Reid Emily, Harvie Daniel, Miegel Rohan, Spence Charles, Moseley G Lorimer
Sansom Institute for Health Research, University of South Australia, Adelaide, Australia.
Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
J Pain. 2015 Jan;16(1):11-8. doi: 10.1016/j.jpain.2014.10.001. Epub 2014 Oct 19.
Spatial summation of pain is well accepted but surprisingly understudied. Area-based summation refers to the increase in pain evoked by increasing the area of stimulation. Distance-based summation refers to the increase in pain evoked by increasing the distance between multiple stimuli. Although transcutaneous electrical stimulation has several advantages over other experimental pain paradigms, whether or not this modality evokes spatial summation remains unknown. We aimed to answer this question in order to lay the foundation for critical studies of spatial summation. Twenty-five healthy participants received stimuli on their forearm, and the primary outcome, pain intensity, was compared across 5 spatial configurations-1 with a single stimulus and 4 paired configurations at 0-, 5-, 10-, and 20-cm separations. Importantly, the potential confounder of a proximal-distal gradient in nociceptive sensitivity was removed in this study. Pain intensity was higher in response to the paired stimuli than in response to the single stimulus (P < .001), and the paired stimuli separated by 5, 10 and 20 cm, evoked greater pain than stimuli at a separation of 0 cm (P < .001), thus confirming both area- and distance-based summation, respectively. We conclude that transcutaneous electrical stimulation is appropriate for future investigations of spatial summation.
Distance-based summation is likely implicated in some clinical pain. However, current understanding for spatial summation is limited. This study demonstrates that transcutaneous electrical stimulation is safe, feasible, and valid for future investigations of spatial summation and will allow critical questions to be answered.
疼痛的空间总和已被广泛接受，但令人惊讶的是，相关研究却很少。基于面积的总和是指通过增加刺激面积所诱发的疼痛增加。基于距离的总和是指通过增加多个刺激之间的距离所诱发的疼痛增加。尽管经皮电刺激相对于其他实验性疼痛范式有几个优点，但这种方式是否会诱发空间总和仍不清楚。我们旨在回答这个问题，以便为空间总和的关键研究奠定基础。25名健康参与者在前臂接受刺激，并比较了5种空间配置下的主要结果——疼痛强度，其中1种为单个刺激，4种为配对配置，刺激间距分别为0厘米、5厘米、10厘米和20厘米。重要的是，本研究消除了伤害性感受敏感性近端-远端梯度这一潜在混杂因素。配对刺激引起的疼痛强度高于单个刺激（P <.001），且间距为5厘米、10厘米和20厘米的配对刺激比间距为0厘米的刺激诱发的疼痛更强烈（P <.001），从而分别证实了基于面积和基于距离的总和。我们得出结论，经皮电刺激适用于未来的空间总和研究。
基于距离的总和可能与某些临床疼痛有关。然而，目前对空间总和的理解有限。这项研究表明，经皮电刺激对于未来的空间总和研究是安全、可行且有效的，将有助于回答关键问题。
