Clinical evaluation of gamma knife radiosurgery for intracranial arteriovenous malformation

Aim of the study is to compare our treatment results or gamma knife radiosurgery for arteriovenous malformation (AVM) and to obtain factors determining nidus obliteration and/or adverse effect. We analyzed 236 patients with AVM treated between June 1990 and February 1994. The patients consisted of 137 men and 99 women, and ranged in age from 4 to 71 years. AVM volume ranged 0.7 to 37.7 ml. Maximum and peripheral doses ranged from 18.2 to 60.0 Gy and 10.0 to 28.0 Gy, respectively. Complete obliteration rates at 1, 2, and 3 years were 36.2, 68.9, and 86.6%, respectively. The mean time to complete obliteration was 21.4 months. Univariated analysis revealed that calculated target volume, peripheral dose, peripheral percent dose, and treatment optimality were significant factors for complete obliteration. In multivariate analysis, calculated target volume, treatment optimality, and CT-based planning were significant factors. The actuarial risk of post-radiosurgical brain edema at 2 years was 20.0%. In both univariate and multivariate analysis, calculated target volume was the only significant factor. Symptomatic complications developed in 10.0% of patients at 2 years, but no significant factors were identified. Permanent complications and severe neurological deficits were seen in 4.4 and 2.8% of patients, respectively. Our results were similar to those reported previously. Accurate CT-based planning contributed to an improved obliteration rate. (author)