The best source I can find on spreading (though aimed at type 1 crps) is called the 2014-outcome-crps-type1-systematic-review. It seems to be a review of over 1500 papers on the subject, which are then filtered on quality measures. I plan on reading it more, but what i'm gathering is that their are likely sub-categories of CRPS. Or at least thats the only way I can rationalize information like the following from that study:


However, the estimations on spread, remission, pain-increase, etc... paint a much better picture then those posted by a lot of other sources and with a lot more weight.