Long term effects of Gamma knife Radiosurgery for treatment of cerebral arteriovenous malformations

Background: The Gamma Knife Radiosurgery (GKR) is an established management option for Cerebral Arteriovenous Malformations (AVMS). Therapeutic benefits of radiosurgery for arteriovenous malformations are complete obliteration of nidus with minimal neurological deficit. Methods: Radiosurgery was performed between February 2003 and April 2010 at Kamraniye day clinic, Tehran, Iran, using the Leksell gamma knife model B (Elektra Instruments AB, Stockholm, Sweden) on 82 consecutive patients with AVMs. The male-to-female ratio was 1.4:1(48M, 34F). The age of the patients ranged from 9 to 70 years (mean, 28.5±12 years). The marginal dose to the AVM nidus was 45 to 85% (median, 60%) isodose and ranged from 14 to 30 Gy (mean, 20.57±13Gy).The maximum dose ranged between 20 to 60 Gy (mean, 37.5 Gy ± 10.17Gy ). Follow up of patients for complete AVM obliteration and in the case of complications MRI were performed. Results: Complete obliteration of AVM was achieved in 56 cases (68.29%). It was marked in average 3.62 [SD=3.19] years (from 1 to 5 years) after GKR. Partial obliteration (≥50% reduction of the nidus volume) was marked in 24 cases(31%), and less than 50% reduction of the nidus volume was marked in 2 cases(2.4%) with a follow-up of 5 years. Complete obliteration of AVM had statistically significant associations with smaller score of Spetzler-Martin arteriovenous malformation grading system for AVMs. (p< 0.05) Conclusion: The Gamma Knife Radiosurgery can offer total and partial obliteration to acceptable percent of treated AVM with a low risk of morbidity. Higher success observed in patients with Spetzler-Martin Grade I and II AVMs, which was attributed to smaller volume of AVMs in this group.