University of Washington, 325 Ninth Avenue, Seattle WA 98104-2499, USA.
Brain Stimul. 2009 Jul;2(3):163-7. doi: 10.1016/j.brs.2009.02.001.
The resting motor threshold (rMT) is an important factor in the selection of treatment intensity for patients receiving repetitive transcranial magnetic stimulation (rTMS). In many clinical studies to date, due to concerns about potential drift, the rMT has been routinely re-measured weekly or every fifth session.
Our aim is to investigate whether ongoing treatment with rTMS affects the rMT, the degree of change, and whether frequent remeasurement is needed.
Clinical data were drawn from 50 medication free patients receiving treatment for major depression with rTMS in a large U.S. NIH-sponsored multisite study. Four measurements of rMT were obtained including before and after the double blind phase, followed by weekly measurements during the open phase. Active treatment consisted of 75 four second trains of 10Hz stimulation applied over 37.5 minutes with the coil over the left DLPFC at 120% rMT.
For the group as a whole, there was no significant change in the rMT during a minimum of 2 weeks of treatment with prefrontal rTMS (p=0.911, one way ANOVA). The average within-subject coefficient of variation was 6.58%. On average the last rMT was 2.45% less than the baseline rMT (range 32.3% increase, 40.6% decrease).
Daily left prefrontal rTMS over several weeks as delivered in this trial does not cause systematic changes in rMT. While most subjects had <10% variance in rMT over time, 5 subjects had changes of approximately 20% from baseline, raising dosing and safety issues if undetected. We recommend that clinical trials of rTMS have periodic retesting of rMT, especially if the dose is at or near the edge of the TMS safety tables.
静息运动阈值(rMT)是接受重复经颅磁刺激(rTMS)治疗的患者选择治疗强度的一个重要因素。在迄今为止的许多临床研究中，由于担心潜在的漂移，rMT 通常每周或每五次治疗重新测量一次。
我们旨在研究 rTMS 的持续治疗是否会影响 rMT、变化程度，以及是否需要频繁重新测量。
从美国国立卫生研究院(NIH)赞助的一项大型多中心研究中接受 rTMS 治疗的 50 例无药物治疗的重度抑郁症患者的临床数据中提取资料。在双盲阶段前后共获得 4 次 rMT 测量值，随后在开放阶段每周测量一次。活性治疗包括在左背外侧前额叶皮质（DLPFC）上用 120%rMT 施加 75 个 4 秒 10Hz 刺激的 4 秒 4 秒刺激，共 4 秒 10Hz 刺激，每个线圈持续 37.5 分钟。
对于整个组，在前额叶 rTMS 治疗至少 2 周期间，rMT 没有显著变化（p=0.911，单向方差分析）。个体内变异系数的平均值为 6.58%。平均而言，最后一次 rMT 比基线 rMT 低 2.45%（范围为增加 32.3%，减少 40.6%）。
在本试验中，每周多次左前额 rTMS 治疗不会导致 rMT 的系统变化。虽然大多数受试者的 rMT 随时间变化的方差小于 10%，但 5 名受试者的 rMT 基线变化约为 20%，如果未检测到，会引起剂量和安全性问题。我们建议 rTMS 的临床试验定期重新测试 rMT，尤其是在剂量处于 TMS 安全表的边缘或接近边缘时。
