On the importance of placebo timing in rTMS studies for pain relief
On the importance of placebo timing in rTMS studies for pain relief
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DOI：
10.1016/j.pain.2010.12.027
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发表时间：
2011-06-01
期刊：
影响因子：
7.4
通讯作者：
Garcia-Larrea, Luis
中科院分区：
文献类型：
--
作者：
Andre-Obadia, Nathalie;Magnin, Michel;Garcia-Larrea, Luis
运动皮层重复经颅磁刺激 (rTMS) 缓解神经性疼痛的功效是基于双盲研究与安慰剂的对比得出的。然而，在这些研究中，与安慰剂效果相比，积极干预措施的镇痛效果仍然不大。这一观察结果促使我们根据主动和假 rTMS 干预的相对时间重新评估安慰剂对疼痛缓解的内在作用。在一项包含 45 名患者的随机对照研究中，我们比较了在主动 rTMS 之前或之后进行的假 rTMS 的镇痛效果，而主动 rTMS 本身可能是成功的，也可能是不成功的。在成功或不成功的主动 rTMS 后进行假 rTMS 治疗时，安慰剂镇痛效果显着不同。当 rTMS 成功后，安慰剂治疗会产生显着的镇痛效果（平均疼痛减少 11%），而 rTMS 失败后，安慰剂会导致疼痛加剧（疼痛增加 6%）。仅当在任何主动 rTMS 之前应用假干预时，安慰剂评分才与基线保持不变。这些结果可能反映了无意识的条件学习。在缓解疼痛的 rTMS 研究中，应该考虑安慰剂相对于积极干预措施的时机，在其他情况下也可能如此。先前的 rTMS 可以增强安慰剂效应，镇痛效果低至 10%，这一事实表明，治疗试验中 30% 的疼痛减轻阈值可能过于严重，因为较小的镇痛效果也可能具有临床意义。 (C) 2010 年国际疼痛研究协会。由 Elsevier B.V. 出版。保留所有权利。
The efficacy of repetitive transcranial magnetic stimulation (rTMS) of the motor cortex for neuropathic pain relief is founded on double-blind studies versus placebo. In these studies, however, the analgesic effect of active interventions remained modest compared with the placebo effect. This observation led us to re-evaluate the intrinsic placebo action on pain relief according to the relative timing of active and sham rTMS interventions. In a randomized controlled study including 45 patients, we compared the analgesic effect of sham rTMS that either preceded or followed an active rTMS, which could be itself either successful or unsuccessful. Placebo analgesia differed significantly when the sham rTMS session followed a successful or an unsuccessful active rTMS. Placebo sessions induced significant analgesia when they followed a successful rTMS (mean pain decrease of 11%), whereas they tended to worsen pain when following an unsuccessful rTMS (pain increase of 6%). Only when the sham intervention was applied before any active rTMS were placebo scores unchanged from the baseline. These results probably reflect an unconscious conditioned learning. The timing of placebo relative to active interventions should be taken into account in rTMS studies for pain relief, and possibly in other conditions too. The fact that placebo effects could be enhanced by a previous rTMS with an analgesic effect as low as 10% suggests that a 30% pain decrease threshold in therapeutic trials may be too severe because smaller analgesic effects may have a clinical significance too. (C) 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.