Chronic fatigue syndrome natural history

Disease Course
The severity of CFS varies from patient to patient, with some people able to maintain fairly active lives. By definiton, however, CFS significantly limits work, school and family activities.

While symptoms vary from person to person in number, type and severity, all CFS patients are functionally impaired to some degree. CDC studies show that CFS can be as disabling as multiple sclerosis, lupus, rheumatoid arthritis, heart disease, end-stage renal disease, chronic obstructive pulmonary disease (COPD) and similar chronic conditions.

CFS often follows a cyclical course, alternating between periods of illness and relative well-being. Some patients experience partial or complete remission of symptoms during the course of the illness, but symptoms often reoccur. This pattern of remission and relapse makes CFS especially hard for patients and their health care professionals to manage. Patients who are in remission may be tempted to overdo activities when they're feeling better, which can exacerbate symptoms and fatigue and cause a relapse. In fact, postexertional malaise is a hallmark of the illness.

The percentage of CFS patients who recover is unknown, but there is some evidence to indicate that the sooner symptom management begins, the better the chance of a positive therapeutic outcome. This means early detection and treatment are of utmost importance. CDC research indicates that delays in diagnosis and treatment may complicate and prolong the clinical course of the illness.

It can be inferred from the 2003 Canadian clinical working definition of ME/CFS that there are 8 categories of symptoms:
 * Fatigue: Unexplained, persistent, or recurrent physical and mental fatigue/exhaustion that substantially reduces activity levels and is not relieved (or not completely relieved) by rest.


 * Post-exertional malaise: An inappropriate loss of physical and mental stamina, rapid muscular and cognitive fatigability, post exertional malaise and/or fatigue and/or pain and a tendency for other associated symptoms to worsen with a pathologically slow recovery period of usually 24 hours or longer. According to the authors of the Canadian clinical working definition of ME/CFS, the malaise that follows exertion is often reported to be similar to the generalized pain, discomfort and fatigue associated with the acute phase of influenza. Although common in CFS, this may not be the most severe symptom in the individual case, where other symptoms (such as headaches, neurocognitive difficulties, pain and sleep disturbances) can dominate.


 * Sleep dysfunction: "Unrefreshing" sleep/rest, poor sleep quantity, insomnia or rhythm disturbances. A study found that most CFS patients have clinically significant sleep abnormalities that are potentially treatable. Several studies suggest that while CFS patients may experience altered sleep architecture (such as reduced sleep efficiency, a reduction of deep sleep, prolonged sleep initiation, and alpha-wave intrusion during deep sleep) and mildly disordered breathing, overall sleep dysfunction does not seem to be a critical or causative factor in CFS. Sleep may present with vivid disturbing dreams, and exhaustion can worsen sleep dysfunction.


 * Pain: Pain is often widespread and migratory in nature, including a significant degree of muscle pain and/or joint pain (without joint swelling or redness, and may be transitory). Other symptoms include headaches (particularly of a new type, severity, or duration), lymph node pain, sore throats, and abdominal pain (often as a symptom of irritable bowel syndrome). Patients also report bone, eye and testicular pain, nerve pain and painful skin sensitivity. Chest pain has been attributed variously to microvascular disease or cardiomyopathy by researchers, and many patients also report painful tachycardia. A systematic review assessing the studies of chronic pain in CFS found that although the exact prevalence is unknown, it is strongly disabling in patients, but unrelated to depression.


 * Neurological/cognitive manifestations: Common occurrences include confusion, forgetfulness, mental fatigue/brain fog, impairment of concentration and short-term memory consolidation, disorientation, difficulty with information processing, categorizing and word retrieval, and perceptual and sensory disturbances (e.g. spatial instability and disorientation and inability to focus vision), ataxia (unsteady and clumsy motion of the limbs or torso), muscle weakness and "twitches". There may also be cognitive or sensory overload (e.g. photophobia and hypersensitivity to noise and/or emotional overload, which may lead to "crash" periods and/or anxiety). A review of research relating to the neuropsychological functioning in CFS was published in 2001 and found that slowed processing speed, impaired working memory and poor learning of information are the most prominent features of cognitive dysfunctioning in patients with CFS, which couldn't be accounted solely by the severity of the depression and anxiety.


 * Autonomic manifestations: Common occurrences include orthostatic intolerance, neurally mediated hypotension (NMH), postural orthostatic tachycardia syndrome (POTS), delayed postural hypotension, lightheadedness, extreme pallor, nausea and irritable bowel syndrome, urinary frequency and bladder dysfunction, palpitations with or without cardiac arrhythmias, and exertional dyspnea (perceived difficulty breathing or pain on breathing).


