RT Journal Article SR Electronic T1 P-019 Preoperative embolization of intracranial tumors using Onyx JF Journal of NeuroInterventional Surgery JO J NeuroIntervent Surg FD BMJ Publishing Group Ltd. SP A24 OP A24 DO 10.1136/neurintsurg-2011-010097.53 VO 3 IS Suppl 1 A1 S Dashti A1 T Yao YR 2011 UL http://jnis.bmj.com/content/3/Suppl_1/A24.1.abstract AB Introduction Tumor surgery in the central nervous system is often filled with complexities. Some tumors are particularly hypervascular and may pose an added level of difficulty to surgical resection; in these cases preoperative embolization may assist the surgeon in accomplishing better resection with lower surgical blood loss. With the refinement of endovascular techniques, embolization of tumors has become more efficacious and safe. Liquid embolic agents are particularly appealing, as they allow greater control and penetration into the tumor mass. In this series, the authors report their experience with patients undergoing preoperative intracranial tumor embolization with Onyx liquid embolic agent.Methods We retrospectively reviewed the records of all patients undergoing preoperative intracranial tumor embolization at our institution between 2009 and 2011. Transarterial Onyx embolization was used in all cases.Results 11 patients underwent preoperative embolization in the last year: eight meningiomas and three glomus tumors. All meningiomas were embolized through the middle meningeal artery. Extensive penetration was achieved in all glomus tumors, but in none of the meningiomas. Meningioma onyx penetration was moderate in 2, mild in 3, and proximal in 2. There was one major procedure-related morbidity: optic nerve ischemia secondary to non-target embolization of the ophthalmic artery through anastomotic channels with the meningeal artery. This resulted in near-complete vision loss in the affected eye. There was no procedure-related mortality. Median estimated blood loss from subsequent surgery was 300 ml.Conclusion Preoperative embolization of central nervous system tumors with Onyx liquid embolic agent can be performed relatively safely and effectively in selected patients. The main advantage of Onyx over other embolizates is the superior control and extensive penetration that can be achieved in hyper-vascular tumors such as glomus tumors. This converts a very bloody lesion to an avascular Onyx cast that allows surgical resection with significantly reduced blood loss. Non-target vessel embolization remains the main complication. There may be a decreased risk of hemorrhagic complications when compared to particle embolization.