Department of Physiotherapy, Pain and Exercise Research Luebeck (P.E.R.L.), Institute of Health Sciences, University of Luebeck, Luebeck, Germany.
Laboratory of Pain Research, Institute of Physiotherapy and Health Sciences, The Jerzy Kukuczka Academy of Physical Education, Katowice, Poland.
Pain. 2021 Jun 1;162(6):1771-1780. doi: 10.1097/j.pain.0000000000002186.
When nociceptive stimulation affects a larger body area, pain increases. This effect is called spatial summation of pain (SSp). The aim of this study was to describe SSp as a function of the size or distance of a stimulated area(s) and to test how this function is shaped by the intensity and SSp test paradigm. Thirty-one healthy volunteers participated in a within-subject experiment. Participants were exposed to area-based and distanced-based SSp. For area-based SSp, electrocutaneous noxious stimuli were applied by up to 5 electrodes (5 areas) forming a line-like pattern; for distance-based SSp, the same position and lengths of stimuli were used but only 2 electrodes were stimulated. Each paradigm was repeated using pain of low, moderate, and high intensity. It was found that the pattern of pain intensity followed a logarithmic (power) rather than a linear function. The dynamics of the pain increase were significantly different across pain intensities, with more summation occurring when pain was perceived as low. Results indicated that area-based SSp is more painful than distance-based SSp when low and moderate but not when high pain intensity is induced. Presented findings have important implications for all studies in which the spatial dimension of pain is measured. When the area or separation between nociceptive stimulation increases, pain does not increase linearly and the pattern of the pain increase is a result of the interaction between intensity and the number of nociceptive sites. A power function should be considered when predicting the size of a nociceptive source.
当伤害性刺激影响更大的身体区域时，疼痛会加剧。这种效应被称为疼痛的空间总和（SSp）。本研究的目的是描述作为刺激区域的大小或距离的函数的 SSp，并测试这种功能如何受到强度和 SSp 测试范式的影响。31 名健康志愿者参与了一项个体内实验。参与者暴露于基于区域和基于距离的 SSp。对于基于区域的 SSp，通过多达 5 个电极（5 个区域）施加电刺激来产生线状模式；对于基于距离的 SSp，使用相同的位置和长度的刺激，但仅刺激 2 个电极。每个范式都使用低、中、高强度的疼痛重复。结果发现，疼痛强度的模式遵循对数（幂）而不是线性函数。疼痛强度的动力学在不同的疼痛强度下有显著差异，当疼痛被感知为低强度时，会有更多的总和。结果表明，当疼痛强度较低和中等时，基于区域的 SSp 比基于距离的 SSp 更疼痛，但当疼痛强度较高时则不然。所提出的发现对所有测量疼痛空间维度的研究都具有重要意义。当伤害性刺激的面积或分离增加时，疼痛不会线性增加，疼痛增加的模式是强度和伤害性部位数量之间相互作用的结果。在预测伤害性来源的大小时，应考虑幂函数。
