Cortical Excitability after Mild Traumatic Brain Injury in Children

Abstract

Objective: To determine if cortical excitability is different in pediatric mTBI one month after injury, and if this is related to symptom persistence. Background: Mild traumatic brain injury (mTBI) is common, and children are at an increased risk for persistent symptoms. The reasons for this are unclear. Cortical inhibition may be altered following adult mTBI. We hypothesized that cortical excitability may be different following pediatric mild TBI, and may differ in children who remain symptomatic. Methods: A cross-sectional controlled cohort study was performed. Children (aged 8-18 years) with mTBI were recruited as part of the PlayGame Trial (www.playgametrial.ca). Participants were grouped into those returning to pre-injury symptom scores (asymptomatic) and those with persistent symptoms (symptomatic) at one month using the post-concussion symptom inventory. Healthy controls had no history of brain injury. Single and paired-pulse TMS protocols were performed. The primary outcome measure was cortical silent period (cSP). Secondary outcomes included stimulus-response curves (SRC), intracortical facilitation (ICF), and short and long interval intracortical inhibition (SICI/LICI). Results: Twenty-five symptomatic, 23 asymptomatic, and 25 controls were studied. Groups were similar in age (control median [range]: 14.49 [8.4-18.8], asymptomatic: 14.76 [9.3-17.9], and symptomatic: 15.34 [8.3-17.0] years), sex, and time post-injury (symptomatic: 40 [32-54], asymptomatic 40.5 [28-57] days). cSP was similar across groups (mean [95[percnt] confidence interval]): 114.58 [95.53 - 133.63] in controls, 115.89 [97.78 - 134] in asymptomatic, and 104.15 [86.34 - 121.96] in symptomatic children, (F (2, 70) = 0.53, p = 0.591). No differences in SRC, SICI, LICI, or ICF were observed across groups. Procedures were well tolerated with no adverse events. Conclusions: TMS is well tolerated by children following mTBI. Unlike similar studies in adult mTBI, children with mTBI did not show altered cortical excitability at one month post-injury. Disclosure: Dr. Seeger has nothing to disclose. Dr. Kirton has nothing to disclose. Dr. Barlow has nothing to disclose.