Altered motor system function in post-concussion syndrome as assessed via transcranial magnetic stimulation

Mitchell B Locke; Stephen L Toepp; Claudia V Turco; Diana H Harasym; Michel P Rathbone; Michael D Noseworthy; Aimee J Nelson

doi:10.1016/j.cnp.2020.07.004

Altered motor system function in post-concussion syndrome as assessed via transcranial magnetic stimulation

Clin Neurophysiol Pract. 2020 Aug 6:5:157-164. doi: 10.1016/j.cnp.2020.07.004. eCollection 2020.

Authors

Mitchell B Locke¹, Stephen L Toepp¹, Claudia V Turco¹, Diana H Harasym², Michel P Rathbone³, Michael D Noseworthy^{2

4

5}, Aimee J Nelson¹

Affiliations

¹ Department of Kinesiology, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
² School of Biomedical Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada.
³ Department of Medicine, Division of Neurology, McMaster University, Hamilton, Ontario L8N 3Z5, Canada.
⁴ Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
⁵ Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario L8N 4A6, Canada.

Abstract

Objective: It is unclear why specific individuals incur chronic symptoms following a concussion. This exploratory research aims to identify and characterize any neurophysiological differences that may exist in motor cortex function in post-concussion syndrome (PCS).

Methods: Fifteen adults with PCS and 13 healthy, non-injured adults were tested. All participants completed symptom questionnaires, and transcranial magnetic stimulation (TMS) was used to measure intracortical and transcallosal excitability and inhibition in the dominant motor cortex.

Results: Cortical silent period (p = 0.02, g = 0.96) and ipsilateral silent period (p = 0.04, g = 0.78) were shorter in the PCS group compared to the control group which may reflect reduced GABA-mediated inhibition in PCS. Furthermore, increased corticomotor excitability was observed in the left hemisphere but not the right hemisphere.

Conclusions: These data suggest that persistent neurophysiological differences are present in those with PCS. The exact contributing factors to such changes remain to be investigated by future studies.

Significance: This study provides novel evidence of lasting neurophysiological changes in PCS.

Keywords: Concussion; Inhibition; Motor cortex; Post-concussion syndrome; Transcranial magnetic stimulation.