I think the heat problem is related directly to whatever is the primary disease pathology is in MS. I think it may be directly connected to venous drainage, from both brain and spinal cord. There is in my case some kind of pathology in my spine, which affects my walking and may be related to the definite left-sided disabilities I have, including eye muscles, arm muscles, leg muscles, and ankle-foot nerves. This nervous problem is also extremely heat-sensitive. My hot laptop makes my legs twitch. So does too many blankets in bed.
I have to have summer air temp in my house at 73 degrees Fahrenheit or lower to be sure of minimum discomfort. Some people find this too cool. I also use a ceiling fan at night.
My first sign of overheating is that the skin on my hands feels like it is burning. This can be treated with cold water on my wrists, but if I remain overheated, eventually my core temperature will rise and more drastic cooling will be required. If I am overheated too long, the resulting symptoms remain a long time after I cool off, worst case, for weeks.
I suspect there is a primary cooling problem. I went for my usual 1-block walker-walk, in 98.6 Fahrenheit degree heat, with neck and head coolers. I went about 100 feet farther than usual, and slowed to a crawl before i could return. I had to be pushed back, seated on my walker.
There may be some symptoms which are not affected by temperature, but I don't know what they are.
"Try - Just A Little Bit Harder" - Janis Joplin
CCSVI procedure Albany Aug 2010
'MS' is over - if you want it
Patients sans/without patience