Treatment Result of Cerebral Arteriovenous Malformations Treated by Linac-Based Stereotactic Radiosurgery

Abstract

Introduction: To report our preliminary treatment result of AVMs treated by Linac-based Stereotactic Radiosurgery (X-knife). Materials and Methods: From 1996 to 2004, there were 117 patients treated by X-knife for their brain lesions in this hospital. The median follow-up time was 42 months (range: 6-107 months). These included 26 cerebral AVMs. There were 7 female and 19 male. The mean age at time of SRS was 29 years (range, 8-71 years). For Spetzler-Martin score distribution, there were score 1 (n=9), score 2(n=5), score 3(n=4) and score 4(n=8), respectively. Mean target volume was 7.9 c.c.. Mean peripheral or minimal dose was 13 Gy. Results: No patient had died during the study interval. Twenty-four patients had at least one MRI/MRA follow-up and 8 had catheter angiography. The crude rate of cure was 62.5% (5/8). The crude rate of combined total and partial obliteration was 79.2% (19/24). Median time to complete disappearance of the nidus on MRI/MRA was 28 months (range, 1-82). Median time to complete obliteration verified by conventional angiography was 63 months (range, 33-72). Hemorrhage rate before and after radiosurgery were recorded in 61.5% and 7.7%, respectively. Three patients (11.5%) had brain necrosis with permanent neurological defects and all were treated in the early stage in this study. Significant risk factors for brain necrosis showed target volume more than 7c.c. (P=0.002) and maximum cone size more than 3.0 cm (P=0.04). Conclusion: The results of AVM treated by Linac-based SRS in our institute were comparable with other reported data. However, larger sample size with a longer follow-up is needed for a more conclusive comment.