Chronic fatigue syndrome, the basics.
Introduction
Chronic fatigue syndrome, or CFS, is a debilitating
and complex disorder characterized by profound fatigue that is not improved
by bed rest and that may be worsened by physical or mental activity. Persons
with CFS most often function at a substantially lower level of activity
than they were capable of before the onset of illness. In addition to these
key defining characteristics, patients report various nonspecific symptoms,
including weakness, 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.
Definition
of CFS
A great deal of debate has surrounded the issue
of how best to define CFS. In an effort to resolve these issues, an international
panel of CFS research experts convened in 1994 to draft a definition of
CFS that would be useful both to researchers studying the illness and to
clinicians diagnosing it. In essence, in order to receive a diagnosis of
chronic fatigue syndrome, a patient must satisfy two criteria:
- Have severe chronic fatigue of six months or
longer duration with other known medical conditions excluded by clinical
diagnosis; and
- Concurrently have four or more of the following
symptoms: substantial impairment in short-term memory or concentration;
sore throat; tender lymph nodes; muscle pain; multi-joint pain without
swelling or redness; headaches of a new type, pattern or severity; unrefreshing
sleep; and post-exertional malaise lasting more than 24 hours.
The symptoms must have persisted or recurred during
six or more consecutive months of illness and must not have predated the
fatigue.
For more detailed information regarding the definition
of CFS, please go to the CDC's CFS
Definition page.
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.
Risk
Factors for CFS
- People of every age, gender, ethnicity and socioeconomic
group can have CFS.
- CFS affects women at four times the rate of men.
- Research indicates that CFS is most common in
people in their 40s and 50s.
- Although CFS is much less common in children
than in adults, children can develop the illness, particularly during the
teen years.
Defining
CFS Symptoms
- CFS is marked by extreme fatigue that has lasted
at least six months; is not the result of ongoing effort; is not substantially
relieved by rest; and causes a substantial reduction in daily activities.
- In addition to fatigue, CFS includes eight characteristic
symptoms:
- postexertional malaise (relapse of symptoms after
physical or mental exertion);
- unrefreshing sleep;
- substantial impairment in memory/concentration;
- muscle pain;
- pain in multiple joints;
- headaches of a new type, pattern or severity;
- sore throat; and
- tender neck or armpit lymph nodes.
- Symptoms and their consequences can be severe.
CFS can be as disabling as multiple sclerosis, lupus, rheumatoid arthritis,
congestive heart failure and similar chronic conditions. Symptom severity
varies from patient to patient and may vary over time for an individual
patient.
Diagnosis
of CFS
- There are no physical signs that identify CFS
- There are no diagnostic laboratory tests for
CFS.
- People who suffer the symptoms of CFS must be
carefully evaluated by a physician because many treatable medical and psychiatric
conditions are hard to distinguish from CFS. Common conditions that should
be ruled out through a careful medical history and appropriate testing
include mononucleosis, Lyme disease, thyroid conditions, diabetes, multiple
sclerosis, various cancers, depression and bipolar disorder.
- Research conducted by the Centers for Disease
Control and Prevention (CDC) indicates that less than 20% of CFS patients
in this country have been diagnosed.
Treatment
of CFS
- Since there is no known cure for CFS, treatment
is aimed at symptom relief and improved function. A combination of drug
and nondrug therapies is usually recommended.
- No single therapy exists that helps all CFS patients.
- Lifestyle changes, including prevention of overexertion,
reduced stress, dietary restrictions, gentle stretching and nutritional
supplementation, are frequently recommended in addition to drug therapies
used to treat sleep, pain and other specific symptoms.
- Carefully supervised physical therapy may also
be part of treatment for CFS. However, symptoms can be exacerbated by overly
ambitious physical activity. A very moderate approach to exercise and activity
management is recommended to avoid overactivity and to prevent deconditioning.
- Although health care professionals may hesitate
to give patients a diagnosis of CFS for various reasons, it’s important
to receive an appropriate and accurate diagnosis to guide treatment and
further evaluation.
- Delays in diagnosis and treatment are thought
to be associated with poorer long-term outcomes. For example, CDC’s research
has shown that those who have CFS for two years or less were more likely
to improve. It’s not known if early intervention is responsible for this
more favorable outcome; however, the longer a person is ill before diagnosis,
the more complicated the course of the illness appears to be.
Recovery
from CFS
- CFS affects each individual differently. Some
people with CFS remain homebound and others improve to the point that they
can resume work and other activities, even though they continue to experience
symptoms.
- Recovery rates for CFS are unclear. Improvement
rates varied from 8% to 63% in a 2005 review of published studies, with
a median of 40% of patients improving during follow-up. However, full recovery
from CFS may be rare, with an average of only 5% to 10% sustaining total
remission.
Possible
Causes of CFS
- Despite an intensive, nearly 20-year search,
the cause of CFS remains unknown. Many different infectious agents and
physiologic and psychological causes have been considered, and the search
continues.
- Much of the ongoing research into a cause has
centered on the roles of the immune, endocrine and nervous systems may
play in CFS. More recently, interactions among these factors are under
evaluation.
- Genetic and environmental factors may play a
role in developing and/or prolonging the illness, although more research
is needed to confirm this. CDC is applying cutting-edge genomic and proteomic
tools to understand the origins and pathogenesis of CFS.
- CFS is not caused by depression, although the
two illnesses often coexist, and many patients with CFS have no psychiatric
disorder.
* Not all hormonal aberrations necessarily exclude
a diagnosis of CFS. See "Hypothalamic-Pituitary Adrenal (HPA) Axis"
on the Possible Causes of
CFS page.
Facts
and information for this page compliments of Centers
for Disease Control and Prevention Atlanta, Georgia.
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