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. Examples of typical tumors with prominent blood supply include: hemangioblastoma, meningioma, juvenile nasal angiofibroma, aneurysmal bone cyst, paraganglioma’s (carotid body, glomus vagale, glomus jugulare), hemangiopericytoma and vascular metastases from renal cell, thyroid, and chorio cancers.
Prior to undergoing tumor embolization it is necessary to perform either a cerebral angiogram or a spinal angiogram. A cerebral or spinal angiogram provides a roadmap of the blood vessels of the brain or spine and indicates the blood supply to a tumor. Physicians use this blood vessel roadmap to determine how a particular patient’s brain is supplied with blood and whether a tumor has prominent blood supply that is amenable to embolization treatment.
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.