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Chronic Fatigue Syndrome

Chronic Fatigue Syndrome

Chronic Fatigue Syndrome

General Information

Chronic fatigue syndrome, or CFS, is a devastating and complex disorder. People with CFS have overwhelming fatigue and a host of other symptoms that are not improved by bed rest and that can get worse after physical activity or mental exertion. They often function at a substantially lower level of activity than they were capable of before they became ill.

Besides severe fatigue, other symptoms include muscle pain, impaired memory or mental concentration, insomnia, and post-exertion malaise lasting more than 24 hours. In some cases, CFS can persist for years.

Researchers have not yet identified what causes CFS, and there are no tests to diagnose CFS. Moreover, because many illnesses have fatigue as a symptom, doctors need to take care to rule out other conditions, which may be treatable.

Case Definition

There are several case definitions for CFS and all require fatigue as one of the symptoms. CDC uses the 1994 CFS case definition, which requires meeting three criteria:

  1. The individual has had severe chronic fatigue for 6 or more consecutive months and the fatigue is not due to ongoing exertion or other medical conditions associated with fatigue (these other conditions need to be ruled out by a doctor after diagnostic tests have been conducted)
  2. The fatigue significantly interferes with daily activities and work
  3. The individual concurrently has 4 or more of the following 8 symptoms:
    • post-exertion malaise lasting more than 24 hours
    • unrefreshing sleep
    • significant impairment of short-term memory or concentration
    • muscle pain
    • pain in the joints without swelling or redness
    • headaches of a new type, pattern, or severity
    • tender lymph nodes in the neck or armpit
    • a sore throat that is frequent or recurring

These symptoms should have persisted or recurred during 6 or more consecutive months of illness, and they cannot have first appeared before the fatigue.

Symptoms

Chronic fatigue syndrome can be misdiagnosed or overlooked because its symptoms are similar to so many other illnesses. Fatigue, for instance, can be a symptom for hundreds of illnesses. Looking closer at the nature of the symptoms though, can help a doctor distinguish CFS from other illnesses.

Primary Symptoms

As the name chronic fatigue syndrome suggests, fatigue is one part of this illness. With CFS, however, the fatigue is accompanied by other symptoms. In addition, the fatigue is not the kind you might feel after a particularly busy day or week, after a sleepless night, or after a single stressful event. It’s a severe, incapacitating fatigue that isn’t improved by bed rest and that is often worsened by physical activity or mental exertion. It’s an all-encompassing fatigue that can dramatically reduce a person’s activity level and stamina.

People with CFS function at a significantly lower level of activity than they were capable of before they became ill. The illness results in a substantial reduction in work-related, personal, social, and educational activities.

The fatigue of CFS is accompanied by characteristic illness symptoms lasting at least 6 months. These symptoms include:

  • increased malaise (extreme exhaustion and sickness) following physical activity or mental exertion
  • problems with sleep
  • difficulties with memory and concentration
  • persistent muscle pain
  • joint pain (without redness or swelling)
  • headache
  • tender lymph nodes in the neck or armpit
  • sore throat

Other Symptoms

The symptoms listed above are the symptoms used to diagnose CFS. However, many CFS patients and patients in general may experience other symptoms, including:

  • brain fog (feeling like you’re in a mental fog)
  • difficulty maintaining an upright position, dizziness, balance problems or fainting
  • allergies or sensitivities to foods, odors, chemicals, medications, or noise
  • irritable bowel
  • chills and night sweats
  • visual disturbances (sensitivity to light, blurring, eye pain)
  • depression or mood problems (irritability, mood swings, anxiety, panic attacks)

It’s important to tell your health care professional if you’re experiencing any of these symptoms. You might have CFS, or you might have another treatable disorder. Only a health care professional can diagnose CFS.

What’s the Clinical Course of CFS?

The severity of CFS varies from patient to patient. Some people can maintain fairly active lives. For most patients, however, CFS significantly limits their work, school, and family activities for periods of time.

While symptoms vary from person to person in number, type, and severity, all CFS patients are limited in what they can do to some degree. CDC studies show that CFS can be as disabling as multiple sclerosis, lupus, rheumatoid arthritis, heart disease, end-stage renal disease, chronic obstructive pulmonary disease (COPD), and similar chronic conditions.

CFS often affects patients in cycles: Patients will have periods of illness followed by periods of relative well-being. For some patients, symptoms may diminish or even go into complete remission; however, they often recur at a later point in time. This pattern of remission and relapse makes CFS especially hard for patients to manage. Patients who are in remission may be tempted to overdo activities when they’re feeling better, but this overexertion may actually contribute to a relapse.

The percentage of CFS patients who recover is unknown, but there is some evidence to indicate that patients benefit when accompanying conditions are identified and treated and when symptoms are managed. High-quality health care is important.

