Cruz-Almeida Yenisel, Naugle Kelly M, Vierck Charles J, Fillingim Roger B, Riley Joseph L
Institute on Aging, University of Florida, Gainesville, FL, USA.
Cognitive Aging & Memory, University of Florida, Gainesville, FL, USA.
BMC Neurosci. 2015 Apr 18;16:21. doi: 10.1186/s12868-015-0164-4.
Pain intensity clamping uses the REsponse-Dependent Stimulation (REDSTIM) methodology to automatically adjust stimulus intensity to maintain a desired pain rating set-point which is continuously monitored from a subject's real-time pain ratings. REDSTIM blinds subjects regarding the pain intensity set-point, supporting its use for assessing intervention efficacy. By maintaining the pain intensity at a constant level, a potential decrease in pain sensitivity can be detected by an increase in thermode temperature (unknown to the subject) and not by pain ratings alone. Further, previously described sensitizing and desensitizing trends within REDSTIM provide a novel insight into human pain mechanisms overcoming limitations of conventional testing methods. The purpose of the present study was to assess the test-retest reliability of pain intensity clamping using REDSTIM during three separate sessions.
We used a method for testing changes in pain sensitivity of human subjects (REDSTIM) where the stimulus temperature is modulated to clamp pain intensity near a desired set-point. Temperature serves as the response variable and is used to infer pain sensitivity. Several measures were analyzed for reliability including average temperature and area under the curve (AUC). Intraclass correlation coefficients were calculated for each measure at pain rating set-points of 20/100 and 35/100.
Sixteen healthy individuals (mean age = 21.6 ± 3.9) participated in three experiments two days apart at both pain rating set-points. Most reliability coefficients were in the moderate to substantial range (r's = 0.79 to 0.94) except for the negative AUC (r = 0.52), but only at the 20/100 pain rating set-point.
The present study supports the test-retest reliability of pain intensity clamping using the REDSTIM methodology while providing a novel tool to examine human pain modulatory mechanisms and overcoming common shortcomings of conventional quantitative sensory testing methods.
疼痛强度钳夹法采用响应依赖刺激（REDSTIM）方法自动调整刺激强度，以维持从受试者实时疼痛评分中持续监测的期望疼痛评分设定点。REDSTIM使受试者对疼痛强度设定点不知情，支持其用于评估干预效果。通过将疼痛强度维持在恒定水平，可以通过热刺激器温度升高（受试者不知情）而非仅通过疼痛评分来检测疼痛敏感性的潜在降低。此外，REDSTIM中先前描述的敏化和脱敏趋势为克服传统测试方法的局限性提供了对人类疼痛机制的新见解。本研究的目的是评估在三个独立时段使用REDSTIM进行疼痛强度钳夹的重测信度。
我们采用一种测试人类受试者疼痛敏感性变化的方法（REDSTIM），其中刺激温度被调制以将疼痛强度钳夹在期望设定点附近。温度作为响应变量，用于推断疼痛敏感性。分析了包括平均温度和曲线下面积（AUC）在内的几种测量指标的信度。在疼痛评分设定点为20/100和35/100时，计算每个测量指标的组内相关系数。
16名健康个体（平均年龄 = 21.6 ± 3.9）在两个疼痛评分设定点分别于相隔两天的时间参与了三项实验。除了负AUC（r = 0.52）外，大多数信度系数处于中度到高度范围（r值 = 0.79至0.94），但仅在20/100疼痛评分设定点时如此。
本研究支持使用REDSTIM方法进行疼痛强度钳夹的重测信度，同时提供了一种用于研究人类疼痛调节机制并克服传统定量感觉测试方法常见缺点的新工具。
