Multiple Sclerosis: Fatigue
How is fatigue related to multiple sclerosis?
Fatigue is the most common symptom of multiple sclerosis (MS). It occurs in 75 percent to 95 percent of patients with MS. Fatigue can occur at all stages of the disease. The symptom is not related to the severity or to the duration of MS. At times, fatigue interferes with function and is an important symptom to manage. There are a variety of ways to combat fatigue in MS.
What causes fatigue in patients with multiple sclerosis?
The exact cause of MS-related fatigue is still unknown. There are several theories on the subject:
- One theory is that fatigue is related to the general activation of the immune system. Chemical messengers are called cytokines; these levels are higher in patients with MS and may be higher still in patients with fatigue. One way of describing this is that you may feel like you have a virus all of the time.
- Another theory is that people with MS may have to use more parts of their brain to do the same task as someone without MS; in essence, they are working harder.
- Another theory is that fatigue is related to reduced electrical transmission of signals in the brain.
Whatever the theory, we know that fatigue from MS is a very real part of the disease.
What are symptoms of fatigue?
There are two major types of fatigue in MS. These two types of fatigue are probably separate problems related to the MS.
The first type is a general feeling of tiredness. It may feel as if one has not slept the night before. This feeling may be worse in the afternoons or after activity. People may feel that they are unable to do as many tasks without getting tired as they did before.
A second type of fatigue is muscular. In this type, there is increased weakness after repeated activity. Often, this occurs with walking. People may find that they are dragging one leg or are more unsteady.
Are there other causes of fatigue besides the MS?
Obviously, people with MS can be tired for other reasons. For example, they may have sleep disorders that interfere with restful sleep. People with MS may have a condition called restless leg syndrome, where they feel that they have to move their legs to get relief. They may also have periodic leg movements, which is when legs kick involuntarily during sleep. Another condition affecting sleep is sleep apnea, which is also common among the general population.
Certain medications may affect sleep or cause fatigue. Alcohol or drug use may alter sleep or cause drowsiness. Sometimes, people have other medical conditions, such as infections, anemia, or a reduced thyroid function, which can increase fatigue.