Chronic Fatigue Syndrome

Description

Diagnosis

It is very difficult to diagnose chronic fatigue syndrome. For one thing, even experts do not have a clear idea of what fatigue actually is or what mechanisms in the brain or nervous system are responsible for it. The best diagnostic approach is to determine if the patient matches the criteria for CFS and to rule out any other possible causes of symptoms.

Personal and Medical History

A physician should first take a careful personal and family medical history, which may include a psychological profile, as well as perform a thorough physical examination. Patients should be prepared to answer certain questions:

• When did the fatigue first begin?
• Does anything make it worse or better?
• Is it better at certain times of the day?
• Does physical activity make it worse?
• Are there any other symptoms?
• Has anyone else in the family ever complained of fatigue?
• Is your personal and professional life stressful?

The physician may also ask about any changes in weight or request a patient to monitor morning and afternoon body temperatures. The patient should report any drugs being taken, including vitamins and over-the-counter or herbal medications.

Laboratory Tests

Inexpensive tests, including thyroid and liver function tests, blood count, and sedimentation rate, are typically recommended to rule out specific conditions causing persistent fatigue. No blood, urine, or other laboratory test can specifically diagnose CFS. If any are abnormal, they are not useful for diagnosing chronic fatigue syndrome specifically and the physician should look for other causes of these abnormalities.

Exercise Tests

Some experts recommend exercise tests. In general, CFS patients cannot exercise to the capacity of their peers. A 2003 study found that exercise capacity varied widely among patients who met the AMA guidelines for chronic fatigue syndrome. Exercise tests then may help determine the severity of the condition. Some studies suggest that CFS patients have higher than normal ratings of perceived exertion (RPE), which describes the effort, a person attributes to exercise. Scores range from 0 (falling asleep) to 20 (maximum all-out exertion). In a 2003 study, however, the perceptions of how hard they were exercising did not differ between CFS patients and their nonCFS peer.

Tilt Test for Neurally Mediated Hypotension

Simply measuring blood pressure will not identify CFS patients whose condition might be caused by neurally mediated hypotension (an abnormal drop in blood pressure). A tilt test, whereby an individual lies on a table tilted upright at a 70-degree angle for a prolonged period, may confirm CFS caused by neurally mediated hypotension if the patient feels lightheaded, sick, and faint after several minutes.

Identifying Conditions That Rule Out Chronic Fatigue Syndrome

Among the many other common conditions that can lead to feelings of temporary exhaustion are the following:

• Depression.
• Infections.
• Pregnancy.
• Extreme exercise.
• Excessive stress.

In most of these cases, fatigue can be relieved with adequate rest. It is important to note that longstanding fatigue can be the harbinger of a serious medical or psychological problem. A number of more serious conditions may cause persistent fatigue and other symptoms of CFS and should be ruled out. Patients and physicians should not overlook these diseases, even if they have been previously treated, because they may not have completely resolved or may cause residual fatigue. Physicians can usually distinguish these diseases from CFS after a clinical evaluation and laboratory testing.

Infectious Mononucleosis and Epstein-Barr Virus. Infectious mononucleosis is marked by fatigue and swollen glands. It primarily affects adolescents and young adults. Some patients may have lingering fatigue that lasts for many months and blood tests that indicate a persistence of the Epstein-Barr virus (EBV), which causes mononucleosis. At one time, some experts believed that EBV would turn out to be the cause of chronic fatigue syndrome. However, many healthy persons without CFS have the same signs of low-level EBV infection, and, conversely, many patients with CFS show no signs of EBV infection. Because of these and other findings, researchers generally do not believe there is any direct link between Epstein-Barr virus infection and CFS.

Autoimmune Diseases. Some diseases, including systemic lupus erythematosus, multiple sclerosis, and rheumatoid arthritis, are caused by autoimmunity, a condition in which the person's immune system attacks the body's own tissues. The early symptoms of these conditions may mimic some of those that appear in CFS, such as muscle and joint pain and fatigue. These diseases, like CFS, also occur more often in women than in men. Autoimmune diseases evolve slowly, and even if a diagnosis of chronic fatigue syndrome is considered, physicians should keep track of any changes in symptoms over time in order to rule out these serious illnesses. It should also be noted that some experts are concerned that many patients who actually have CFS will be mistakenly diagnosed with these diseases, particularly multiple sclerosis, and subjected to unnecessary treatments.

Post-Lyme Syndrome. A delayed response or recurrence of previously treated Lyme disease (called post-Lyme syndrome) may be mistaken for chronic fatigue syndrome in people who live in areas where there are outbreaks. Although the two disorders are similar, one study found that CFS patients reported more flu-like syndromes and those with post-Lyme disease performed significantly worse on tests of mental functioning and motor control. If CFS patients are mistakenly diagnosed and treated for Lyme disease, they may take prolonged courses of antibiotics that can have serious side effects, ultimately doing more harm than good.

