Most of us enjoy the warm weather months; the longer days, lots of sunshine, and time enjoying the great outdoors. For some individuals living with MS, however, summertime heat can be tough and cause their MS symptoms to be temporarily worse. So what is really going on?
Under normal physiologic conditions in everyone with and without demyelinating disease, nerve conduction between nerve cells via axons is slowed when the core body temperature is elevated. This can happen even with a half-to-one degree elevation in core body temperature. This happens to everyone, but generally if myelin is intact, we don’t notice this slowing at all; we still can conduct our activities without interruption from neurological symptoms or fatigue. If someone with MS has demyelinated axons, however, nerve conduction is slowed as a result of the demyelination, leading to symptoms of numbness, tingling, fatigue, difficulty walking, weakness, etc.. When heat is introduced to this picture, there is even more nerve conduction slowing as a result of the combination of normal physiologic responses to heat and demyelinated axons. Unfortunately, this leads to old MS symptoms and sometimes new MS symptoms, presenting themselves when your core body temp is elevated. The important thing to remember is that YOU ARE NOT DOING ANY NEUROLOGICAL DAMAGE BY BEING HOT. It is important, however, to remember that you can still enjoy the activities that may increase your core body temperature, but you may experience symptoms.
Furthermore, it is important to note that symptoms will resolve when your core body temp returns to its normal temperature. So we advise folks to prepare ahead of time: if you are in the heat, make sure to be well hydrated and carry a bottle of ice water with you in the summertime, when outside sit in the shade to cool down, and exercise in air-conditioned facilities if possible. There are also accessories such as cooling vests, cooling scarves and cooling hats to help you maintain a normal core temp during the warm weather. Remember to be safe; if you are working out and are overheated you may be more at risk of feeling weak or unsteady. So rest, do stretching exercises or grab a cold drink of water. Most of all, the objective is to have fun and enjoy the activities the summertime has to offer. Remember to be prepared and listen to your body.