A major factor in the duration of and complications related to the resection of brain and spinal tumors is tumor vascularity-the density and richness of blood supply. In selected cases, the surgeon may request that an endovascular embolization is performed in an attempt to interrupt the blood supply of the tumor prior to surgery. The blood vessels feeding the tumor are accessed using angiographic techniques; a catheter is navigated to the origin of feeding vessels and imaging is obtained to assure that blood flows only to the tumor and is not shared with critical structures i.e. viable brain tissue or the eye. Once this is determined, embolic material is released thereby obstructing arterial vessels. This technique is most commonly used for meningioma and glomus tumors of the skull base.