This means pretty much all neurodegenerative diseases are syndromes. Sigh and I believe it too.
There have been cases of remissions from MS, and they're most definitely not all through the treatment of the same cause.
Actually, a consideration of the variations within multiple sclerosis may well be informative when considering the issues around diverse forms of ME/CFS and whether the subsets belong together or not. Four main subtypes of MS have been classified: relapsing remitting, secondary progressive, primary progressive, and progressive relapsing. The graphs under Classification here demonstrate the difference in disease progression:
http://en.wikipedia.org/wiki/Multiple_sclerosis
There is no dispute, on the wiki page at least, that "MS is a disease", and the recognition of MS is based on the unifying feature of damage to the myelin sheaths around the axons of the brain and spinal cord. But despite that unifying diagnostic feature, there is a considerable difference between the primary progressive form (which a friend of mine has) and the other forms. For primary progressive MS, there is still no treatment (just a vaguely promising small-scale trial with LDN) and the prognosis is really quite grim. For the other forms, there are a variety of new and emerging treatments, and the variation in response is such that it seems quite believable that some people with some forms of MS may be able to treat themselves successfully with dietary solutions.
When I think of the situation of my friend with primary progressive MS, looking at people recommending diets to cure other forms of MS, I am reminded of the situation of people with severe ME hearing about treatments that help some people with ME/CFS. It's understandable that such people would want to make a clear distinction between their own disease and that of people with a different form, but equally the example of MS does illustrate that a single disease can also have subtypes, with different disease progressions.
As I suggested before, the classification game is always somewhat artificial and depends on the current state of knowledge. The four types of MS might in future be recognised as more distinct conditions, with four different causes, which happen to share a common symptom. Maybe when we know more, they won't really "belong together" in the same way as they do now. ME/CFS might conceivably be divided into the same four sub-types, based on the same understanding of the interaction of genetic, autoimmune and environmental factors, and we might in future come to realise that the subtypes of MS and ME/CFS really have more in common with each other, and with subtypes of other diseases, than the family resemblances
within MS and
within ME/CFS - and then the whole classification system could be rewritten completely. Or more straightforwardly, it's very likely that at least some ME patients have a disease that is more properly considered as a type of MS...and possibly most ME/CFS patients belong in the same broad family of illnesses as MS. Until we understand all these diseases much better, we really can't know how the classification should work.
That's why I don't think it's a good idea to hold hard and fast to any assumptions about the appropriate classification system for ME/CFS; CCC ME may well turn out to have further subtypes, and those may belong in the same family with much of non-CCC 'ME/CFS', there may be a family of related conditions or there may be multiple completely unrelated conditions within the definition (and the broader the definition, the more likely this is to be true). And we may classify all this quite logically now, and then in 50 years time when the diseases are all thoroughly understood, those classifications might again seem old-fashioned. For now, it's all just vague guesses really, though I do believe we should take ICC ME as the starting point for research, not least because that is the definition most likely to deliver a well-defined cohort with a single disease, and thus the most likely to lead to an understanding that might illuminate the whole field.
