Too Good to be True?
by June Barker
The essay below was written in 1993 by the wife of an AN patient Dick Barker, on the basis of the research they conducted in 1990, after Dick's diagnosis. June has a PhD in physiology, has done research on (animal) tumors, and is familiar with radiation technology.
An acoustic neuroma does harm only by compressing surrounding tissues. If its growth can be stopped, symptoms should get no worse than they are. With only the symptom of minor hearing loss, my husband was being told to have an operation that risked more severe nerve damage to hearing and facial nerves, and it was a potentially life-threatening operation even with a highly-skilled surgeon. Thus when we heard of the alternative of radiosurgery, it seemed too good to be true.
We got hold of the specifications for the instrumentation that was being used. Since I had patented multi-detector equipment to measure radiation flowing through the brain, I was able to assess what the 3 Leksell group had designed for focusing multiple, pencil-sized beams of radiation, and whether or not their instrumentation could really do what they claimed.
I was very favorably impressed by all aspects of the design and engineering. They could indeed deliver radiation to the tumor without harm to the vital centers nearby. Even the nerves should be fairly safe. The question then became, what is this radiation dose intended to do to the tumor tissue? The objective of neuroradiosurgery for the acoustic neuroma is to shut down the blood vessels that supply the tumor, and thus to stop its growth. Another main use of the procedure is to close off abnormal brain blood vessels. The radiation dosage that can shut down blood vessels while doing little harm to the adjacent nerves is now pretty well established; Dr Steiner has led the way in this respect.
This does not mean that the facial and other adjacent nerves are 100% safe, but it does mean they are safer than in most surgical removals. The blood vessels are not destroyed instantly by the radiation but will close when the damaged blood vessel linings swell up and block the lumen. With its blood flow blocked, the tumor can no longer grow. The tumor may get smaller or stay the same size; in either case, some of it remains. The important point is that its growth stops.
Here Dick's case falls into an unusual category. His tumor has not grown since it was treated, but it also had no measureable growth in the three-month period before treatment. We therefore cannot say that the Gamma Knife treatment was effective. Should he have had the treatment? Most physicians would say yes. But as a physiologist who has measured growth of animal tumors and seen many stay the same size for long periods, I personally would have waited for growth to begin. That means repeated MRIs every 6-12 months. The waiting and watching might be psychologically stressful, but one has to realize that for older men the growth rate can be so slow that many die without ever knowing they had an acoustic neuroma. Women (especially young women and genetic cases: neurofibromatosis) have faster growth rates, so that delays for them are a greater risk since surgical complications are lowest for smaller neuromas.
Throughout the decision-making period we found no physicians or neurosurgeons who were not aghast over our decision to try radiosurgery. But having read the original literature on radiosurgery and compared the surgical aproach, we had to come to our own decision that radiosurgery was best. If it did not work, the surgical option was still open. Although we heard rumors that radiosurgery would make the surgical operation more difficult, I found no scientific papers specifying this, nor could anyone relaying the rumor give me the name of any surgeon who had experienced the problem. I suspect that it is only a rumor.
For New Jerseyans, the two nearest Gamma Knife locations are Virginia and Pittsburgh. Dr Steiner in Virginia was chosen for his publications and years of experience and role in the development of the equipment and procedure. These are, of course, our personal opinions and experiences.
I will close with yet another opinion -- that neuroradiosurgery will become the first choice treatment for neuromas of less than 2cm within the next 15 years. The instrumentation and procedural details are now available; the delay will be due to the usual time lag in educating physicians about the new technology. A patient can bypass these physicians by asking one of those already providing the treatment if radiosurgery is appropriate treatment for his/her neuroma.
Last Edited: Wednesday, October 30, 2002