Yes, there is a Progressive Relapsing variant of MS. But it is really part of the RR/SP type of MS as far as I know.
So people with PPMS can have relapses where they feel especially lousy for a while, then hopefully revert to the more usual (for the individual) standard of rubbish.
But the type of MS which includes RR and SP can also become PR. This is what’s happened to me. I was RR from 1997 to about 2016 when my neurologist reluctantly declared that I was now ‘in a more progressive phase’. By this I took him to mean SP. and indeed I hadn’t had a real relapse for a couple of years by then. I think he was reluctant because he was a neuro who wanted everyone on a DMD if at all possible. I seemed by then to have run out of options for DMDs (he used to write them all down and one by one draw a line through them because of my history with side effects).
Then last year I had one smallish sensory type of relapse (more like the kind of relapse you might get with PP I think), where everything just felt worse for a couple of weeks. That was followed by a genuine, real relapse of the kind where my legs just gave up on me. Bizarrely (and fortuitously as it turned out) the very day it started, I had an MRI already booked in. So the neurologist had clinical evidence of new inflammatory demyelinating lesions. I took steroids for that relapse and they worked better than ever before. Not only did the relapse completely remit, it actually seemed to help improve my long-standing foot drop. When I saw my rehab neurologist a month later, he was astonished that the dorsiflexion of my right foot had improved, he checked his records from 7 years before and said he’d never seen improvement like that before. It didn’t last, but for a while I could almost walk without FES or any kind of orthotic device.
So it was confirmed, I’d gone from RR to SP then had it confirmed that actually I was PR. Not that it helps that much, just means that now I can have further disabling relapses in addition to general gradual progression. I’m soon to restart Copaxone, I’m not absolutely certain that it will actually ward off further relapses - it stopped working for me about 13 years ago! But it’s worth a go.