CFS Case Definition

Overview

Chronic fatigue syndrome (CFS) is a debilitating and complex disorder characterized by intense fatigue that is not improved by bed rest and that may be worsened by physical activity or mental exertion. People with CFS often function at a substantially lower level of activity than they were capable of before they became ill. The cause or causes of CFS have not been identified, and no specific diagnostic tests are available. Therefore, a CFS diagnosis requires three criteria:

  1. The individual has had severe chronic fatigue for 6 or more consecutive months that is not due to ongoing exertion or other medical conditions associated with fatigue (these other conditions need to be ruled out by a doctor after diagnostic tests have been conducted)
  2. The fatigue significantly interferes with daily activities and work
  3. The individual concurrently has 4 or more of the following 8 symptoms:
    • post-exertion malaise lasting more than 24 hours
    • unrefreshing sleep
    • significant impairment of short-term memory or concentration
    • muscle pain
    • pain in the joints without swelling or redness
    • headaches of a new type, pattern, or severity
    • tender lymph nodes in the neck or armpit
    • a sore throat that is frequent or recurring

These symptoms should have persisted or recurred during 6 or more consecutive months of illness and they cannot have first appeared before the fatigue.

Other Symptoms Accompanying CFS

While the following symptoms are not part of the CFS case definition and do not contribute to the diagnosis of CFS, some patients may also have these additional symptoms:

  • 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, such as tingling
  • weight loss

Causes

Despite a vigorous search, scientists have not yet identified what causes CFS. While a single cause for CFS may yet be identified, another possibility is that CFS has multiple causes. Conditions that have been studied to determine if they cause or trigger the development of CFS include infections, immune disorders, stress, trauma, and toxins.

Infection

Various types of infections have been studied to determine if they might cause or trigger CFS:

  • Epstein-Barr virus infection, also known as mononucleosis
  • Human herpesvirus 6 infection, a virus that can cause problems for people with impaired immune systems, such as AIDS patients or organ transplant recipients taking immune-suppressant drugs
  • Enterovirus infection, a type of virus that enters through the gastrointestinal track and can have no symptoms, mild flu-like symptoms, or rarely severe and even deadly symptoms
  • Rubella, a viral infection also known as German measles
  • Candida albicans, a fungus that causes yeast infections
  • Bornaviruses, which cause borna disease, an infectious neurological syndrome
  • Mycoplasma, a cause of atypical pneumonia
  • Ross River virus, which causes Ross River Fever, a mosquito-borne tropical disease
  • Coxiella burnetti, the agent that causes Q fever
  • Human retrovirus infection, such as HIV, the virus that causes AIDS, or xenotropic murine leukemia virus-related virus (XMRV), a gammaretrovirus

Could One Type of Infection Lead to CFS?

Researchers from around the world have studied if a single type of infection might be the cause of CFS, analyzed the data, and not yet found any association between CFS and infection. Researchers are still analyzing samples from CFS patients using the latest molecular methods to search for previously unknown infections (pathogen discovery). To date, these studies suggest that no one infection or pathogen causes CFS and that the illness may be triggered by a variety of illnesses or conditions. In fact, infection with Epstein-Barr virus, Ross River virus, and Coxiella burnetti will lead to a post-infective condition that meets the criteria for CFS in approximately 10-12% of cases. People who had severe symptoms when they became infected were more likely than those with mild symptoms to later develop CFS symptoms. The possibility remains that there may be a variety of different ways in which patients can develop CFS.

Immune System and Allergies

Studies have looked to see if changes in a person’s immune system might lead to CFS. The findings have been mixed. Similarities in symptoms from immune responses to infection and CFS lead to hypotheses that CFS may be caused by stress or a viral infection, which may lead to the chronic production of cytokines and then to CFS.

Antibodies against normal parts of the body (auto-antibodies) and immune complexes have been seen in some CFS patients. However, no associated tissue damage typical of autoimmune disease has been described in CFS patients. The opportunistic infections or increased risk for cancer observed in persons with immunodeficiency diseases or in immunosuppressed individuals is also not observed in CFS.

T-cell activation markers have been reported to be different between groups of CFS patients and healthy persons, but not all investigators have consistently observed these differences.

Allergic diseases and secondary illnesses such as sinusitis could be one predisposing factor for CFS, but not all CFS patients have allergies. Many patients do, however, report intolerances for certain substances that may be found in foods or over-the-counter medications, such as alcohol.

Hypothalamic-Pituitary Adrenal (HPA) Axis

The central nervous system plays an important role in CFS. Physical or emotional stress, which is commonly reported as a pre-onset condition in CFS patients, alters the activity of the hypothalamic-pituitary-adrenal axis, or HPA axis, leading to altered release of corticotrophin-releasing hormone (CRH), cortisol, and other hormones. These hormones can influence the immune system and many other body systems.

