75% - 80% of all DX'd with RRMS will switch to SPMS. When you've exceed 6 on the EDSS scale you are considered to be SPMS. Here's a link to help you understand the Disability Scale used for MS. https://www.nationalmssociety.org/NationalMSSoc...

The neurologist is constantly evaluating you against this scale every time he examines you. Most doctors in the USA will not officially document your records as having SPMS because the DMD's are only approved by the USA FDA for use in the treatment of MS and Insurance won't cover the DMD's for SPMS. Therefore most USA MS Specialists prefer to keep the door open for treatment options.

A very rudimentary way of knowing the change has occurred is that you can't walk without the use of a mobility aird.

For me it was just a steady decline in my health. No matter what I Did as far as exercise, PT, OT, other alternative treatments I just felt weaker and more fatigued. I knew something was wrong as I was doing so much to fight the illness and nothing really helped long term

When I was RRMs I could use a cane to walk, I was also not falling down as much, as I do now. To walk now I only use a Rollator since I need the Stability of two hands to keep me moving these days.

Here is an explanation from the NMSS.

http://www.nationalmssociety.org/What-is-MS/Typ...

What? lol