Executive dysfunction in patients with temporal lobe epilepsy and its correlation with P300

Abstract

To explore the changes of executive function in patients with temporal lobe epilepsy and analyze its correlation with P300 event-related potentials. Fifty patients with temporal lobe epilepsy and 30 age, gender and education-matched healthy control subjects were assessed by neuropsychological tests, including Montreal cognitive assessment (MoCA), working memory, verbal fluency, trail making, digit span, digit symbol and Stroop color-word interference to detect P300 event-related potentials. In temporal lobe epilepsy group, the scores in MoCA, verbal and non-verbal working memory, verbal fluency, digit span, digit symbol and Stroop test were lower than those of the normal control group. And trail making tests A and B became prolonged (P < 0.05). Comparing with normal control group, temporal lobe epilepsy patients had prolonged latency [(332 ± 33)ms] and decreased P300 amplitude [(10 ± 8)µV] (P < 0.05). Comparing epileptogenic focus group on the left and right sides, there was statistically significant difference in verbal working memory (P < 0.05). There was a negative correlation of P300 latency and MoCA, non-verbal working memory, digit span and digit symbol test scores (r = -0.29--0.45, P < 0.05). And a positive correlation of P300 amplitude and MoCA, non-verbal working memory, digit symbol conversion and Stroop scores was also found (r = 0.37-0.47, P < 0.05). P300 amplitude was more relevant to overall cognitive level and executive functions. Temporal lobe is involved in the regulation of executive functions. Besides a wide range of cognitive impairment, temporal lobe epilepsy patients have a number of executive dysfunctions, including working memory, cognitive flexibility, attention and inhibitory control ability. And an impairment of verbal working memory is evident in left-sided lesion. Their manifestations include decreased latency and amplitude of P300 on executive function tests. Therefore these two objective parameters may be employed to evaluate the cognitive impairment in patients with temporal lobe epilepsy.