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Chronic Fatigue Syndrome

Discover the surprising facts and effective strategies to overcome Chronic Fatigue Syndrome, and regain your energy and vitality once and for all.

USMLE Guide: Chronic Fatigue Syndrome


Chronic Fatigue Syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a complex disorder characterized by severe, unexplained fatigue that is not relieved by rest and is accompanied by a range of other symptoms. This guide aims to provide a comprehensive overview of the key aspects related to CFS for the USMLE exam.


  • CFS predominantly affects individuals in their 30s to 50s, with a higher prevalence in women.
  • It is estimated that between 0.2% to 2.5% of the general population worldwide may be affected by CFS.
  • The exact cause of CFS is unknown, with various factors such as infections, immune dysfunction, and genetic predisposition being implicated.

Clinical Presentation

  • The hallmark symptom of CFS is persistent and disabling fatigue that lasts for at least six months and is not improved by rest.
  • Other common symptoms include unrefreshing sleep, cognitive impairment (referred to as "brain fog"), muscle pain, joint pain, sore throat, and tender lymph nodes.
  • Symptoms must significantly impair daily functioning and be present for at least six months for a diagnosis of CFS.

Diagnostic Criteria

  • CFS is a diagnosis of exclusion, as there are no specific laboratory tests or imaging studies available to confirm it.
  • The diagnosis is based on the following criteria:
    1. Severe chronic fatigue for at least six months that is not alleviated by rest.
    2. Concurrently experiencing at least four of the following symptoms: impaired memory or concentration, sore throat, tender lymph nodes, muscle pain, multi-joint pain, headaches, unrefreshing sleep, and post-exertional malaise lasting more than 24 hours.
    3. Other medical conditions that could explain the symptoms must be ruled out.


  • There is no definitive cure for CFS, so management is focused on symptom relief and improving quality of life.
  • A multidisciplinary approach involving healthcare professionals from various specialties is often necessary.
  • Treatment modalities include:
    • Cognitive-behavioral therapy (CBT): Helps patients cope with their symptoms and develop strategies to manage their fatigue.
    • Graded exercise therapy (GET): Gradual and individualized exercise programs to improve physical function without exacerbating symptoms.
    • Symptomatic pharmacotherapy: Medications may be prescribed to manage pain, sleep disturbances, and other specific symptoms.
    • Patient education and support: Providing patients with accurate information, support groups, and resources can significantly improve their well-being.


  • The prognosis of CFS varies among individuals, with some experiencing significant improvement over time, while others may have a chronic and relapsing course.
  • Early intervention and a comprehensive treatment approach can positively influence the prognosis.
  • It is essential to address the impact of CFS on patients' overall well-being, including mental health, social support, and occupational aspects.


Chronic Fatigue Syndrome is a debilitating condition characterized by persistent fatigue and a range of associated symptoms. Diagnosis is based on excluding other potential causes and fulfilling specific criteria. Management focuses on symptom relief, rehabilitation, and support. Understanding the epidemiology, clinical presentation, diagnostic criteria, management, and prognosis of CFS is crucial for healthcare professionals preparing for the USMLE exam.

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