For anyone facing one, a little uncomfortable but NOT painful. I had two shots without any sedation (a local on each side of the spine). I have to stay put for three days (My "nurse" is on duty 24/7, now). Most of the time the shots do not take affect for between 3 days to 2 weeks.
I was SCARED going in as it was reminiscent of a myelogram that I had in the early 80s when everything that could go wrong went wrong.
This post is mostly for Jim so he knows what to expect. My daughter-in-law was asleep when they did hers. I guess it depends on the doctor. My surgeon told me I could have sedation, but from my perspective after speaking with the doctor who was going to do it, I really didn't need it and didn't want to be groggy afterward. They still insist that someone take you, wait for you, and take you home. CYA, I suspect.
Another thing they told me is that many times they have to do two or three shots. My surgeon said to call him in two weeks to let him know whether this session was successful. Now, I just hope it works.