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.

Thanks MD for the added info on CRPS 1 & 2. My doctors all told me that "true causalgia or CRPS 2" is as you said very rare. They even went on to explain that the location where my iatrogenic nerve injuries occurred that caused the causalgia is even more rare - in fact my case is being written up for medical study in the journals of orthopedic surgery. I hope the article/study prevents this from happening to anyone else!!

Praying we all find ways to get maximum pain relief so we can enjoy every minute of this precious life,
Tessa