As I pass by the hall thermostat, I check to see how warm or cold it may be inside and outside the house. During the summer months, if the outside temperature approaches 90°F, I feel a twinge of sadness. Why? Hot weather, humidity, multiple sclerosis, and I do not play well together.
Impaired body temperature regulation
People with MS may have difficulty regulating body temperature due to impaired neural control of autonomic and endocrine (hormonal) functions. This means that the part of the brain that senses core body temperature and tries to keep it in balance at about 98.6°F doesn’t work as effectively as it should. Some people with MS may even have a naturally low core body temperature which in turn exacerbates their sensitivity to heat. At a recent medical visit, my body temperature clocked in at 95.9°F which means that a “normal” body temperature would represent a fever for me.
Heat sensitivity and MS
Many people with MS can become sensitive to excessive heat and humidity leading to a temporary worsening of symptoms, called a pseudo-exacerbation, when their body temperature rises. Common activities, like exercising, taking hot showers or baths, or summertime activities such as sunbathing, can exacerbate symptoms. Even very small increases in body temperature of one-quarter to one-half of a degree can interfere with the efficient transmission of nerve impulses along demyelinated nerves.
This temporary worsening of symptoms in people with demyelinating disease is also called the Uhthoff’s Phenomenon. Originally noted by Wilhelm Uhthoff in 1890, some patients with MS experience a “marked deterioration of visual acuity during physical exercise.” While Uhthoff primarily associated this phenomenon with reversible optic symptoms, including blurriness, double vision, and blind spots, it has since been associated with other neurological symptoms that fluctuate with temperature, illness, or stress.
Staying cool in the heat
To combat the effects of hot weather, here are some of the best ways to keep cool when you are out and about enjoying the summer months:
- Wear clothing that is lightweight, loose-fitting, made of natural fabrics (cotton, silk, linen), light-colored (to reflect heat), and/or wicks moisture from the body which is helpful in high humidity environments
- Stay hydrated by drinking plenty of water and avoiding caffeine, and mist yourself with water to help your body stay cool as the water evaporates
- Run cold water over your wrists for 10 seconds on each hand, wrap a wet handkerchief, towel, or cloth around the back of the neck, and/or apply ice to the inside of your wrists, back of the neck, or top of the head to provide quick relief; always carry a large ziploc-type bag in which you can put ice to make an instant ice pack when away from home
- Sit in the shade and avoid strenuous activity during peak sunlight hours (10 am - 3 pm), go inside to take advantage of air-conditioning, or take a dip in a cool pool (<85°F)
- Drink iced beverages, snack on frozen bite-sized pieces of fruit, or freeze bottles of water and sip on the water as it melts throughout the day
- Use cooling vests and equipment that help to reduce body temperature and provide temporary relief by a variety of methods (see review of cooling vests at ActiveMSers); you may even qualify for a free cooling vest from MSAA or MSF
It’s always good to think and plan ahead, especially because heat has shown to affect cognitive abilities in people with MS. Once you get overheated, fatigued, and brain-fogged, it becomes much more difficult to do something proactive to help yourself. I’m lucky in that my husband keeps a close eye on me when we’re working outside and makes sure that I rest, drink enough cold liquids, and go inside before I get too overly exhausted and overheated. As I prepare for the summer, this is a great reminder that there are ways to fight back against the negative effects of the summer heat and humidity.