Most CRPS patients are in severe constant pain. Various meds and treatments can reduce pain levels, so it's best for him to learn multiple ways to manage his pain. It's a delicate balance of learning to use an effected limb enough but not too much. If he hasn't tried warm water therapy I highly recommend it.

While nerve entrapment surgery may help, it might also permanently increase his pain or cause spread. The best way to protect against this is to have a block before the surgery, but if he had a bad reaction that option is out. It would be worthwhile for him to try a ketamine infusion and if he responds well but still needs surgery, ketamine can be used in the anesthesia to help reduce the chance of an exacerbation of pain and symptoms or spread.