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

Objective: 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). Methods: 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). Results: 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. Conclusions: At 18th trial the estimations were converged in terms of precision and accuracy, and good reliability was achieved at that stage. Significance: RMT estimation with the PEST-MLE is a rapid and reliable approach that can be implemented for future clinical and scientific studies.