Re: [HeidiLiane] According to the CDC...Possible causes of CFS

[Guest guest]

Stacie: Thanks for a good article. I have the NMH or orthostatic hypotension and problems associated with it. I had the tilt table test done nearly two years ago. They did other testing as well including a QSART test which showed the small fiber neuropathy that I am coping with now. It all seems part of the syndrome.

S.

[HeidiLiane] According to the CDC...Possible causes of CFS

Here is list of possible causes that the CDC has listed on their

website...I thought I would share. The website link tot his info is..

http://www.cdc.gov/cfs/cfscauses.htm . I thought it was interesting

that they listed nutritional deficency as one of the causes.

The cause or causes of CFS remain unknown, despite a vigorous search.

While a single cause for CFS may yet be identified, another

possibility is that CFS represents a common endpoint of disease

resulting from multiple precipitating causes. As such, it should not

be assumed that any of the possible causes listed below has been

formally excluded, or that these largely unrelated possible causes

are mutually exclusive. Conditions that have been proposed to trigger

the development of CFS include virus infection or other transient

traumatic conditions, stress, and toxins.

Infectious Agents

Due in part to its similarity to acute or chronic infections, CFS was

initially thought to be caused by a virus infection (i.e., Epstein-

Barr (EBV) mononucleosis). It now seems clear that CFS is not caused

exclusively by any single recognized infectious disease agent. CDC's

four-city surveillance study found no association between CFS and

infection by a wide variety of human pathogens, including EBV, human

retroviruses, human herpesvirus 6, enteroviruses, rubella, Candida

albicans, and more recently bornaviruses and Mycoplasma. Taken

together, these studies suggest that among identified human

pathogens, there appears to be no causal relationship for CFS as a

whole. However, the possibility remains that CFS may have multiple

causes leading to a common endpoint, in which case some viruses or

other infectious agents might have a contributory role for a subset

of CFS cases. Recently published research suggests that infection

with Epstein-Barr virus, Ross River virus and iella burnetti will

lead to a post-infective condition that meets the criteria for CFS in

approximately 12% of cases. The severity of the acute illness was the

only factor found to predict which individuals would have persistent

symptoms characteristic of CFS at the six-month and one-year period

following infection.

Immunology

It has been proposed that CFS may be caused by an immunologic

dysfunction, for example inappropriate production of cytokines, such

as interleukin-1, or altered capacity of certain immune functions.

One thing is certain at this juncture: there are no immune disorders

in CFS patients on the scale traditionally associated with disease.

Some investigators have observed anti-self antibodies and immune

complexes in many CFS patients, both of which are hallmarks of

autoimmune disease. However, no associated tissue damage typical of

autoimmune disease has been described in patients with CFS. The

opportunistic infections or increased risk for cancer observed in

persons with immunodeficiency diseases or in immunosuppressed

individuals is also not observed in CFS. Several investigators have

reported lower numbers of natural killer cells or decreased natural

killer cell activity among CFS patients compared with healthy

controls, but others have found no differences between patients and

controls.

T-cell activation markers have also been reported to have

differential expression in groups of CFS patients compared with

controls, but again, not all investigators have consistently observed

these differences. One intriguing hypothesis is that various

triggering events, such as stress or a viral infection, may lead to

the chronic expression of cytokines and then to CFS. Administration

of some cytokines in therapeutic doses is known to cause fatigue, but

no characteristic pattern of chronic cytokine secretion has ever been

identified in CFS patients. In addition, some investigators have

noted clinical improvement in patients with continued high levels of

circulating cytokines; if a causal relationship exists between

cytokines and CFS, it is likely to be complex. Finally, several

studies have shown that CFS patients are more likely to have a

history of allergies than are healthy controls. Allergy could be one

predisposing factor for CFS, but it cannot be the only one, since not

all CFS patients have it.

Hypothalamic-Pituitary Adrenal (HPA) Axis

Multiple laboratory studies have suggested that the central nervous

system may have an important role in CFS. Physical or emotional

stress, which is commonly reported as a pre-onset condition in CFS

patients, activates the hypothalamic-pituitary-adrenal axis, or HPA

axis, leading to increased release of cortisol and other hormones.

Cortisol and corticotrophin-releasing hormone (CRH), which are also

produced during the activation of the HPA axis, influence the immune

system and many other body systems. They may also affect several

aspects of behavior. Recent studies revealed that CFS patients often

produce lower levels of cortisol than do healthy controls. Similar

hormonal abnormalities have been observed by others in CFS patients

and in persons with related disorders like fibromyalgia. Cortisol

suppresses inflammation and cellular immune activation, and reduced

levels might relax constraints on inflammatory processes and immune

cell activation. As with the immunologic data, the altered cortisol

levels noted in CFS cases fall within the accepted range of normal,

and only the average between cases and controls allows the

distinction to be made. Therefore, cortisol levels cannot be used as

a diagnostic marker for an individual with CFS. A placebo-controlled

trial, in which 70 CFS patients were randomized to receive either

just enough hydrocortisone each day to restore their cortisol levels

to normal or placebo pills for 12 weeks, concluded that low levels of

cortisol itself are not directly responsible for symptoms of CFS, and

that hormonal replacement is not an effective treatment. However,

additional research into other aspects of neuroendocrine correlates

of CFS is necessary to fully define this important, and largely

unexplored, field.

Neurally Mediated Hypotension

Rowe and coworkers conducted studies to determine whether

disturbances in the autonomic regulation of blood pressure and pulse

(neurally mediated hypotension, or NMH) were common in CFS patients.

The investigators were alerted to this possibility when they noticed

an overlap between their patients with CFS and those who had NMH. NMH

can be induced by using tilt table testing, which involves laying the

patient horizontally on a table and then tilting the table upright to

70 degrees for 45 minutes while monitoring blood pressure and heart

rate. Persons with NMH will develop lowered blood pressure under

these conditions, as well as other characteristic symptoms, such as

lightheadedness, visual dimming, or a slow response to verbal

stimuli. Many CFS patients experience lightheadedness or worsened

fatigue when they stand for prolonged periods or when in warm places,

such as in a hot shower. These conditions are also known to trigger

NMH. One study observed that 96% of adults with a clinical diagnosis

of CFS developed hypotension during tilt table testing, compared with

29% of healthy controls. Tilt table testing also provoked

characteristic CFS symptoms in the patients. A study (not placebo-

controlled) was conducted to determine whether medications effective

for the treatment of NMH would benefit CFS patients. A subset of CFS

patients reported a striking improvement in symptoms, but not all

patients improved. A placebo-controlled trial of NMH medications for

CFS patients is now in progress.

Nutritional Deficiency

There is no published scientific evidence that CFS is caused by a

nutritional deficiency. Many patients do report intolerances for

certain substances that may be found in foods or over-the-counter

medications, such as alcohol or the artificial sweetener aspartame.

While evidence is currently lacking for nutritional defects in CFS

patients, it should also be added that a balanced diet can be

conducive to better health in general and would be expected to have

beneficial effects in any chronic illness.

Stacie

http://www.cdc.gov/cfs/cfscauses.htm

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