--is often considered to be a subcategory of Complex Regional Pain Syndrome, due to the similar trophic changes that occur in the skin, and it does share a number of similarities to small-fiber neuropathies, though it tends to be elicited more by exercise than many other small-fiber syndromes.

There seems to be some form of hyperactive axonal reflex involved that doesn't seem to "shut off" properly.

There are at least a few genetic mutations that have been found in people with this, although the majority are still classified as idiopathic. Perhaps with the continued research into the human genome more genetic mutations will be found.

http://www.neuro.wustl.edu/NEUROMUSC...rythromelalgia