Crps2 is very rare. Also, it is a more potent stimulus than crps 1. It's a genes environment interaction. One one end is spontaneous crps1 (probably largely genetic) and on the other end is major causalgia / crps 2 (largely environment)
Then there is everything in between from sprains to major crush multiple fractures. Major crush injuries probably nail numerous intermediate sized nerves. It's a spectrum.

Anecdotally, ketamine is not efficacious for crps2. There are just a couple positive case reports. Very weak evidence. I have seen some coma
Trials where they give huge doses and it
Works for a week and all comes back. They stopped doing it -
Bad for their numbers. For most crps patients, ketamine is
not great. For a lucky few it is great. It blocks the nmda and some opiod receptors. Very dirty drug. Crps has multiple mechanisms. One could make a cogent argument that it is the most complicated disease state. One thing is for sure- you only understand it if you have it!

I did 2 days a gram of ket each day and
Puked hallucinated and no pain relief. Never again.