Limited evidence for reliability of low and high frequency rTMS over the motor cortex

Kilian Prei; Carolina Kanig; Mirja Osnabruegge; Berthold Langguth; Wolfgang Mack; Mohamed Abdelnaim; Martin Schecklmann; Stefan Schoisswohl

doi:10.1016/j.brainres.2023.148534

Limited evidence for reliability of low and high frequency rTMS over the motor cortex

Brain Res. 2023 Dec 1:1820:148534. doi: 10.1016/j.brainres.2023.148534. Epub 2023 Aug 14.

Authors

Kilian Prei¹, Carolina Kanig², Mirja Osnabruegge³, Berthold Langguth¹, Wolfgang Mack⁴, Mohamed Abdelnaim¹, Martin Schecklmann¹, Stefan Schoisswohl³

Affiliations

¹ Department of Psychiatry and Psychotherapy, University of Regensburg, Universitätsstraße 84, 93053 Regensburg, Germany.
² Department of Psychiatry and Psychotherapy, University of Regensburg, Universitätsstraße 84, 93053 Regensburg, Germany; Department of Human Sciences, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany. Electronic address: carolina.kanig@unibw.de.
³ Department of Psychiatry and Psychotherapy, University of Regensburg, Universitätsstraße 84, 93053 Regensburg, Germany; Department of Human Sciences, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany.
⁴ Department of Human Sciences, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany.

PMID: 37586677
DOI: 10.1016/j.brainres.2023.148534

Abstract

Objective: The aim of this study was to investigate the reliability of low-frequency and high-frequency repetitive transcranial magnetic stimulation (rTMS) on healthy individuals over the motor cortex. A secondary outcome was the assessment if low-frequency rTMS results in inhibition and high-frequency rTMS results in facilitation.

Methods: In this experiment, 30 healthy participants received on four consecutive days one session each with application of 1 Hz or 20 Hz rTMS over the left motor cortex. 1 Hz and 20 Hz were applied in alternating order, whereby the starting frequency was randomized. Motor evoked potentials (MEPs) were measured before and after each session. Reliability measures were intraclass and Pearson's correlation coefficient (ICC and r).

Results: ICCs and r values were low to moderate. Notably, within subgroups of less confounded measures, we found good r values for 20 Hz rTMS. The group-level analysis did not demonstrate a clear low-frequency inhibition and high-frequency facilitation pattern. At the single-subject level, only one participant exhibited significant changes consistent with the expected pattern, with concurrent decreases in MEPs following 1 Hz sessions and increases following 20 Hz sessions.

Conclusion: The investigated neuromodulatory protocols show low to moderate reliability. Results are questioning the low-frequency inhibition and high-frequency facilitation pattern.

Significance: Methodological improvements for the usage of rTMS are necessary to increase validity and reliability of non-invasive brain stimulation.

Keywords: Cortical excitability; Motor evoked potential (MEP); Repetitive transcranial magnetic stimulation (rTMS); Test-retest reliability; Variability.