I have become a human thermometer. I cannot stand to be cold, I freeze when most people are comfortable. But if I get hot, I get weaker than a newborn kitten. I used to love hot baths, but I can't do that anymore because I become a dishrag afterwards. My thyroid has stayed normal for years. The brain does so much we don't really know about, any amount of lesions can alter anything we consider normal, and as Alex said, brain stem lesions definitely would mess with the thermostat.
If you have brain stem lesions you can have trouble regulating temperature.
Thanks for the clarifications. That's what I thought they meant by heat intolerance in MS but I wasn't sure.
I do believe I have a problem with my autonomic nervous system. I've looked up the symptoms before and have a lot of the symptoms that are described, like the getting overheated and sweating issue, and the lightheadedness when I stand. The only thing that doesn't fit is the intermittent double vision.
I agree that Uhthoff's phen. and body temp regulation are different issues. Both can happen with MS. I tend not to get Uhthoff's, but I do have major problems with temperature regulation. I sweat much more easily than others do, especially my face and scalp. Yuck. Pre-MS I was pretty normal in this regard.
The problem lies with the autonomic nervous system, which controls a lot of bodily functions. You can Google this for lots of info. This is relatively rare in MS, but it does happen. I have other autonomic dysfunction as well, agreed on by neuros.
I don't know whether the poster does have MS, or what else can cause these things, but that's what neuros are for. Good luck.
Uhthoff's phenomenon, as JJ explained, has less to do with the body's ability to regulate temperature than the exacerbation of past damage (pseudo-flares) from slowed nerve signals. For example, on the days I work half days, I arrive at 12 even through I only start at one because I know it will take me about a half hour for my left eye to come back 'online' from an hour of travel on two forms of toasty public transport. I haven't done anything physically taxing, I've just basked long enough in heightened ambient temperatures to trigger echoes of a past flare (ON in left eye four years ago).
I've had all my levels tested including my thyroid levels and they all came back normal. It's like my body can't control it's temperature. I didn't have this problem last summer.
To me what you are describing whilst exercising (running), wouldn't actually be unexpected, if you are also getting hot and sweating more readily even when your not running.
You'd be hitting heat exhaustion/heat stroke territory a lot faster than normal, if your body already isn't cooling through your skin properly, the addition of running would be demanding oxygen goes to the muscles in your legs and away from your skin. Your body would be battling a lot harder than normal, to get enough oxygen where it needs to go, to your skin to cool you down, to your leg muscles to keep you running, and to your brain but there just isn't enough going where it needs to go at once creating an imperfect balance..
MS doesn't usually cause people to overheat and sweat more easily, sweating issues can be a secondary issue an MSer deals with but generally heat intolerance (Uhthoff’s) in MS causes a temporary worsening of their MS symptoms. Heat basically slows down nerve impulse in the demylinated nerves and it doesn't need to be much, less than a degree increase to the body’s core temperature can be enough to cause symptoms of heat intolerance in an MSer.
Hot weather is a common MS problem but what your describing just doesn't sound right to me, i would suggest you see your GP because sweating could be a something like a thyroid or hormonal issue and worth getting checked.