Descending analgesia - When the spine echoes what the brain expects
Descending analgesia - When the spine echoes what the brain expects
复制标题
DOI：
10.1016/j.pain.2006.11.011
复制
发表时间：
2007-07-01
期刊：
影响因子：
7.4
通讯作者：
Marchand, Serge
中科院分区：
文献类型：
--
作者：
Goffaux, Philippe;Redmond, William John;Marchand, Serge
由心理因素引起的疼痛变化（例如，安慰剂镇痛）被认为是由特定皮质区域的活动引起的。然而，当受试者期望疼痛缓解时，皮质下核团，包括导水管周围灰质和延髓吻腹侧区，也显示出选择性激活。这些脑干区域向脊柱发送抑制性投射，并产生弥漫性镇痛反应。遗憾的是，脊髓机制在预测安慰剂镇痛强度方面的确切作用尚不清楚。在这里，我们表明，对疼痛的期望从根本上改变了人类脊髓伤害性反应的强度。我们发现，与镇痛的预期相反，痛觉过敏的预期完全阻断了脊髓伤害性反射下降抑制的镇痛作用。体感诱发脑电位和疼痛评分进一步证实了脊髓丘脑皮层反应的变化与预期和脊髓反应的变化一致。这些研究结果提供了直接的证据表明，预期的疼痛调制是由内源性疼痛调节系统介导的，影响伤害性信号处理在中枢神经系统的最早阶段。因此，预期效应既取决于大脑中发生的事情，也取决于脊柱中发生的事情。此外，完全抑制通常由下行抑制产生的镇痛反应表明，抗镇痛预期可以阻断有效治疗的疗效，这对临床实践具有重要意义。(C)2006年国际疼痛研究协会。Elsevier B.V.出版，保留所有权利。
Changes in pain produced by psychological factors (e.g., placebo analgesia) are thought to result from the activity of specific cortical regions. However, subcortical nuclei, including the periaqueductal gray and the rostroventral medulla, also show selective activation when,subjects expect pain relief. These brainstem regions send inhibitory projections to the spine and produce diffuse analgesic responses. Regrettably the precise contribution of spinal mechanisms in predicting the strength of placebo analgesia is unknown. Here, we show that expectations regarding pain radically change the strength of spinal nociceptive responses in humans. We found that contrary to expectations of analgesia, expectations of hyperalgesia, completely blocked the analgesic effects of descending inhibition on spinal nociceptive reflexes. Somatosensory-evoked brain potentials and pain ratings further confirmed changes in spino-thalamo-cortical responses consistent with expectations and with changes in the spinal response. These findings provide direct evidence that the modulation of pain by expectations is mediated by endogenous pain modulatory systems affecting nociceptive signal processing at the earliest stage of the central nervous system. Expectation effects, therefore, depend as much about what takes place in the spine as they do about what takes place in the brain. Furthermore, complete suppression of the analgesic response normally produced by descending inhibition suggests that anti-analgesic expectations can block the efficacy of pharmacologically valid treatments which has important implications for clinical practice. (C) 2006 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.