparison was made between patients with and without edema. Results  Brain edema was found in 13/329 unruptured brain AVMs (3.9%). Neurological deficit (46.2%), venous thrombosis (38.5%), venous ectasia (84.6%), stenosis (38.5%), and contrast stagnation in the draining veins (84.6%) were more frequent in patients with brain edema than without edema. Eight patients with brain edema received specific treatment (embolization = 5, surgery = 2, radiosurgery = 1). Clinical features correlated well with change in degree of edema in six. Three of five embolized patients were stable or showed improvement after the procedure. On follow-up, however, intracranial hemorrhage developed in three. Conclusion  Brain edema in unruptured brain AVMs is rare, 3.9% in this series. Venous outflow abnormalities are frequently associated and appear to contribute to the development of edema. Progressive nonhemorrhagic symptoms are also associated, with a possible increased risk of hemorrhage. Palliative embolization arrests the nonhemorrhagic symptoms in selected patients, although it may not have an effect on hemorrhagic risk.