Myalgic Encephalomyelitis/Chronic Fatigue Syndrome¶
Chapter 461 | Part 13: Neurologic Disorders
KEY CLINICAL POINTS¶
- ME/CFS is a chronic, complex illness with multisystem manifestations, comparable in functional impairment to multiple sclerosis and rheumatoid arthritis.
- Diagnosis requires persistent fatigue >6 months, postexertional malaise (PEM), unrefreshing sleep, and cognitive impairment/orthostatic intolerance.
- Prevalence is 836,000–3.3 million in the U.S., with 80% of cases undiagnosed; 3–4 times more common in women.
- No approved treatments exist; management focuses on symptom relief, pacing, and avoiding overexertion.
- Differential diagnosis includes fibromyalgia, POTS, and chronic overlapping pain conditions.
1. DEFINITION & OVERVIEW¶
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic, complex illness with multisystem manifestations and long-term impact on functional impairment comparable to multiple sclerosis, rheumatoid arthritis, and congestive heart failure. The hallmark is persistent, unexplained fatigue resulting in significant impairment in daily functioning, with worsening symptoms following physical/mental exertion (postexertional malaise).
Table 461-1: 2015 IOM Diagnostic Criteria¶
| Criteria | Details |
|---|---|
| Substantial reduction in activity | Lasts >6 months, impairs occupational/educational/social/personal life |
| Fatigue | Profound, new/definite onset, not due to ongoing exertion, not alleviated by rest |
| Postexertional malaise (PEM) | Worsening of symptoms after physical/mental/emotional exertion that would not have caused problems pre-illness |
| Unrefreshing sleep | Persistent difficulty falling or staying asleep |
| Cognitive impairment/orthostatic intolerance | Thinking/concentration difficulties or orthostatic intolerance present |
1.1 Clinical Features¶
Persistent fatigue >6 months, postexertional malaise (PEM), unrefreshing sleep, cognitive impairment (brain fog), orthostatic intolerance, and additional symptoms including headache, sore throat, tender lymph nodes, muscle/joint aches, feverishness, sleep disturbances, psychiatric issues, and abdominal cramps.
1.2 Diagnostic Criteria¶
The 2015 Institute of Medicine (IOM) criteria require: (1) substantial reduction in pre-illness activity levels >6 months, (2) fatigue not alleviated by rest, (3) PEM, (4) unrefreshing sleep, and (5) cognitive impairment/orthostatic intolerance. These criteria are used for diagnosis.
2. EPIDEMIOLOGY¶
ME/CFS affects 836,000–3.3 million Americans, with 80% of cases undiagnosed. Prevalence is 3–4 times higher in women, peaking in 40–50 years of age. Socioeconomically disadvantaged groups show increased risk. Annual medical costs and lost income in the U.S. range from $18 to $51 billion.
2.1 Demographics¶
Highest prevalence in 40–50 years of age; affects all races/ethnicities. Children and adolescents may also be affected. Socioeconomically disadvantaged groups have increased risk.
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Etiology remains unclear, but infectious agents (e.g., Epstein-Barr virus, SARS-CoV-2) and immune dysfunction are implicated. Pathophysiology involves complex interactions of environmental, genetic, and behavioral factors affecting multiple homeostatic systems, including the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system, and intestinal microbiome.
3.1 Infectious Triggers¶
Postinfectious fatiguing illness resembling ME/CFS is associated with viral (e.g., Epstein-Barr, Ross River virus) and nonviral pathogens (e.g., Coxiella burnetti, Giardia). ~10% of infected individuals remain ill ≥ 6 months. SARS-CoV-2 infection is also linked to prolonged fatigue.
3.2 Immune and Neurological Abnormalities¶
Immune dysfunction includes antinuclear antibody elevations, reduced immunoglobulin subclasses, impaired lymphocyte proliferation, and altered cytokine production. Neurological findings include brain structure changes, autonomic dysfunction, and HPA axis abnormalities.
4. CLINICAL FEATURES¶
Symptoms include persistent fatigue, PEM, unrefreshing sleep, cognitive impairment, orthostatic intolerance, and additional manifestations such as headache, sore throat, tender lymph nodes, muscle/joint pain, feverishness, sleep disturbances, psychiatric issues, and abdominal cramps.
