Hi,
I too have CRPS and have had the disease for over four years. Nerve blocks are the standard treatment in the beginning stages of this disease and are usually done in a series of 3 to see how effective the treatment is and it is also used as a tool for confirming the diagnosis of CRPS because the block only blocks the sympathetic activity so if you get relief (nomatter how short term) than you know the pain is related to CRPS.
Also, I just wanted to let you know that there is a forum for CRPS titled RSD (reflex sypmpathtic dystrophy which is the old name for CRPS). Good luck and I hope to see you on that forum too. :0)
Sarah