Radiation-induced organized hematoma after gamma knife radiosurgery for arteriovenous malformation

Abstract

Purpose This study aimed to evaluate the incidence of a late complication, radiation-induced organized hematoma (RIOH), after gamma knife radiosurgery (GKRS) for arteriovenous malformation (AVM). Materials and Methods Between May 1991 and June 2012, 694 patients underwent GKRS for AVM. All patients were administered a marginal dose of 12–18 Gy with 50% isodose line. When the AVM was not obliterated after 3 years, additional GKRS was performed. Results Thirteen (1.9 %) patients with RIOH were analyzed in our study. Except for 1 patient, 12 patients underwent multiple GKRS for remnant AVM (twice in 6 patients, thrice in 2 patients, four times in 2 patients, after external radiation therapy in 1 patient, and after Novalis stereotactic radiosurgery in 1 patient). The mean duration of RIOH development was 12.6 years (range, 7.7–21 years). Of the 13 patients, 9 (69.2%) needed surgery because RIOH enlargement was detected on follow-up magnetic resonance imaging. Conclusions Not only bleeding from AVM during the latent period after GKRS but also RIOH should be carefully followed up because of the necessity for decompression.