Here I have to disagree with you Aaron....a lot of the systems in our bodies are inter-related. For example, if someone suffers from a digestive system disorder, let's say malabsorbtion for some reason, their bones will be brittle from lack of calcium, their skin dry and flaky, their nerves out of whack, their sperm count low, etc. Hence any diagnosis that is "systemic". A rash can be indicative of many other things that have gone awry in a body....for example, lupus, leukemia, pregnancy (though that one is not really a disorder...), herpes, allergies, etc. I think it would be reasonable to assume that it is possible for a "rash" per se of the nervous system, or in other terms a general inflammation of the nerve pathways, to cause all the twitching and tingling. It could very likely be set off by a reaction of the mylin to foreign objects in the body: toxins, viruses, bacteria... The same way that our skin reacts to the presence of a foreign substance, either through direct contact (hence contact dermatitis), or systemically through an allergic reaction to something that has entered the body....thus giving you hives.
I think if we are to find answers to the cause of this disorder, then I think we need to think creatively. Who knows! BFS may just turn up as an allergic reaction to stress and adrenalin (though that sounds a little far fetched!...but who knows. The scientific world has laughed in the face of many a man with zany ideas who in the end, turned the whole way we think around!!!! Galileo, Lister and Leuvenheuk for example.
I hope I didn't make you mad by disagreeing,...just wanted to point that out.
Cheers! `jen