What is Uhthoff’s Phenomenon?
There are all sorts of things that people tell you not to do when you have MS – don’t smoke, don’t drink, don’t allow yourself to get stressed out, don’t go in the hot tub, don’t go out on a hot day, don’t feed them after midnight… hmm, that last one may be about gremlins.
So, what is with all these rules? Well, some of the rules stem from the desire to prevent disease progression. For example, smoking cigarettes can greatly speed up disease progression in MS. I follow a neurologist on YouTube, Dr. Aaron Boster, who says that smoking cigarettes can speed up MS disease progression by close to 50%. Thankfully, I never took up smoking, so this is an easy rule for me to follow. Most of these rules, however, stem from the possibility that you could temporarily exacerbate MS symptoms. For example, I asked my neurologist about the warnings around drinking alcohol when you have MS. Do they recommend against drinking alcohol because any given glass of wine may blast a new hole in an MS patient’s brain, or do they recommend against it because it can worsen an MS patient’s already troublesome balance and coordination? Dr. Schneider confirmed that a glass or two of wine on a Friday night isn’t risking any new lesions. Many MS patients struggle with balance and coordination, and alcohol only makes that worse. As I currently don’t struggle with balance and coordination, there isn’t currently a need to become a teetotaler. I was relieved to get this confirmation. If drinking alcohol risked turning my brain to Swiss cheese, I wouldn’t hesitate to say farewell to my excellent scotch collection, but I’m happy that this isn’t necessary. Certain disease modifying therapies (DMTs) are known to be hard on the liver, and this is another reason why some MS patients steer clear of alcohol.
Uhthoff’s phenomenon (also known as Uhthoff’s sign or Uhthoff’s syndrome) is the temporary worsening of MS symptoms when an MS patient is exposed to heat. When you hear that MS patients should avoid hot tubs, saunas, hot weather, etc., it’s because many MS patients experience Uhthoff’s phenomenon. When the body temperature rises, even by as little as 0.5°C, nerve impulses are either blocked or slowed in the damaged nerves. When the body temperature returns to normal, the symptoms associated with Uhthoff’s phenomenon typically reverse. The phenomenon is named after Wilhelm Uhthoff, the German ophthalmologist who first described it back in 1890. Back in the days before MRI machines and lumbar punctures, the hot water bath test was used as a diagnostic tool for MS (just as it sounds, this test involved raising the patient’s body temperature using hot water and waiting to see if it caused MS symptoms to appear).
I experience Uhthoff’s phenomenon in the form of a tingling sensation in my middle, ring, and pinky finger of my left hand. I usually only experience these symptoms when I have been running long distances or otherwise exerting myself very hard. I have also triggered it by exposing myself to extreme hot weather on a couple of occasions.
I asked my neurologist about the common warnings around heat exposure when you have MS. I had read that MS patients shouldn’t take hot baths, shouldn’t use hot tubs or saunas, and shouldn’t go out in the heat. He confirmed that this advice is intended to help those patients who are debilitated by Uhthoff’s phenomenon (albeit temporarily). I asked whether experiencing Uhthoff’s phenomenon is a sign that I should back off when I am out running. He had no concerns about my running. To the contrary, exercise is one of the things that you can do to improve your prognosis when you have MS, so he encouraged me to run as much as I want. He explained that Uhthoff’s phenomenon is a sign that there is pre-existing nerve damage, but it is not a sign that you are causing new nerve damage. So long as the patient isn’t bothered by the symptoms, there’s no need to try to prevent Uhthoff’s phenomenon. So, I will continue to run, notwithstanding my tingling fingers.
