Multiple Sclerosis, or MS, is an autoimmune disease in which immune cells attack and destroy the myelin sheath which insulates neurons in the brain and spinal cord.  When the myelin is destroyed, nerve messages are sent more slowly and less efficiently.  Scar tissue then forms over the affected areas, disrupting nerve communication.  MS symptoms occur when the brain and spinal cord nerves cease to communicate properly with other parts of the body.

Approximately 350,000 individuals have been diagnosed with MS in the United States and more than one million persons worldwide are afflicted with MS.  An estimated 10,000 new MS cases are diagnosed in the USA annually.  Initial symptoms typically manifest themselves between the ages of 20 and 40; symptoms rarely begin before 15 or after 60 years of age.  Women are almost twice as likely to get MS as men, especially in their early years.  People of northern European heritage are more likely to be affected than people of other racial backgrounds, and MS rates are higher in the United States, Canada, and Northern Europe than in other parts of the world.

The causes of fatigue in MS are still being investigated.  It is thought to result from a combination of factors, partly caused by the disease itself – known as primary multiple sclerosis-related fatigue (PMSF), and partly the result of other factors (secondary fatigue) that affect a person with MS more significantly than people without the disease.

Until 26 years ago, primary multiple sclerosis-related fatigue (PMSF) was a largely unrecognized symptom of MS.1  PMSF can be the initial manifestation of MS, and can signal impending relapse.2  PMSF is the most common symptom affecting over 70% of all persons with MS.  PMSF is an experience of overwhelming tiredness, lack of energy, and a feeling of exhaustion.  PMSF comes on suddenly, and is overwhelming in proportion to any activity undertaken.  Neuromuscular fatigue occurs when nerve signals to muscles become confused when someone is performing repeated movements.  Neuromuscular fatigue is another type of PMSF.

PMSF can severely affect an MS patient’s quality of life and ability to function even if the level of MS disability appears to be insignificant to the observer.  PMSF has a severe effect on MS patients’ ability to feel as though they have control over their illness.

Pharmacological treatment options for PMSF are limited, and no drug has been approved by the U.S. Food and Drug Administration for the treatment of PMSF.

  1. Freal JE, Kraft GH, Coryell JK. Symptomatic fatigue in multiple sclerosis. Arch Phys Med Rehabil. 1984;65:135-138.
  2. Bakshi R, Shaikh ZA, Miletich RS, et al. Fatigue in multiple sclerosis and its relationship to depression and neurologic disability. Mult Scler 2000; 6: 181–185.