We respectively evaluated the effectiveness of low-dose gamma knife surgery (GKS) for small cerebral arteriovenous malformations (AVMs) in Chiba Cardiovascular Center. One-hundred consecutive cases with small (<10 cc) AVM treated with ≤20 Gy at the periphery were analyzed. The survival curves for angiographical complete occlusion, radiation-induced edema and latency period bleeding were calculated by the Kaplan-Meier method, and the prognostic values of 9 covariates were obtained. The complete obliteration rate at 4 years was 91.6%. On multivariate analysis, the only significant prognostic factor was peripheral dose (p=0.0101). Radiation-induced edema was observed in 62.7%. Seven cases (12.5%) developed minor transient symptoms. The only permanent delayed radiation injury was cyst formation in 1 case. The significant prognostic factors for radiation-induced edema were peripheral dose (p=0.0387) and nidus volume (p=0.0161). Bleeding during the latency period was relatively rare (2.0%).
In conclusion, our low-dose GKS using ≤20 Gy at the periphery provides excellent results for small AVMs.
