• Sofie Carrette, Kristl Vonck, Debby Klooster, Robrecht Raedt, Evelien Carrette, Jean Delbeke, Wytse Wadman, Silvia Casarotto, Marcello Massimini, and Paul Boon.
• 4Brain, Department of Neurology, Ghent University Hospital, Ghent, Belgium. Electronic address: Sofie.Carrette@ugent.be.
• Neuromodulation. 2024 Jun 5.

ObjectivesThis study investigates the way theta burst stimulation (TBS) applied to the motor cortex (M1) affects TMS-evoked potentials (TEPs). There have been few direct comparisons of continuous TBS (cTBS) and intermittent TBS (iTBS), and there is a lack of consensus from existing literature on the induced effects. We performed an exploratory trial to assess the effect of M1-cTBS and M1-iTBS on TEP components.Materials And MethodsIn a cross-over design, 15 participants each completed three experimental sessions with ≥one week in between sessions. The effect of a single TBS train administered over M1 was investigated using TEPs recorded at the same location, 20 to 30 minutes before and in the first 10 minutes after the intervention. In each session, a different type of TBS (cTBS, iTBS, or active control cTBS) was administered in a single-blinded randomized order. For six different TEP components (N15, P30, N45, P60, N100, and P180), amplitude was compared before and after the intervention using cluster-based permutation (CBP) analysis.ResultsWe were unable to identify a significant modulation of any of the six predefined M1 TEP components after a single train of TBS. When waiving statistical correction for multiple testing in view of the exploratory nature of the study, the CBP analysis supports a reduction of the P180 amplitude after iTBS (p = 0.015), whereas no effect was observed after cTBS or in the active control condition. The reduction occurred in ten of 15 subjects, showing intersubject variability.ConclusionsThe observed decrease in the P180 amplitude after iTBS may suggest a neuromodulatory effect of iTBS. Despite methodologic issues related to our study and the potential sensory contamination within this latency range of the TEP, we believe that our finding deserves further investigation in hypothesis-driven trials of adequate power and proper design, focusing on disentanglement between TEPs and peripherally evoked potentials, in addition to indicating reproducibility across sessions and subjects.Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is NCT05206162.Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.

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