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The Fatigue Factor

© Pamela Martin

Mental Fatigue

Not only does MS fatigue drain a patient physically, but it can also cause mental distress. Remember the child's game of trying to pat your head and rub your stomach at the same time? It was hard to concentrate on both tasks at the same time, so ultimately, you ended up not doing either chore very well. Many people with MS can relate to that feeling of being mentally overwhelmed. Often, the dysfunctional nervous system is working overtime, processing the enormous sensory data that we experience daily. Because the process is disrupted and inefficient, it may be difficult to hold a conversation and listen to background music at the same time. Or someone may find it impossible to drive at night because the array of lights and sounds are disconcerting. Similarly, I was once struck dumb and unable to answer a store clerk who simply asked me for my telephone number. Because my senses were already overloaded from the shopping experience, my brain simply shut down when faced with a simple question. At that moment I was just mentally worn out.

What Causes MS-related Fatigue?

Although scientists have no definitive answer, a couple of likely theories are presented regarding the cause of MS fatigue.

Location, Location, Location. One theory holds that fatigue is related to the loss of myelin-the protective coating of the nerve fiber. The locations where the myelin loss occurs are responsible for the severity and type of fatigue. In this scenario, it is the cerebral abnormalities themselves that contribute to fatigue. The random placement of myelin lesions or loss could account for the variety of ways people with MS experience the symptoms of fatigue.

Interestingly, a 1999 study found fatigue severity did not correlate with myelin scarring or deterioration as observed on MRI.¹ Correspondingly, a 1998 study suggested that the differences in fatigue levels could not be solely explained by the degree of disease activity or disability.² There is certainly a great need for more study in this area.

Poor Body Functioning. It has also been speculated that the general deterioration of overall functioning as a result of having MS may simply exhaust the body's storehouse of energy. Muscle weakness and decreased nerve conduction are the obvious culprits. But some researchers have noted that altered metabolism and inadequate respiration are other energy-depleters. Again, further investigation is needed in this area.

Treatments

Above all, patients must consult with their physician or other health care professional to determine the value of treatments available for MS fatigue. The prescription drug, Neurontin®, which is used to control tremors and spasms, has been reported by some users to relieve fatigue as well (although the reasons for this are not totally understood). In addition, amantadine (Symmetrel®) and pemoline (Cylert®) have been helpful to a small number of MS patients. Unfortunately, others have found them to be complete failures at remitting fatigue, and have caused unwanted side effects.