Kosek Eva, Hansson Per
Section of Clinical Pain Research, Department Surgical Sciences, Karolinska Institute/Hospital, S-171 77 Stockholm, Sweden.
Eur J Pain. 2002;6(6):413-25. doi: 10.1016/s1090-3801(02)00041-1.
The aim of this study was to investigate the influence of experimental pain intensity in the local and referred pain area on somatosensory perception thresholds in the area of referred pain. Pain was induced by intramuscular electrical stimulation of the left infraspinatus muscle in 12 healthy individuals. The stimulation corresponded to the local pain threshold ("mild local pain"), the referred pain threshold ("mild referred pain"), and a pain intensity corresponding to 2 on a 10-point category scale in the referred pain area ("moderate referred pain"). Quantitative sensory testing was performed to assess perception thresholds in the referred pain area and the homologous contralateral area before and during stimulation. Perception thresholds to light touch (LTTs), pressure pain (PPTs), and to innocuous as well as noxious warmth and cold were assessed. During stimulation the LTTs increased in the referred pain area compared to baseline, uninfluenced by pain intensity. Perception thresholds to innocuous cold and warmth increased bilaterally during the stimulation, without relation to pain intensity. Heat pain thresholds were not affected. Compared to baseline, PPTs increased bilaterally during stimulation corresponding to "mild local pain" and "mild referred pain", respectively, and a further increase was seen during "moderate referred pain". The decreased sensitivity to innocuous cold, warmth, and pressure pain was bilateral, indicating activation of endogenous net inhibitory mechanisms interacting bilaterally. We found no influence of pain intensity on somatosensory thresholds restricted to the referred pain area and light touch was the only affected modality in the referred pain area only.
本研究旨在探讨局部和牵涉痛区域的实验性疼痛强度对牵涉痛区域体感知觉阈值的影响。对12名健康个体的左冈下肌进行肌内电刺激以诱发疼痛。刺激强度分别对应局部疼痛阈值（“轻度局部疼痛”）、牵涉痛阈值（“轻度牵涉痛”）以及牵涉痛区域10分制量表上相当于2分的疼痛强度（“中度牵涉痛”）。在刺激前和刺激期间进行定量感觉测试，以评估牵涉痛区域和对侧同源区域的知觉阈值。评估了轻触觉（LTTs）、压痛（PPTs）以及无害和有害的温热觉的知觉阈值。在刺激期间，与基线相比，牵涉痛区域的LTTs升高，且不受疼痛强度影响。刺激期间，双侧无害冷觉和温觉的知觉阈值升高，与疼痛强度无关。热痛阈值未受影响。与基线相比，在分别对应“轻度局部疼痛”和“轻度牵涉痛”的刺激期间，双侧PPTs升高，在“中度牵涉痛”期间进一步升高。对无害冷觉、温觉和压痛的敏感性降低是双侧性的，表明内源性净抑制机制的激活具有双侧相互作用。我们发现疼痛强度对仅限于牵涉痛区域的体感阈值没有影响，并且轻触觉是仅在牵涉痛区域受影响的唯一感觉模式。
