Estimation of the resting motor threshold (RMT) in transcranial magnetic stimulation using relative-frequency and threshold-hunting methods in brain tumor patients.

Abstract

Application of transcranial magnetic stimulation is often based on the resting motor threshold. The aim of this study was to validate recent findings on the advantage of resting motor threshold estimation using adaptive threshold-hunting algorithms over the Rossini-Rothwell method in a clinical sample and healthy subjects. Resting motor thresholds in 115 patients with a brain tumor and 10 healthy subjects were assessed using the Rossini-Rothwell method and compared to an adaptive threshold-hunting algorithm. In healthy subjects, this measurement was repeated twice to capture test-retest reliability of both methods. Efficiency of both methods was assessed by comparing the number of pulses needed for resting motor threshold estimation. There was no significant difference between the Rossini-Rothwell method and the adaptive threshold-hunting algorithm in patients and healthy controls with limits of agreement between ± 12V/m. There was a strong intraclass correlation and both methods showed a good test-retest reliability. However, the adaptive threshold-hunting algorithm was significantly faster. The adaptive threshold-hunting algorithm was more efficient in assessing the resting motor threshold, while reaching comparable results as the Rossini-Rothwell method. Thus, our results support the advantage of adaptive threshold-hunting algorithms to determine the resting motor threshold also in a clinical sample.