Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Eur J Pain. 2021 Jul;25(6):1241-1253. doi: 10.1002/ejp.1743. Epub 2021 Feb 18.
Antinociceptive effects of transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) have been extensively studied in the past years. However, M1 does not work in isolation, but it rather interacts within a network, the so-called resting-state motor network.
To explore the anti-nociceptive effects of a new multifocal tDCS approach administered to regions linked to the resting state motor network (network-tDCS) compared to sham tDCS.
Healthy individuals were included in this randomized, parallel and double-blinded study comprising two consecutive interventions with 24-hr interval of either active (n = 19) or sham (n = 19) network-tDCS. Prolonged pain was induced by application of topical capsaicin on the dorsum of the hand during a 24-hr period. Assessments of corticomotor excitability (transcranial magnetic stimulation), pain ratings (numerical rating scale, NRS), skin pain sensitivity on the arm (heat and mechanical), temporal summation of pain (TSP) and conditioned pain modulation (CPM) were performed at baseline (Day1-baseline), after 25 min of capsaicin application and before the first tDCS session (Day1-post-cap), and after the second tDCS session (Day2).
Comparing Day2 to Day1-baseline measures, there was reduced corticomotor excitability (p < .05) and impaired CPM-effect (p < .05) after sham but not after active network-tDCS. Pain NRS ratings increased at Day2 compared to Day1-post-cap (p < .01) in both groups whereas no significant changes were found in pain sensitivity and TSP.
Present findings demonstrate that tDCS applied over regions linked to the resting state motor network reverts the inhibition of corticomotor excitability and CPM impairment both provoked by prolonged experimental pain for 24 hr.
These findings highlight that the stimulation of the resting state motor network with multifocal tDCS may represent a potential cortical target to treat chronic pain, particularly in patients exhibiting maladaptive corticomotor excitability and impaired conditioned pain modulation effects.
过去几年，人们广泛研究了经颅直流电刺激（tDCS）对初级运动皮层（M1）的镇痛作用。然而，M1 并非孤立工作，而是在一个被称为静息状态运动网络的网络中相互作用。
探索一种新的多焦点 tDCS 方法对与静息状态运动网络（网络-tDCS）相关区域的镇痛作用，与假刺激 tDCS 进行比较。
本研究为随机、平行、双盲研究，纳入 19 名健康志愿者，在 24 小时的间隔内分别接受真刺激（n=19）或假刺激（n=19）的网络-tDCS。在 24 小时期间，在手背涂辣椒素诱发持续性疼痛。在基线（第 1 天基线）、涂辣椒素后 25 分钟（第 1 天涂后）和第二次 tDCS 治疗前（第 1 天治疗后）以及第二次 tDCS 治疗后（第 2 天），进行皮质运动兴奋性（经颅磁刺激）、疼痛评分（数字评分量表，NRS）、手臂皮肤痛觉敏感性（热和机械）、疼痛时间总和（TSP）和条件性疼痛调制（CPM）评估。
与第 1 天基线相比，第 2 天 sham 组的皮质运动兴奋性降低（p<0.05），CPM 效应受损（p<0.05），而真刺激组则没有。与第 1 天涂后相比，两组的 NRS 评分在第 2 天都增加（p<0.01），而疼痛敏感性和 TSP 没有显著变化。
本研究结果表明，在静息状态运动网络的相关区域应用 tDCS 可逆转 24 小时持续实验性疼痛引起的皮质运动兴奋性抑制和 CPM 损伤。
这些发现强调，用多焦点 tDCS 刺激静息状态运动网络可能成为治疗慢性疼痛的潜在皮质靶点，特别是在表现出皮质运动兴奋性过度和 CPM 效应受损的患者中。
