Neuropsychological correlates of the electroencephalogram in epileptics: III. Generalized nonepileptiform abnormalities.

A broad battery of neuropsychological tests was given to 111 adult epileptics treated primarily with phenytoin. The patients were grouped according to degree of generalized nonepileptiform EEG abnormalities in waking EEGs. In patients classified as None/Mild, Moderate, or Marked in terms of these EEG abnormalities performances on 15 neuropsychological measures were contrasted. Statistically significant differences across the groups were found on 13 of the 15 neuropsychological variables. An orderly decrease in performance occurred as a correlate of an increase in EEG abnormalities. These results were compared to a similar analysis of the correlates of topographic distribution of epileptiform discharges (Absent, Focal, Generalized). It was discovered that degrees of generalized slow wave EEG abnormalities were more potent in differentiating levels of neuropsychological performance than epileptiform discharges. Nevertheless, when discharges and degree of nonepileptiform abnormalities were simultaneously considered, a maximal level of correlation was reached.