The most comprehensive list of doctors who do this procedure can be found in the facebook group for this topic.
https://www.facebook.com/groups/232392623486874/
If you send a request to join the group, the moderators have to okay your membership. Once you have joined, if you look in the group's files, there is a long list of doctors recommended by group members. It's a really great group with a huge wealth of information. It's the most informative and comprehensive source on the matter on the web at this moment so if you are researching this surgery, I would highly suggest you join.
I personally have had great success with the stimulator I had put in 6+ years ago. This particular website seems to have a negative view of the surgery for some reason but there are a lot of us out there who have had overwhelming success with this treatment option. It's not a cure, just another tool like anything else, but between my stim and regular Botox injections, my pain has been reduced by at least 80%.