What causes temperature sensitivity in multiple sclerosis?
A person suffering from MS will experience demyelinating plaques [2] in the brain, spinal cord, and optic nerves. This will affect the functions of the central nervous system. Heat will further slow down nerve impulse transmission in these regions.
This explains that heat worsens the symptoms that a person who has MS may be experiencing. Since the myelin is not in its most functional state yet, heat as a stressor would bring out the symptom of numbness that gradually improves.
A situation where the symptoms of MS [3] worsen as a result of heat is a phenomenon referred to as Uhthoff’s sign. The most common symptom flare due to heat is blurred vision.
Factors that cause overheating in the body include:
- Increased activity
- Hot baths and showers
- Hot weather
- Hot tubs
- Saunas
People with MS should be careful of these factors. These sources can trigger a phenomenon known as pseudo exacerbation [4]. This is when one experiences a worsening symptom due to heat exposure.
In the case of pseudo-exacerbation, the worsening symptoms go back to normal after the body’s temperature gets stable. There is no permanent damage such as new lesions, loss of myelin, or inflammation. This is unlike a case of true relapse.
Coldness can also cause MS symptoms to flare up. Certain people are more sensitive to cold than heat. A common symptom worsening that occurs due to extreme coldness is spasticity.
While some people with MS are sensitive to both heat and cold. Usually, different temperature extremes cause different symptoms to worsen.
Heat sensitivity will require you to be more careful about the activities you choose to perform. Avoid endurance activities as it increases the temperature in the body. Instead, go for resistance exercise.