Treede Rolf-Detlef, Cole Jonathan D
Institute of Physiology, University Hospital Eppendorf, D-2000 Hamburg 20 Germany Wessex Neurological Centre, Southampton General Hospital, Southampton SO9 4XY UK Institute of Physiology and Pathophysiology, Johannes Gutenberg University Mainz, D-6500 MainzGermany.
Pain. 1993 May;53(2):169-174. doi: 10.1016/0304-3959(93)90077-3.
In the skin surrounding a site of injury, hyperalgesia develops to mechanical stimuli. Two types of secondary hyperalgesia (to light touch and punctate stimuli) have recently been differentiated, based on different durations and sizes of the area involved. We studied secondary hyperalgesia in a subject who had a loss of myelinated afferent nerve fibres below the neck that spared the A delta group. Stroking with a cotton swab was not perceived anywhere on affected skin either before or after injection of 60 micrograms of capsaicin. Thus, there was no hyperalgesia to light touch. Capsaicin injection into the volar forearm evoked normal pain and flare. A von Frey probe exerting a force of 40 mN was perceived as sharp. The sensation of sharpness was more pronounced up to 2 cm outside the flare zone for at least 16 min following the injection (tested with a 200 mN von Frey probe). Thus, hyperalgesia to punctate stimuli developed as in healthy subjects. These data support the model that hyperalgesia to light touch (allodynia) is due to sensitisation of central pain-signaling neurones to low-threshold mechanoreceptor input (A beta fibres). In contrast, punctate hyperalgesia is likely to be due to sensitisation to nociceptor input (A delta or C fibres).
在损伤部位周围的皮肤中，对机械刺激会产生痛觉过敏。基于所涉及区域的不同持续时间和大小，最近区分出了两种继发性痛觉过敏（对轻触觉和点状刺激的痛觉过敏）。我们对一名颈部以下有髓传入神经纤维缺失但Aδ组神经纤维未受影响的受试者的继发性痛觉过敏进行了研究。在注射60微克辣椒素之前和之后，用棉签轻擦在受影响的皮肤上任何部位都没有感觉。因此，对轻触觉不存在痛觉过敏。向掌侧前臂注射辣椒素会引起正常的疼痛和红晕。施加40毫牛顿力的von Frey探针被感知为尖锐。在注射后至少16分钟内，在红晕区域外2厘米范围内，尖锐感更为明显（用200毫牛顿的von Frey探针测试）。因此，对点状刺激的痛觉过敏和健康受试者一样出现了。这些数据支持了这样一种模型，即对轻触觉的痛觉过敏（异常性疼痛）是由于中枢痛觉信号神经元对低阈值机械感受器输入（Aβ纤维）的敏化所致。相比之下，点状痛觉过敏可能是由于对伤害感受器输入（Aδ或C纤维）的敏化所致。
