I don't think it's a for sure... from what I understood from my neuro, it's a tool to get a reading. If you're throwing o bands then it'l confirm it, if you're not, you can still have MS and not show any. (That's me). :) So he says it's a good yardstick to keep a baseline of what's going on in the spinal fluid but it's not the definitive answer.
For him with me, it was the continuous quarterly visits with repeated reviews of the neuro exams, listening to my symptoms (new ones kept cropping up- increased imbalance, vertigo, stumbling, more numb parts of my body - face quadrant, left arm, hands, feet, big toes... then finally the kicker was optic neuritis flare up and blurry vision in the right eye) Still I passed Evoke potential tests, MRI's, and the LP... go figure... yet, with all the other stuff he was convinced after trying to disprove it for 18 mos that it was MS... and so far it's running true to form.
Now we'll be discussing progression therapy next week... yeah or nay.