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Chronic fatigue syndrome

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Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), post-viral fatigue syndrome (PVFS), and various other names, is a syndrome (or group of syndromes) of unknown and possibly multiple etiologies, affecting the central nervous system (CNS), immune, and many other systems and organs. There is no simple diagnostic test; CFS is a diagnosis of exclusion, although recent research indicates biological hallmarks of the syndrome, and a diagnostic test is predicted soon. Most definitions (other than the 1991 UK Oxford criteria) require a number of features, the most common being severe mental and physical exhaustion or depletion which is "unrelieved by rest" (according to the 1994 Fukuda definition), and is often worsened by even trivial exertion (controversially, the Oxford and Fukuda criteria require this to be optional only). CFS occurs more often, but not exclusively, in women, possibly due to immunological factors (women are overall more susceptible to similar disorders). CFS is most easily diagnosed when formerly active adults become ill, but it has been reported in persons of all ages, including young children and particularly teenagers.

Patients with this diagnosis commonly report many other symptoms which are far more onerous than these research diagnostic criteria; including pain, muscle weakness, loss of brain function, hypersensitivity, orthostatic intolerance, digestive disturbances, depression, immune system weakness, and cardiac and respiratory problems. These symptoms, like the syndrome's hallmark 'fatigue', range from mild to life-threateningly severe. Some cases resolve or improve over time, and where available, treatments bring a degree of improvement to many others. Most diagnostic criteria insist that these symptoms must be present for at least six months, and all insist on there being no other cause for the fatigue: i.e. the fatigue must be idiopathic, not caused by conditions such as radiation treatment for cancer, or diabetes. CFS remains a controversial diagnosis, and even its terminology and classification are controversial.

Contents

History

Originally studied since the late 1930s as an immunological neurological disorder under the medical term "myalgic encephalomyelitis" (ME), CFS has been classified by the World Health Organization (WHO) as a disease of the central nervous system since 1969. In 1992 and early 1993 the terms "post-viral fatigue syndrome" (PVFS) and "chronic fatigue syndrome" (CFS) were added to ME under the exclusive ICD-10 designation of G93.3.

Lacking a diagnostic test of any kind, CFS has historically been mis-diagosed, for example in patients presenting CFS symptoms with similar biological conditions or infections (such as Lyme or Epstein-Barr) (the latter of which is often the cause of glandular fever, or infectious mononucleosis), or psychological conditions (ranging from depression to hypochondria). A lack of information and awareness has led to many patients being stigmatized as hypochondriac or lazy.

However, on Tuesday, June 13th 2006 a coroner "of Brighton and Hove Coroners Court, UK, recorded the cause of death of a 32-year-old woman as acute anuric renal failure (failure to produce urine) due to dehydration as a result of CFS. The deceased woman [...] had suffered from CFS for six years." [First official UK death from chronic fatigue syndrome - New Scientist] Previous cases have listed CFS as the cause of death in the US and Australia [Inquest Implications: Marshall E, Williams, M, June 2006]

Nomenclature

There are a number of different terms which have been identified at various times with this disorder.

Symptoms

According to the 1994 Fukuda definition there are eight main categories of symptoms in CFS:

Course

Onset

Some cases of CFS start gradually, but the majority start suddenly, often triggered by a 'flu-like viral or similar illness. People with CFS may improve or recover after several months, or many years, or not at all. It is not known whether any CFS sufferer has truly recovered to pre-illness levels, or whether their symptoms have merely subsided enough for them to live a more normal life. Some sufferers have a remission for months or years only to later relapse, often more severely.

Sudden onset cases

Many people with CFS report a sudden, drastic start to their illness. Some people can remember a specific day or even hour when they first became ill.

Often CFS starts with, or is triggered by, another illness. Many people report getting a case of the 'flu', exposure to an allergen (a cough or sniffle caused by paint, a new pet, or construction dust), or a severe infection such as bronchitis, from which they seem never to fully recover and which slowly evolves into CFS. Some patients claim that vaccination, especially with recombinant vaccine against hepatitis B, is another cause of acute onset CFS. Other patients begin with Lyme disease, which despite a standard course of treatment, may 'evolve' clinically from the symptoms of acute Lyme to those of CFS. Because CFS symptoms bear a striking similarity to those of late-stage Lyme disease (Donta, 2002), this has become an area of great controversy. Some clinicians assume the Lyme infection has been eradicated after a course of treatment and diagnose CFS by the Fukuda definition, while others treat such cases as seronegative, chronic Lyme infection (see The Lyme controversy). Other, noninfectious triggers may include car accidents, moving house, and stressful life situations. Some patients say they felt unusual or uneasy for a short period (days or weeks) before the onset.

