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Understanding and avoiding Uhthoff’s phenomenon

By Gay Falkowski

Do one or more of your MS symptoms flare when your body temperature rises? If so, you may be one of the many people who experience Uhthoff's phenomenon (also known as Uhthoff's syndrome, Uhthoff's sign, and Uhthoff's symptom).
Wilhelm Uhthoff, a German professor of ophthalmology, first described the condition in 1890. Some people with optic neuritis, he observed, had a temporary worsening of vision after they exercised. Though Uhthoff initially blamed exercise for the decline, researchers later concluded heat was the culprit. More specifically, their body’s sensitivity to heat and reaction to a rising core temperature – not the exercise – was what caused their vision to worsen.
Today, in addition to optic neuritis, Uhthoff’s phenomenon encompasses many other symptoms affected by increased temperatures, such as fatigue, pain, cognitive difficulty, and bladder sensitivity. The following facts and tips may help you better understand Uhthoff’s phenomenon, how to prevent it, and what to do if you think you’re experiencing it.
1) The exact science of Uhthoff’s phenomenon is not yet understood. However, some studies have shown that even a slight increase in core body temperature can slow or block the conduction of nerve impulses in demyelinated nerves. In simple terms, this means your body has a difficult time sending and receiving internal signals.
2) Uhthoff’s phenomenon is temporary. Once the body’s core temperature returns to normal, symptom flares subside.
3) Uhthoff’s phenomenon does not signal you have new lesions, lasting neurological damage, or a rapid progression of MS.
4) Uhthoff’s phenomenon is not the same as a relapse or exacerbation. In fact it is considered a pseudo-exacerbation.
5) Not everyone with MS is heat sensitive. Some people do not experience Uhthoff’s phenomenon when their core body temperature rises.
6) For those who are heat sensitive, any source of heat can trigger Uhthoff’s phenomenon. Some examples are: hot and humid weather, a blow dryer, fever, a sauna, hot (or even warm) baths and showers, and hormonal changes.
7) Prevention is the key to avoiding Uhthoff’s phenomenon. Stay away from triggers and prepare for instances when you know you’ll be exposed to heat. Equip yourself with cold packs, cooling accessories, cold water and other hydration drinks, misting bottles, and portable fans. Loose, cotton clothing is best for good ventilation.
8) Individuals who are susceptible to Uhthoff’s phenomenon do not need to avoid exercise. Studies show exercise can be helpful in managing MS symptoms, reducing the risk of comorbidities, and promoting overall wellness. They should, however, take necessary precautions such as exercising in a cool environment and wearing cooling accessories.
9) Consider pre-cooling the body before exercise. In one study, heat-sensitive individuals with MS immersed their lower bodies in 62-degree Fahrenheit water for 30 minutes before exercising. They reported exercising in greater comfort and with fewer side effects than usual.
10) Hydrotherapy is another exercise option for heat-sensitive individuals. The recommended water temperature is a moderately cool 80 to 84 degrees F. Temperatures lower than 80 degrees are not recommended because of the risk of triggering spasticity.
11) If, despite your best efforts to prevent overheating, you believe you’re experiencing Uhthoff’s phenomenon, the best remedy is to cool down as quickly as possible.
12) In general, medical intervention isn’t necessary for Uhthoff’s phenomenon, as symptoms will subside after your core body temperature returns to normal. Recovery is not always immediate, and can take several hours or more to fully resolve.
13) You may want to seek medical attention if:

* You’ve never experienced heat-related symptoms of MS before
* You’re uncertain that your symptoms are Uhthoff’s or MS-related
* You have accompanying symptoms unrelated to MS
* Your symptoms don’t improve after you’ve cooled down