Residual and compensatory changes of resting-state EEG in successful recovery after moderate TBI

Purpose:Even in years after recovery from moderate traumatic brain injury(moderate TBI),patients complain about residual cognitive impairment and fatigue.We hypothesized that non-linear and linear resting-state electroencephalography(rs EEG)features might also reflect neural underpinnings of these deficits.Methods:We analyzed a 10-minute rs EEG in 77 moderate TBI-survivors and 151 healthy volunteers after cognitive and psychological assessment.The rs EEG analysis included linear measures,such as power spectral density and peak alpha frequency,and non-linear parameters such as Higuchi fractal dimension,envelope frequency,and Hjorth complexity.Results:The patients with moderate TBI had higher scores for fatigue and sleepiness and lower scores for mood and life satisfaction than controls.The behavioral test for directed attention showed a smaller and non-significant between-group difference.In rs EEG patterns,moderate TBI-group had significantly higher deltaand theta-rhythm power,which correlated with higher sleepiness and fatigue scores.The higher beta and lower alpha power were associated with a higher attention level in moderate TBI patients.Non-linear rs EEG features were significantly higher in moderate TBI patients than in healthy controls but correlated with sleepiness and fatigue scores in both controls and patients.Conclusion:The rs EEG patterns may reflect compensatory processes supporting directed attention and residual effect of moderate TBI causing subjective fatigue in patients even after full physiological recovery.