Table 461-2: Additional Symptoms¶
| Symptom | Description |
|---|---|
| Joint pain | Without swelling or redness |
| Muscle aches | |
| New headaches | |
| Tender lymph nodes | |
| Sensitivity to stimuli | Light, noise, smells |
| Sore throat | |
| Shortness of breath |
| Symptom | Description |
|---|---|
| Irregular heartbeat | |
| Alcohol intolerance | |
| Temperature regulation issues | Feeling feverish/chilled |
4.1 Additional Symptoms¶
Joint pain without swelling, muscle aches, new headaches, tender lymph nodes, sensory sensitivity, sore throat, shortness of breath, irregular heartbeat, alcohol intolerance, and temperature regulation difficulties.
5. DIFFERENTIAL DIAGNOSIS¶
Differential diagnosis includes fibromyalgia, chronic fatigue syndrome, postural orthostatic tachycardia syndrome (POTS), chronic overlapping pain conditions, sleep disorders, psychiatric conditions, and other systemic illnesses. Comorbid conditions include allergies, Sjögren’s syndrome, Ehlers-Danlos syndrome, mast cell activation syndrome, and dysautonomia.
Table 461-3: Comorbid Conditions¶
| Condition | Description |
|---|---|
| Chronic overlapping pain conditions | Fibromyalgia, chronic migraine, TMJ, IBS, endometriosis, vulvodynia, UCPPS |
| Postural orthostatic tachycardia syndrome (POTS) | |
| Allergies | |
| Sjögren’s syndrome | |
| Ehlers-Danlos syndrome | |
| Mast cell activation syndrome (MCAS) | |
| Dysautonomia | |
| Multiple chemical sensitivities |
5.1 Comorbid Conditions¶
Chronic overlapping pain conditions (fibromyalgia, chronic migraine, IBS), POTS, allergies, Sjögren’s syndrome, Ehlers-Danlos syndrome, mast cell activation syndrome, dysautonomia, and multiple chemical sensitivities.
6. INVESTIGATIONS & DIAGNOSIS¶
Diagnosis is based on patient-reported symptoms fitting the IOM criteria. Laboratory tests include CBC, ESR, electrolytes, renal/liver function, thyroid function, iron studies, celiac screening, and urinalysis. No single test confirms ME/CFS; investigations aim to exclude other conditions.
6.1 Laboratory Tests¶
Complete blood count, erythrocyte sedimentation rate, electrolytes, fasting glucose, renal function tests (BUN, GFR), liver function tests (bilirubin, ALT, AST, ALP, GGT, total protein, albumin/globulin ratio), C-reactive protein, thyroid function (TSH, free T4), iron studies (serum iron, TIBC, ferritin), celiac screening, and urinalysis.
7. MANAGEMENT & TREATMENT¶
No approved drugs exist. Management includes individualized plans addressing problematic symptoms, nonpharmacologic therapies (sleep hygiene, massage, acupuncture), low-dose medications, and avoiding narcotics. Pacing and activity management are critical to prevent PEM. Therapeutic trials of acyclovir, fludrocortisone, modafinil, and rituximab have shown limited benefit.
7.1 Nonpharmacologic Approaches¶
Sleep hygiene, massage, acupuncture, heat/cold packs, and activity pacing to avoid overexertion. Education on recognizing PEM and avoiding the 'push and crash' cycle is essential.
7.2 Pharmacologic Management¶
Medications should start at low doses with gradual titration. Avoid narcotics. Consider low-dose stimulants for sleep disorders. No FDA-approved treatments exist.
8. PROGNOSIS & COMPLICATIONS¶
Prognosis is variable; most patients experience chronic disability. Complications include deconditioning, reduced quality of life, and comorbid conditions. Early evaluation and supportive care can improve outcomes, but long-term recovery is uncommon.
9. SPECIAL CONSIDERATIONS¶
ME/CFS requires careful evaluation for comorbid conditions. Management must consider pregnancy, pediatric/elderly populations, and environmental factors. Patients are more sensitive to medications with fewer toxicities at lower doses.
10. KEY POINTS & CLINICAL PEARLS¶
- ME/CFS is a complex, multisystem illness with no definitive diagnostic test. 2. Diagnosis requires meeting IOM criteria, including PEM and unrefreshing sleep. 3. Management focuses on symptom relief, pacing, and avoiding overexertion. 4. No FDA-approved treatments exist; nonpharmacologic approaches are critical. 5. Early recognition and multidisciplinary care improve outcomes.