Staud Roland, Price Donald D, Fillingim Roger B
Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32610, USA.
J Pain. 2006 Aug;7(8):575-82. doi: 10.1016/j.jpain.2006.02.005.
Temporal summation of second pain or windup (WU(SP)) can be reliably evoked in normal human subjects by repetitive heat pulses to the skin at frequencies of 0.33 Hz or more. This phenomenon is dependent on activation of peripheral C-nociceptors and central N-methyl-D-aspartate receptors, resulting in windup of C-fiber-evoked discharges of dorsal horn neurons. Several investigations of heat pain summation have used Peltier devices for intermittent-contact heat pulses to the skin. This method returns the skin to an adapting temperature between each stimulus and can result in distinct first and second pain sensations. An alternative method of temporal summation consists of continuous-contact heat stimuli by computerized Peltier thermodes that can provide rapid heat pulses. Previously used continuous-contact heat pulse trains, however, seemed to lack characteristics that result in efficient WU(SP). The present study sought to obtain psychophysical evidence that reliable WU(SP) can be elicited with an advanced pulse design by using a computerized heat-foil/Peltier thermode. WU(SP) was elicited by repetitive thermal stimulation of the hands at frequencies of 0.33 Hz but not 0.25 and 0.17 Hz. WU(SP) stimuli were either adjusted to resemble the heat transfer characteristics of intermittent-contact stimulus trains, or they remained unadjusted. The estimated transmission velocity of impulses giving rise to second pain and WU(SP) was characteristic of C fibers. More pronounced second pain and efficient WU(SP) could be elicited with adjusted than with unadjusted heat pulse trains. Thus, specifically designed continuous-contact heat pulses can be used to elicit distinct second pain and robust WU(SP), thereby providing an efficient psychophysical test of this phenomenon.
Temporal summation testing is rapidly becoming a relevant psychophysical tool for the study of chronic pain disorders. The results of this study will allow more efficient use of currently available constant-contact thermodes for clinical and research applications.
通过以0.33Hz或更高频率对皮肤进行重复性热脉冲刺激，可在正常人类受试者中可靠地诱发第二痛的时间总和或windup（WU(SP)）。这种现象依赖于外周C类伤害感受器和中枢N-甲基-D-天冬氨酸受体的激活，导致背角神经元的C纤维诱发放电增强。几项关于热痛总和的研究使用珀耳帖装置对皮肤进行间歇性接触热脉冲刺激。这种方法在每次刺激之间使皮肤恢复到适应温度，并可导致明显的第一痛和第二痛觉。时间总和的另一种方法是通过计算机控制的珀耳帖热电极进行连续接触热刺激，其可提供快速热脉冲。然而，先前使用的连续接触热脉冲序列似乎缺乏能有效诱发WU(SP)的特征。本研究试图获得心理物理学证据，即通过使用计算机化热箔/珀耳帖热电极的先进脉冲设计可诱发可靠的WU(SP)。通过以0.33Hz而非0.25Hz和0.17Hz的频率对手部进行重复性热刺激来诱发WU(SP)。WU(SP)刺激要么进行调整以类似于间歇性接触刺激序列的热传递特性，要么保持未调整状态。引发第二痛和WU(SP)的冲动的估计传导速度具有C纤维的特征。与未调整热脉冲序列相比，调整后的热脉冲序列可引发更明显的第二痛和更有效的WU(SP)。因此，专门设计的连续接触热脉冲可用于诱发明显的第二痛和强烈的WU(SP)，从而为该现象提供一种有效的心理物理学测试方法。
时间总和测试正迅速成为研究慢性疼痛障碍的一种相关心理物理学工具。本研究结果将使目前可用的恒接触热电极在临床和研究应用中得到更有效的利用。
