Fighting Fatigue in MS

Q) Why do my patients with multiple sclerosis experience so much fatigue, and what can I do to help them?

Fatigue is an extremely common symptom of multiple sclerosis (MS) and one of the most disabling complications of the disease.¹ More than 75% of patients with MS experience fatigue, which can worsen motor function, sleep quality, mood, and overall quality of life.^1,2 Fatigue can also adversely affect employment; among patients with MS who reduce their work hours from full- to part-time, 90% do so because of fatigue.³

The Multiple Sclerosis Clinical Council Guidelines define MS-related fatigue as a “significant lack of physical and/or mental energy that is perceived by the individual or caretaker to interfere with usual or desired activity.”⁴ Described as “overwhelming,” this type of fatigue is generally unrelated to activity level.⁵ It differs from fatigue experienced by patients without MS in that it generally comes on suddenly, impairs functioning, and prevents patients from attending to responsibilities.^1,5,6

Patients with MS may have primary or secondary causes of fatigue. Primary fatigue is believed to result from the disease itself. Although it is not well understood, one hypothesis suggests that it is caused by an immune-related process involving inflammation and immune-mediated neurodegeneration.⁷ Another theory relates it to impaired nerve conduction.⁸

Secondary fatigue is unrelated to MS itself, and it is often treatable. Common causes include anemia, infection, or insomnia (see Table 1).^9,10 These possibilities should be considered and ruled out in all patients with MS who complain of fatigue. A comprehensive history, exam, and evaluation performed by the clinician may help identify alternative reasons for fatigue.

Once any secondary causes have been addressed, primary fatigue should be evaluated and managed. One method for assessing the severity of fatigue and its impact on functional disability is to discuss it with the patient. The Fatigue Severity Scale can also be used as a measure; this self-assessment is quick, easy, and can be downloaded for free at www.saintalphonsus.org/documents/boise/sleep-Fatigue-Severity-Scale.pdf.¹¹Identifying potential triggers of fatigue can help clinicians develop appropriate interventions. Heat intolerance is common and can precipitate or contribute to fatigue; cooling equipment can be a helpful solution (see Figure). Urinary tract infections frequently cause fatigue and can exacerbate many symptoms of MS. Bladder dysfunction and subsequent nocturnal wakening may contribute to the problem. Psychological stress is another common trigger; managing it can reduce fatigue.^1,12 Screening for depression in patients with MS who complain of fatigue is imperative; if diagnosed, it must be addressed as the first line of treatment.¹