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Intramuscular Pressure is Almost Three Times Higher in Fibromyalgia Patients: A Possible Mechanism for Understanding the Muscle Pain and Tenderness

Discussion in 'BioMedical ME/CFS Research' started by Joan Crawford, Jul 20, 2021 at 11:29 AM.

  1. Joan Crawford

    Joan Crawford Senior Member (Voting Rights)

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    Chester, UK
    Apologises if this has been posted - I searched and could not find it.

    Intramuscular Pressure is Almost Three Times Higher in Fibromyalgia Patients: A Possible Mechanism for Understanding the Muscle Pain and Tenderness


    Robert S. Katz, Frank Leavitt, Alexandra Katz Small and Ben J. Small
    The Journal of Rheumatology September 2020, jrheum.191068; DOI: https://doi.org/10.3899/jrheum.191068

    Objective Widespread pain in the fibromyalgia syndrome (FMS) is conventionally viewed as arising from disordered central processing. This study examines intramuscular pressure in the trapezius as an alternative mechanism for understanding FMS pain.

    Methods 108 patients who satisfied the ACR criteria for FMS and 30 patients who met the ACR criteria for another rheumatic disease comprised the study groups. Muscle pressure was measured in mmHg using a pressure gauge attached to a No. 22 needle inserted into the mid portion of the trapezius muscle. In addition, FMS patients and rheumatic disease controls had dolorimetry testing, digital palpation, and reported pain scores.

    Results Muscle pressure was substantially higher in patients with FMS with a mean value of 33.48± 5.90 mmHg. Only 2 of 108 patients had muscle pressure of <23 mmHg. The mean pressure in rheumatic disease controls was 12.23±3.75 mmHg, with a range from 3-22 mmHg. FMS patients were more tender than controls based on both dolorimetry (p<0.001) and digital palpation (p<0.001). The mean pain score in patients with FMS and controls was 6.68±1.91 and 1.43±1.79 (p<0.001).

    Conclusion Pressure in the trapezius muscle of patients with FMS is remarkably elevated and may be an intrinsic feature of FMS that could be monitored as part of the diagnostic evaluation. The burden of the pressure abnormality may help explain the diffuse muscle pain of FMS. Therefore, FMS as a disorder of exclusively central pain processing should be revisited. Therapeutically, the reduction of muscle pressure may change the clinical picture significantly.


    Any thoughts on this as a finding? Reliable testing method use? Easy to carry out in routine clinical practice? Value clinically?
    Milo, MEMarge, Louie41 and 14 others like this.
  2. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    The relatively high sensitivity and specificity is rather curious. I'd like this to be replicated by blind examiners before getting too excited. The FMS pain score vs muscle pressure plot suggests the association is weak, but that could be due to too much variation in the anchoring of the pain rating scores themselves.

    Proposed mechanism:
    Louie41, alktipping, Michelle and 6 others like this.
  3. Michiel Tack

    Michiel Tack Senior Member (Voting Rights)

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    Sounds interesting because the differences between groups are enormous, especially since they didn't use healthy controls but patients with other rheumatic conditions.

    Looks like more than a weak correlation to me:

    Louie41, alktipping, Michelle and 2 others like this.
  4. Jonathan Edwards

    Jonathan Edwards Senior Member (Voting Rights)

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    Hydrostatic pressure in relaxed muscle should be slightly below atmospheric. That suggests to me that the pressures here are indications of muscle contraction. It would not be surprising if people with a diagnosis of fibromyalgia contracted the trapezius harder when a needle was stuck in.
    Louie41, alktipping, Michelle and 5 others like this.
  5. Trish

    Trish Moderator Staff Member

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    It looks pretty weak to me. Knock out 3 outliers, and you have a pretty even spread across the range of pain levels for each pressure level.
  6. Peter Trewhitt

    Peter Trewhitt Senior Member (Voting Rights)

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    Interesting but like @Trish indicates it looks like three individuals are contributing a lot to the heavy lifting.

    Also it would be interesting to have data from other comparator groups, as even if the association is robust, it would be good to have more confirmation about the possible direction of any causality.

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