Fatigue in Multiple Sclerosis

Fatigue seen in MS is complex but can be broken down into several different aspects and causes that contribute to it as follows:

Normal fatigue – This is the fatigue that we all feel toward the end of the day. It is often worse in those with MS because of the extra effort that may be needed for accomplishing various tasks that may be more difficult in those with MS. It is responsive to rest and everyone has it to some degree.

Fatigue due to depression – One aspect of depression is loss of energy. It is difficult to do anything when you are significantly depressed. Depressed people often sit around, unable to generate the energy to do anything. Half of those with MS will have significant depression at some time during the course of their disease. This can be aggravated by some of the medications that we use. Interferons can cause or aggravate depression and in a few instances, it is necessary to change medications to manage the depression. Fortunately we have an increasing number of disease modifying treatment options that do not induce depression.

Handicap related fatigue – This is an exaggeration of normal fatigue caused by the extra effort expended to overcome a handicap. If you have a weak leg, it takes more effort to walk, if you have a clumsy hand, work with it requires a great deal more effort. If you are having memory or cognitive difficulty, mental tasks will require more effort and more concentration that can be very fatiguing.

Disease process related fatigue – In the authors opinion, this is due to the chronic activation of the immune system. This can be a very profound generalized fatigue. It can be total exhaustion, like you feel when you have the flu and the immune system is activated to fight it except you don’t have the fever. It can be difficult to get out of bed. You can barely get up to go to the bathroom. Medications may help but better control of the MS is important because disease related fatigue is usually an indication that your disease is active even if you don’t have other symptoms of an attack. When very profound, a course of steroids may help.

Nerve fiber fatigue – This is a fatigue that is specific to demyelination. After a certain amount of use, the demyelinated nerve fibers quit conducting and nothing you can do other than rest will fix it. The most commonly recognized form of nerve fiber fatigue is seen in walking where the individual may be able to walk a certain distance and the legs just quit. It is not painful but the muscles refuse to work. It take a lot more energy for a demyelinated nerve fiber to conduct and once the energy supply in the nerve is exhausted, rest is required for recovery. This can sometimes be seen with loss of vision in very bright light conditions. This fatigue is often exaggerated or caused by an increase in body temperature.

Impaired Sleep – This is a very frequent and sometimes complex problem in MS. See section on sleep problems in MS.

Medications induced fatigue and drowsiness – Many medications used to treat problems seen in MS can cause drowsiness. These include muscle relaxants such as baclofen (Lioresal®), tizanidine (Zanaflex®). Anxiolytic drugs used to treat anxiety are often sedative. Benzodiazepine drugs such as diazepam (Valium®) and clonazepam (Klonopin®) among others are somewhat sedative as are tricyclic antidepressants such as amitriptyline (Elavil®), nortriptyline and several others. There are many other medications that can cause drowsiness. If the drowsiness occurred soon after starting a new medication, check and see if has sedative effect.

Management of fatigue can be difficult . First, it requires of a careful exploration of what is causing the fatigue and it is often multifaceted. One of the best treatments for disease related fatigue is counter intuitive but regular exercise usually will markedly improve disease process related fatigue. You have to begin slowly because if you overdo it, you will feel it for several days, begin easy and slowly build it up. In my practice, I have never had someone who exercised regularly who had significant disease related fatigue. Why this works I don’t know but it does.

Medications for fatigue in MS include:

Amantadine – relatively inexpensive, works well in about half of the patients

Modafanil and armodafanil (Provigil° and Nuvigil°) expensive but work in the vast majority of patients. These are not FDA approved so it can be difficult to get payers to pay for them.

Amphetamines and methylphenidate (can be useful but their use is restricted and they are addictive).

You should discuss your fatigue with your doctor and come up with a plan for its management.

 

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