Also
@Jonathan Edwards I think when many people say "multi-system disease" they mean there are symptoms emanating from many bodily systems.
@JenB.
Multi system disease does not have any well-defined meaning but in as much as it does have a meaning to physicians it means
pathological change in multiple types of tissue. So diabetes, lupus and rheumatoid arthritis are multi system but MS is not, despite there being symptoms everywhere.
As you know, I play devil's advocate because I want ME advocacy to be effective. For me as an academic physician if an advocate says 'ME is a multi system disease' that is a giveaway that they don't really understand what such terms imply. Being a multi system disease does not make something a more important health problem. MS is as bad as it gets. Schizophrenia is as bad as it gets. Microcephaly from zika is as bad as it gets. None of those are multi-system.
One of my vices is telling tales out of school I guess. But I try only to do it in good faith. At the recent dinner party in London, all names in ME research you can think of were sitting round a table (many of them) together with representatives of government funding bodies from UK and US. There was a lot of talk of 'physical multi-system disease' etc.. What struck both Jo Cambridge and myself was that the US funding representative seemed to buy in to this, along with advocates and charitable representatives from both sides of the Atlantic. But I am pretty sure that the UK funding representatives saw it as window dressing by people who think it sounds good but not something with any real scientific meaning.
In modern natural science everything is ''physical', including malingering and belief in leprechauns. If we want to formulate a clear scientific hypothesis that distinguishes ME from unhelpful illness beliefs we need a different distinction. if you take someone like Jim Baraniuk, who probably understands ME better than anyone on the planet, he is not going to argue about whether or not it is physical. Nor is he likely to think 'multi-system' is helpful. These terms are used by researchers who think they are selling points. What intrigues me is that US authorities seem to be buying in, but, more as I would have expected, UK authorities sit there politely indicating that they are not impressed.
I guess the moral of that is that the best way to advocate for ME may be a subtle matter, depending on where you are. But my approach is to make sure one sees hype for what it is. And particularly if the hype obscures more important issues - like focusing on trying to work out exactly what pathological mechanism would fit the real symptoms of ME rather than the misconceptions about fatigue etc.
I personally see no need to classify ME as anything like neurological or multi system. The terms do not mean anything very useful. The important thing is that it is severely disabling. And the disability seems to have more to do with the brain than anything else. People with severe muscle disease can often carry on a very reasonable life as long as they do not sign on for manual labour. But an chapter on lupus does not start by saying it is a primarily rheumatological disease. There is no point. It details what the disease is like in terms of symptoms and pathology.