Injections in the area where you have RSD/CRPS should never be done. It's dangerous.

Typically...for injuries in the lower part of the body they do injections in the back. Lumbar sympathetic block is the kind I had initially (RSD started in my left ankle). For hands/arms they typically do the injection in the neck.

It's always important to remember that ANY injections, blood draws, etc can cause the RSD/CRPS to spread. Done correctly the risk is reduced but still there. That doesn't mean you shouldn't have the treatments as they are going to be your best shot at remission...but you need to go in with eyes open and know the risks. ANY trauma can cause spread.

Spread from injections used to treat RSD/CRPS is rare but does happen. Unfortunately I know from experience that it can happen. I now have RSD in my back, both arms and hands, and my neck after spread from my last LSB.