It probably depends on where your AN is located. Even if it is small, if it is "intracanalicular," near the cochlea, my understanding is that there is a much higher risk of radiation damage to your hearing. My AN is/was both in and out of the canal. My doc said they would plan my CK sessions so that the cochlea and "labyrinthine structures" could be "spared."
I'm two months out from my CK treatments, and my audiometry last month showed my hearing has actually improved (steroids?). But I have a long ways to go yet before I know the outcome. I know that Phyl had CK, and she did not lose any hearing. You could ask the question on
www.cyberknife.com, but you will probably get the same answer as your doc at Stanford. Of course, Stanford has some of the most knowledgeable, experienced CK docs when it comes to ANs, so they should know best.