Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, 02215, MA, USA; Champalimaud Research & Clinical Centre, Champalimaud Centre for the Unknown, Lisbon, Portugal; Department of Psychiatry and Mental Health, Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal; NOVA Medical School, NMS, Universidade Nova de Lisboa, Lisbon, Portugal.
Champalimaud Research & Clinical Centre, Champalimaud Centre for the Unknown, Lisbon, Portugal; Department of Psychiatry and Mental Health, Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal; NOVA Medical School, NMS, Universidade Nova de Lisboa, Lisbon, Portugal.
Brain Stimul. 2021 Sep-Oct;14(5):1118-1125. doi: 10.1016/j.brs.2021.07.013. Epub 2021 Jul 27.
When repetitive transcranial magnetic stimulation (rTMS) is used to treat medication refractory depression, the treatment pulse intensity is individualized according to motor threshold (MT). This measure is often acquired only on the first day of treatment, as per the protocol currently approved by Food and Drug Administration.
Here, we aimed to assess daily MT variability across an rTMS treatment course and simulate the effects of different schedules of MT assessment on treatment intensity.
We conducted a naturalistic retrospective study with 374 patients from a therapeutic rTMS program for depression that measures MT daily.
For each patient, in almost half the TMS sessions, MT varied on average more than 5% as compared to the baseline MT acquired in the first treatment day. Such variability was only minimally impacted by having different TMS technicians acquiring MT in different days. In a smaller cohort of healthy individuals, we confirmed that the motor hotspot localization method, a critical step for accurate MT assessment, was stable in different days, arguing that daily MT variability reflects physiological variability, rather than an artifact of measurement error. Finally, in simulations of the effect of one-time MT measurement, we found that half of sessions would have been 5% or more above or below target intensity, with almost 5% of sessions 25% above target intensity. The simulated effects of weekly MT measurements were significantly improved.
In conclusion, MT varies significantly across days, not fully dependent on methods of MT acquisition. This finding may have important implications for therapeutic rTMS practice regarding safety and suggests that regular MT assessments, daily or at least weekly, would ameliorate the effect.
当重复经颅磁刺激（rTMS）用于治疗药物难治性抑郁症时，根据运动阈值（MT）来确定治疗脉冲强度。根据食品和药物管理局目前批准的方案，通常仅在治疗的第一天获得该措施。
在这里，我们旨在评估 rTMS 治疗过程中的每日 MT 变异性，并模拟不同 MT 评估时间表对治疗强度的影响。
我们对来自治疗性 rTMS 抑郁计划的 374 名患者进行了自然回顾性研究，该计划每天测量 MT。
对于每个患者，在几乎一半的 TMS 疗程中，MT 平均比第一天治疗中获得的基线 MT 变化超过 5％。这种变异性仅受到不同的 TMS 技术人员在不同的日子中获取 MT 的影响极小。在较小的健康个体队列中，我们证实了电机热点定位方法（准确评估 MT 的关键步骤）在不同的日子中是稳定的，这表明每日 MT 变异性反映了生理变异性，而不是测量误差的伪影。最后，在一次 MT 测量效果的模拟中，我们发现有一半的疗程会比目标强度高或低 5％或更多，几乎有 5％的疗程比目标强度高 25％。每周 MT 测量的模拟效果得到了显著改善。
总之，MT 在不同天之间变化很大，不完全依赖于 MT 采集方法。这一发现可能对治疗性 rTMS 实践具有重要意义，因为它涉及到安全性，并且表明定期的 MT 评估，无论是每天还是至少每周，都将改善效果。
