Role of stereotactic radiosurgery in a multidisciplinary therapeutic approach for arteriovenous malformations

OBJECTIVE: The main goal of the treatment of cerebral arteriovenous malformations (AVM) is to eliminate the risk of hemorrhage. At present, microsurgical resection (MSR), endovascular embolization (EVT), and stereotactic radiosurgery (STR) are selected as the therapeutic options. In this study, the role of STR in a multidisciplinary strategy for AVM is discussed. MATERIALS: The data in this study are all based on the experience of STR with 714 AVMs in our hospital (78 were treated after MSR, 100 after EVT). RESULTS: The associated factors for nidus obliteration were nidus volume, delivered radiation dose, and past history of hemorrhage from AVM. The major benefit of MSR is the immediate elimination of hemorrhagic risks, but the procedure can be invasive in the eloquent area or the deep cerebral regions. EVT is less invasive than MSR, but revascularization of the AVM can take place. However, after MSR or EVT, a marked shrinkage of nidus volume is expected, and STR is successfully applicable for the residual AVM. It is very difficult to selectively resect the nidus component in the non-eloquent area without affecting the nidus in the eloquent area during MSR. On the other hand, the AVM becomes much less vascularized a few years after STR, and safe MSR is feasible in most cases. CONCLUSIONS: For AVM with large nidus involving the eloquent area or the deep cerebral region, the strategy using STR for the surgically intractable regions followed by MSR a few years later may be effective and simultaneously can eliminate the uncertain risks of radiation-induced complications, such as chronic encapsulated hematoma, growing cyst formation, and bleeding from obliterated nidus, taking place even years after AVM obliteration by STR.