Riverwild, thanks for your oh so comprehensive reply. Don't worry about the questions. i'll respond as I can.

My neuro is head of the MS center in a large city and very busy. I've got an appt w/ him in a couple weeks but have to wait until then to really learn more. In meantime, I'm just back and forth w/ nurses (who often don't really know much). I trust his reading of MRI's. Usually just after I have them done I've got appt w/ him, pop up to his floor and see everything on his computer as he does. He "reads" the info while showing it to me, and the radiologist's report coming after always backs him up. But the nurse didn't/can't tell me WHY he doesn't think it's PML.

Strange, isn't it, that Biogen doesn't have a site with all this needed info and maybe even a site for patients to share info among themselves?

Is it really true that they know the diff between MS and PML lesions? Cuz I couldn't find any good info like that anywhere. I know MS tends to be periventricular, but other than that?

My last infusion was exactly a week ago. I spoke w/ a nurse at the clinic beforehand and she presumably spoke with neuro before OK-ing it. It's just hard never knowing what's going on. And I guess I kinda assume nobody can truly tell me what's going on either? That it's all guesswork to a large extent?

But thanks for that info on steroids, how typical it is to worsen before improving. In past I've always improved almost immediately on them, so this is different for me in lots of ways. And I'm in process of doing a vid retrospective on my life just now so I get anxious that I won't even be able to get it done. Cuz if I do get PML I am not sticking around to be so severely disabled! I actually haven't even heard about the JCV assay. Did that just come out and is it proven reliable?

I so appreciate and concur about the difficulty of cognitive problems, which hits our very sense of who we are. My neuro sez that though most MS-ers are affected that way to some extent, only a quarter are hit in a major way. It takes me about ten times longer to do anything involving thinking and my brain even starts to literally HURT if I do it too long.

Again, thanks so much for your response!