From what I understand, there is something called double crush (or multiple crush) syndrome. What happens is that a nerve that is impinged is much more sensitive further down the nerve. Fix the biggest problem and the others calm down on their own.
For example, I have a minor impingement in my neck and carpal tunnel but it is expected that once the TOS is fixed that my carpal tunnel symptoms will disappear. That's what I've been told anyway. So far, it is not looking like my neck impingement is causing any issues at all.