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CC BY-NC-ND 4.0 · International Journal of Epilepsy 2025; 11(S 02): S1-S56
DOI: 10.1055/s-0045-1813046
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Exploring Cortical Dynamics in Juvenile Myoclonic Epilepsy Through TMS-EEG Studies

Authors

  • Deepak Chadha

    1   NIMHANS, Bengaluru, Karnataka, India

  • Shubham Gupta

    1   NIMHANS, Bengaluru, Karnataka, India

  • V. S. Sreeraj

    1   NIMHANS, Bengaluru, Karnataka, India

  • Urvaksh M. Mehta

    1   NIMHANS, Bengaluru, Karnataka, India

  • L. G. Vishwanathan

    1   NIMHANS, Bengaluru, Karnataka, India

  • K. Raghavendra

    1   NIMHANS, Bengaluru, Karnataka, India

  • C. M. Ravindranadh

    1   NIMHANS, Bengaluru, Karnataka, India

  • Sanjib Sinha

    1   NIMHANS, Bengaluru, Karnataka, India

  • Ajay Asranna

    1   NIMHANS, Bengaluru, Karnataka, India
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Introduction: TMS-EEG advances epilepsy research by overcoming conventional EEG limitations, enabling analysis of cortical excitability and epileptic networks, and unraveling the mechanisms of epileptogenesis in JME.

Methods: This prospective study analyzed 30 JME patients and matched controls using a 32-channel TMS-compatible EEG system. Single-pulse TMS (100 trials) was delivered to the motor and dorsolateral prefrontal cortex via a figure-of-eight coil, localized using neuro-navigation. TMS-evoked potentials and cortical oscillations were analyzed in MATLAB.

Result: The mean age was similar between patients (26.6 ± 9.5 years) and controls (27.5 ± 8.5). Seizure onset averaged 15 years, with a mean epilepsy duration of 12 years. Patients showed higher resting motor thresholds (50 vs. 46 μV, p = 0.032) and increased TMS-evoked potentials, with peak differences at ~100 ms (motor cortex) and ~185 ms (DLPFC). Cluster-based permutation analysis confirmed significant group differences within 119 to 170 ms (motor) and 117 to 170 ms (DLPFC), primarily driven by N100 and P185 components. Cortical oscillations were analyzed using event-related spectral perturbation (ERSP) and inter-trial coherence (ITC), comparing global scalp activity and local region-of-interest channels at the stimulation site at various frequency bands. The ERSP and ITC were reduced in JME patients. Motor cortex stimulation showed pronounced ERSP differences in the α-band, while ITC differences were most notable in the gamma band. DLPFC stimulation revealed ERSP differences across all bands, with ITC differences mainly in the α- and β-bands globally.

Conclusion: This study reveals increased cortical excitability, impaired inhibition, and network synchronization in JME, indicating disrupted cortico-cortical and thalamocortical connectivity. TMS-EEG markers may serve as potential epilepsy biomarkers and provide insights into epileptogenesis.



Publication History

Article published online:
24 October 2025

© 2025. Indian Epilepsy Society. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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