Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
Eur J Pain. 2022 Sep;26(8):1679-1690. doi: 10.1002/ejp.1990. Epub 2022 Jun 27.
Habituation is a response decrement resulting from repeated stimuli. Reduced habituation to noxious stimuli is considered to be a proxy for central sensitization in subjects with chronic pain. Despite numerous investigations of pain habituation in relation to central sensitization, there is no consensus on the most sensitive and reliable readout, as well as analysis approach. Therefore, this study compared the usability and reliability of different readouts and habituation analysis approaches to measure pain habituation in response to repetitive heat simulation.
Three blocks of 20 contact heat stimuli were applied on the volar forearm of 20 healthy subjects on two separate visits. Habituation was assessed by three different readouts: pain ratings, contact heat evoked potentials (CHEPs) and heat-induced sympathetic skin responses (SSRs). In addition, two different habituation analysis approaches were used: between the three stimulation blocks (between-block) and within the first stimulation block (within-block).
Significant between-block habituation for SSRs (p < 0.001), but not for pain ratings (p = 1.000) and CHEPs (p = 0.078) was found. There was significant within-block habituation for pain ratings (p = 0.012) and SSRs (p < 0.001), but not for CHEPs (p = 0.246). Only the between-block habituation of heat-induced SSR was reliable between the two visits (first to second block: intraclass correlation coefficient [ICC] = 0.58, p = 0.030; first to third block: ICC = 0.64, p = 0.015).
Heat-induced SSR as a measure of pain-autonomic interaction revealed the strongest pain habituation and showed the highest test-retest reliability.
习惯化是一种由于重复刺激而导致的反应减退。在患有慢性疼痛的患者中，对有害刺激的习惯化减少被认为是中枢敏化的替代指标。尽管有许多关于疼痛习惯化与中枢敏化关系的研究，但对于最敏感和可靠的读数以及分析方法仍没有共识。因此，本研究比较了不同读数和习惯化分析方法在测量重复热模拟引起的疼痛习惯化中的可用性和可靠性。
在两次单独访问中，将三个 20 次的接触热刺激块应用于 20 名健康受试者的掌侧前臂。通过三种不同的读数评估习惯化：疼痛评分、接触热诱发电位（CHEPs）和热诱导的交感皮肤反应（SSRs）。此外，使用了两种不同的习惯化分析方法：在三个刺激块之间（块间）和在第一个刺激块内（块内）。
发现 SSR 有显著的块间习惯化（p<0.001），但疼痛评分（p=1.000）和 CHEPs（p=0.078）没有。疼痛评分（p=0.012）和 SSRs（p<0.001）有显著的块内习惯化，但 CHEPs 没有（p=0.246）。只有热诱导 SSR 的块间习惯化在两次访问之间是可靠的（第一块到第二块：组内相关系数 [ICC] = 0.58，p=0.030；第一块到第三块：ICC = 0.64，p=0.015）。
作为疼痛自主相互作用的测量指标，热诱导 SSR 显示出最强的疼痛习惯化，并显示出最高的测试-重测可靠性。
