I have been a quiet observer of this forum for a while and have found it very helpful. Thank you all for your insights. My wife was diagnosed six years ago, and has tried all of the ABC's - no luck. She has progressed pretty rapidly. We began Tysabri three months ago. Her strenght seems to be improving, however I am noticing some very disturbing things. She is having a very hard time concentrating, she seems to be having a really hard time with things that were easy (our kids math homework??), she is noticing it too - and it is upsetting her. We really don't know what to do. We are feeling like we don't have any other options left. Where do we go from here if this is not an option. We are obviously aware (and anxious) of the possibility of PLM - but do not want to give up on this treatment option, as our nuro has made us feel like we have no other option. I would love any of your insights.