I don't remember exactly what my neurosurgeon had told me, yet will do my best to paraphrase: When (former) California governor Pete Wilson had some type of surgery on his throat, he also experienced similar to you. His voice was affected. My doc had stated, too, that it's not uncommon for some people to also lose their voice (temporarily) following surgery on the C-Spine, such as ACDF.

I Googled about P. Wilson and his surgery, and found this:

http://articles.latimes.com/1996-05-...hroat-problems