After spending the morning researching Many prominent sources, such as The national MS society, my MSSA, Cleveland clinic, John Hopkins hospital, The University of Kentucky neuro science center, And Cedar Sinai clinic just to mention a few They all had a common thread or definition.
They all stated that primary progressive MS was an MS that Progressed steadily from onset. In other words as soon as you were diagnosed you steadily declined with disablity without having any remittance or relapses and as involved relapsing and remitting MS. So if your MS started out as relapsing and Remitting MS where you had periods of flares or worsening of MS followed by remissions where your MS improved then you could not be diagnosed as primary progressive MS ever.
I am not a doctor trying to give you advice about your MS I'm simply repeating the statements given by the above MS Professionals. I'm also not trying to tell you your doctor is wrong I'm just trying to tell you to research what they are telling you and ask questions the next time you go in to see your doctor.
I am currently in secondary progressive MS. It is not uncommon for people who start out as relapsing and remitting MS to slide into secondary progressive MS years after they were diagnosed. I have a slow but steady decline in my disability and my walking is very severely affected. About 10 to 12 years ago I had a steady decline in my disability. My walking was severely affected as was a pronounced period of continual falls. It was a girlfriend of mine who was a physical therapist who noticed I wasn't having any relapsing or remitting going on and stated I should talk to my neurologist about the possibility of me advancing to the next stage of MS. When I checked sure enough I had advanced according to the disability scale to secondary progressive MS. I switched Neurlobgists and he put me on Ocrevus. It slowed down and stopped the continual slide I had going on with my disability. That is just one of several medications market that might help with secondary progressive MS and primary progressive MS besides relapsing and remitting MS. There are other DMT's on the market today that help with secondary progressive MS and cut down on the slow but steady decline you have with your disability. Check with your neurologist to look at the options that are out there today.
I hope this helps clear up the definition of PPMS or Primary Progressive MS. If not I hope this has inspired you to research the topic and take notes and take these with you to your next appointment to your neurologist and ask questions. Knowledge is power. Fancy59.