Treatment of arteriovenous malformations with linear accelerator-based radiosurgery compared with Gamma Knife surgery.

OBJECT: The authors sought to compare the outcomes of patients with arteriovenous malformations (AVMs) treated by Gamma Knife surgery (GKS) with those of patients treated by linear accelerator-based (LINAC) radiosurgery. METHODS: One hundred and eighty-seven patients with AVMs were treated at our institution between 1992 and 2003. Ninety-one patients were treated with GKS and 96 patients were treated with LINAC radiosurgery. Patient and treatment characteristics in the two groups included the following. In the LINAC group, the median age was 33 years (range 9-66 years); the median dose was 16 Gy (70% isodose line); the median treated AVM volume was 5.5 cm3; and 46% of patients in this group were treated after hemorrhage. In the GKS group, the median age was 38 years (range 6-63 years); the median dose was 20 Gy (50% isodose line); the median treated AVM volume was 4.3 cm3; and 44% of patients in this group were treated after hemorrhage. Obliteration of AVMs was determined by performing computed tomography (CT) angiography and/or magnetic resonance (MR) angiography and angiography. Patient follow-up evaluation included obtaining an MR angiogram/MR image or CT angiogram at 6 months, at 1 year, and then annually thereafter. Angiography was performed to confirm obliteration when MR angiography and/or CT angiography no longer revealed evidence of an AVM. The 5-year estimated AVM obliteration rate was 66% in the entire patient group; the LINAC group was 60%; the GKS group was 72%; this difference was not statistically significant (p = 0.97). Twelve patients who underwent treatment with LINAC radiosurgery underwent retreatment with GKS and one was retreated with LINAC radiosurgery. The obliteration rate was 82%. Six patients treated with GKS were retreated with GKS, but the follow-up time is of short duration. Chronic toxicity occurred in 8% of both the GKS and the LINAC groups (p = 0.61). Posttreatment hemorrhage during the time of risk before AVM obliteration was 13% in the GKS group and 6.2% in the LINAC group (p = 0.05). CONCLUSIONS: Treatment of patients with AVMs by using LINAC radiosurgery and GKS treatment produces high obliteration rates with acceptable long-term radiation toxicity in the patients treated.