This 2008 article is quite old now because the TREND consortium has done further, more recent research work looking at both the possibilities of distinct phenotypes in CRPS and potential causes.

For anyone who doesn't know, TREND is the Dutch consortium headed by a Professor of Neurology in the Netherlands which was set up and funded by their government cash revenues from oil and gas taxation to perform an 8 year programme of comprehensive research into a wide range of aspects of the underlying pathology and the treatment of CRPS. The research is multi- centre and many of the papers were carried out with international partners in other institutions and organisations. The final research papers will all have been published now or will be finalised very soon since the 8 year research period ended in the last couple of years.

TREND is the single most comprehensive, high quality programme of research that has been done anywhere in the world into CRPS and the professor who is the scientific director of TREND is one of, if not the, leading global expert on CRPS. He still treats patients in clinic as well as being actively involved in CRPS research and has been for most of his career so he sees both the research side and the real day to day needs and issues of his patients. Their research is also carried out to very high standards. Not all research is created equal - there is a lot of so called 'research', clinical case studies, papers and advice out there that isn't what you think it is - it has massively flawed methodology, tiny sample size, is poorly carried out, isn't referenced or the conclusions are unsupportable and so on - much of it isn't peer reviewed before publication either and that isn't always obvious.

I recommend checking out the TREND website (published in Dutch and English). Many of the papers themselves are not published in full free of charge on there but it is a great start point.