Chronic fatigue syndrome

Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME) is a multi-system illness characterised by overwhelming fatigue

and functional impairment.

Pathophysiology

CFS is not just a syndrome of fatigue, and it is not a psychiatric condition. The terms chronic fatigue syndrome may be overly simplistic, but the term myalgic encepahlomyelitis is also not entirely accurate as there is limited evidence to support the idea that it is inflammation of the brain that causes the disease.

Unfortunately, the pathophysiology is not entirely clear.

• 65-90% of CFS patients initially have an acute viral illness, it may be related to post-acute viral status.
• The deconditioning hypothesis says that bed rest and inactivity has reversible effects of deconditioning (reduced oxygen uptake during exercise testing, VO2 max <85% of predicted maximum) and that these can be reversed through exercise. Patients have reduced physical tolerance and feel extremely exhausted after minimal physical effort.
• There is a cognitive aspect as there are deficits in attention, memory and reaction time as well as autonomic dysfunction.
• Mitochondrial dysfunction and immune dysregulation may also play a role.

Ultimately, it is a diagnosis of exclusion if there are >3 months of symptoms not explained by another condition.

⚠️ Risk factors

• Female sex - 2-3 times more common in women than men.
• EBV infection - 13% of adolescents who have had infectious mononucleosis develop CFS after 6 months.
• COVID-19 infection - post-COVID syndrome may be related to CFS but research needs to prove/disprove this.

😷 Presentation

The major symptom is a persistent, disabling fatigue. This fatigue is not alleviated by sleep or rest. It was previously required that the fatigue be present for >6 months but NICE has reduced this timeframe to 3 months in their 2021 guidelines on CFS. The fatigue may take a relapsing remitting course, with the remissions only being mild but not a return to the normal baseline level (>50% fatigue).

• Physical and mental intolerance/post-exertional fatigue - minor levels of physical activity are not well tolerated. Even mental exertion makes symptoms worse.
• Attention impairment
• Cognitive dysfunction - “brain fog”, inability to concentrate, short-term amnesia. Patients may report difficulty finding words or numbers.
• Sore throat
• Malaise and arthralgia
• Headaches
• Unrefreshing sleep - insomnia, hypersomina, disturbed sleep-wake cycle.
• Lymphadenopathy - tender axillary, cervical or subauricular lymph nodes.

🔍 Investigations

It is a diagnosis of exclusion, there is currently no diagnostic test and it needs to be recognised based on clinical presentation and ruling out other causes.

🧰 Management

🥇 There is no cure for CFS and its management relies solely on symptom management.

🥇 Patients should be referred to specialist CFS service if they meet the diagnostic criteria and have had symptoms for >3 months.

We should also advise patients on:

1. Exercise - patients should not undertake exercise that is not overseen by the specialist CFS team. They should feel as if they are ready to progress and shouldn’t push themselves.
2. Rest and sleep - explain the importance of rest periods incorporation into their daily routine and the importance of good sleeping habits.
3. Orthostatic intolerance - patients with CFS may have orthostatic intolerances and may be prescribed medication if need be.
4. Pain - headaches and neuropathic pain is common and may be treated accordingly.
5. Medication - there is no cure so it should be explained that there is no medicine to fix CFS. Medication may aid symptom management

CBT may also be used as a supportive therapy, but once again it is not a curative treatment.