Abstract
The roles of stereotactic radiosurgery (SRS) for cerebral arteriovenous malformation (AVM) and intracranial dural arteriovenous fistula (AVF) are reviewed. Good indications for SRS to treat AVM are lesions that are small and deep-seated. The target is precisely covered with the prescription doses. The optimal prescription dose appeared to be 20 Gy. Our retrospective review of 321 AVM cases treated with gamma knife (GK) revealed approximately 80% of cases showed complete nidus obliteration on angiography 4 years after GK treatment. For AVM with a high risk of latency-period bleeding with angio-architectural structures such as a large volume, high flow shunt, extracranial arterial blood supply and intra-nidus aneurysm, we have been endeavoring to embolize the target. However, we noted transient radiation-induced edema in about 40% of cases, bleeding during the latency period in 5% and delayed radiation injury in 10%. Delayed radiation injuries included radiation necrosis, cyst formation, and chronic encapsulated hematoma. On the contrary, the indications for SRS to treat AVF are generally limited to residual shunting after interventional treatment. The AVF target is divided into the two types, one involving the only shunt point and the other the entire involved sinus or dura. AVF treated with SRS tend to show earlier obliteration than AVM without serious delayed radiation injury.
