Arteriovenous malformation radiosurgery

Abstract

Stereotactic radiosurgery (SRS) is an accepted management strategy for many patients with intracranial arteriovenous malformations (AVM). The goal of AVM SRS is nidus obliteration without new neurologic deficits from either radiation-related complications or post-SRS hemorrhage. Over the past 30 years, advances in neuroimaging, dose-planning software, and radiation delivery devices have improved patient outcomes after AVM SRS. The most important factor associated with nidus obliteration is the radiation dose delivered to the margin of the AVM. Patients receiving an AVM margin dose of 15 Gy have a 60–70 % chance of obliteration whereas patients receiving ≥20 Gy have an approximately 90 % chance of cure. Radiation-related complications relate to the overall brain radiation exposure, which is a function of treatment volume and prescribed radiation dose. Patients with AVMs in deep locations such as the basal ganglia, thalamus, and brainstem are at greatest risk for radiation-related complications. The primary drawback of AVM SRS when compared to surgical resection is that the patient remains at risk for hemorrhage until the AVM has gone onto complete obliteration. Recent studies have shown that the risk of bleeding is either unchanged or decreased following AVM SRS. The radiosurgery-based AVM score (RBAS) was developed to predict outcomes after AVM SRS. Based on three factors (AVM volume, patient age, AVM location), the RBAS has been validated by numerous centers using the Gamma Knife®, modified LINAC, and the CyberKnife®. The RBAS allows an accurate prediction of outcomes from SRS to assist in the management for individual AVM patients.​