I share your concern, and I can only advise you to speak with your neurologist and doctor.

Good luck, and I'm interested to hear the thoughts of others as well.

We went to Colorado for a field trip a couple of years ago when Shelbi was 14, 9 years post surgery, and she was clear to go. We went up on the Continental Divide, I believe it is over 11,000 ft,  (I think), but she was fine as far as her Dr. was concerned.  We didn't make it all the way up because she started feeling bad and had a headache, but she had also taken a rough fall on some skis earlier that day, which I believe contributed to the feeling bad. Anyways, her Dr. was fine with every place in CO that we were going. Something I wish I would have thought of that I didn't realize existed until we were in a shop on our last day there, was some little bottles of oxygen.  They were just in a gift shop for I think around $10. So that may be something to have on stand by if your daughters' dr. clears her to go, then if she gets to feeling a little bad up high she could breath that in. maybe it would help. But I completely understand your aprehension, I worry and get scared before we do anything out of our normal routine. Have fun if you get to go.