I can tell you I had a cortisone shot in my ankle, prior to the diagnosis of RSD and within 24 hours, my pain had tripled, every step I took, It felt like those foam peanuts where in there and I was crushing them.
Thats when the 1st dr. said I think you have RSD. The stimulator trial was easy to get hooked up (30 min. or so, done under local) and if you have a decent dr. he/she will tell you that unless you have more then 50% improvement they would not recommend the surgery for permenance. good luck