Ask the Experts

Question: In discussing a forthcoming surgery, my neurosurgeon proposed to use a technique called embolization to block the blood vessels to the tumor and make it a little smaller. If that’s the case, why not just do the embolization and not remove the tumor? Isn’t that less dangerous? – Altheada J., New York

Answer: Embolization is the delivery of a material rather like glue into a blood vessel which supplies a tumor to block the blood supply to the tumor, permitting easier tumor removal with reduced blood loss. Embolization is commonly used for certain types of vascular tumors. Because hemangioblastomas are among the most vascular of all tumors, it is reasonable to think that it would be worthwhile with them.

Tumors that are ideally suited for embolization receive their blood supply from vessels that provide a significant blood supply to the tumor, and that only supply the tumor — not the brain, brainstem, cerebellum, or spinal cord.

Hemangioblastomas, however, rarely have a predominant source of blood from one or only a few vessels. Instead, the vessels feeding blood to hemangioblastomas are always a myriad of microscopic vessels that penetrate the tumor capsule, not a single dominant vessel, or even a few single vessels, that can be selectively blocked with benefit.

Thus, embolization has little to offer, is rarely indicated, and it may be associated with complications such as the emboli (the glue or particulate material) passing beyond the tumor and blocking a vessel that supplies the brain or other nerve tissue, causing a stroke. It can also cause the tumor to hemorrhage. The same is true for spinal tumors, although embolization may carry even more risk with spinal tumors because of the potential of blocking the anterior spinal artery and infarcting the spinal cord, causing damage to the cord due to interrupted blood supply.

In my experience with complete surgical removal of 329 hemangioblastomas in patients with VHL, we have never used embolization, or felt that it was needed.

The use of embolization alone for treatment would only provide incomplete treatment of the tumor being embolized, and would still be associated with the risks described above. In fact the embolization is only effective for the first 1-2 days because the body finds another route around the blockage.

-- Edward H. Oldfield, M.D., Chief of Surgery, National Institute for Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland