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Chronic Fatigue Syndrome




  ICD10 G933
  ICD9


Chronic fatigue syndrome ('''CFS'''), also known as '''myalgic encephalomyelitis''' ('''ME'''), '''post-viral fatigue syndrome''' ('''PVFS''') and various other names, is a Syndrome of unknown and possibly multiple Etiologies , affecting the Central Nervous System (CNS), Immune , and many other systems and organs. Most Definitions other than the 1991 UK Oxford criteria, require a number of features, the most common being severe mental and physical depletion, which according to the 1994 Fukuda definition is "unrelieved by rest", and is usually made worse by even trivial exertion (controversially the Oxford and Fukuda criteria require this to be optional only). However, patients usually contend that they have many, often severe symptoms which are far more onerous than the research diagnostic criteria, such as pain, muscle weakness, loss of brain function, Hypersensitivity , Orthostatic Intolerance , digestive disturbances, depression, immune and in some cases life-threatening cardiac and respiratory problems. It is these symptoms exacerbated by extremely low stamina that cause greatest suffering, not "fatigue" , which more properly describes a normal state of recovery unrelated to Pathology . Some cases resolve or improve over time, and where available, treatments bring a degree of improvement to many others.


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. This is an artifact of the WHO not allowing multiple categorizations of a single condition, rather than being an indication of two disjoint disorders.


NOMENCLATURE

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


SYMPTOMS

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

It should be noted that lists of diagnostic criteria (such as the Oxford and Fukuda lists) were designed for selection and exclusion of participants for research studies and, as such, are quite narrow in scope. Some patients have CFS despite the fact that their symptoms do not match the strict research diagnostic criteria.


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 completely after a few 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. Other patients begin with Lyme Disease , which despite adequate Lyme treatment, may 'evolve' from the clinical symptoms and definition of Lyme to those of CFS (this is permitted by the Fukuda definition). Other triggers can 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. It is possible that not all cases of CFS are chronic: some people may have CFS for four months, recover, and never get diagnosed, some claim. 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 and active 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, however.


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 with greater recovery time. Some contend from this that prognoses such as deterioration or relapse-remission must be due to sufferers' activity patterns, however this is far from proven, since in many sufferers at least, fluctuations are not solely related to exertion but can include responses to infection, changes in temperature (e.g. hot or cold weather), physical or emotional stressors, and unknown disease process, but they maintain:

The cyclical pattern 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.

However, many sufferers who are severely affected particularly find this "behaviourist" hypothesis simplistic and offensive as it leads to the blaming of patients and denial of social support and medical care since the condition can be seen as supposedly self-controllable and self-limiting and already scarce services may be withdrawn if the sufferer is unfortunate enough to deteriorate.


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, although CFS does not appear to be directly fatal or damagingly progressive. Often, the symptoms change over time, or cycle through time. 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.


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, fatigue and 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 "Fukuda")

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 rapidly changing, with more doctors willing to diagnose it and more diagnoses occurring each year. 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 behavioural -- condition, possibly due to the extreme uncertainty of its Etiology , and the lack of accepted 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. 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.


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 , 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 Migraine s, 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). The evidence has not been consistent with these hypotheses, however, and they are generally no longer believed to explain the etiology of CFS. (Soto & Straus, 2000)

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 Polio virus, 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 invisible, many persons 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 with 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 make a social awareness of the issue.


REFERENCES



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