Hi NS - I had gamma knife surgery in July 2014. The hearing in my AN ear was 92% prior to the procedure. I experienced fluctuations in my hearing for the first week - ear felt "stuffed up", loud noises were bothersome, hearing was muffled, some ringing or echoing, etc. I also did not know what to do. The doctor had prescribed a steroid for "sudden or severe changes" in my condition. I did take the steroid and felt some temporary relief, but six months out I can tell you that my hearing fluctuates daily. I think this is a function of the swelling that takes place after the procedure as well as weather changes and other stresses that your body endures. I would recommend talking to your doctor, if possible (I chose to have the procedure done in Pittsburgh, so I do not have the luxury of much medical advice). Personally, though, I would expect frequent changes for quite some time. I have a hearing test in a few weeks, but I would estimate that my hearing now ranges from 20-30% in the AN ear.
Other comments - to me what was most scary was that about two weeks out I started suffering numbness in my tongue and the AN side of my face. Again, this is something that comes and goes. I have learned to live with it.
Good luck with your recovery!