If people knew only about RRMS and not PP and SP, there would be far less interest in it. And, yes, what Jenny said about MRI. Imaging technology changed everything especially for those with RR MS who languished exactly as we do before that technology identified RR as the same disease as PP and SP. But, I do sometimes wonder if the over-reliance on MRI is not now sweeping some with ME into the MS basket. Tricky stuff, all of this!