I'd guess that there are many different forms and types of RSD and that most involve a compromise of the sympathetic nervous system. This can manifest in many many ways.

I'd also guess that the SNS stays active after an injury and what's needed is a device that can see this activity. When it starts it can be easily fixed but it becomes entrenched if it's allowed to go on for more than a couple years. It seems that until we have mental problems doctors are reluctant to diagnose it.

This disease might be wiped out in ten or twenty years but this might not help sufferers and merely prevent new cases.