Department of Prosthodontics, Hospital of Stomatology, Tongji University, Shanghai Engineering Research Centre of Tooth Restoration and Regeneration, Shanghai, China.
Shanghai Mental Health Centre, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
Arch Oral Biol. 2017 Oct;82:241-246. doi: 10.1016/j.archoralbio.2017.06.014. Epub 2017 Jun 17.
We aimed to investigate the influence of high frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex on excitability of the masseter inhibitory reflex (MIR) in healthy subjects. Our goal in conducting this study was to obtain a better understanding of the subcortical and cortical networks related to the excitability of the central masticatory pathway.
Twenty healthy volunteers participated in this study. MIRs were evaluated both before and after high frequency rTMS to elicit motor evoked potentials (MEPs) using single- and double-shock techniques over the motor cortex. During measurements, the latency and duration of silent periods (SPs) with single magnetic stimulation, and the recovery of SP2 with the double-shock technique, were recorded in basal conditions and immediately after high frequency rTMS. The "real" rTMS condition consisted of 20 stimulus trains delivered at 10Hz with a 5-s stimulation duration and an intensity of 70% of the active motor threshold (AMT) over the right optimal motor spot for the masseter muscle.
were also compared to those obtained after "sham" rTMS 1 week later RESULTS: Using the double-shock technique, SP2 recovery time was significantly shorter after high frequency rTMS compared to the basal condition (from 100 to 400ms; p<0.001), while at ISIs of 500 and 600ms, no significant effect was observed (p=0.084, p=0.948). There was also no significant change in the SP latency or duration between groups (p>0.05).
High frequency, sub-threshold rTMS of the motor cortex had a facilitative after-effect on the excitability of the MIR. This effect was likely mediated through increased cortical drive to brainstem reflex pathways, which would ultimately accelerate MIR recovery.
我们旨在探究高频重复经颅磁刺激（rTMS）对健康受试者咬肌抑制反射（MIR）兴奋性的影响。我们进行这项研究的目的是更好地了解与中枢咀嚼通路兴奋性相关的皮质下和皮质网络。
20 名健康志愿者参与了这项研究。使用单刺激和双刺激技术，在运动皮质上诱发运动诱发电位（MEPs），分别在高频 rTMS 前后评估 MIR。在测量过程中，记录了单磁刺激时静默期（SP）的潜伏期和持续时间，以及双刺激技术时 SP2 的恢复情况，分别在基础状态和高频 rTMS 后即刻进行记录。“真实”rTMS 条件由 20 个刺激序列组成，频率为 10Hz，刺激持续时间为 5s，强度为右最佳咬肌运动点的 70%主动运动阈值（AMT）。
与 1 周后“假”rTMS 后的结果相比，高频 rTMS 后使用双刺激技术时 SP2 恢复时间明显缩短（从 100 到 400ms；p<0.001），而在 ISI 为 500 和 600ms 时，未观察到显著影响（p=0.084，p=0.948）。组间 SP 潜伏期或持续时间也无显著变化（p>0.05）。
皮质下阈下高频 rTMS 对 MIR 的兴奋性具有促进后的效应。这种效应可能是通过增加皮质对脑干反射通路的驱动来介导的，这最终将加速 MIR 的恢复。
