Hi. I had one lumbar sympethetic block which was not good for me and in the start before I knew it was rsd they thought it was tarsal tunnel and I had it in the limb which is a huge no. I now can't even allow a finger on there so I can't imagine an injection. Anyhow I have read that overtreating with blocks is not good but you can have many and I think it is supposed to get you to a point where with PT you won't need them. I do have a friend who got way too many of these and made her rsd spread.