Chronic fatigue syndrome is a complex condition characterized by extreme, long-lasting exhaustion. This disorder affects many different body systems, and is often disabling. The main symptom of chronic fatigue syndrome (CFS) is tiredness that does not improve with rest and prevents you from carrying out normal daily activities. The term “chronic fatigue syndrome” was adopted in 1988, when researchers considered fatigue to be the major symptom. Today, physicians and patient groups often refer to this disorder as “chronic fatigue and immune-dysfunction syndrome” (CFIDS) to stress that it involves many other symptoms. Symptoms vary among patients, and can even change in the same person over time. Another name for CFS is myalgic encephalomyelitis.
The cause and cure of CFS are not known. Because it resembles other disorders and can be hard to recognize, doctors often miss it. CFS itself cannot be cured—thus, treatment focuses on relieving symptoms. The disorder may last for years. Although patients usually improve over time, most do not recover completely.
The people who first brought CFS to wide public notice in the 1980s were mostly affluent women. Thus, the illness was nicknamed “yuppie flu.” Since then, researchers have found that the disorder occurs in a wide range of social and economic classes and all races and ethnic groups.
Scientists do not know the exact prevalence of CFS because the disorder is so hard to define. The CDC estimates that up to half a million people in the US have the symptoms of CFS, but have not been diagnosed by a doctor. The chronic fatigue and immune dysfunction syndrome (CFIDS) Association of America (www.cfids.org), a patient support group, estimates the number to be about 800,000. They estimate that 90% of people with CFS have not been diagnosed and are not receiving care.
No one knows what causes CFS. Many physicians suspect that a variety of factors, including viruses and other germs, immune system disorders, brain abnormalities, and blood pressure disorders act together to trigger it. Scientists are studying several possible causes of CFS. In time they may discover a single cause, or find that several factors work together to produce the disorder. Because CFS is so hard to define, some physicians still believe that it is not a real disease, but is psychological in origin. However, the National Institute of Allergy and Infectious Diseases recognizes CFS as a serious illness, and the Centers for Disease Control and Prevention (CDC) have developed criteria to define it.
The following are some possible causes of CFS.
- Viruses and other germs. Many patients develop CFS after an illness resembling a viral infection, and researchers first believed that a virus was the cause. Epstein-Barr virus, which causes mononucleosis, was especially suspect. However, scientists have been unable to link CFS with any specific agent as the single cause. They are trying to discover whether any infectious organisms play a partial role in causing CFS.
- Immune system disorders. Some research has found that people with CFS have either overactive or underactive immune systems. However, these people do not have the diseases that are usually associated with overactive immune systems, such as lupus and rheumatoid arthritis, and they are not more likely to develop cancer or infections, as may people with depressed immune systems.
- Brain abnormalities. Studies show that people with CFS have abnormally low brain levels of a hormone called corticotropin, which helps in coping with stress. These people often report that they were under a great deal of stress just before the condition began. Scientists think that, due to the low hormone levels, their immune systems might overreact to stress, causing the symptoms of CFS. However, CFS patients who were given a replacement hormone that restored their hormone levels to normal did not get better. This result suggests that low hormone levels do not directly cause CFS.
- Blood pressure disorders. Some evidence suggests that CFS is related to a blood pressure disorder called neurally mediated hypotension (NMH), in which the brain signals the heart to slow down when you stand up. Your blood pressure falls, temporarily depriving your brain of oxygen, so that you become light-headed and may even faint. Many people with CFS have such symptoms when they stand for long periods, and scientists are testing whether the medicines given to people with NMH might also help those with CFS.
CFS can begin in different ways. Aside from fatigue, people with CFS experience a variety of other symptoms such as difficulty concentrating, sore throat, and muscle aches that either persist or come and go for more than six months. CFS often begins after you have had a cold, an intestinal virus, or bronchitis. Teenagers and young adults sometimes get it after a bout of mononucleosis. Other people find that CFS starts during a period of high stress. But for some people it comes on slowly, and there is no distinct, triggering event. You feel too tired to carry out your normal daily routine, and may be easily exhausted by any activity.
Early in the illness, the most common symptoms are sore throat, fever, muscle pain, and muscle weakness. At this point you may sleep a great deal, but as time passes you may instead have difficulty falling asleep, or may wake up too soon.
