Tumor embolization is a procedure that can be performed prior to a planned surgical resection. Embolization shuts down the blood supply to a tumor reducing blood loss during surgical resection. A secondary benefit from embolization can be that tumor margins are more easily identified and a tumor can be removed more completely and with less effort. Tumors of the spine, head, and neck that can be embolized have relatively large blood vessels supplying the tumor.
● meningiomas:see Preoperative embolization of intracranial meningioma.
● juvenile nasopharyngeal angiofibromas
● paraganglioma’s (carotid body tumor, glomus vagale, glomus jugulare),
● vascular metastases from renal cell, thyroid, and chorio cancers.
A sheath is placed in the femoral artery and a guide catheter is positioned as close as possible to the vessels of interest e.g., in case of a meningioma the guide catheter tip is positioned in the proximal ECA. Angiography and roadmapping are performed through the guide catheter. Using fluoroscopy and road mapping, a microcatheter is advanced over wire into the branches supplying the tumor. Angiography is performed through the microcatheter to ascertain the branch supplies the tumor and no concerning collaterals with intracranial circulation exist. A blank road map is obtained and embolization commenced. PVA particles or Onyx may be used for embolization. In case of Onyx, a DMSO compatible catheter must be used. PVA may be cheaper and quicker to use for tumor embolization. However, the devascularization is not durable and the occluded ves- sels may recanalize; therefore, with PVA the surgery should be performed within a few days of the embolization.
If a tumor has a prominent blood supply then flow can be shut down to the tumor using 3 types of agents. All agents essentially perform the same task, i.e. reducing blood flow; however, they have slightly different properties and are used for different benefits.
NBCA or Onyx™ are polymer agents that consolidate over time and have similar properties to conventional superglues that are pushed through a catheter flowing forward from the catheter tip into vessels just short of the tumor itself. When forward flow stops they form a dense plug stopping blood supply to the tumor.
Microspheres or microbeads are tiny polyvinyl alcohol spheres or particles suspended in a sterile solution that are pushed through a catheter flowing forward from the catheter tip into vessels just short of the tumor itself. As they flow forward the vessel narrows and the particles lodge within the vessel forming a dam. As more particles lodge again a dense plug forms and blood flow stops.
Microcoils are tiny coils, similar to a “miniature slinky,” made from platinum or platinum like alloys that are pushed through a catheter with a special pusher rod. The coil deploys at the tip of the catheter and initially forms a mesh within the vessel being treated. More coils can then be deployed into the mesh. As coils are deployed the mesh structure reduces blood flow and when enough mesh is present, blood flow stops.
Embolization before surgical resection of tumors has been demonstrated to reduce intraoperative blood loss, but the optimal time that should elapse between embolization and tumor resection has not been established. We evaluated whether immediate surgical resection (< or =24 h) after embolization or delayed surgical resection (>24 h) was more effective in minimizing intraoperative blood loss.
Embolization for feeders other than ECA and use of liquid materials could increase the complication rate in intracranial tumor embolization 1).