Intracortical and intercortical networks in patients after stroke: a concurrent TMS-EEG study

Zhongfei Bai; Jack Jiaqi Zhang; Kenneth N K Fong

doi:10.1186/s12984-023-01223-7

Intracortical and intercortical networks in patients after stroke: a concurrent TMS-EEG study

J Neuroeng Rehabil. 2023 Aug 2;20(1):100. doi: 10.1186/s12984-023-01223-7.

Authors

Zhongfei Bai^{1

2}, Jack Jiaqi Zhang¹, Kenneth N K Fong³

Affiliations

¹ Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR.
² Department of Rehabilitation, Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Centre), School of Medicine, Tongji University, Shanghai, China.
³ Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR. rsnkfong@polyu.edu.hk.

Abstract

Background: Concurrent transcranial magnetic stimulation and electroencephalography (TMS-EEG) recording provides information on both intracortical reorganization and networking, and that information could yield new insights into post-stroke neuroplasticity. However, a comprehensive investigation using both concurrent TMS-EEG and motor-evoked potential-based outcomes has not been carried out in patients with chronic stroke. Therefore, this study sought to investigate the intracortical and network neurophysiological features of patients with chronic stroke, using concurrent TMS-EEG and motor-evoked potential-based outcomes.

Methods: A battery of motor-evoked potential-based measures and concurrent TMS-EEG recording were performed in 23 patients with chronic stroke and 21 age-matched healthy controls.

Results: The ipsilesional primary motor cortex (M1) of the patients with stroke showed significantly higher resting motor threshold (P = 0.002), reduced active motor-evoked potential amplitudes (P = 0.001) and a prolonged cortical silent period (P = 0.007), compared with their contralesional M1. The ipsilesional stimulation also produced a reduction in N100 amplitude of TMS-evoked potentials around the stimulated M1 (P = 0.007), which was significantly correlated with the ipsilesional resting motor threshold (P = 0.011) and motor-evoked potential amplitudes (P = 0.020). In addition, TMS-related oscillatory power was significantly reduced over the ipsilesional midline-prefrontal and parietal regions. Both intra/interhemispheric connectivity and network measures in the theta band were significantly reduced in the ipsilesional hemisphere compared with those in the contralesional hemisphere.

Conclusions: The ipsilesional M1 demonstrated impaired GABA-B receptor-mediated intracortical inhibition characterized by reduced duration, but reduced magnitude. The N100 of TMS-evoked potentials appears to be a useful biomarker of post-stroke recovery.

Keywords: Cortical excitability; Intracortical inhibition; Stroke; TMS-evoked potentials.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Electroencephalography
Evoked Potentials
Evoked Potentials, Motor / physiology
Humans
Stroke Rehabilitation*
Stroke*
Transcranial Magnetic Stimulation