I've had just one truly massive, disabling flare and that was in 1995. It got me diagnosed, although I had dealt with symptoms coming and going for 4 or 5 years prior.

The primary area of attack for me has always been my legs. Some time in 2003, without any noticeable flareup, my walking and balance just started getting worse. In my opinion, that increase in disability without a distinct flare was the hallmark of becoming SPMS.

However, I have had flares since then, too. But also a gradual progression of disability. This could be because the attacks keep hitting the same areas and I end up with axonal damage. Or that glutamate thing that I don't quite comprehend yet (must read more).

At any rate, I think it stands to reason that repeated myelin destruction in the same areas along a nerve axon will result in permanent effects. All the more reason to battle inflammation and modify disease activity as we are able.