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For people with MS, who are usually sensitive to heat, keeping comfortable during the hot days of summer requires planning and precaution. Add exercise and travel to warm climates to the mix, and heat management becomes a bigger challenge. However, with proven strategies and cooling devices, you can remain active and stay cool in spite of heat’s effect on MS. You should first understand how and why heat impacts MS.
Heat’s Effects on MS
There are no exact statistics, but many people with MS are heat sensitive. With a rise of just 1/4–1/2º in core body temperature, you may start to notice symptoms such as vision changes, fatigue,weakness, spasticity, bladder and bowel problems, or confusion (Table). These neurologic symptoms might seem like a relapse or exacerbation of MS, but they are actually “pseudoattacks.” Pseudoattacks do not reflect worsening MS or cause more damage; they are temporary, tending to reverse quickly once the body becomes cooler.
Any hot environment can bring on a pseudoattack: hot tubs, stuffy rooms, hot summer weather, or heavy clothing that doesn’t “breathe.” The heat generated by vigorous exercise may be another trigger. The link between heat and MS symptoms became clear more than a century ago and served as the basis of MS diagnosis from the 1950s to the 1980s. People were placed in a hot bath and monitored for the onset of symptoms, particularly the transient blurred vision known as Uhthoff ’s sign. This practice ended with the advent of magnetic resonance imaging, or MRI, a much more accurate diagnostic technology.
Source of Sensitivity
By destroying the myelin covering of nerves, MS is responsible for slow, inefficient transmission of electrical signals in the brain and spinal cord. This is the basis of true symptoms of MS. Scientists suspect that in pseudoattacks, the heat frazzles these signals even more and gives rise to short-lived pseudosymptoms. The same process could underlie sensitivity to extreme cold, which is also common in people with MS. In either case, the precise means by which temperature extremes translate to pseudoattacks are not yet known.
Preventing Heat-Related Symptoms
You can avoid heat-related pseudoattacks, even during exercise, by planning ahead, taking precautions, and paying attention to your body. Be sure to:
- Check weather predictions and temperature before going outdoors.
- Choose cooler times of day—early mornings and evenings—for outdoor workouts.
- Stay indoors with a fan or air-conditioning at times of extreme heat and humidity.
- Before activity, “pre-cool” by taking a lukewarm bath or shower and gradually cooling the water.
- Sip cool water or chilled fruit juice during the day (avoid caffeine) and carry water with you.
- Wear loose, lightweight clothing or special cooling apparel.
- If swimming, make sure the water temperature is 80–84º F.
- Stop exercising and cool down if warning signs appear, such as tingling in the feet, heavy legs, confusion, fatigue, or symptoms listed in the Table.
- Take a cool shower or bath to bring down body temperature quickly, or apply ice to the forehead, wrists, ankles, or underarms.
Remember, no 2 people will react to heat in the same way or cool down at the same rate. Generally, cooling down after overheating takes a few hours. Some evidence suggests that people who heat up and experience heat-related symptoms the fastest also cool down the fastest.
Garments and Devices for Cooling
Cooling the body is of proven benefit to people with MS. It has been shown to speed up nerve transmission, restore eye function, increase walking ability, reduce fatigue, and resolve other pseudosymptoms. Cooling is free of side effects and need not be expensive to achieve. The simplest remedies—a cool shower or bath, cool drinks, ice, a cool compress, a pack of frozen vegetables—can be as effective as more sophisticated methods.
Special cooling devices and garments such as portable fans and cooling vests, wrist bands, and blankets are available to help keep the body cool in hot temperatures. Click here for a list of suppliers.
