Pain is not the only symptom with RSD. Sometimes the other issues can be more severe if pain is relatively low. Does does pain or any of his symptoms reduce his ability to work or his quality of life? Were they more severe at an earlier point?

Any procedure, even a flu shot, carries risks for RSD patients. Ketamine is a great option. It could put him into full remission. You might want to join the Ketamine Klub on Facebook, it's supposed to best a great resource on Ketamine.

Good luck.