Exploratory investigation into mild brain injury and discriminant analysis with high frequency bands (32-64 Hz)

QEEG variables (five activation, two relationship variables, 19 locations and five bands up to 64 Hertz) were collected under eyes closed condition (under both 32 and 64 Hertz conditions) on 91 subjects, consisting of 32 mild brain-injured subjects (no loss of consciousness greater than 20 minutes) and 52 normals over the age of 14. An additional seven subjects who were unconscious greater than 20 minutes were available for analysis. Previous discriminant function analysis developed by Thatcher et al. was employed on the eyes closed 32 Hertz condition to ascertain its robustness for time periods greater than 1 year and for significant periods of unconsciousness. A separate discriminant for subjects was developed, employing only frontal high frequency coherence figures. The Thatcher discriminant could reliably (79%) identify all subjects up to 43 years post accident. The high frequency discriminant effectively identified 87% of the brain injured across all time periods (without significant loss of consciousness) and 100% of subjects within 1 year of accident. The combination of the discriminants resulted in a 100% accuracy rate for the 39 brain injured subjects for which discriminate values were available.