Gradual onset

Other cases have a very slow, gradual onset, sometimes spread over years. People with gradual onsets may not realize there is anything wrong for quite some time. Patients may believe they have a minor illness, or ascribe their weakened condition to stress, and assume they will improve with time. It is only when the patient realized that their condition is truly debilitating, or the stress is removed and the symptoms remain, that the patient will begin to seek treatment.

There is no standard course for CFS. For a patient to be officially diagnosed with chronic fatigue syndrome, the symptoms must have persisted for at least six months. However, the Fukuda paper also contains a definition of "chronic fatigue" which is reserved for those who do not meet the full criteria for CFS. Since the 50% rule of Holmes et al was dropped, it is possible that there are people with CFS whose level of disability is so low that they never seek treatment, or receive an accurate diagnosis, though this is not permitted by the Canadian definition.

Activity levels

Activity levels vary widely among CFS patients. While some are able to lead a relatively normal life, others are totally bed-bound and unable to care for themselves. Almost all patients find they must drastically reduce their activity from pre-illness levels, regardless of their previous level of athleticism, and must severely modify or give up physical hobbies and exercise. Many patients find themselves unable to work full-time, or at all. A considerable number of CFS cases in many countries are on disability benefits or private insurance, or have made claims and been denied.

One notable CFS sufferer is soccer legend Michelle Akers, who reported struggling with the illness for many of the later years of her career. However, more severe sufferers felt that an active professional athlete "poster child" like Akers helped to trivialize the syndrome in the eyes of the public, and made it much more difficult for highly incapacitated patients to be taken seriously. It is worth noting that the condition can strike persons of all activity levels, and that a few patients may have had high levels of physical health and activity before onset.

Post-exertion symptom exacerbation

One of the most common and recognizable aspects of CFS is what is called "post-exertional malaise". When people with CFS exert themselves beyond their limits (and their limits may change daily), their symptoms worsen. The harder the exertion and the longer it lasts, the worse the symptoms will be afterward, and with greater recovery time.

A cyclical pattern often occurs when patients work harder because they "feel better" or are having a "good day", leading them to think they can exert themselves more than usual. However, the excess exertion leads to worse symptoms on the following day. Thus it is difficult for patients to maintain an even level of activity, or to tell if they are improving. In sufferers without a diagnosis of CFS, or a proper understanding of how CFS affects exertion, this can lead to a "downward spiral", where a sufferer will try to work harder to make up for the previous day's lack instead of resting. This exhausts them further, and often can trigger a relapse or worsening of their condition. If the original exertion, which can be physical or mental in nature, was particularly severe, the sufferer may deteriorate to a point where they are unable to care for themselves. Many cases then result in hospitalisation because the condition has deteriorated a great deal. However, it must be noted that patients may deteriorate due to co-morbid illness, or for unknown reasons, and patient exertion cannot be blamed for a patient's deterioration; the condition is not so easily managed.

Duration

People with CFS may improve after a few months, or after many years, or never at all. They may reach a plateau at some constant level of health, or may progressively decline. Often, the symptoms change over time, or cycle irregularly. Relapses are common, especially after stressful life events or additional illness. Exertion can cause not merely a relapse, but a worsening of overall health. Un-diagnosed cases of CFS often worsen as the sufferer attempts to return to a 'normal' level of activity, only to make their condition worse through exertion.

The average CFS patient is moderately to severely affected, and may expect to remain so for the duration of her or his life. It is not known whether any patients truly 'recover' entirely from the illness, or merely recuperate enough to regain previous levels of activity. Few patients report a total 'cure'. CFS can prove to be fatal, as in the case in the UK of Sophia Mirza, where the coroner recorded a verdict of "Acute aneuric renal failure due to dehydration arising as a result of CFS". The pathologist said, "ME describes inflammation of the spinal cord and muscles. My work supports the inflammation theory. There was inflammation in the basal root ganglia." CFS has been linked to heart damage and cardiac arrest among other causes of death; research has not yet progressed to determine whether this is in fact the case, and some patients die from co-morbid diseases. No research has yet been done on CFS life expectancy.

Diagnosis

At this time, there is no accepted conclusive test or series of tests of chronic fatigue syndrome. CFS is therefore largely an exclusionary diagnosis. If a doctor suspects a patient may have CFS they should begin the diagnostic process by eliminating other potential causes of the patient's symptoms. "Chronic fatigue" and similar symptoms can be caused by a wide variety of conditions which should be investigated, although treatment of the patient's symptoms can begin before a complete diagnosis is made. In a patient displaying CFS symptoms including new migraines, for example, it is safe and reasonable to treat the migraines while attempting to rule out other possible causes of the patient's fatigue.

