Study Comparing Onyx and TRUFILL in Brain Arteriovenous Malformations (AVMs)

Inclusion Criteria: * The patient or patient's guardian understands and will sign the informed consent for the procedure * The patient has a confirmed diagnosis of a brain AVM in the cerebral cortex, cerebellum or dura mater as visualized by angiography or cross sectional imaging. * The brain AVM has a Spetzler-Martin grade of I, II, III, or IV. If the brain AVM has a Spetzler-Martin grade of I or II, the anticipated benefit of embolization for surgical resection is greater than the risk of the embolization procedure (e.g., patient stability). * The patient is a candidate for surgical resection of the AVM post embolization. * The patient is clinically and neurologically stable, for a minimum of 24 hours prior to embolization. * The patient agrees to have, and is capable of completing, all study-related exams and procedures. * Patient of any age. Exclusion Criteria: * The patient is pregnant. * The patient has a brain AVM with high flow arteriovenous fistulae that the investigator has determined to be unsuitable for embolization. * The brain AVM has a Spetzler-Martin grade of V. * The patient is participating in another research study involving another investigational device, procedure or drug. * The brain AVM has been previously treated with another embolization agent