Fatigue: Another frequent complaint associated with fibromyalgia is fatigue. In fact, it occurs so commonly that some doctors think fibromyalgia and chronic fatigue syndrome are the same disease. The severity of the fatigue can range from mild to incapacitating. In its worse form, fatigue can be so debilitating that some people have trouble keeping their jobs. No amount of sleep at night or rest during the day provides any relief.

Fibrofog: Another common symptom is a mental haziness some people call fibrofog. This refers to the inability to concentrate, memory loss, and depression that take place with fibromyalgia.

Other symptoms associated with this illness are headaches, nervousness, numbness, dizziness, and intestinal problems.

Independent studies support of the idea of a systemic biochemical abnormality in fibromyalgia. Four independent studies reported elevation by 2-3 times of substance P, the neuropeptide in spinal fluid. Substance P is a neurotransmitter released when axons [The single process of a nerve cell that under normal conditions conducts nervous impulses away from the cell body and its remaining processes (dendrites - One of the two types of branching protoplasmic processes of the nerve cell (the other being the axon)] are stimulated. Increased levels of substance P increase the sensitivity of nerves to pain or heighten awareness of pain. The elevated levels in the spinal cord (from an injury or trauma, particularly in the upper spinal region, may trigger the development of fibromyalgia in some people.). cause a fairly normal stimulus to result in exaggerated nociception [the reception and transmission of painful or injurious stimuli.]. Some researchers think that neither elevated substance P nor low serotonin alone can be primary originating agents but that the dual dysfunction may be accountable for fibromyalgia.

Other researchers believe fibromyalgia is caused by a lack of deep sleep. It is during stage 4 sleep that muscles recover from the prior day’s activity and the body refreshes itself. Sleep studies show that as people with fibromyalgia enter stage 4 sleep, they become more aroused and stay in a lighter form of sleep. Even though they may sleep for a long period of time, they get poor quality sleep. Also, when researchers took normal volunteers and did not allow them to enter into stage 4 sleep, they developed symptoms similar to fibromyalgia.

Other groups of researchers have focused on the neuroendocrine (pertaining to the anatomic and functional relationships between the nervous system and the endocrine system) aspects of fibromyalgia and found hypothalamic-pituitary-adrenal (HPA) axis dysfunction in these patients. The HPA is a critical component of the stress-adaptation response. In a normally functioning system, the anterior pituitary is stimulated by corticotropin-releasing hormone (CRH) to release adrenocorticotropic hormone (ACTH). The adrenal cortex then is stimulated by ACTH to produce glucocorticoids, which are powerful mediators of the stress-adaptation response. Circadian regulation and the stress-induced stimulation of the HPA axis are, in part, regulated by serotonin. Serotonin metabolism perturbations (as well as premorbid HPA-axis abnormalities) may explain HPA-axis abnormalities in fibromyalgia.

The effects of abnormal serotonin metabolism may be exaggerated by HPA-axis dysfunction. Low central serotonin actually may be caused by HPA-axis hypoactivity.

Some authors have noted the following 5 main measurable neuroendocrine abnormalities associated with HPA-axis dysfunction:

Some studies have found that nerve growth factor was 4 times higher in the spinal fluid of patients with fibromyalgia. This factor is key to the pathophysiology of fibromyalgia, since the process enhances substance P production in the afferent (Inflowing; conducting toward a center, denoting certain arteries, veins, lymphatics, and nerves.) neurons, thereby increasing the sensitivity or awareness to pain. Nerve growth factor possibly plays a role in spreading or redistributing perceived pain signals.

Mounting evidence suggests the reality of a genetic predisposition for developing fibromyalgia. The inheritance pattern is autosomal(any chromosome other than the sex chromosomes (X or Y) -dominant. Some investigators submit that the genetic predisposition requires either reaching a critical age or sustaining an external insult such as trauma or illness.

Although the pathologic, physiologic, nor the biochemical mechanism resulting in the development of fibromyalgia is not understood completely, the currently known abnormalities substantiate the proposal that fibromyalgia can no longer be considered a subjective pain condition. Many research groups suggest that fibromyalgia may be a condition of abnormal central processing of the transmission of pain.

Jason, Ph.D. Leonard A.; Fenell, MSW, CSW-R Patricia; Taylor, Ph.D., Renee R.
Handbook of Chronic Fatigue Syndrome John Wiley & Sons:Hoboken, New Jersey, 2003

Source Citation: "Chronic fatigue syndrome." Toni Rizzo, PhD. The Gale Encyclopedia of Medicine. Second Edition. Jacqueline L. Longe, Editor. 5 vols. Farmington Hills, MI: Gale Group, 2001

"The Facts about Chronic Fatigue Syndrome." Centers for Disease
Control. www.cdc.gov/ncidod/diseases/cfs/facts1.htm

"Chronic Fatigue Syndrome." National Institutes of Health. http://www.nih.gov