Background Conditioned pain modulation (CPM) evaluates the effect of a painful conditioning stimulus (CS) on a painful test stimulus (TS). Using painful cutaneous electrical stimulation (PCES) as TS and painful cold water as CS, the pain relief was paralleled by a decrease in evoked potentials (PCES-EPs). We now aimed to compare the effect of CPM with cognitive distraction on PCES-induced pain and PCES-EP amplitudes. Methods PCES was performed using surface electrodes inducing a painful sensation of 60 (NRS 0–100) on one hand. In a crossover design healthy subjects (included: n = 38, analyzed: n = 23) immersed the contralateral hand into 10 °C cold water (CS) for CPM evaluation and performed the 1-back task for cognitive distraction. Before and during the CS and 1-back task, respectively, subjects rated the pain intensity of PCES and simultaneously cortical evoked potentials were recorded. Results Both CPM and cognitive distraction significantly reduced PCES-EP amplitudes (CPM: 27.6 ± 12.0 μV to 20.2 ± 9.5 μV, cognitive distraction: 30.3 ± 14.2 µV to 13.6 ± 5.2 μV, p < 0.001) and PCES-induced pain (on a 0–100 numerical rating scale: CPM: 58 ± 4 to 41.1 ± 12.3, cognitive distraction: 58.3 ± 4.4 to 38.0 ± 13.0, p < 0.001), though the changes in pain intensity and PCES-amplitude did not correlate. The changes of the PCES-EP amplitudes during cognitive distraction were more pronounced than during CPM (p = 0.001). Conclusions CPM and cognitive distraction reduced the PCES-induced pain to a similar extent. The more pronounced decrease of PCES-EP amplitudes after distraction by a cognitive task implies that both conditions might not represent the general pain modulatory capacity of individuals, but may underlie different neuronal mechanisms with the final common pathway of perceived pain reduction.

中文翻译：

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与条件性疼痛调制相比，认知任务的分心对电生理测量的影响更大

背景 条件性疼痛调制 (CPM) 评估疼痛性条件刺激 (CS) 对疼痛测试刺激 (TS) 的影响。使用痛苦的皮肤电刺激 (PCES) 作为 TS 和痛苦的冷水作为 CS，疼痛缓解与诱发电位 (PCES-EPs) 的降低并行。我们现在旨在比较 CPM 与认知分心对 PCES 引起的疼痛和 PCES-EP 振幅的影响。方法 使用表面电极进行 PCES，一方面诱发 60 (NRS 0-100) 的疼痛感。在交叉设计中，健康受试者（包括：n = 38，分析：n = 23）将对侧手浸入 10 °C 冷水 (CS) 中进行 CPM 评估，并执行 1-back 任务以进行认知分心。分别在 CS 和 1-back 任务之前和期间，受试者对 PCES 的疼痛强度进行评分，同时记录皮层诱发电位。结果 CPM 和认知分心均显着降低 PCES-EP 振幅（CPM：27.6 ± 12.0 μV 至 20.2 ± 9.5 μV，认知分心：30.3 ± 14.2 μV 至 13.6 ± 5.2 μV，p < 0.001）和 PCES 诱发的疼痛（a 0-100 数字评分量表：CPM：58 ± 4 至 41.1 ± 12.3，认知分心：58.3 ± 4.4 至 38.0 ± 13.0，p < 0.001），尽管疼痛强度和 PCES 幅度的变化不相关。认知分心期间 PCES-EP 振幅的变化比 CPM 期间更明显（p = 0.001）。结论 CPM 和认知分心在相似程度上减少了 PCES 引起的疼痛。