Cortical and Physical Function following Mild Traumatic Brain Injury.

PURPOSE: To prospectively examine the association between intracortical inhibition and functional recovery following mild traumatic brain injury (mTBI).

METHODS: Twenty individuals with mTBI and twenty matched control participants were assessed using transcranial magnetic stimulation (TMS), the Attentional Network Test (ANT), 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 5 testing time points. Individuals with mTBI were assessed within 72 hours of injury, and again at one week, two weeks, one month, and two months post-injury. After initial testing, control participants followed a similar timeline.

RESULTS: At the 72-hour 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-hour 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: While cognitive and motor functions were significantly impaired in the mTBI group acutely following injury, levels of intracortical inhibition were not associated with recovery in either functional domain.