I just had a spinal cord stimulator put in to deal with my chronic leg pain, and I have to say it helps about 80% but I am off tramadol and only using 2 advil a day so I label this a great success. Mine is the size of a thin pacemaker.
I wanted to let people know that Australia is doing a final trial now that will allow stimulators as small as match head to be put where needed. There also will other refinements as well, but I have not done all the research until it is approved.
It should be done in about a year or so, but it is great that the research and development continues around dealing specifically with chronic pain.
Australia seems to be cutting edge on chronic pain issues, so if you are doing research, take a look on the google search engine for Australia as well.
Just FYI- the nice thing about the stimulator is that it can be taken out, and does not drug you out!