 The decision to treat brain arteriovenous malformations depends on the symptoms that they cause ( such as seizures or headaches ) . The bleeding risk is predicted by previous episodes of hemorrhage , and whether on the CTA or MRA scan the AVM appears to be deep seated or have deep venous drainage . Size of the AVM and the presence of aneurysms appears to matter less . In HHT , some lesions ( high @-@ flow arteriovenous fistulae ) tend to cause more problems , and treatment is warranted . Other AVMs may regress over time without intervention . Various modalities are available , depending on the location of the AVM and its size : surgery , radiation @-@ based treatment and embolization . Sometimes , multiple modalities are used on the same lesion . 
