Impact of operator experience on transcranial magnetic stimulation

To determine the impact of an operator's experience on transcranial magnetic stimulation (TMS) measurement.

Operator B (beginner), operator E (expert), and 30 healthy participants joined the study consisting of two experiments. In each experiment, each operator performed a TMS protocol on each participant in a random order.

Compared with operator E, operator B exhibited higher resting motor threshold (RMT) in experiment I (60.1 ± 13.0 vs. 57.4 ± 10.9% maximal stimulation output, p = 0.017) and the difference disappeared in experiment II (p = 0.816). In 1-mV motor evoked potential (MEP) measurement, operator B exhibited higher standard deviation indicating lower consistency in experiment I compared with experiment II (1.05 ± 0.40 vs. 1.05 ± 0.16 mV with unequal variances, p = 0.001) and had poor intrarater reliability between the experiments (intraclass correlation coefficient = -0.130). There was no difference in the results of active motor threshold, silent period, paired-pulse stimulation, or continuous theta burst stimulation between the operators.

An operator's experience in TMS may affect the results of RMT measurement. With practice, a beginner may choose a more precise stimulation location and have higher consistency in 1-mV MEP measurement.

We recommend that a beginner needs to practice for precise stimulation locations before conducting a trial or clinical practice.