The origin of myopain: An integrated hypothesis of focal muscle changes and sleep disturbance in patients with the fibromyalgia syndrome

Robert M. Bennett

    Research output: Contribution to journalArticlepeer-review

    28 Scopus citations


    Objectives: Current ideas regarding the pathogenesis of the fibromyalgia syndrome espouse 2 major theories, the central and the peripheral. Herein a review of both theories is presented and an attempt made to integrate several apparently unrelated observations into a coherent hypothesis. Results: The peripheral component of musculo-skeletal in fibromyalgia is generally considered to arise in muscle. However no global muscle defect has ever been demonstrated. On the other hand several studies have suggested focal muscle changes in terms of: reduced high energy phosphates, scattered red-ragged fibers, focal changes in oxygen tension and repetitive "contraction bands." These changes may result from muscle micro-trauma [MMT]-a universal experience after unaccustomed exercise. MMT causes a disruption of the sarcolemmal membrane leading to an influx of Ca++ ions and contraction of the involved units-the cause of the papable band? ATP dependent Ca++ pumps attempt to correct the influx and in the process deplete sarcolemmal stores of high energy phosphates. Involvement of muscle spindles in the vicinity of sarcomeric onctraction would reset muscle tension, giving rise to a sensation of stiffness. It is envisaged that there is a genetic polymorphism in susceptibilty to MMT, and that fibromyalgia patients are at one extreme end of the curve. Most susceptible individuals will not develop fibromyalgia unless they also develop the alpha-delta sleep anomaly. This is an acquired central defect which may provide a "double-hit" in the form of impaired growth hormone [GH] secretion-seen clinically as low levels of somatomedin-C. GH is essential for normal muscle homeostasis and repair of MMT. As GH is produced during stage 4 sleep, its impaired secretion may be the link between sleep and myopain. Conclusions: An analysis of contemporary research suggests that myopain in fibromyalgia may result from a convergence of both a peripheral factor-an increased susceptibility to muscle micro-trauma, and a central factor-the suboptimal secretion of growth hormone secondary to the alpha-delta sleep anomaly.

    Original languageEnglish (US)
    Pages (from-to)95-112
    Number of pages18
    JournalJournal of Musculoskeletal Pain
    Issue number3-4
    StatePublished - 1993


    • Fibromyaliga
    • Growth hormone
    • Muscle micro-trauma
    • Sleep disturbance

    ASJC Scopus subject areas

    • Rheumatology


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