Myalgic encephalomyelitis / chronic fatigue syndrome

Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) (also known as chronic fatigue and immune dysfunction syndrome [CFIDS] or systemic exertion intolerance disease [SEID]) is a poorly understood but complex, debilitating and disabling condition. The lack of understanding of the pathophysiological basis of the disease and the absence of a universally accepted case definition or diagnostic test make defining, diagnosing and treating the condition difficult. For the same reasons, research is also challenging, and controversy exists around many aspects of ME/CFS.

ME/CFS appears to affect all age groups, with a peak incidence in adults between their twenties and forties, and is twice as common in femalesWorking Group of the Royal Australasian College of Physicians, 2002. Prevalence is estimated to be around 1%Lim, 2020Sandler, 2020; however, estimates vary with definitions and diagnostic methods used. Prognostication is difficult because of the heterogeneity of severity and duration of symptoms, and because patients with ME/CFS often have co-occurring conditions. Research has focused on treatment in the past but is now also endeavouring to understand the pathophysiological basis and identify biomarkers for ME/CFS.

Several sets of diagnostic criteria are used in clinical practice for ME/CFS, though none are universally accepted. The most common are the Canadian Consensus Criteria 2003 (CCC), The Centers for Disease Control and Prevention 1994 (CDC or Fukuda) criteria and the International Consensus Criteria 2011 (ICC). Although there are differences, they all include the following as important diagnostic criteria:

  • postexertional malaise—worsening of symptoms after physical or mental activity with a prolonged recovery period (usually 24 hours or more)
  • unrefreshing sleep or sleep disturbance
  • pain (eg headaches, muscle or joint pain)
  • cognitive changes (eg impaired memory or concentration)
  • disability—due to interference in cognitive and physical functioning. Many sufferers are unable to continue in employment.

ME/CFS should be considered in patients with unexplained, disabling fatigue lasting longer than 6 months in adults or 3 months in children and adolescents1Noor 2021National Institute for Health and Care Excellence 2021, with the hallmark feature of severe postexertional malaise. Symptoms are not improved with rest.

People with ME/CFS often have co-occurring conditions, including autonomic dysfunction (which can manifest as postural orthostatic tachycardia syndrome [POTS]), and fibromyalgiaLapp, 2019Nelson, 2019Noor, 2021Van Cauwenbergh, 2014. These conditions often have symptoms in common with ME/CFS. POTS is an abnormal orthostatic response resulting in symptoms in the upright position; the main patterns of presentation being postural tachycardia, orthostatic hypotension, reflex syncope and chronic isolated orthostatic intolerance. Fibromyalgia is an enigmatic condition of unclear pathophysiology characterised by widespread pain, fatigue, cognitive disturbance and multiple somatic symptoms. Other co-occurring conditions that have been described in people with ME/CFS include temporomandibular joint (TMJ) dysfunction, sensory hypersensitivities, migraines, allergies and intolerances, irritable bowel syndrome, sleep disorders, depression and endometriosisLapp, 2019Noor, 2021Robinson, 2016.

Although there is considerable debate surrounding management of ME/CFS, accepted approaches to care includeBateman, 2021Rowe, 2017:

  • acknowledgement of symptoms and the disability experienced by patients
  • regular follow-up and the establishment of a good therapeutic relationship with the general practitioner
  • setting appropriate expectations that take into consideration that ME/CFS is a chronic disease
  • advising patients about activity scheduling and pacing—see National Institute for Health and Care Excellence (NICE) advice on energy management
  • investigation and management of co-occurring conditions (eg fibromyalgia, postural orthostatic tachycardia syndrome [POTS]) and complications. Refer for autonomic studies if POTS is suspected, as drug therapy may be helpful for vasomotor instability
  • management of associated symptoms; for example, sleep disturbance can be managed with good sleep hygiene first and consideration of medications such as melatonin; see Insomnia in adults.

Exercise treatment for ME/CFS remains controversial. Incorporating physical activity and exercise for people with ME/CFS requires individualised assessment and advice; for information, see National Institute for Health and Care Excellence (NICE). NICE advises against offering patients an exercise program based on fixed incremental increases, such as graded exercise therapy (GET).

At the time of writing, there is insufficient evidence to support the use of any drug therapy for ME/CFS. Trials of some drugs initially showed promise, but follow-up trials have failed to show significant impact on disease outcomes.

For more advice on ME/CFS, see:

1 Timeframes may vary; for example, the UK National Institute for Health and Care Excellence (NICE) now recommends ME/CFS be considered after 3 months in patients of all ages with specific symptoms (see URL)Return