Question from Zet:
In January 2006 I have been diagnosed (by contrast MRI) with left intracanalicar AN (VS) 3 by 5 milimeter size. My present symptoms are: diminished hearing in higher frequences, difficulty of using telefone with left ear and occassional unsteadiness with also occassional (few seconds) numbness of LHS of the lower lip with several days apart. I am a 58 years old electrical engineer and after doing research on available radiation treatments (my neurosurgeon advised against surgery) I ruled out proton beam (as too new for AN) and Novalis (as not accurate enough). What is left are Gama Knife and Cyberknife. My question to you are as follows: 1. Which system is better suited for such small, intracanalicar AN? 2. What are the most experienced facilities/teams using each of the system specifically for AN in USA? 3. What is a typical doses used by UVA for such cases at hte center of the tumor and at its margin? 4. What are the statistics of “success rate” in arresting the growth and/or shrinkage and hearing preservation?
More and more, acoustic neuromas are being diagnosed earlier and smaller. Your description of your tumor and your clinical state would make likely make you an excellent candidate for radiosurgical treatment.
With regard to the choice of radiosurgical tools, the Gamma Knife is the gold standard for intracranial radiosurgery. It’s accuracy comes in part from MRI guidance and fixing the radiation sources and target. There is no room for error in intracranial radiosurgery. As one of the oldest and most established GK center’s in the world, the University of Virginia has one of the most experienced teams in treating benign skull based tumors such as acoustic neuromas. Every case is unique but we typically use a dose of 12 to 13 Gy to the margin of the tumor and treat at the 40-60% isodose.
Our published results include a 96% rate of tumor control with 70% of tumors eventually going on to demonstrate substantial tumor shrinkage. We have observed a less than 1% risk of facial or trigeminal neuropathy. The hearing preservation rate is approximately 60% following Gamma Knife surgery.