What a Sham(e): Sham-Controlled Conditioned Pain Modulation Effects on Pressure but Not Heat Pain Thresholds in Healthy Volunteers

IF 3.4 2区医学 Q1 ANESTHESIOLOGY

European Journal of Pain Pub Date : 2025-07-01 DOI:10.1002/ejp.70067

Madeleine Hau, Laura Sirucek, Iara De Schoenmacker, Robin Lütolf, Lindsay Gorrell, Michèle Hubli, Petra Schweinhardt

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Abstract

Background

Conditioned pain modulation (CPM) is a well-established experimental paradigm to study descending pain modulation in humans, measuring the pain modulatory effect of a painful conditioning stimulus (CS) on a painful test stimulus (TS). Control conditions using a non-painful CS accounting for modulatory effects not attributable to the painfulness of the CS are seldom included. Thus, this study aimed to differentiate CPM effects from perceived changes of the TS unrelated to the painfulness of the CS by comparing effects of a painful and a control CS on four different TS.

Methods

Forty-nine healthy participants underwent a combined parallel and sequential CPM paradigm with a cold water bath (median NRS 8/10) as painful and an ambient-temperature sham water bath (median NRS 0/10) as non-painful control CS. TS were pressure and heat pain thresholds (PPT, HPT) (parallel and sequential) and temporal summation of pain (TSP, sequential) (pressure and heat). Larger TS changes with the painful compared to the control CS were interpreted as sham-controlled CPM effects.

Results

A parallel sham-controlled CPM effect was only detected for PPT (significantly larger PPT increases during the painful compared to the control condition (p = 0.009)). HPT increased for both conditions without a significant difference between conditions (p = 0.152). TSP was successfully induced but not modulated by either CS (p > 0.05).

Conclusion

This study demonstrates sham-controlled CPM effects on PPT, but not on HPT, most likely due to heat adaptation or habituation. This challenges the interpretation of prior studies using CPM paradigms with HPT as TS without a control condition.

Significance

This study highlights the importance of including control conditions in CPM paradigms using HPT as TS. HPT increased similarly during a painful and a control condition, most likely due to adaptation and habituation. Although these are known effects, CPM studies rarely control for them. Pressure pain thresholds increased more during the painful than during the control condition, making it a more suitable TS, especially when a control condition is absent.

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真假(e)：假控制的条件疼痛调节对健康志愿者压力痛阈的影响，而不是热痛阈

条件疼痛调节（CPM）是研究人类下行疼痛调节的一种成熟的实验范式，测量疼痛条件刺激（CS）对疼痛测试刺激（TS）的疼痛调节作用。使用非疼痛性中枢神经系统来考虑非疼痛性中枢神经系统的调节作用的控制条件很少被包括在内。因此,本研究旨在通过比较疼痛性和对照性疼痛对四种不同疼痛性的影响，来区分CPM效应与感知到的与疼痛性无关的TS变化。方法49名健康参与者接受了平行和顺序CPM组合范式，其中冷水浴（中位NRS 8/10）为疼痛，室温假水浴（中位NRS 0/10）。作为无痛控制CS。TS是压力和热痛阈值（PPT， HPT）（平行和顺序）和疼痛时间总和（TSP，顺序）（压力和热）。与对照CS相比，疼痛引起的较大TS变化被解释为假控制CPM效应。结果平行假对照CPM效应仅在PPT组被检测到（与对照组相比，PPT在疼痛时显著增加（p = 0.009））。两种情况下HPT均升高，但两种情况间无显著差异（p = 0.152）。两种CS均能成功诱导TSP，但未调节TSP （p > 0.05）。结论本研究表明假控制CPM对PPT有影响，但对HPT没有影响，这很可能是由于热适应或习惯。这挑战了先前使用CPM范式与HPT作为TS而没有控制条件的研究的解释。本研究强调了在CPM范式中将HPT作为TS纳入控制条件的重要性。HPT在疼痛条件和控制条件下相似地增加，很可能是由于适应和习惯化。虽然这些都是已知的影响，但CPM研究很少控制它们。压力疼痛阈值在疼痛过程中比在控制条件下增加更多，使其成为更合适的TS，特别是在没有控制条件的情况下。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

European Journal of Pain 医学-临床神经学

CiteScore

7.50

自引率

5.60%

发文量

163

审稿时长

4-8 weeks

期刊介绍： European Journal of Pain (EJP) publishes clinical and basic science research papers relevant to all aspects of pain and its management, including specialties such as anaesthesia, dentistry, neurology and neurosurgery, orthopaedics, palliative care, pharmacology, physiology, psychiatry, psychology and rehabilitation; socio-economic aspects of pain are also covered. Regular sections in the journal are as follows: • Editorials and Commentaries • Position Papers and Guidelines • Reviews • Original Articles • Letters • Bookshelf The journal particularly welcomes clinical trials, which are published on an occasional basis. Research articles are published under the following subject headings: • Neurobiology • Neurology • Experimental Pharmacology • Clinical Pharmacology • Psychology • Behavioural Therapy • Epidemiology • Cancer Pain • Acute Pain • Clinical Trials.