Hi. Well, in terms of studies, that seems to be a hard one. I also looked for the same information, but didn't find much. Maybe someone here knows, but there is not much research about crps treatment in general, let alone for different presentations of the disease. On top of the fact that there aren't many studies, they are hard to interpret because they have different end-points. Some treatment might be judged "not effective" for improving mobility but it might be pretty good at relieving pain. There was a review from Cochrane that concluded that the is low quality evidence that these blocks are not effective:

O'Connell NE, Wand BM, McAuley J, Marston L, Moseley GL. Interventions for treating pain and disability in adults with complex regional pain syndrome. Cochrane Database of Systematic Reviews 2013, Issue 4. Art. No.: CD009416. DOI: 10.1002/14651858.CD009416.pub2.

That said, here you will find anecdotal evidence that the blocks have helped some members, including myself. I was in a similar situation as you describe. I've had relatively mild crps in my foot for 1.5 years, and it hasn't spread. I wouldn't say my pain was minimal, but it was much less than what a lot of crps patients have. It was *mostly* tolerable but constant and interfered with my life. It was what the doctor called deep somatic pain, with no pain in my skin or from normal touch. I also had coldness and swelling. No weakness or stiffness.

Anyway, I had four lumbar sympathetic blocks earlier this year, about 1 year after the crps started (but right after I was diagnoses, because my symptoms were relatively mild and therefore missed the dx). The doc thought he could put it remission with the blocks, but it didn't. The blocks did help, however. Starting with the first block, I had much less pain when I was resting. I still had a lot of pain while walking, but I was able to sleep better. Also the pain when walking was a little less. After the first one, the other blocks only seemed to be less and less improvement. The doctors ended up deciding to put me on gabapentin, which I guess means remission is a no go for me.

The other members of this forum will tell you everyone is different so my experiance might not be relevant, but I would have the blocks again given what improvement I did get, even if not remission.

Good luck.