Deepwell's post encouraged me to check this type of pain relief out and I found this link from the Cleveland Clinic. A doctor explains the procedure and also answers questions in this interview. I think it's an excellent explanation.
I put a hot link to the site but when you try to open it it says that page can't be found. Soooo, if you want to read about this, Google "Implantable Devices for Pain: The Inside Story" and it should be the first site that comes up. It's on medicinenet.com.
Sherrine