Backfog, a spinal cord stimulator IS surgically implanted into the epidoral space of your spine.. it IS surgery!!! It's not pleasant either.. I've had it done 5 times and am about to have major cervical surgery done to "fix" some issues and get another stim. (I'll have to go for 2 trials as I'm having dual leads for cervical and thoracic areas).
My mother went through SCS trials, and has now had her permentant one for about 7 years. She is horrible at charging it up, but when she does have it charged, it really helps. It's something I'm going to start looking into for the future