Rasmussen Vibe Maria, Ellehuus-Hilmersson Catarina, Rotbøll-Nielsen Per, Werner Mads Utke
Department of Anesthesia, Vejle Sygehus/Sygehus Lillebælt, Kabbeltoft 25, DK 7100 Vejle, Denmark.
Department of Internal Medicine, University Hospital of Skåne, SE 221 85 Lund, Sweden.
Scand J Pain. 2015 Oct 1;9(1):81-86. doi: 10.1016/j.sjpain.2014.12.001.
Background and aims Quantitative sensory testing of thermal perception (QTT) is a valuable method in clinical and experimental assessment of the function of small nerve fibres. Previous studies have indicated existence of spatial summation for warmth, cool and heat pain stimulation, but study designs and assessment methods have not always been mutually consistent. The aims of this study were, first, to examine spatial summation of QTT by differently sized contact thermodes, and, second, to evaluate if these differences are significant from a clinical and scientific perspective. Methods Sixteen healthy subjects were included. Warmth detection (WDT), cool detection (CDT) and heat pain (HPT) thresholds were assessed in random order, with the stimulation areas of the contact thermodes of 3.0, 6.3 and 12.5 cm2, blinded to the subjects. Assessments were made bilaterally at volar part of the distal arm and medial part of the lower leg. Data analyses were by a mixed model with random effect for subject and fixed-effects for the variables, site (arm/leg), thermode area (ln thermode area) and side (dominant/non-dominant), in addition to conventional pairwise non-parametric comparisons. Results Data from 2 subjects were excluded. In the remaining 14 subjects only 4 subjects were able to identify the correct sequence of thermode sizes. The model demonstrated highly statistical significant relationships regarding main effects: thermode area (P < 0.0001) and stimulation site (P < 0.0001; except for CDT P = 0.011). The only significant interaction was between thermode area*site (P = 0.005) for CDT. The study demonstrated in 17 of 18 possible comparisons between thermode size and stimulation site, a significant spatial summation for WDT, CDT and HPT. Conclusion This randomized, single-blind study of thermal thresholds demonstrated spatial summation and that considerable deviations may occur if values obtained with differing thermode sizes are used uncritically. Implications Data from the present study enable interpolation of thermal thresholds with differing thermode sizes, facilitating comparisons across studies.
背景与目的 热觉定量感觉测试（QTT）是临床和实验中评估小神经纤维功能的一种有价值的方法。先前的研究表明，在温暖、凉爽和热痛刺激方面存在空间总和现象，但研究设计和评估方法并不总是相互一致。本研究的目的，一是通过不同大小的接触式热刺激器来检验QTT的空间总和，二是从临床和科学角度评估这些差异是否显著。方法 纳入16名健康受试者。以随机顺序评估温暖觉检测（WDT）、冷觉检测（CDT）和热痛（HPT）阈值，使用面积分别为3.0、6.3和12.5平方厘米的接触式热刺激器进行刺激，受试者对此不知情。在双侧的前臂掌侧和小腿内侧进行评估。数据分析采用混合模型，对受试者采用随机效应，对变量、部位（手臂/腿部）、热刺激器面积（热刺激器面积的自然对数）和侧别（优势侧/非优势侧）采用固定效应，此外还进行常规的成对非参数比较。结果 排除了2名受试者的数据。在其余14名受试者中，只有4名能够识别热刺激器大小的正确顺序。该模型显示出关于主要效应的高度统计学显著关系：热刺激器面积（P < 0.0001）和刺激部位（P < 0.0001；冷觉检测除外，P = 0.011）。唯一显著的交互作用是冷觉检测中热刺激器面积*部位之间的交互作用（P = 0.005）。该研究在热刺激器大小与刺激部位之间18种可能的比较中有17种显示，温暖觉检测、冷觉检测和热痛阈值存在显著的空间总和。结论 这项关于热阈值的随机单盲研究证明了空间总和现象，并且如果不加批判地使用不同热刺激器大小获得的值，可能会出现相当大的偏差。意义 本研究的数据能够对不同热刺激器大小的热阈值进行插值，便于不同研究之间的比较。
