Hello S.Paull,
As Mark said, each case is unique, so we can't predict the outcome here. However, you should be aware that, for legal liability purposes, a surgeon typically has to review with a patient the potential impact of an operation (including what the "worst case" could be). I remember my surgeon going over such a list with me before my tongue surgery/neck dissection, and I came away wondering if I would lose ALL use of my left arm and the function of the left side of my face and neck, and my vocal cords. (However, the surgeon tempered that warning with his best judgment that the result would probably not be close to that.)
I did end up with a lot of swelling that took many months to go away. Also, it took well over a year for some of the facial and neck muscles to get back to "normal", but some of this was more an issue of appearance than functionality. The net long term result was that I lost none of the use of my arm or neck, and have an almost invisible 6-inch scar under the jaw line that hardly anyone notices, unless it's pointed out to them.
If you have confidence in your surgeon, ask for his/her best judgment as to the outcome (realizing that some of it still depends on what they find when they go in to do the procedure). If you have doubts about the responses you're getting, you may want to consider going for a second opinion.
Cathy