Agree entirely with Wb.
You haven’t got a different disease the day after going to the hospital, than you did the day before, just because a boffin has made a pronouncement over it. “IT” doesn’t know what’s been said!
I’m not sure quite how a diagnosis of “mildly progressive” can be given from an MRI anyway.
The switch from RRMS to SP isn’t a black and white thing. You don’t go to bed with one, but wake up with the other. In general, there is a tapering of the number of relapses, and a tendency still to accrue disability, even without obvious relapses. But the two aren’t mutually exclusive. Some people with RRMS have always sensed slight gradual deterioration, even when they’re not relapsing (I’m one of them, but it’s very slow, touch wood). Others with an SPMS Dx continue to have the odd relapse.
So really, it’s not like flicking a switch - it’s a continuum.
A slight aside, but following on from what Pat says, I do think it could be possible for someone not to notice they’d had relatively benign RRMS for years, and hence only to be diagnosed when it was already secondary, or becoming that way.
I’m still RRMS (officially speaking, at least, until I’m told otherwise). I was diagnosed in the latter half of 2010. I’ve always been sure I’d had symptoms since at least 2006, without suspecting anything sinister. Recently, I stumbled on correspondence dating back to early 2004 (about 6.5 years before diagnosis), complaining that my legs were sore, think something’s wrong with me, blah-blah.
If there’s anything in this, and it’s not just coincidence, that would mean I’ve now had it over nine years, rather than the 2.5 on paper. Which is rather comforting, in a way, as nine years without stick or wheelchair sounds a lot more encouraging than two!
But I definitely think there’s mileage in the theory that milder RRMS cases (I hesitate ever to call it “mild”, but you know what I mean) could have been going on for years, before the person notices anything’s the matter. The more time goes on, the more I’m uncovering evidence from years ago, that points to me already having it back then.
I don’t think diagnosis was the start at all. I think it was the culmination of years of unsuspected illness.