Radiosurgical treatment of arteriovenous malformations in a retrospective study group of 33 children: the importance of radiobiological scores

Purpose: Arteriovenous malformations’ (AVMs) obliteration depends on several factors; among the many factors that must be considered to obtain a high rate of obliteration and a low rate of complications, Flickinger-Pollock Score (FPS) seems to have an important role but still have to be validated in the pediatric population while Paddick-Conformity Index (PCI) still has no demonstration of its utility on the outcome and is considered only as a treatment quality marker. Methods: We retrospectively analyzed 33 consecutive children (2–18years) with an AVM, treated with stereotactic radiosurgery Gamma Knife (SRS-GK) from 2001 to 2014 in our institution. We assess angiographic (DSA) Obliteration Rate (OR) as well FPS and PCI to draw conclusions. Results: DSA-OR was 60.6% with a rate of hemorrhage of 0%. median target volume (TV) was 3.60cc (mean 4.32 ± 3.63; range 0.15–14.2), median PD was 22Gy (mean 21.4± 2.6; range 16.5–25). Median percentage of coverage was 98% (mean 97 ± 3; range 84–100). The median modified FPS was 0.78 (mean 0.89 ± 0.52; range 0.21–2.1) and highly correlate with OR (p = 0.01). The median PCI was 0.65 (mean 0.65 ± 0.14; range 0.34–0.95) A PCI lower than 0.57 highly correlates with final OR (p = 0.02). Conclusion: SRS-GK was safe and gradually effective in children. A prescription dose-like that used in adult population (i.e. > 18 and between 20 and 25Gy) is essential to achieve obliteration. A PD of 23Gy and 22Gy did impact OR, respectively (p= 0.02) and (p = 0.05). FPS and PCI are valuable scores that seem to correlate with the OR also in the pediatric population although further prospective studies are needed to confirm these observations.