Polianskis Romanas, Graven-Nielsen Thomas, Arendt-Nielsen Lars
Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction (SMI), Aalborg University, Frederik Bajers Vej 7, D-3, DK-9220 Aalborg, Denmark.
Eur J Pain. 2002;6(6):475-84. doi: 10.1016/s1090-3801(02)00058-7.
The study assessed the influence of stimulus modality on adaptation or facilitation of pain during tonic cold and tourniquet pressure stimulation. Experimental set-up for the cold stimulation consisted of a thermo-tank with water, cooled to 3 degrees C, circulation pump, electronic thermometer and an electronic 10 cm visual analogue scale (VAS). Experimental set-up for the tonic pressure stimulation consisted of a pneumatic tourniquet cuff, a computer-controlled air compressor, and an electronic VAS. The first experiment assessed temporal profiles of pain intensity and skin temperature during immersion of the non-dominant hand and lower arm into cold water for 3 min or until the pain tolerance limit was reached. The second experiment assessed temporal profile of cuff pain intensity during constant compressions for 10 min beginning at pain intensities of 2, 4, and 6 cm on the VAS ("VAS 2", "VAS 4" and "VAS 6" sessions). Subjects enduring cold stimulation for less than 3 min were defined as non-adapting to cold and vice versa. The intensity of cold pain in non-adapting subjects increased significantly faster than in adapting subjects and reached significantly higher magnitude. The course of pain intensity during constant compression, estimated by a linear regression line, was increasing or decreasing, representing facilitation or adaptation of pain, respectively. The typical profile of adaptation consisted of an "overshoot" in pain intensity, followed by a decrease in pain intensity. There was significant correlation in VAS slopes between sessions separated by 2-5 days, suggesting consistent pattern in pain responses to tonic pressure stimulation. Adaptation or facilitation rates and the overshoot magnitude were dependent on the initial pain intensity (2, 4, or 6 cm on the VAS). The facilitation rate was highest and the adaptation rate was lowest during the "VAS 2" session, while the facilitation rate was lowest and the adaptation rate was highest during the "VAS 6" session. The overshoot magnitude was lowest during "VAS 6" session. Adapting and non-adapting/facilitating responses to cold and to pressure during "VAS 6" session were not correlated, suggesting that pain course and therefore stimulus tolerance during tonic stimulation are modality-specific. The results of the study suggest that tolerance of tonic painful pressure and cold stimulations is specific to stimulus modality and may represent separate nociceptive mechanisms.
该研究评估了刺激方式对持续性冷刺激和止血带压力刺激期间疼痛适应或易化的影响。冷刺激的实验装置包括一个装有冷却至3摄氏度水的热箱、循环泵、电子温度计和一个10厘米的电子视觉模拟量表（VAS）。持续性压力刺激的实验装置包括一个气动止血带袖带、一台计算机控制的空气压缩机和一个电子VAS。第一个实验评估了非优势手和下臂浸入冷水中3分钟或直至达到疼痛耐受极限期间疼痛强度和皮肤温度的时间变化情况。第二个实验评估了在VAS上疼痛强度分别为2厘米、4厘米和6厘米（“VAS 2”、“VAS 4”和“VAS 6”时段）开始持续压缩10分钟期间袖带疼痛强度的时间变化情况。持续冷刺激少于3分钟的受试者被定义为对冷不适应，反之亦然。不适应冷刺激的受试者的冷痛强度比适应冷刺激的受试者显著增加得更快，且达到的强度显著更高。通过线性回归线估计的持续压缩期间的疼痛强度过程分别呈增加或减少趋势，分别代表疼痛的易化或适应。典型的适应过程包括疼痛强度的“过冲”，随后疼痛强度降低。相隔2至5天的时段之间的VAS斜率存在显著相关性，表明对持续性压力刺激的疼痛反应存在一致模式。适应或易化率以及过冲幅度取决于初始疼痛强度（VAS上的2厘米、4厘米或6厘米）。在“VAS 2”时段易化率最高，适应率最低，而在“VAS 6”时段易化率最低，适应率最高。“VAS 6”时段的过冲幅度最低。“VAS 6”时段对冷和压力的适应与不适应/易化反应不相关，表明持续性刺激期间的疼痛过程以及因此的刺激耐受性是特定于刺激方式的。该研究结果表明，对持续性疼痛压力和冷刺激的耐受性特定于刺激方式，可能代表不同的伤害感受机制。
