The University of Liverpool's Pain Research Institute at the Institute for Translational Medicine were involved in running a significant clinical trial of low-dose, IV immunoglobulin for treating long-standing CRPS pain. They have just recently announced that the trial of the promising treatment has been a failure. The announcement can be found here:

Promising treatment for Complex Regional Pain Syndrome ineffective - News - University of Liverpool

The announcement also contains a link to the full details of the published randomised clinical trial.