Li Chong, Zhang Nannan, Han Qiong, Zhang Lifang, Xu Shuo, Tu Shuting, Xie Yong, Wang Zhiyong
Department of Rehabilitation Medicine, First Affiliated Hospital of Fujian Medical University, Fujian, China.
Front Mol Neurosci. 2022 Apr 12;15:887426. doi: 10.3389/fnmol.2022.887426. eCollection 2022.
High-frequency repetitive transcranial magnetic stimulation (rTMS) induces analgesic effects in both experimental pain and clinical pain conditions. However, whether rTMS can modulate sensory and pain thresholds on sensory fibers is still unclear. Here, we compared the effects of three rTMS paradigms on sensory and pain thresholds conducted by different sensory fibers (Aβ, Aδ, and C fibers) with sham stimulation and investigate the potential brain activation using functional near-infrared spectroscopy (fNIRS).
Forty right-handed healthy subjects were randomly allocated into one of four groups. Each subject received one session rTMS [prolonged continuous theta-burst stimulation (pcTBS), intermittent theta-burst stimulation (iTBS), 10 Hz rTMS or sham]. Current perception threshold (CPT), pain tolerance threshold (PTT), and fNIRS were measured at baseline, immediately after stimulation, and 1 h after stimulation, respectively.
Significant differences between treatments were observed for changes for CPT 2,000 Hz between baseline and 1 h after rTMS ( = 6.551, < 0.001): pcTBS versus sham ( = 0.004) and pcTBS versus 10 Hz rTMS ( = 0.007). There were significant difference in average HbO μm in the right frontopolar cortex (FPC) [channel 23: = 0.030 (pcTBS versus sham: = 0.036)], left dorsolateral prefrontal cortex (DLPFC) [channel 7: = 0.006 (pcTBS versus sham: = 0.004)], left FPC [channel 17: = 0.014 (pcTBS versus sham: = 0.046), channel 22: = 0.004 (pcTBS versus sham: = 0.004)] comparing four group in 1 h after stimulation in PTT 2000 Hz (Aβ-fiber).
Prolonged continuous theta-burst stimulation can regulate sensitivity on Aβ fibers. In addition, single-session pcTBS placed on left M1 can increase the excitability of DLPFC and FPC, indicating the interaction between M1 and prefrontal cortex may be a potential mechanism of analgesic effect of rTMS. Studies in patients with central post-stroke pain are required to confirm the potential clinical applications of pcTBS.
高频重复经颅磁刺激（rTMS）在实验性疼痛和临床疼痛状态下均能产生镇痛效果。然而，rTMS是否能调节感觉纤维上的感觉和疼痛阈值仍不清楚。在此，我们比较了三种rTMS模式对由不同感觉纤维（Aβ、Aδ和C纤维）传导的感觉和疼痛阈值的影响，并与假刺激进行对比，同时使用功能近红外光谱（fNIRS）研究潜在的脑激活情况。
40名右利手健康受试者被随机分为四组之一。每位受试者接受一次rTMS治疗[延长连续θ爆发刺激（pcTBS）、间歇性θ爆发刺激（iTBS）、10 Hz rTMS或假刺激]。分别在基线、刺激后即刻和刺激后1小时测量电流感知阈值（CPT）、疼痛耐受阈值（PTT）和fNIRS。
在rTMS后1小时与基线相比，2000 Hz的CPT变化在各治疗组间存在显著差异（F = 6.551，P < 0.001）：pcTBS与假刺激相比（P = 0.004）以及pcTBS与10 Hz rTMS相比（P = 0.007）。在2000 Hz（Aβ纤维）的PTT刺激后1小时，四组比较时，右侧额极皮质（FPC）[通道23：P = 0.030（pcTBS与假刺激相比：P = 0.036）]、左侧背外侧前额叶皮质（DLPFC）[通道7：P = 0.006（pcTBS与假刺激相比：P = 0.004）]、左侧FPC[通道17：P = 0.014（pcTBS与假刺激相比：P = 0.046），通道22：P = 0.004（pcTBS与假刺激相比：P = 0.004）]的平均HbO变化存在显著差异。
延长连续θ爆发刺激可调节Aβ纤维的敏感性。此外，置于左侧M1的单次pcTBS可增加DLPFC和FPC的兴奋性，表明M1与前额叶皮质之间的相互作用可能是rTMS镇痛作用的潜在机制。需要对中风后中枢性疼痛患者进行研究以证实pcTBS的潜在临床应用。
