Some people who have MS have an intolerance to heat. It makes the MS symptoms worse.

Back before they had all this technology to help with the diagnostic process for MS, they used to put people suspected of having MS in a hot bath and watch their reaction. If they had MS like symptoms crop up, they got dx'd and treated with prednisone.

But, on the other hand, some people do not react to heat at all.

In my case, I do. I am heat intolerant and have to really watch the heat and in addition, I have to make sure I keep my core temperature down. I have what's known as Uhtoff's Syndrome which causes pseudo-exacerbations if I allow myself to get over heated for an extended period of time. In some people, it only affects their vision. With me, if affects my legs and hands. They go completely numb. I have to lower my body temperature and make sure I am re-hydrated. If I don't I can put myself right into a full blown exacerbation.

Clear as mud? Good...we are ok now!