Thank you for your reply.
Actually, when I say prevent disability, I am not speaking about 100% prevention. I wonder if by taking all this stuff available could possibly make you less disabled than you would have been if you didn't take anything at all.
So far, my conclusion is no. Disability can't be prevented, at all. If you don't get it in the form of relapses you will get it by a slow progression inbetween, but without the very acute phase, which can be managed by steroids or plasmapheresis.
Shortest joke: "We may not be able to cure MS but we can manage its symptoms."