The body produces most of its heat as a natural consequence of being alive. This activity is called the resting metabolic rate. Everything else one does adds more heat: sitting up, smiling, movement of every kind. There is even a 24-hour cycle of body temperature that can affect those who are most heat-sensitive.
Exposure to a warm environment raises body temperature. A short walk on a hot day or sitting in a hot car may result in significant problems for a person with MS.
Heat not only causes an increase in symptoms for many, but people with MS may have impaired
heat-loss mechanisms. Sweating in response to high temperatures or exercise may be less than normal. Increased blood flow to the skin--the mechanism which brings heat to the body surface so it
can be lost--may also be less than normal. The heart rate may not increase normally in response to heat or physical excercise. Moreover, low levels of physical activity often result in a lower volume of blood in the body, further reducing one's heat-dissipating capacity. Heat (or cold) may be stored in the
legs and arms.
Think first in terms of prevention. Plan to avoid hot environments, long car trips, excercise in warm
places, or spending time out of doors during the heat of the day. Protection helps. Wearing light-colored
cotton clothing is far cooler than wearing nothing at all. Keep your head covered and avoid direct sunlight. Be sure your fluid intake is adequate. (Since muscle cramping can occur if sweat loss is replaced by water alone, drink diluted fruit juice or electrolyte-balanced "sports" drinks.)
For emergency heat relief, many people carry a cooler of drinks and cold gel pads. Pads can be used on the head, neck, or extremities. A spray bottle to moisten clothing will promote evaporative heat loss. You can also take advantage of the way cold is stored in your legs, arms, or back. Since legs constitute
a considerable percentage of body mass, you can essentially create your own refrigerator to carry with you by using deep cooling.
Sit in a bathtub or put your legs into a large plastic wastebasket of tepid water. Add cold water gradually, allowing yourself time to accommodate to the cold. You'll need at least 30 minutes of cold exposure to accomplish deep cooling. The cooler blood in your legs and lower body will slowly circulate and keep your temperature down.
While it is always easier to stay out of trouble than to correct problems once they have developed, remember that you will recover from heat-related neurologic problems when you body cools down.
Dr. Jack Petajan is a neurologist at the University of Utah Medical Center who serves the Society as a member of the national Clinic Committee.
c1996 National Multiple Sclerosis Society