How does the Dr decide what type of MS you have?

That's a tricky question to answer, but generally its determined by advancement of symptoms, do they regress or simply progress and how quickly do they progress, and how long they regress (if they do). Another factor they might include is the response to DMD (disease modifying drugs) like copaxone, or tybirsa (sp?). And at times who knows if they're not just spinning a wheel and tossing a dart to determine it .

Just remember doctors, regardless of what they may believe, aren't gods nor prophets, and ms is still a bit of a guessing game. If your rolling straight on to rock bottom, PPMS is likely what ya got but it could surprise you with a sudden stop and backing up (RRMS) or it may simply pause for a bit (SPMS). And then there's the wonderful "clinical isolated syndrome" which means you look like a duck, quack like a duck but we're still not sure how well you'll taste in orange sauce.

what starz said.

that's a good Q to ask your dr. start to write these Q's down so you can ask when you see him/her.

A Doc couldn't have explained it any better than Starz just did. .
After awhile and initial DX you'll be able to tell, yourself, by the way your
MS behaves.

Soon, I hope they will have meds that treat us as individuals, instead of,
as a big group of one.

I actually decided that I had MS and Primary Progressive, the evidence fit, it was just a question of finding a doctor that would listen and order the correct tests to confirm it.

I've had this question for my neurologist since I was first diagnosed. And his answer is always, "the problem with PPMS is that there is no treatment". I always found that odd. But then I realized what he was talking about.

If he diagnoses me with PPMS, then I am not eligible for any DMD and he's basically given up on me. I'm 30, have two young children, and since MS type is somewhat of a guessing game, he refuses to give me the diagnosis of PPMS until it becomes blaringly obvious. PPMS is not a diagnosis that can be made right away anyway... it takes years to see what's going on. A symptom journal that you keep up to date can help figure out the puzzle over time.

For now, my diagnosis is RRMS despite me really not remitting from anything. Tysabri has certainly kept me stable though so I'm trying to stay positive in thinking that it is a relapsing form. I start Lemtrada in one week, and some neuros are prescribing it for progressive MS despite it not being marketed for this use. So I have some hope that regardless of what type I have, I might do well with this drug.