204 Pediatrics Arteriovenous Malformations Treatment With Stereotactic Radiosurgery Gamma Knife: Our Institutional Experience.

INTRODUCTION: Arteriovenous malformations (AVMs) are the most common cause of intracranial hemorrhages in children. It is estimated that 12.18% will be symptomatic during the childhood. AVM obliteration depends on several factors, among the most important is a proper stereotactic nidus definition followed by delivery of an adequate dose.

METHODS: We retrospectively reviewed 24 children (13 girls and 11 boys) treated with stereotactic radiosurgery Gamma knife (SRS GK) between 2001 and 2014. The median patient age was 14 years (range, 6-18 years.). The mean AVM volume was 4.5 cm (range, 0.15-18.50 cm). The mean marginal dose for the single treatment group (21 patients) was 22.48 Gy (range 18-25 Gy). We confirm closure by angiography when MRI shows potential obliteration. Mean follow-up was 60 months.

RESULTS: Of 12 (50%) children affected by neurological deficits before treatment, 5 (42%) were stable, 4 (33%) improved, 3 (25%) completely recovered at last follow-up. Eight (33%) children presented with epilepsy, of whom 5 (62, 5%) were stable after treatment, 2 (25%) improved, and 1 (12.5%) healed; 12 (50%) presented with hemorrhage, while we observed also 1 (4%) case of hemorrhage in the latency period; no patient died because of rebleeding. Conformity index of the plans is 0.63 (0.34-0.95); the mean Pollock-Flickinger Score is 0.80. Complete obliteration was achieved for 16 AVMs (66.7%). Five AVMs were reduced (20.8%); 3 were stable (12, 5%). No new neurological deficits were discovered after the SRS treatment and at last follow-up. None of patients presented bleeding after an angiographically verified obliteration.

CONCLUSION: Radiosurgery is a safe and effective treatment for AVMs in the pediatric population. Crucial for success is the use of a prescription dose between 18 and 25 Gy, that is the same prescription doses for adult population. Following this paradigm, it is possible to obtain results that fall on the higher end of the distribution curve that vary from 35% to 95%.