Classification of complex-partial seizure patients using the P300 auditory evoked response and working memory ability

The primary purpose of the study was to define P300 parameters that can be used to identify the focal side in temporal lobe epilepsy patients. P300 auditory evoked responses recorded from 18 scalp electrodes were studied in epilepsy patients suffering from intractable complex partial seizures prior to undergoing unilateral left (n = 14) or right (n = 4) temporal lobectomy. Eleven control subjects also participated.;Previous studies of this type relied on analysis of variance (ANOVA) and similar statistical techniques to help discern between group differences in raw measures of P300 amplitude and latency. These methods had only limited success. This study used several variables derived from amplitude and latency data as within-subject measures. The variables were used to compare the left and right hemispheres to each other in a manner similar to that used in quantitative EEG. Several P300 parameters reliably distinguished groups and other parameters reliably identified the hemisphere of epileptic focus. Our findings support the hypothesis that damage to temporal and medial temporal structures affects P300 distribution and latency. Several quantifiable measures are provided to highlight P300 abnormalities in epileptic patients.;A secondary concern was the use of P300 as an index of cognitive processing, specifically working memory. Scores from the short-term Logical Memory and Visual Reproduction subtests of the Wechsler Memory Scale (Russell Revision) were correlated with P300 amplitude. The findings support the contention that P300 and verbal working memory are related.