Study Procedures Once the subject has agreed to participate in the study and has signed the consent form, the baseline visit can be performed. A full medical history will be taken and a physical exam will be done as per local routine practice for an embolization procedure. The Cognard scale will be performed to assess the grade of a DAVF and the Spetzler Martin grade will be assessed if a brain AVM is to be treated; these are standard scoring systems for brain DAVFs and AVMs. A neurological exam will be done and any abnormalities will be documented.