Precision, accuracy, and reliability of a threshold hunting method for transcranial magnetic stimulation

To investigate precision, accuracy, and reliability of a threshold hunting method to estimate resting motor threshold (RMT) using parameter estimation by sequential testing and maximum likelihood estimation (PEST-MLE).

In 53 healthy participants, single pulse transcranial magnetic stimulation was delivered to estimate RMT with cutoff values of 0.05 mV and 0.2 mV. RMT was inferred from 30-trial PEST-MLE algorithm for at maximum two days with two estimation sessions per day, comprising Sessions 1 to 4. Precision and accuracy were assessed within each session. Repeatability was assessed using intraclass correlation coefficient (ICC), reproducibility coefficient (RC), and standard error of measurement (SEM).

For both 0.05 mV and 0.2 mV, 18 trials were needed to have good accuracy. ICC greater than 0.8 was achieved for within-day comparison but the ICC of between-day comparison was lower. RC and SEM were around 10 % and 5 %, respectively.

At 18th trial the estimations were converged in terms of precision and accuracy, and good reliability was achieved at that stage.

RMT estimation with the PEST-MLE is a rapid and reliable approach that can be implemented for future clinical and scientific studies.