My neuro never mentioned it, but this is interesting...I'd actually never heard of it before!
Of course, there is our regular disability scale, and our "relapsing/remitting" scale. In other words, some days I'm able to walk a bit, and other days--or weeks--I'm not able to walk much at all!
So while the underlying disability level remains constant, there are some things that we may be able to do one day, and then find that we can't even attempt to do a day or a week later...
And so it goes with this messed-up disease....