Hi, Lori:
I'm so sorry to learn that you still don't have full facial sensation 15 months post surgery and radiation. I also underwent surgery (retrosigmoid) and radiation (FSR) and never experienced any real facial nerve complications. This seems to be a situation specific to your AN. As such, I would rely on your doctor's opinion, as he has the expertise and knowledge of your situation none of us can possibly have.
As for shrinkage: apparently, there is no definite time frame. My first post-radiation MRI (June, 2007) showed some shrinkage and the beginnings of necrosis. This was just 8 months after my FSR treatments ended. My next MRI (December, 2007) also showed necrosis and shrinkage. However, I've read of post-radiation AN patients that didn't see any shrinkage for 18 to 24 months. I would assume that once the AN does begin to shrink, it will relieve pressure on the facial nerve. However, sometimes the tumor substance can be 'stuck' to the nerve, making it difficult for radiation to reach and, obviously, slowing shrinkage possibilities. I'm certain there may be other AN radiation patients here who could offer something more concrete but this is about the best I can do, and so, I hope it will be of some use to you.
Jim