Psychosis and Severe Mental Disorders. The Centers for Disease Control (CDC), which set up the definitions in the US for research in chronic fatigue syndrome, recognize depression as one of the symptoms of CFS. However, the CDC rules out chronic fatigue syndrome as a diagnosis for anyone with a history of major depression or other severe psychiatric disorders, including bipolar disorder and schizophrenia. Depression or anxiety not associated with a psychosis or severe mental illness does not rule out CFS.

Symptoms of major depression include the following:

• A depressed mood every day.
• Significant weight gain or loss (10% or more of an individual's typical body weight).
• Insomnia or excessive sleeping.
• Restlessness or a sense of being slowed down.
• Low energy every day.
• Worthless or inappropriately guilty feelings.
• An inability to concentrate or to make decisions.
• Suicidal thoughts.

Major depression is likely to be the responsible condition in the presence of several of these symptoms and if there are no physical symptoms (such as sore throat, aches and pains, or fever). And the longer fatigue has continued without such physical symptoms, the more likely that the diagnosis is depression.

Of note, a persistent form of minor depression called dysthymia may be more difficult to differentiate from CFS and may actually account for a subset of CFS cases. Dysthymia is characterized by many of the same symptoms that occur in major depression but they are less intense and last much longer, at least two years. The symptoms of dysthymia have been described as a "veil of sadness" that covers most activities.

A 2001 study suggested that patients with depression and those with CFS differ in how they perceive their illnesses:

• Patients with depression had significantly lower self-esteem, more thought distortions (e.g., focusing on the negative, personalizing their situations), and believed their conditions stemmed from psychological factors.
• CFS patients, even those with concurrent depression or dysthymia, tended to identify medical causes as the source of their problems and to focus on physical symptoms.

A number of patients who are diagnosed with CFS report having felt depressed before the onset of chronic fatigue. Many other CFS patients, however, felt alert and mentally sound before the onset of CFS symptoms. Many of these previously healthy patients become depressed and anxious because they feel so exhausted all the time. CFS may also lead to highly stressful socioeconomic situations, such as social isolation and poverty, that can contribute to and even cause emotional disorders in susceptible individuals, which in turn can worsen CFS.

Sleep Disturbances. Certain sleep disorders may cause persistent fatigue and be confused with CFS:

• Sleep apnea is a common disorder that can cause daytime fatigue without the patient being aware of the problem. This is actually a breathing disorder often marked by loud snoring and thrashing in bed. A person may not realize the problem exists unless it is brought to his or her attention by a sleeping partner or observer.
• Narcolepsy is a peculiar and rare disorder in which a person suddenly falls asleep without any previous signs of fatigue.
• Other sleep disorders that cause daytime fatigue include insomnia and restless legs syndrome.

Conditions that Cause Joint Pain, Muscle Aches, or Both. A number of illnesses cause one or more of CFS symptoms including arthritic symptoms, fever, and fatigue.

Severe Obesity. People who are severely obese often have symptoms of chronic fatigue because of the stress imposed by the weight. People who are obese are also at particular risk for sleep apnea, which can confuse the diagnosis.

Other Medical Conditions that Usually Rule Out CFS. Many diseases, both benign and serious, can fully explain prolonged or chronic fatigue, including hepatitis, anemia, hemochromatosis (a hereditary disease caused by iron overload) infections, various forms of cancer, neuromuscular diseases (such as myasthenia gravis), hypothyroidism, and diabetes.

Drugs and Alcohol. Fatigue is a side effect of many prescription and over-the-counter medications, such as antihistamines. In addition, dependency on or abuse of alcohol or illicit drugs may manifest as chronic fatigue. Medications should be considered as a possible cause of fatigue if an individual has recently started, stopped, or changed medicines. Withdrawal from caffeine can produce depression, fatigue, and headache.

Conditions That Do Not Rule Out Chronic Fatigue Syndrome

Many diagnosable conditions cause symptoms similar to CFS but they can overlap and so their presence does not necessarily rule CFS out as a co-disorder. In fact, CFS patients appear to be at high risk for developing depression and additional health problems, particularly those with similar symptoms (e.g., fibromyalgia, irritable bowel syndrome, chronic pelvic pain, chemical sensitivities, and temporomandibular disorder).

Some tests may be positive for one or more of these diseases. However, if the results are ambiguous or weak or if they have been treated successfully, CFS should not be ruled out if the patient still also meets the criteria for it.