I dont have MS but would think that cold would make MS worse because it deranges my immune system. It suppresses mine, but then in an attempt to overcome that, my body compensates by turning on my immune system, but it does not do so in the usual way, such that it actually causes damage to my brain, such that for many hours afterward, if I get cold long enough, my dopamine is suppressed, and my brain feels like it has a scar across the front and I feel slightly sick. This brain symptom may not be as pronounced in others as it is for me due to the fact I have some brain damage , making injury to it easier. But have you notice that after being real cold for a longish time, when you get back inside you will feel sleepy? That would probably be due to the fact that when my brain is in the process of healing after injury it makes me very sleepy, the cold not causing the injury directly , but indirectly by triggering thi above described imperfect immunity enhancement.
PS I know it is my immune system that is in this compensating state that is causing the brain damage rather than the cold because as soon as my immune system , which I can monitor as described in another thread, gets turned on, my tinnitus gets worse, and it always gets worse immediately when my brain is being injured.