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Updated: Aug 9, 2026
Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury
Published on: November 19, 2012
Cortical excitability after pediatric mild traumatic brain injury
Trevor A Seeger1, Adam Kirton1, Michael J Esser2
1Cumming School of Medicine, University of Calgary, Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Canada; Alberta Children's Hospital Research Institute, Alberta Children's Hospital, Calgary, Canada.
Introduction:
Mild traumatic brain injury (mTBI) outcomes are variable, and 10-15% may suffer from prolonged symptoms beyond 3 months that impair the child's return to normal activities. Neurophysiological mechanisms of mTBI are incompletely understood, particularly in children, but alterations in cortical excitability have been proposed to underlie post-concussion syndrome. Improved understanding is required to advance interventions and improve outcomes.
Objective/Hypothesis:
To determine if cortical excitability is altered in children with mTBI, and its association with clinical symptoms.
Methods:
This was a cross-sectional controlled cohort study. School-aged children (8-18 years) with mTBI were compared to healthy controls. Cortical excitability was measured using multiple TMS paradigms in children with (symptomatic) and without (recovered) persistent symptoms one-month post-injury. Primary outcome was the cortical silent period (cSP), a potential neurophysiological biomarker of GABAergic inhibition. Secondary outcomes included additional TMS neurophysiology, safety and tolerability. Associations between neurophysiology parameters and clinical symptoms were evaluated.
Results:
Fifty-three children with mTBI (55% male; mean age 14.1 SD: 2.4 years; 35 symptomatic and 27 asymptomatic participants) and 28 controls (46% male; mean age 14.3 SD: 3.1 years) were enrolled. cSP duration was similar between groups (F (2, 73) = 0.55, p = 0.582). Log10 long interval intracortical inhibition (LICI) was reduced in symptomatic participants compared to healthy controls (F (2, 59) = 3.83, p = 0.027). Procedures were well tolerated with no serious adverse events.
Conclusions:
TMS measures of cortical excitability are altered at one month in children with mTBI. Long interval cortical inhibition is decreased in children who remain symptomatic at one month post-injury.
