EEG and cognitive performance following closed head injury

Ten closed head-injured patients and 10 matched control subjects participated in a study that examined quantitated EEG data during cognitive task performance. The head-injured patients performed significantly worse than controls on all four tasks and had significantly higher EEG amplitudes and amplitude variances. A discriminant analysis function correctly identified 0% of the subjects on the basis of the EEG data. Frequency analysis indicated that these higher amplitudes were a product of across-frequency increases in voltage. In addition, EEG data were significantly correlated with performance on one cognitive task in the head-injured group. Results suggest that, contrary to standard clinical EEG findings, identifiable EEG changes may persist for years following moderate to severe closed head injury, and these changes are related to residual cognitive deficits.