 * Neuroendocrine manifestations: Common occurrences include poor temperature control or loss of thermostatic stability, subnormal body temperature and marked daily fluctuation, sweating episodes, recurrent feelings of feverishness and cold extremities, intolerance of extremes of heat and cold, digestive disturbances and/or marked weight change - anorexia or abnormal appetite, loss of adaptability and worsening of symptoms with stress.


 * Immune manifestations: Common occurrences include tender lymph nodes, recurrent sore throat, recurrent flu-like symptoms, general malaise, new sensitivities to food and/or medications and/or chemicals (which may complicate treatment). At least one study has confirmed that most CFS patients reduce or cease alcohol intake, mostly due to personal experience of worsening symptoms (although the cause of this is unknown and may not be strictly "immunological" as implied by the symptom list).

Recovery
A systematic review of 14 studies of the outcome of untreated people with CFS found that "the median full recovery rate was 5% (range 0–31%) and the median proportion of patients who improved during follow-up was 39.5% (range 8–63%). Return to work at follow-up ranged from 8 to 30% in the three studies that considered this outcome." .... "In five studies, a worsening of symptoms during the period of follow-up was reported in between 5 and 20% of patients." It is not known whether any patients truly "recover" entirely from the illness, or achieve remission from a relapsing, remitting illness. Few untreated patients report a total "cure".

Deaths
CFS is unlikely to increase the risk of an early death. A systematic review of 14 studies of the outcome of CFS reported 8 deaths, but none were considered directly attributable to CFS. To date there have been two studies directly addressing life expectancy in CFS. In a preliminary 2006 study of CFS self-help group members, it was reported that CFS patients were likely to die at a younger than average age for cancer, heart failure, and suicide. However, a much larger study of 641 CDC criteria diagnosed patients with CFS, who were followed up for a mean of 9 years, showed no excess risk of dying from any cause.

People diagnosed with CFS may die, as in the case in the UK of Sophia Mirza, where the coroner recorded a verdict of "Acute anuric renal failure due to dehydration arising as a result of CFS." According to Sophia's mother, Sophia became intolerant to water and managed only 4 fluid ounces per day. The pathologist said, "ME describes inflammation of the spinal cord and muscles. My work supports the inflammation theory...The changes of dorsal root ganglionitis seen in 75% of Sophia's spinal cord were very similar to that seen during active infection by herpes viruses." This was seen as a form of recognition by the ME community. Previous cases have listed CFS as the cause of death in the US and Australia

Co-morbidity
Many CFS patients will also have, or appear to have, other medical problems or related diagnoses. Co-morbid fibromyalgia is common, although there are differences in pain complaints. Fibromyalgia occurs in a large percentage of CFS patients between onset and the second year, and some researchers suggest 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, such as elevated nitric oxide/peroxynitrite. As previously mentioned, many CFS sufferers also experience symptoms of irritable bowel syndrome, temporomandibular joint pain, headache including migraines, and other forms of myalgia. Clinical depression and anxiety are also commonly co-morbid. Compared with the non-fatigued population, male CFS patients are more likely to experience chronic pelvic pain syndrome (CP/CPPS), and female CFS patients are also more likely to experience chronic pelvic pain. CFS is significantly more common in women with endometriosis compared with women in the general USA population.

Social issues
Many patients find that a chronic fatigue syndrome diagnosis carries a considerable stigma, and has frequently been viewed as malingering, hypochondriac, phobic, "wanting attention" or "yuppie flu". As there is no objective test for the condition at this time, it has been argued that it is easy to invent or feign 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 CFS patients would greatly prefer to be healthy and independent. A study found that CFS patients endure a heavy psychosocial burden. 2,338 respondents of a survey by a UK patient organization highlights that those with the worst symptoms often receive the least support from health and social services. A study found that CFS patients receive worse social support than disease-free cancer patients or healthy controls, which may perpetuate fatigue severity and functional impairment in CFS. A survey by the Thymes Trust found that children with CFS often state that they struggle for recognition of their needs and/or they feel bullied by medical and educational professionals. The ambiguity of the status of CFS as a medical condition may cause higher perceived stigma. A study suggests that while there are no gender differences in CFS symptoms, men and women have different perceptions of their illness and are treated differently by the medical profession. 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 are at a high risk of suicide.

A lack of information and awareness has led to many patients to feel stigmatized. CFS patients may not receive total medical and social acceptance and they state that some people trivialise the illness. When the illness is coupled with unaccommodating family, friends, colleagues, often due to stigma, and social repercussions such as financial needs, housing problems, the struggle to obtain disability benefits or insurance, discrimination and misconception within the care sector, it can put demands on the sufferer exceeding their safe capabilities. Many sufferers say that they need to do things for themselves during the time in which they feel better as there is no-one to delegate these tasks to.