I do not know the cause. I myself have M.S., I was diagnosed in 2002 but had it 7years befor that. The doctors here in my area did NOT catch it. I do know stress is a big NO NO. The heat kills me along with the humidity. I have been on every ABC, R drug and tysabri infusions. Now I am on the pill form, GILENYA. Woo Hoo, it is so nice not getting shots! There are 5 of us 1st cousins that have it. It runs on both sides of my family. I just say LORD, give it to e and NOT my kids nor grandaughter. God gave me broad shoulders, now I know why! Thank god I can still walk, just not too far. Things could ALWAYS be worse!