CDC 1994 criteria (aka \" According to the 1994 CDC [case definition], a diagnosis of CFS requires that the following conditions be met (otherwise, the diagnosis is idiopathic chronic fatigue).

Primary symptom: incapacitating fatigue

Incapacitating fatigue that is:

Additional symptoms

The fatigue must be accompanied by a minimum of 4 of the following eight symptoms:

Other systems

Some scoring systems, while being considered imperfect, have been proposed to quantify CFS symptoms for research purposes. These include: [Other ability/disability scales] designed for similar symptoms to those of CFS have also been used.

Controversies

Historically, many doctors have been unfamiliar with CFS, and some have refused to diagnose it. This situation is changing somewhat, with more doctors willing to diagnose it. In the UK, the Chief Medical Officer's report stated that all doctors should consider CFS as a serious chronic illness — though it is not stated whether this is a serious physical illness — and treat patients accordingly. Similar progress has been made in the United States.

There remains considerable skepticism amongst some medical professionals about the existence of CFS as a 'real' — i.e. medical as opposed to behavioral — condition, possibly due to the extreme uncertainty of its etiology, and the lack of testing for biomedical signs. As is common historically with new or unexplained conditions, many people are inclined to believe that a condition with few to no biomedical markers may be, or even must be, psychological in origin. This has led to frustration in many patients, who feel strongly that their disability is not psychological, but biological, in cause and effect. Some more vocal patients' groups maintain that research into CFS (ME) in the UK has been mostly hijacked by the psychologists/psychiatric lobby, who they claim hold significant power within the medical fraternity, with a resultant "abuse of patients' rights". The UK and the Netherlands have particularly seen disagreements between biomedical researchers and their adherents, and psychiatrists (particularly proponents of cognitive behavioral therapy, or CBT) and supporters of the theory that CFS is psychological in origin, and can be "cured" entirely by therapy and exercise.

Patients whose illnesses are consistent with the older and Canadian definitions tend most to resent the elevation of what they see as a trivialising, nonspecific sensation of "fatigue" to a principle descriptor. It is thus often important to be able to differentiate between the illness experience of needful patients and an epistemic construct that may or may not select the same target, until a better definition and diagnostic testing is widely accepted.

Epidemiology

Due to problems with the definition of CFS, estimates of its prevalence vary widely. Studies in the United States have found between 75 and 420 cases of CFS for every 100,000 adults.

Far more women than men get CFS — between 60 and 85% of cases are women; however, there is some indication that the prevalance among men is under reported. Members of ethnic minorities and low income classes are slightly more likely to develop CFS. Though people of all ages can get CFS, and precise statistics are not available, the prevalence among children and adolescents appears to be lower than for adults. Among minors with CFS, about half are boys and half girls.

CFS occurs both in isolated cases and large-scale outbreaks. In a number of documented cases several people in a building or large numbers of people in a community came down with the disease essentially simultaneously, suggesting that it is (in at least some cases) partly due to an infectious agent. Blood relatives of people who have CFS appear to be more predisposed. However, CFS does not appear directly contagious; caretakers, partners and others in close contact with persons with CFS for years do not develop CFS any more frequently (excluding relatives, as earlier).

Disease associations

Some diseases show a considerable overlap with CFS, and it may be hard to distinguish between them. People with fibromyalgia have muscle pain and sleep disturbances. Those with multiple chemical sensitivities (MCS) are sensitive to chemicals and have sleep disturbances. Many veterans with Gulf War syndrome (GWS) have symptoms almost identical to CFS. Post-polio syndrome also bears a strong and remarkable resemblance to CFS. Some researchers maintain these disorders are all expressions of a general, yet undefined, syndrome with protean symptoms.

Other disorders with known causes and treatments that may produce CFS-like symptoms are Lyme disease[link], gluten intolerance (celiac disease and related disorders), and vitamin B12 deficiency. There may also be correlation with polycystic ovary syndrome (PCOS). Thyroid disorders, anemia, and diabetes can present similar symptoms, and must be ruled out. Psychiatric disorders, especially depression, can appear to cause similar symptoms as well, and patients must be carefully screened to determine whether depression is co-morbid with, causing, or being caused by CFS or another syndrome.

