Cortical and Physical Function after Mild Traumatic Brain Injury

Purpose The aim of this study was to prospectively examine the association between intracortical inhibition and functional recovery after mild traumatic brain injury (mTBI). Methods Twenty individuals with mTBI and 20 matched control participants were assessed using transcranial magnetic stimulation, the Attentional Network Test, and gait analysis. Hierarchical linear modeling was used to longitudinally examine potential differences between groups and relationships in the pattern of recovery in cortical silent period (CSP) duration, cognitive reaction time, and single- and dual-task walking speeds across five testing time points. Individuals with mTBI were assessed within 72 h of injury, and again at 1 wk, 2 wk, 1 month, and 2 months postinjury. After initial testing, control participants followed a similar timeline. Results At the 72-h time point, the group with mTBI had longer reaction time (b = -91.76, P = 0.01), similar single-task walking speed (b = 0.055, P = 0.10), and slower dual-task walking speed (b = 0.10, P = 0.012) compared with control participants. The CSP duration also tended to be longer in individuals with mTBI than controls at the 72-h time point (b = -16.34, P = 0.062). The change is CSP duration over time was not significantly associated with the change in reaction time (b = -0.19, P = 0.47), single-task walking speed (b = 0.0001, P = 0.53), or dual-task walking speed (b < 0.001, P = 0.68). Conclusion Although cognitive and motor functions were significantly impaired in the mTBI group acutely after injury, levels of intracortical inhibition were not associated with recovery in either functional domain.