To receive a diagnosis of CFS, you must have severe fatigue that has lasted at least six months without any other explanation, and must have at least four of the following symptoms: poor short-term memory or difficulty concentrating; a sore throat; tender lymph nodes; muscle and joint aches; a new type of headache that you never had before; sleep that does not make you feel rested; and fatigue after exercise that lasts more than 24 hours Table 01. Among the many other symptoms patients experience are sensitivity to noise, light, food, medicines, and chemicals; difficulty sleeping; pain in the abdomen and digestive problems; mood swings; psychological problems such as anxiety, depression, and irritability; chronic cough; diarrhea; dizziness; dry eyes or mouth; earaches; irregular heartbeat; inability to tolerate alcohol; jaw pain; morning stiffness; nausea; night sweats; shortness of breath; weight loss; odd tingling sensations in the skin; and decreased interest in sex. It is important to remember that having any or even a combination of several of these disorders does not necessarily mean that you have CFS.
Table 1. Diagnosis and Symptoms of CFS
You must meet both of the following criteria to be diagnosed with CFS 1. You have severe fatigue that has lasted at least 6 months, and you have not been diagnosed with any other illness that could explain your symptoms. 2. You have had at least 4 of the following symptoms for 6 months, and these symptoms did not begin before the fatigue: ???Poor concentration or short-term memory ???Sore throat ???Tender lymph nodes ???Muscle and joint aches ???Headaches of a type you haven?t had before ???Unrestful sleep ???Fatigue that lasts over 24 hours after exercise Other common symptoms of CFS Sensitivity to noise, light, food, medicines, and chemicals Sleep problems Abdominal pain Digestive distress Mood swings, anxiety, depression, and irritability Chronic cough Diarrhea Dizziness Dry eyes or mouth Earaches Irregular heartbeat Intolerance to alcohol Jaw pain Morning stiffness Nausea Night sweats Shortness of breath Weight loss Odd tingling sensations in the skin Decreased interest in sex
The course of CFS varies from one patient to another. The symptoms of CFS can vary in an individual and from person to person. The illness involves many ups and downs. Many people reach a point early in their illness where the symptoms stop getting worse. After that, periods of feeling worse alternate with periods of feeling better.
Several illnesses have symptoms similar to those of CFS. A number of other illnesses involve symptoms similar to those of CFS; especially the profound fatigue. A diagnosis of one of these conditions rules out a diagnosis of CFS:
- fibromyalgia syndrome
- neurasthenia (chronic mental and physical weakness and fatigue)
- multiple chemical sensitivities (a syndrome of fluctuating symptoms that affects more than one body system and is provoked by exposure to low levels of chemicals, foods, or other agents in the environment)
- chronic mononucleosis
- sleep disorders such as narcolepsy
- major depression
- bipolar affective disorder
- eating disorders
- autoimmune disease such as lupus or multiple sclerosis
- some hormonal disorders
- certain infections
- chronic mononucleosis
- low thyroid function
- alcohol or drug abuse
- reactions to prescription medication.
Although anyone can get CFS, it is more common in women. CFS is two to four times more common in women than in men, and scientists do not know why. Adolescents can have CFS, but they get it less often than adults do. CFS has been reported in children under the age of 12.
No one knows for sure whether CFS is contagious. There is no scientific evidence showing that CFS can be given from one person to another. Most people who come in contact with people who have the illness do not develop it. Studies of groups of cases in the same locations did not reveal any infectious organism that could be transmitted from person to person.
There is no test for CFS. Diagnosis involves making sure you have no other disorder, and then deciding whether you meet the CDC criteria for CFS Table 01. To meet the CDC criteria, you must have severe fatigue that has lasted at least six months, and not have been diagnosed with any other illness that could explain your symptoms. In addition, you must have had certain symptoms for six months that did not begin before your fatigue began. Such symptoms include poor concentration or short-term memory, sore throat, and tender lymph nodes. Many symptoms of CFS mimic those of other diseases—as a result, CFS is hard to diagnose.
Your doctor will conduct a physical examination and a series of tests to rule out other conditions that may be causing your symptoms. Such tests include questions about your medical history and a mental status examination to test your concentration and memory. You will also have standard laboratory tests of your blood and urine. If the results suggest some other illness, you may be tested further to confirm the diagnosis.
If your doctor finds no other cause for the symptoms and you meet the CDC criteria, you may in fact have CFS.
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