Chronic Fatigue Syndrome
Chronic fatigue syndrome (CFS) is a debilitating and complex disorder characterized by profound fatigue that is not improved by bed rest and may be worsened by physical, emotional or mental stress. Patients report various nonspecific symptoms, including weakness, chemical sensitivities, allergies, poor immune function, muscle pain, impaired memory and/or mental concentration, insomnia, and post-exertional fatigue lasting more than 24 hours. In some cases, CFS can persist for years. The cause, or causes, of CFS have not been identified and no specific diagnostic tests are available. Moreover, since many illnesses have incapacitating fatigue as a symptom, care must be taken to exclude other known and often treatable conditions before a diagnosis of CFS is made.
Diagnostic Criteria for Chronic Fatigue Syndrome
Major Criteria:
1. new onset of fatigue causing 50% reduction in activity for at least six months
2. exclusion of other illnesses that can cause fatigue
Minor Criteria:
1. presence of eight of 11 symptoms, or
2. presence of six of 11 symptoms and two of three signs:
Symptoms
1. mild fever
2. recurrent sore throat
3. painful lymph nodes
4. muscle weakness
5. muscle pain
6. migratory joint pain
7. prolonged fatigue after exercise
8. recurrent headaches
9. neurological or psychological complaints, such as:
• depression
• excessive irritability
• forgetfulness
• sensitivity to bright light
• confusion
• inability to concentrate
10. sleep disturbances
11. sudden onset of symptom complex
Signs
1. low-grade fever
2. non-exudative pharyngitis (sore throat)
3. tender lymph nodes
Similar Medical Conditions
A number of illnesses have been described that have a similar spectrum of symptoms to CFS. These include fibromyalgia syndrome, myalgic encephalomyelitis, neurasthenia, multiple chemical sensitivities, and chronic mononucleosis. Although these illnesses may present with a primary symptom other than fatigue, chronic fatigue is commonly associated with all of them.
Other Conditions That May Cause Similar Symptoms
In addition, there are a large number of clinically defined, frequently treatable illnesses that can result in fatigue. Diagnosis of any of these conditions would exclude a definition of CFS unless the condition has been treated sufficiently and no longer explains the fatigue and other symptoms. These include hypothyroidism, sleep apnea and narcolepsy, major depressive disorders, chronic mononucleosis, bipolar affective disorders, schizophrenia, eating disorders, cancer, autoimmune disease, hormonal disorders*, subacute infections, obesity, alcohol or substance abuse, and reactions to prescribed medications.
Other Commonly Observed Symptoms in CFS
In addition to the eight primary defining symptoms of CFS, a number of other symptoms have been reported by some CFS patients. The frequencies of occurrence of these symptoms vary from 20% to 50% among CFS patients. They include abdominal pain, alcohol intolerance, bloating, chest pain, chronic cough, diarrhea, dizziness, dry eyes or mouth, earaches, irregular heartbeat, jaw pain, morning stiffness, nausea, night sweats, psychological problems (depression, irritability, anxiety, panic attacks), shortness of breath, skin sensations, tingling sensations, and weight loss.
Possible Causes of CFS
Due to weakened immunity, individuals with chronic fatigue have terrible problems with energy as well as reoccurring bouts with the flu, colds, sinusitis, and other immune problems. As with so many complex chronic illnesses, CFS may be aggravated by a wide variety of environmental and physiological challenges. Food allergies, environmental sensitivities (odors), heavy metal toxicity (mercury, aluminum, etc.), yeast overgrowth, parasites, and vitamin/mineral deficiencies can all contribute to CFS.
The cause, or causes, of CFS remain unknown despite a vigorous search. While a single cause for CFS may yet be identified, another possibility is that CFS represents a common endpoint of disease resulting from multiple precipitating causes. As such, it should not be assumed that any of the possible causes listed below has been formally excluded, or that these largely unrelated possible causes are mutually exclusive. Conditions that have been proposed to trigger the development of CFS include virus infection or other transient traumatic conditions, stress, and toxins.
General Theories
Unfortunately, some physicians believe that CFS is a component of a psychological disorder or a symptom of other problems, similar to anemia and high blood pressure. Indeed, no primary cause has been found that explains all cases of CFS. A number of experts believe that CFS is caused by a combination of conditions that overwhelm the person’s stress coping abilities. These conditions or triggers may include the following:
• Genetic factors.
• Brain abnormalities or inability of the self-regulating mechanisms.
• A hyper-reactive immune system.
• Viral, bacterial, fungal, mycoplasma or other infectious agents.
The majority of patients report some preceding moderate to serious physical (eg, a chronic viral infection) or emotional event (eg, episode of depression). Some experts theorize that such events alone or in combination coupled in people with certain neurological and genetic abnormalities may overwhelm the person’s ability regulate their own homeostatic self-regulating systems.
Dysfunction of the Hypothalamus-Pituitary-Adrenal Axis
Researchers investigating CFS are looking at the abnormalities in the brain system known as the hypothalamus-pituitary-adrenal axis. This system produces or regulates hormones and brain chemicals that control important functions, including sleep, response to stress, and depression. This is our self-regulating, homeostatic system. Stress Hormone
Deficiencies
A number of studies on CFS patients have observed deficiencies in cortisol levels, a stress hormone produced in the hypothalamus. Deficiencies may be the reason why CFS patients have an impaired and weaker response to psychological or physical stresses (such as infection or exercise).
Abnormalities in Neurotransmitters
Other research has reported that some patients with CFS have abnormally high levels of serotonin, a neurotransmitter (chemical messenger in the brain). Such elevated levels in the brain are associated with fatigue. Yet another study reported that deficiencies in dopamine and norepinephrine, other important neurotransmitters, may play a role in CFS.
Infections
Because most of the features of CFS resemble those of a lingering viral illness, many researchers have focused on the possibility that a virus or some other infectious agent causes the syndrome in some cases.