Muscle fiber velocity and electromyographic signs of fatigue in fibromyalgia
ABSTRACT Introduction: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. Methods: sEMG was performed on the biceps brachii muscle of 13 women with FM and 14 matched healthy controls during prolonged dynamic exercises, unloaded, and loaded up to 20% of maximum voluntary contraction. The sEMG parameters were: muscle fiber conduction velocity (CV); skewness of motor unit potential (peak) velocities; peak frequency (PF) (number of peaks per second); and average rectified voltage (ARV). Results: There was significantly higher CV in the FM group. Although the FM group performed the tests equally well, their electromyographic fatigue was significantly less expressed compared with controls (in CV, PF, and ARV). Conclusion: In the patients with FM, we clearly showed functional abnormalities of the muscle membrane, which led to high conduction velocity and resistance to fatigue in electromyography. Muscle Nerve 46: 738-745, 2012.
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ABSTRACT: To develop criteria for the classification of fibromyalgia, we studied 558 consecutive patients: 293 patients with fibromyalgia and 265 control patients. Interviews and examinations were performed by trained, blinded assessors. Control patients for the group with primary fibromyalgia were matched for age and sex, and limited to patients with disorders that could be confused with primary fibromyalgia. Control patients for the group with secondary-concomitant fibromyalgia were matched for age, sex, and concomitant rheumatic disorders. Widespread pain (axial plus upper and lower segment plus left- and right-sided pain) was found in 97.6% of all patients with fibromyalgia and in 69.1% of all control patients. The combination of widespread pain and mild or greater tenderness in greater than or equal to 11 of 18 tender point sites yielded a sensitivity of 88.4% and a specificity of 81.1%. Primary fibromyalgia patients and secondary-concomitant fibromyalgia patients did not differ statistically in any major study variable, and the criteria performed equally well in patients with and those without concomitant rheumatic conditions. The newly proposed criteria for the classification of fibromyalgia are 1) widespread pain in combination with 2) tenderness at 11 or more of the 18 specific tender point sites. No exclusions are made for the presence of concomitant radiographic or laboratory abnormalities. At the diagnostic or classification level, the distinction between primary fibromyalgia and secondary-concomitant fibromyalgia (as defined in the text) is abandoned.Arthritis & Rheumatology 03/1990; 33(2):160-72. · 7.87 Impact Factor
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ABSTRACT: Upper medial trapezius muscle biopsy was obtained from 12 primary fibromyalgia syndrome (PFS) patients (age 17 to 40 years) and studied with histochemistry, light and electron microscopy (EM). No evidence of inflammation was found in any case. Significant histochemical abnormalities were Type II fiber atrophy in 7 and moth-eaten appearance of Type I fibers in 5. EM revealed segmental muscle fiber necrosis with lipid and glycogen deposition as well as subsarcolemmal mitochondrial accumulation in all cases. Papillary projections of sarcolemmal membrane were seen in 11 patients. These observations in 12 PFS cases without obvious muscle trauma indicate definite but nonspecific muscle changes which we suspect are secondary to chronic muscle spasm and ischemia of unknown etiology.The Journal of Rheumatology 01/1985; 11(6):808-13. · 3.17 Impact Factor
Scandinavian Journal of Rheumatology 02/1989; 18(5):321-3. DOI:10.3109/03009748909095036 · 2.61 Impact Factor