Well, if you haven't had any issues with anesthesia in the past, you should be fine with the Ketamine. Having taken it only for depression, I can't speak to its effectiveness besides what I have just read. It seems like it does something very similar to pain as it does with depression and essentially resets your receptors. Are you doing an IV infusion or a localized series of injections? The localized injections look like they have long term effects. In any case, it sounds like it is worth a try for relief from pain.
My mother was resistant to having spinal surgery but ended up giving it a try since it was the simpler surgery and had a 6 week recovery. She woke up from the surgery with no pain. Sometimes trying something new and different is scary as hell, but it may end up being just what you need. What ever your choice, I hope you find something that helps.