The Uhthoff Phenomenon
Uhthoff's Symptom also referred to as Uhthoff's Phenomenon does not display solely in MS patients, however, it was the principal diagnostic test for multiple sclerosis until the 1980's when more accurate test methods became available.
The patient will show a worsening of symptoms with an increase in body temperature. The temperature rise may be the result of exercise, a hot bath, or the prevailing climatic conditions. Most associated with Optic Neuritis this may demonstrate with or without multiple sclerosis. In one study, patients exhibiting Uhthoff's phenomenon without multiple sclerosis were found to be more likely to develop MS than patients with Optic Neuritis who didn't didn't display Uhthoff's Symptom.
An increase in heat can worsen many MS symptoms and cause new ones to appear. As well as Optic Neuritis it is most often seen to exacerbate MS fatigue.
It is thought, and these are just theories, that heat may affect serum calcium, circulatory change, heat shock proteins, and the most popular theory is the blockade of ion channels.
I prefer the explanation, discussed on the fatigue page, that demyelinated nerves suffer a performance drop when used a lot and the associated heat probably worsens this degradation.
- Wearing of a cooling vest
- Cool bath or shower