Some CFS patients produce lower levels of cortisol than do healthy people. Similar hormonal abnormalities have also been observed among CFS patients and in persons with related disorders like fibromyalgia. Cortisol suppresses inflammation and cellular immune activation, and reduced levels might relax constraints on inflammatory processes and immune cell activation. Even though CFS patients had lower levels of cortisol than healthy individuals, their cortisol levels were still within the acceptable range of what is considered normal. Therefore, doctors cannot use cortisol levels as a way to diagnose CFS.

Abnormally Low Blood Pressure and Lightheadedness (Neurally Mediated Hypotension)

Disturbances in the autonomic regulation of blood pressure and pulse have been found in CFS patients. This problem with maintaining blood pressure can be diagnosed by using tilt table testing, which involves laying the patient horizontally on a table and then tilting the table upright to 70 degrees for 45 minutes while monitoring blood pressure and heart rate. Persons with neurally mediated hypotension (NMH) or postural orthostatic tachycardia (POTS) will develop lower blood pressure under these conditions, as well as other characteristic symptoms, such as lightheadedness, visual dimming, or a slow response to verbal stimuli. Others may develop an unusually rapid heart rate also associated with the symptoms of the syndrome. Many CFS patients experience lightheadedness or worsened fatigue when they stand for prolonged periods or when in warm places, such as in a hot shower — all circumstances that are known to trigger NMH or POTS.

NMH and/or POTS share some of the symptoms of CFS. They should be considered in a CFS patients whose symptoms are worsened with changes in position, after eating, following unusual amounts of or inadequate fluid intake, or increases in activity. Not all patients with CFS will have these conditions, however.

Nutritional Deficiency

There is no published scientific evidence that CFS is caused by a nutritional deficiency. While evidence is currently lacking for nutritional defects in CFS patients, it should also be added that a balanced diet can be favorable to better health in general and would be expected to benefit a person with any chronic illness.

Diagnosis

Diagnostic Challenges

For doctors, diagnosing chronic fatigue syndrome (CFS) can be complicated by a number of factors:

  1. There’s no lab test or biomarker for CFS.
  2. Fatigue and other symptoms of CFS are common to many illnesses.
  3. For some CFS patients, it may not be obvious to doctors that they are ill.
  4. The illness has a pattern of remission and relapse.
  5. Symptoms vary from person to person in type, number, and severity.

These factors have contributed to a low diagnosis rate. Of the one to four million Americans who have CFS, less than 20% have been diagnosed.

Exams and Screening Tests for CFS

Because there is no blood test, brain scan, or other lab test to diagnose CFS, the doctor should first rule out other possible causes.

If a patient has had 6 or more consecutive months of severe fatigue that is reported to be unrelieved by sufficient bed rest and that is accompanied by nonspecific symptoms, including flu-like symptoms, generalized pain, and memory problems, the doctor should consider the possibility that the patient may have CFS. Further exams and tests are needed before a diagnosis can be made:

  • A detailed medical history will be needed and should include a review of medications that could be causing the fatigue and symptoms
  • A thorough physical and mental status examination will also be needed
  • A battery of laboratory screening tests will be needed to help identify or rule out other possible causes of the symptoms that could be treated
  • The doctor may also order additional tests to follow up on results of the initial screening tests

A CFS diagnosis requires that the patient has been fatigued for 6 months or more and has 4 of the 8 symptoms for CFS for 6 months or more. If, however, the patient has been fatigued for 6 months or more but does not have four of the eight symptoms, the diagnosis may be idiopathic fatigue.

The complete process for diagnosing CFS can be found here.

For Patients Who Think They Might Have CFS

It can be difficult to talk to your doctor or other health care professional about the possibility that you may have CFS. A variety of health care professionals, including doctors, nurse practitioners, and physician assistants, can diagnose CFS and help develop an individualized treatment plan for you.

CFS can resemble many other illnesses, including mononucleosis, Lyme disease, lupus, multiple sclerosis, fibromyalgia, primary sleep disorders, and major depressive disorder. Medications can also cause side effects that mimic the symptoms of CFS.

Because CFS can resemble many other disorders, it’s important not to self-diagnose CFS. It’s not uncommon for people to mistakenly assume they have chronic fatigue syndrome when they have another illness that will respond to treatment. If you have CFS symptoms, consult a health care professional to determine if any other conditions are responsible for your symptoms. A CFS diagnosis can be made only after other conditions have been excluded.

It’s also important not to delay seeking a diagnosis and medical care. CDC research suggests that early diagnosis and treatment of CFS can increase the likelihood of improvement.

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