Hi Todd,
I hope you seek out consults with the best surgeons you can access, and you can ask them about balance outcomes. Meanwhile, here's my two cents.
I was under Watch and Wait about 2.5 years. My balance issues were profound: weaving when walking commonly; light nausea when swimming (I swam less as a result); uncommonly high number of falls when xc-skiing, especially if I turned my head to look behind me or sharply to the side (I skied less than normal to lower my risk); and weaving and wobbling especially in the dark, such as in the house at night (put the lights on!). I also waterski, and cut back due to falls seeming weird and too frequent. (The falls were related to the AN, for sure, but I think I was in denial to a large degree.) I gave up running. I had trouble hiking. I basically thought I was losing my favorite sports forever...
I made a change of plans to get surgery when my AN was showing a little too fast a growth rate. I was then already deaf in one ear; had facial tiny twitches; some tongue sensation like numbness; constant tinnitus. And--at first, un-noticed as part of the AN side effects--My O2 saturation number was down to around 93, when you want 95 and up normally.
I had microsurgery, with translab at UCSD. Went great. (See other posts, if you want to hear more.) It just went so great, and I had no problems.
After microsurgery (translab), ALL my AN-related balance problems resolved. Very fast. Very completely.
I stopped falling. I stopped weaving. I could swim, ski, waterski again. I have yet to get back to running, but that is the last thing and hope to get back this summer.
The O2 sat. number was back to normal, along with a feeling of wellness when exercising. (The PT person assumed, then, that the AN was interfering with my brainstem, and when that resolved my O2 numbers normalized.)
Now, did a lifetime of balance sports help me recover so well? And/or did the dragging my feet to get surgery mean that my body was used to the change in vestibular nerve function? Did following the PT's instructions and walking a meaningful amount beginning Day 3 after surgery help? Probably all of these. And great surgical care.
The brain, as I understand it, makes new neural pathways after the surgery cuts the vestibular nerve. You are training the brain to interpret where you are in space with just one vestibular nerve on one side, and using your vision and context clues. The "bad" signals from the injured vestibular nerve on the AN side is gone--and that makes it, they told me, easier for your brain to just work with the info that it still has. I thought of it as the absence of bad data. The AN was giving bad data, and post-op it is not giving any data at all.
Apologies to the surgeons and PTs who really know what they're talking about it, but YES, there is good-great balance available after surgery. I don't know how rare my experience it is, but it's possible. I do feel very grateful, that's for sure.
Hope this is helpful. Take good care.
Skier