Residual alterations of brain electrical activity in clinically asymptomatic concussed individuals: An EEG study

Objective: To examine the neural substrates underlying performance on Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) and HeadRehab Virtual Reality (VR) balance and spatial modules in a concussed and control group. Methods: Thirteen controls and seven concussed participants were fitted with a Geodesic 128-channel EEG cap and completed three assessments: EEG baseline, ImPACT testing, and VR balance and spatial modules. Concussed participants completed were tested within 8 (5 +/- 1) days after injury. Results: EEG power was significantly (p <.05) decreased in the concussed group over all testing modalities. EEG coherence was significantly (p <.05) increased in the concussed group during EEG baseline and ImPACT. For VR testing, two conditions showed significant (p <.05) increases in EEG coherence between ROIs, while two different conditions showed significant (p <.05) decreases in coherence levels. Conclusions: Concussed participants passed all clinical concussion testing tools, but showed pathophysiological dysfunction when evaluating EEG variables. Significance: Concussed participants are able to compensate and achieve normal functioning due to recruiting additional brain networks. This allows concussed participants to pass clinical tests while still displaying electrophysiological deficits and clinicians must consider this information when making return-to-play decisions. (C) 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.