Nerve blocks have been used to diagnose RSD/CRPS. If you respond, than it confirms the diagnosis, but if you don't, it doesn't rule it out.

I have to say the same with the bone scan though, too. With a mild and new case it would be surprising if there is no evidence of CRPS on the bone scan.

So long as you are having a block done by an experienced doctor, the potential reward outweighs the risk IMO. It has helped me deal with spread several times over the years. You could potentially go into remission...

Plan to schedule a massage a few days after you have the procedure. It helps remove chemicals you don't want collecting near your spine--maybe not the best description, but...