An EEG severity index of traumatic brain injury

EEG spectral analyses were conducted from 19 scalp locations for patients w ith mild (n = 40), moderate (n = 25), and severe (n = 43) traumatic brain i njury (TBI), 15 days to 4 years after injury. Severity of TBI was judged by emergency hospital admission records (Glasgow Coma Score and duration of c oma and amnesia). Highest-loading EEG variables on each factor that differe d significantly between severe and mild TBI by univariate t-test were enter ed into a multivariate discriminant analysis, yielding 16 variables. Discri minant analysis between mild and severe TBI groups showed classification ac curacy of 96.39%, sensitivity 95.45%, and specificity 97.44%. The EEG discr iminant score also measured intermediate severity in moderate TBI patients. Results were cross-validated in 503 VA patients. Significant correlations between EEG discriminant scores, emergency admission measures, and post-tra uma neuropsychological test scores validated the discriminant function as a n index of severity of injury and a classifier of the extremes of severity.