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FMS FMS is classified as a nonarticular rheumatic disorder. The term fibromyalgia suggests that pain is found in fibrous tissues, muscles, tendons, ligaments, and other “white” connective tissues. Inflammation is not characteristic in FMS, and it is not a muscle disorder. The muscles of patients are normal, as is muscle strength. Alterations in the strength of muscle contractions most likely are attributed to pain or poor muscle conditioning due to lack of activity. (1, 4, 10) Incidence FMS ranks third in frequency of diagnosed rheumatic disorders, following osteoarthritis and rheumatoid arthritis, and FMS symptoms are said to be the second leading cause of work-related disability in the USA. It is estimated that between 3 and 6 million Americans have FMS symptoms, and between 80% and 90% of diagnosed patients are female. Although the onset is usually in patients aged 29 to 37 years, formal diagnosis typically occurs between ages 34 and 53. An average of 5 years passes before a patient receives an appropriate diagnosis. FMS infrequently has been diagnosed in children and the elderly.(1, 4, 5, 8) Etiology Since patients diagnosed with FMS often have other medical conditions, determining the exact etiology is difficult. Most patients cannot cite a single factor that initiated FMS, but some recall either physical trauma or a viral illness as a precipitating event. The precipitating event, in turn, may affect the CNS. (1, 4, 8, 10, 13) The main hypothesis being researched regarding the etiology of FMS is a precipitating event, such as infectious agents, stress, or trauma, causing a CNS shift that uncovers an underlying physiological abnormality. The abnormality is not currently understood, but may be related to sleep physiology or metabolic factors such as pain-related neurotransmitters (substance P, serotonin, or norepinephrine), hormones, enzymes, immune system mediators, cellular byproducts, or energy producing compounds (ATP, ADP, AMP). Note that Substance P is 3 times greater in the spinal fluid of FMS patients than normal subjects, but is at a normal level in the blood. (4, 8, 13, 14) The relationship between sleep disturbances and FMS is particularly interesting. FMS patients have an alpha-EEG arousal sleep disturbance, where their Stage 4 sleep is constantly hindered by bursts of awake-like brain activity. This results in a consistent loss of Stage 4 non-rapid-eye-movement (non-REM) sleep. Stage 4 sleep is needed for tissue restoration, and neuroendocrine and immune function. Studies have shown that normal test subjects deprived of Stage 4 sleep can develop a fibromyalgia-like syndrome. (4, 13, 17) Historically, psychogenic factors were said to contribute to FMS. More recent findings do not support this hypothesis, since FMS may be precipitated or made worse by nonpsychogenic factors such as stress, poor sleep, hormonal fluctuations, trauma, over-exertion, and changes in the weather. EEG evaluations show that the alpha-EEG abnormal sleep pattern in FMS patients is distinctly different than the sleep pattern found in clinically depressed patients. In addition, the location of tender points and histologic findings in FMS patients are consistent over time. Note that many patients that are diagnosed with FMS, however, also have psychological conditions. (4, 8, 13) FMS Presentation The cause of FMS is unknown. Frequently reported musculoskeletal symptoms include: generalized aches and pains of varying intensity, marked stiffness, the sensation of swelling in soft tissue, tender points, and muscle spasms or nodules. Tender points cluster in areas near the neck, shoulders, upper chest wall, and lower back. Note that the symptoms of FMS may remit, chronically vary in intensity, or recur at frequent intervals. (1, 4, 8) Other reported symptoms include waking up without feeling rested (> 60% of patients), chronic tension and migraine headache (about 50% of patients), bowel and bladder irritability (40% to 70% of patients), temporomandibular joint dysfunction (about 90% of patients have jaw discomfort), Raynaud’s phenomenon (30% of patients), depression (20% of patients), multiple chemical sensitivities, excessive fatigue, dysmenorrhea, paresthesias, chest pains, anxiety, and swelling and numbness in extremities. Medical findings often reported in FMS patients include: weakness, mitral valve prolapse, tachycardia, difficulty with concentration or memory, sicca syndrome (dry mouth, eyes and skin), skin mottling, and lupus (4, 8, 13) On physical examination, digital palpation on tender points at predictable symmetrical locations causes extreme localized pain and withdrawal in a FMS patient, as compared to discomfort in a normal subject. Palpation at control sites, such as the forehead, does not produce pain. In addition to tender points, areas of muscle tightness that refer pain to a predictable zone of radiation, called trigger points, are located near tender points. Patients may also have increased skinfold tenderness when a muscle is rolled between the fingers, and a wheal and flare reaction in response to light scratching. (8) Diagnosis In 1990, the American College of Rheumatology established diagnosis criteria for FMS. A positive diagnosis is made when patients have a history of widespread pain for at least 3 months, and pain is present on digital palpation in 11 of 18 designated tender point sites. The digital palpation of tender point sites should be done with a force of about 4 kg/cm2. Patients with FMS usually have tender point thresholds of 2 kg/cm2. The patient must state that the palpation was “painful”, rather than “tender”. (4,5,8,11) In addition to the above exam, a medical history, neurological evaluation, and physical examination are essential for FMS diagnosis. Routine laboratory tests, neurologic exams, and joint evaluations usually yield normal results, unless another concomitant condition exists. The presence of muscle spasm, nodules, reticular skin discoloration, and a nonrestorative sleep pattern are common. Up to 20% of patients have a dysregulation of their ANS, as demonstrated in tilt table testing. (1, 4, 5, 8, 17) Finally, rheumatic, neuromuscular, endocrine or metabolic, neoplastic, infectious, and drug-induced myopathic syndromes must be ruled-out before a positive FMS diagnosis can be made. In particular, the early stages of rheumatoid arthritis, polymyalgia rheumatica, and hypothyroidism have clinical signs and symptoms similar to FMS. See reference 5 for a complete listing of the disorders considered in the differential diagnosis for FMS. (1, 5)
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