Co-morbidity

Many CFS patients will also have, or appear to have, other medical problems or related diagnoses. Fibromyalgia will occur in a large percentage of CFS patients between onset and the second year, and some researchers suggest that fibromyalgia and CFS are related. Similarly, multiple chemical sensitivity (MCS) is reported by many CFS patients, and it is speculated that these similar conditions may be related by some underlying mechanism. As previously mentioned, many CFS sufferers also experience symptoms of irritable bowel syndrome (IBS), temporomandibular joint pain (as in TMJ), headache including migraines, and other forms of myalgia. Clinical depression and anxiety are also commonly co-morbid.

Proposed etiologies and corresponding treatments

The cause of CFS is unknown, although a large number of causes have been proposed, and several proposed causes have very vocal and partisan advocates.

As there is no one identifiable cause or falsifiable diagnosis for CFS, there is also no one treatment protocol or "magic bullet". Due to the multi-systemic nature of the illness, and others like it, an emerging branch of medical science called psychoneuroimmunology is exploring how all the various theories fit together.

The treatments that are proposed and often attempted for CFS are as varied as the suggested causes, and can generally be classified either according to the cause that they presume, or the symptom they propose to treat. Unfortunately, since CFS symptoms tend to vary over time, it is very easy for someone to become convinced that a particular treatment has helped them (or not), regardless of its true effectiveness. Alternative medicine is often proposed for CFS, especially when conventional treatments are too toxic or otherwise poorly tolerated, or simply fail to relieve symptoms. Alternative treatments may also be more affordable or accessible to patients with limited funds or health care coverage.

Allergies

Autonomic nervous system disruption

Damage to ascending reticular activating system

Depression

While depression is not uncommon among CFS patients, there are many CFS patients without depressive signs, suggesting that depression is not a direct cause of the symptoms. There are also patients with pre-existing depression which responded to treatment, but whose CFS symptoms did not improve; and treatment for depression is not particularly effective on CFS patients without depression. While depression may occur in CFS patients, it may be a result of living with CFS, or a secondary product of exercise intolerance, rather than the cause. Depression sufferers have been shown to have lowered immune system responses in some cases, which may explain the slight correspondence between pre-existing depression and CFS.

Hormonal dysfunction

Immune dysfunction

Hyperactive

Underactive

Infectious agents

Bacterial dental infections

Bacterial infections, other

Fungal

Viral

Many members of the Herpesvirus family have been implicated as causative agents in CFS. For many years the ubiquitous Epstein-Barr virus, present in 90% of the population, was the principal suspect. Other viruses implicated include cytomegalovirus, and human herpesvirus type-6 (HHV-6).

More recently, however, similarities to post-polio syndrome have led to a reexamination of the viral link. A number of viruses of the enterovirus family, notably the Coxsackie virus, can produce an infection of the nervous system similar to that caused by the poliovirus, and an even wider range of viruses have been shown capable of triggering an autoimmune reaction that attacks the nervous system. It is believed by some that one of these mechanisms causes damage to areas of the brain responsible for alertness and metabolism, resulting in many of the symptoms of CFS.

Inner-ear disorders

Metabolic disorders

Nutritional deficiency or imbalance

Psychosomatic causes

Spinal problems

Toxic agents

Other treatments

For underlying symptoms and for lifestyle adjustments

Involving therapy

Social issues

Chronic fatigue syndrome carries a considerable stigma, and has frequently been viewed as malingering, hypochondriacal behavior, "wanting attention" or "yuppie flu". As there is no objective test for the condition at this time, many argue that it is easy to "invent" CFS-like symptoms for financial, social or emotional benefits. CFS sufferers argue in turn that the perceived "benefits" are hardly as generous as some may believe, and that most CFS patients would greatly prefer to be healthy and independent.

Patients may find themselves surrounded with misunderstanding of their condition. Since CFS is often invisible to some -- although many sufferers present a somewhat poorly picture -- many will not understand why a newly diagnosed co-worker suddenly "needs" to work from home, use a better chair, or take time off. A CFS sufferer may face disbelief and misunderstanding, and even anger, from persons previously part of the social support structure. Many CFS patients have faced unsupportive families and dubious physicians, and have lost jobs, careers, scholarships and relationships to the syndrome. Anxiety and depression often result from the emotional, social and financial crises caused by CFS. While few studies have been made, it is believed that CFS patients, like other highly disabled and dependent persons, are at a high risk of suicide.

Notable sufferers

Some notable persons who are believed to have suffered from CFS are:

Popular culture references

A 1989 episode of The Golden Girls ("Sick and Tired") dealt with Dorothy developing the illness and trying to cope with doctors who told her it was mental. Bea Arthur (who played Dorothy) wanted to raise social awareness of the issue.

In the first series of Alan Partridge, during a meal with the head of the BBC Alan suggests a program he has thought of involving the illness Knowing ME Knowing You.

References

External links

 

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