Uhthoff Phenomenon in Multiple Sclerosis

UHTHOFF’S PHENOMENON (Or UHTHOFF’S SIGN)

This is a temporary recurrence or worsening of symptoms that people with Multiple Sclerosis experience when their core body temperature increases. It can also occur in people with various optic diseases or other neurologic conditions, but is most often related to MS. It is named after Dr. Wilhelm Uhthoff, a German neuro-ophthalmologist who in 1890 described vision problems in MS patients whose body temperatures were increased when doing vigorous exercise programs. The pathophysiology causing this condition is complex and the mechanism is not completely understood yet. But changes within damaged demyelinated axons certainly is key.  As many as 80% of people with MS are heat-sensitive enough to experience this phenomenon.

 It happened to me—and shocked me—when I did a simple and typical aprés-skiing activity one day in winter 1992, five years after I was diagnosed with MS. My husband and I got into a hot tub with our friends to soothe our tired muscles after a long day of skiing. After a few minutes I began to lose the vision in my right eye!! The whole visual field was going black!

 One of my first MS symptoms in 1987 was optical. I had nystagmus (quivering of the eyeball which causes continuous blurred vision unless the eyeball is kept perfectly still).  Then a few years later I had an episode of vision loss in my right eye. It was like someone gradually pulling down a window shade over my visual field. Within a couple weeks I was completely blind in that eye. After being treated with high-dose steroids, my vision eventually returned after about 5 months. Somewhere I had read something about Uhthoff’s Phenomenon, but I had never experienced it before this hot tub mistake. When my right eye started going blind again like it had before, I suddenly remembered reading about this phenomenon. I immediately climbed out of that hot tub and ran over to a full-size swimming pool which was (luckily) close by. I dove into the cool water of that pool and immersed myself over my head, coming up for air only when I needed to. I’m not sure exactly how long it took, but I think in about 10 minutes the vision returned to my eye. 

 This was a classic case of Uhthoff’s Phenomenon. It can occur when a person’s core body temperature increases just a half-degree Celsius above normal body temperature. So, this would mean having a temp of 99.5o Fahrenheit or higher. The effect is transient, lasting less than 24 hours. But bad things can happen in those 24 hours, especially if it’s muscle weakness which can cause a fall or accident of some kind, even increased risk of drowning. And the worsening of symptoms can be subtle and gradual enough to go undetected for a while until you recognize the need to cool down.  Knowledge about prevention and treatment of this potential problem is important for people with MS. It is not a genuine MS relapse and should be distinguished from new MS symptoms or a true relapse, which should be evaluated by your MS healthcare provider. See your provider if worsening of symptoms after overheating is not relieved by cooling your body.

 Since that 1992 hot tub episode, I have experienced Uhthoff’s Phenomenon in other situations and various places of all kinds when I was being thoughtless, daring, stupid, feeling invincible, too cowardly to back out or quit an activity, and many other reasons. I will share those stories in future blogs to give other information and teach or entertain you.

 The following factors have been noted to trigger Uhthoff’s phenomenon:

menstrual period-related temperature changes; exercise/exertional activity; fever; sun-tanning; hot showers; saunas/steam rooms; hot tubs; cigarette smoking; being outside for extended periods in temperatures above 80 degrees; prolonged direct exposure to the sun. These things can cause various symptoms listed below. Each person’s triggers for bringing on Uhthoff’s can be different, so observing and noting that about yourself is important.

 Symptoms related to Uhthoff’s can include:

different vision problems; core body strength weakness; weakness in arms or legs; pain; pronounced fatigue; balance issues; bladder problems; cognitive changes; sensory changes and abnormal sensations of all kinds.

Try PREVENTION whenever possible:            

avoid direct sun exposure & stay in the shade whenever you can; close window blinds or curtains to prevent direct sunlight into rooms at peak times; take cooler baths and showers; install fans or air-conditioning in your house; wear loose-fitting and breathable clothing; use a cooling product (e.g., cooling vest, neck wrap, or head scarf); exercise in cool rooms; stay out of hot tubs and saunas; avoid aqua therapy (hydrotherapy) in pools with water temps above 78o

EFFECTIVE TREATMENTS:  

Drink cool or cold beverages

Take cool or cold bath or shower

Sit in front of a fan

Wrap cool damp towel around your torso, neck, wrists, forehead

Apply an ice pack            

If you have very severe symptoms, your MS provider might prescribe a medication called 4-aminopyridine or dalfampridine. The first one helps with maintaining proper potassium channel blocker levels which enhances impulse conduction in demyelinated nerve fibers. The second one is an extended-release formulation of this agent.  ________________________________________________________________________

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 REFERENCES:

Opara JA, Brola W, Wylegala AA, Wylegala E. Uhthoff`s phenomenon 125 years later - what do we know today? J Med Life. 2016 Jan-Mar;9(1):101-105. PMID: 27974923; PMCID: PMC5152601

Panginikkod S, Rayi A, Rocha Cabrero F, et al. Uhthoff Phenomenon. [Updated 2022 Oct 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470244/

https://mstrust.org.uk/a-z/uhthoffs-phenomenon

https://multiplesclerosisnewstoday.com/multiple-sclerosis-symptoms/uhthoffs-syndrome/

https://mymsaa.org/ms-information/symptoms/uhthoffs-syndrome/

https://www.nationalmssociety.org/Living-Well-With-MS/Diet-Exercise-Healthy-Behaviors/Heat-Temperature-Sensitivity

https://mymsaa.org/msaa-help/cooling-products/