Wang Kelun, Svensson Peter, Arendt-Nielsen Lars
Center for Sensory-Motor Interaction, Orofacial Pain Laboratory, Aalborg University, Fredrik Bajers Vej 7 D-3, DK-9220 Aalborg S, Denmark Department of Prosthetic Dentistry and Stomatognathic Physiology, Royal Dental College, University of Aarhus, Aarhus, Denmark.
Pain. 1999 Sep;82(3):253-262. doi: 10.1016/S0304-3959(99)00058-5.
The exteroceptive suppression periods (ES) in human jaw-closing muscles can be conditioned by a wide range of somatosensory stimuli and cognitive states. The aim of this study was to examine the effects of tonic experimental jaw-muscle pain versus remote muscle pain on the short-latency (ES1) and long-latency (ES2) reflex in the jaw-closing muscles. Twelve healthy subjects participated in the first experiment with jaw-muscle pain. In random order 5% hypertonic or 0.9% isotonic saline was infused into the left masseter muscle for 15 min. The pain intensity was scored continuously by the subjects on a 10-cm visual analogue scale (VAS). Electromyographic (EMG) activity was recorded bilaterally from the masseter and temporalis muscles during the pre-infusion, early phase of infusion (from 120 to 480 s), late phase of infusion (from 540 to 900 s) and post-infusion. An electrical stimulus was delivered to the skin above the left mental nerve (ipsilateral to the painful muscle) to evoke the ES in the contracting jaw-closing muscles. Ten healthy subjects participated in experiment 2 which was as identical to experiment 1 except that the electrical stimulus was delivered to the right mental nerve (contralateral to the painful muscle). Nine healthy subjects participated experiment 3 where remote muscle pain was induced in the left tibialis anterior muscle. In experiment 1 painful infusion of hypertonic saline caused a significantly later onset latency of ES2 in the left masseter muscle during the late phase of infusion compared to pre-infusion values (P < 0.05). The duration of ES2 in the same muscle was significantly shorter during the late infusion phase compared to pre- and post-infusion values (P < 0.05) and the degree of suppression was significantly reduced during the early infusion compared to the pre-infusion values (P < 0.05). Isotonic saline did not influence the ES1 or ES2. In experiment 2, similar significant inhibitory changes were found in the ES2 on the painful side. In experiment 3, no significant effects on ES1 and ES2 were observed during painful infusion of hypertonic saline into the leg muscle. These results indicate that the effects of tonic jaw-muscle pain on ES2 can be distinguished from a generalized effect of muscle pain. Furthermore, there seems to be a differential and lateralized effect of jaw-muscle pain on the brain stem reflex circuits involved in the generation of ES1 and ES2 probably through a presynaptic mechanism.
人类咬肌的外感受性抑制期（ES）可受多种体感刺激和认知状态的影响。本研究的目的是检验持续性实验性咬肌疼痛与远隔肌肉疼痛对咬肌短潜伏期（ES1）和长潜伏期（ES2）反射的影响。12名健康受试者参与了咬肌疼痛的第一个实验。以随机顺序将5%高渗盐水或0.9%等渗盐水注入左侧咬肌15分钟。受试者在10厘米视觉模拟量表（VAS）上持续对疼痛强度进行评分。在注入前、注入早期（120至480秒）、注入后期（540至900秒）和注入后，双侧记录咬肌和颞肌的肌电图（EMG）活动。向左侧颏神经上方的皮肤（与疼痛肌肉同侧）施加电刺激，以诱发收缩的咬肌中的ES。10名健康受试者参与了实验2，该实验与实验1相同，只是电刺激施加到右侧颏神经（与疼痛肌肉对侧）。9名健康受试者参与了实验3，在该实验中左侧胫骨前肌诱发了远隔肌肉疼痛。在实验1中，与注入前的值相比，高渗盐水的疼痛注入在注入后期导致左侧咬肌中ES2的起始潜伏期显著延迟（P < 0.05）。与注入前和注入后的值相比，同一肌肉中ES2的持续时间在注入后期显著缩短（P < 0.05），并且与注入前的值相比，在注入早期抑制程度显著降低（P < 0.05）。等渗盐水对ES1或ES2没有影响。在实验2中，在疼痛侧的ES2中发现了类似的显著抑制变化。在实验3中，向腿部肌肉注入高渗盐水时，未观察到对ES1和ES2有显著影响。这些结果表明，持续性咬肌疼痛对ES2的影响可与肌肉疼痛的全身性影响区分开来。此外，咬肌疼痛对参与ES1和ES2产生的脑干反射回路似乎存在差异性和侧化效应，可能是通过突触前机制实现的。
