Laboratory for Musculoskeletal Pain and Motor Control, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark.
Eur J Pain. 2012 Feb;16(2):196-203. doi: 10.1016/j.ejpain.2011.06.008.
Sustained isometric muscle contraction (fatiguing contraction) recruits segmental and/or extrasegmental descending inhibition in healthy subjects but not in fibromyalgia (FM). We hypothesized that fatiguing contraction may shift descending pain modulation from inhibition towards facilitation and that the effect of descending pain modulation be dependent on peripheral muscle pain sensitivity.
Pressure pain thresholds (PPT) were measured from 13 points bilaterally in the upper trapezius muscle and from the mid-point bilaterally in the tibialis anterior before-, immediately after-, and 20 min after fatiguing contraction of shoulder abduction in 22 FM patients and 22 matched healthy controls. Rate of fatigue, pain intensity, and the duration of fatiguing contraction were recorded.
The duration of fatiguing contraction was significantly shorter in FM (132.4 ± 25.2 s) than healthy control groups (286.2 ± 24.1 s) (P < 0.05), pain intensity was significantly higher in FM (8.25 ± 0.8 cm) than in healthy controls (5.1 ± 0.65 cm) (P < 0.01), whereas both groups reported similar fatigue intensity (P > 0.05). Following the contraction, PPTs were increased significantly and heterogeneously in the upper trapezius over time, but not, in the tibialis anterior muscle in healthy controls. However, PPT were significantly decreased over time in the tibialis anterior (P < 0.05), but not, in the upper trapezius in FM.
Descending pain modulation shifts from descending inhibition towards descending facilitation following muscle nociception in FM. Peripheral mechanical hyperalgesia and descending facilitation counterbalance the effect of descending inhibition in FM.
在健康受试者中,持续等长肌肉收缩(疲劳收缩)会募集节段和/或节段外下行抑制,但在纤维肌痛(FM)中则不会。我们假设疲劳收缩可能会使下行疼痛调节从抑制转向易化,并且下行疼痛调节的效果取决于外周肌肉疼痛敏感性。
在 22 例 FM 患者和 22 例匹配的健康对照组中,在肩部外展疲劳收缩之前、之后立即和 20 分钟后,从双侧上斜方肌的 13 个点和双侧胫骨前肌的中点测量压力疼痛阈值(PPT)。记录疲劳的速度、疼痛强度和疲劳收缩的持续时间。
FM 组疲劳收缩的持续时间明显短于健康对照组(132.4 ± 25.2 秒比 286.2 ± 24.1 秒)(P < 0.05),FM 组疼痛强度明显高于健康对照组(8.25 ± 0.8 厘米比 5.1 ± 0.65 厘米)(P < 0.01),而两组的疲劳强度相似(P > 0.05)。收缩后,上斜方肌的 PPT 随时间显著增加且不均匀,但健康对照组的胫骨前肌则没有。然而,胫骨前肌的 PPT 随时间显著降低(P < 0.05),但上斜方肌则没有。
在 FM 中,肌肉伤害感受后下行疼痛调节从下行抑制转变为下行易化。外周机械性痛觉过敏和下行易化抵消了 FM 中下行抑制的效果。