Prognostic Factors of Gamma Knife Radiosurgery for Cerebral Arteriovenous Malformation : The Results from 218 Consecutive Patients

Abstract

"Objective: We retrospectively evaluated our experience of the management and long-term outcomes of gamma knife radiosurgery (GKRS) on arteriovenous malformation (AVM) as a primary treatment as well as adjunct therapy. GKRS is widely used in many centers worldwide for the management of AVM. However, the long-term results of GKRS are not well known. In the present study, we retrospectively evaluated our experience of focusing on prognostic factors in the management and long-term outcomes of GKRS on AVM. Materials and Methods: We performed a retrospective review of 218 patients. They were treated with GKRS in our institute from 2007 to 2013. The group included first-time GKRS for cerebral AVM, previous surgical resection, and embolization, excluding previously GKRS-treated patients. We analyzed the association between several factors (gender, age, marginal dose, hemorrhage, marginal dose, nidus volume) and the obliteration rate, which was the cumulative obliteration rate regardless of additional treatment, including repeat GKRS. Results: The univariate analysis of our study identified that a high radiation dose [margin dose ＞16.0Gy (50%), p=0.017] rather than a low radiation dose [margin dose ≤16.0Gy (50%)] and small AVM volume (≤15.0mL, p=0.003) rather than large AVM volume (＞15.0mL) were positive predictors of AVM nidus obliteration. Our study showed that young age (≤18 years) had a better obliteration rate compared with others (＞18 years) in AVM after GKRS (p=0.053). Our findings did not show that gender (p= 0.427) or hemorrhage (p=0.191) had significant effects on nidus obliteration. Comparison of our results with prior studies showed that AVM volume and margin radiation dose had a significant role in the obliteration rate in common. Conclusion: We suggest that AVM with a small volume can be considered good indications for GKRS, and a higher marginal dose [margin dose ＞16.0Gy (50%)] can be an effective factor for higher obliteration with the carefulness of post-radiosurgical complications. Finally, we can expect favorable GKRS results for appropriately selected AVMs in the young population."