Actually, this phenomenon should be known to almost every MS patient – because it is very common. Surprisingly, however, I also find again and again that knowledge about this is not widespread. Wilhelm Uhthoff (1853-1927) is a German ophthalmologist who in 1890 first described that an increase in temperature in an inflamed, pre-damaged optic nerve leads to a reduction in visual acuity. The reason for this observation is that biological processes run faster at higher temperatures and therefore the tendency to “short circuits” (in neurology we speak of conduction blockage) and thus the occurrence of functional disorders of pre-damaged nerves increases compared to normal temperature conditions. The Uhthoff phenomenon is therefore a possible temporary worsening of neurological symptoms in MS patients when body temperature rises.
This increase in body temperature can occur from the outside or from within. Examples of externally induced increases in body temperature are hot summer days, direct sunlight, wellness treatments with hot baths or sauna sessions; examples of internally caused increases in body temperature are sports or fever in the context of an infection. It is important to know that the Uhthoff phenomenon is a temporary symptomatology that is not dangerous and does not indicate a deterioration of the disease.
Not infrequently, MS patients are suddenly confronted with this phenomenon. Example: A young, otherwise healthy woman has suffered an inflammation of the optic nerve. This is completely healed. Now she observes after a stay in the gym that immediately after the workout her visual acuity decreases and this state lasts for more than an hour. More than worried about a possible renewed inflammation of the optic nerve, she seeks advice from friends, relatives, possibly even the family doctor. Unanimously, they advise her to rest. She observes that when she rests, the phenomenon no longer occurs and thus learns avoidance behavior, which is extremely counterproductive.
Therefore, I regularly inform my patients about this phenomenon and emphasize strongly that it is completely harmless. As a rule, intense physical training even leads to a reduction of the Uhthoff phenomenon in the long run, because with better training condition the body temperature increases little. Because the Uhthoff phenomenon is not dangerous, I also have nothing against sauna sessions for MS patients. Usually, you will quickly notice whether you like the sauna or not. If you are stiff as a board afterwards, you probably won’t make sauna sessions your favorite activity. If nothing happens, there is no limit to using the sauna. However, it cannot be denied that there are quite a few MS patients who suffer greatly from this temperature-related deterioration and have considerable discomfort during sports or in the summer months. In such cases, cooling strategies are very useful. There are now a variety of suppliers of cooling vests, shirts and bands. Their purchase can be a very sensible investment.
