Pedersen Juri L, Kehlet Henrik
Department of Surgical Gastroenterology, Hvidovre University Hospital, Kettegaard Allé 30, DK-2650 Hvidovre, Denmark.
Pain. 1998 Jun;76(3):377-384. doi: 10.1016/S0304-3959(98)00070-0.
The aim of the study was to examine the presence of hyperalgesia to heat stimuli within the zone of secondary hyperalgesia to punctate mechanical stimuli. A burn was produced on the medial part of the non-dominant crus in 15 healthy volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min), and assessments were made 70 min and 40 min before, and 0, 1, and 2 h after the burn injury. Hyperalgesia to mechanical and heat stimuli were examined by von Frey hairs and contact thermodes (3.75 and 12.5 cm2), and pain responses were rated with a visual analog scale (0-100). The area of secondary hyperalgesia to punctate stimuli was assessed with a rigid von Frey hair (462 mN). The heat pain responses to 45 degrees C in 5 s (3.75 cm2) were tested in the area just outside the burn, where the subjects developed secondary hyperalgesia, and on the lateral crus where no subject developed secondary hyperalgesia (control area). The burns decreased pain thresholds and increased pain responses to both thermal and mechanical stimuli within the burn (P < 10(-5)). Further, the burns induced secondary hyperalgesia (mean 89 cm2) to punctate mechanical stimuli (P < 10(-5)), and increased the pain response to mechanical stimuli in the areas of secondary hyperalgesia (P < 10(-5)). The pain response to heat stimuli increased over time in the area of secondary hyperalgesia (P < 10(-5)), and so did the pain response to heat on the lateral part of the crus (P < 10(-3)). However, the heat pain response increased more (P = 0.006) and was more intense (P = 0.001) within the zone of secondary hyperalgesia than on the lateral part of the crus. Further, the heat pain response was more intense in the zone of primary hyperalgesia than in the zone of secondary hyperalgesia (P = 0.004), in contrast to the mechanical pain response, which was not significantly different between the two zones of hyperalgesia. In conclusion, secondary hyperalgesia in man is not restricted to mechanical stimuli, as significant hyperalgesia to heat developed within the zone of secondary hyperalgesia to punctate mechanical stimuli. The data, combined with other evidence, suggest differences in the mechanisms accounting for primary hyperalgesia to heat and mechanical stimuli, whereas secondary hyperalgesia to heat and mechanical stimuli may be explained by a common central mechanism.
本研究的目的是检测在点状机械刺激所致继发性痛觉过敏区域内对热刺激的痛觉过敏情况。在15名健康志愿者的非优势小腿内侧，用一个50×25 mm的热刺激器（47℃，7分钟）造成烧伤，并在烧伤前70分钟和40分钟以及烧伤后0、1和2小时进行评估。通过von Frey毛发和接触式热刺激器（3.75和12.5 cm²）检测对机械和热刺激的痛觉过敏情况，并用视觉模拟量表（0 - 100）对疼痛反应进行评分。用硬von Frey毛发（462 mN）评估对点状刺激的继发性痛觉过敏区域。在烧伤区域外侧（受试者出现继发性痛觉过敏的部位）以及小腿外侧（无受试者出现继发性痛觉过敏的对照区域）测试对45℃持续5秒（3.75 cm²）热刺激的疼痛反应。烧伤降低了烧伤部位内对热和机械刺激的疼痛阈值并增加了疼痛反应（P < 10⁻⁵）。此外，烧伤诱发了对点状机械刺激的继发性痛觉过敏（平均89 cm²）（P < 10⁻⁵），并增加了继发性痛觉过敏区域内对机械刺激的疼痛反应（P < 10⁻⁵）。在继发性痛觉过敏区域内，对热刺激的疼痛反应随时间增加（P < 10⁻⁵），小腿外侧对热刺激的疼痛反应也是如此（P < 10⁻³）。然而，继发性痛觉过敏区域内的热痛反应增加得更多（P = 0.006）且更强烈（P = 0.001），相比小腿外侧。此外，原发性痛觉过敏区域内的热痛反应比继发性痛觉过敏区域内更强烈（P = 0.004），这与机械性疼痛反应不同，后者在两个痛觉过敏区域之间无显著差异。总之，人类的继发性痛觉过敏并不局限于机械刺激，因为在点状机械刺激所致继发性痛觉过敏区域内出现了对热的显著痛觉过敏。这些数据与其他证据相结合，提示解释原发性热痛觉过敏和机械性痛觉过敏的机制存在差异，而继发性热痛觉过敏和机械性痛觉过敏可能由共同的中枢机制解释。
