Neuropsychological correlates of the electroencephalogram in epileptics: I. Topographic distribution and average rate of epileptiform activity.

In 57 male and 33 female uncontrolled adult epileptics treated solely by diphenylhydantoin, scores on a broad battery of neuropsychological tests were compared with the separate and simultaneous consideration of the topographic distribution and average rate of occurrence of their EEG epileptiform discharges. These studies were given within a median of 1.24 days of each other. In the battery of tests, it was statistically significant that the group with generalized discharges did the poorest, patients with focal epileptiform activity were intermediate, and those without discharges did the best. When the rates of occurrence of discharges were compared to the neuropsychological test scores, results were less often significantly correlated with the EEG findings. In general, however, individuals with discharges occurring at the rate of more than 1/min did worse than those with fewer discharges. When the topographic distribution and average rate variables were considered in combination, their impacts on psychological performance were cumulative. The results suggest that EEG epileptiform discharges serve as an index of brain function having a bearing upon neuropsychological performance of epileptics.