Correlation between EEG activity and event-related potential (P300) in childhood partial epilepsy

Application of the P300 Event-Related Potential in the Diagnosis of Epilepsy Disorder: A Review

Epilepsy is one of the most serious chronical neurological disorders, affecting more than 50 million people worldwide. It can be defined as a spectrum disorder, and patients with epilepsy possess abnormalities in cognitive functions. A number of factors can cause cognitive dysfunctions in epileptic syndromes, including etiology, the age of onset, type of seizure and severity, duration, and antiepileptic drugs. Event-related potentials (ERPs) are very useful clinical and research instruments to evaluate cognitive function in patients with neuropsychiatry disorders. Event-related potentials directly reflect cortical neuronal activity and provide a particular level of temporal resolution. Among various ERP components, the P300 is the most important component for assessing cognitive processes such as attention, working memory, and concentration. Numerous studies have reported the abnormalities in amplitude or latency of P300 component of ERP in epileptic patients, and these abnormalities are indicative of cognitive dysfunction. Therefore, the purpose of this review is to consolidate the existing literature in connection with the use of P300 in epileptic patients.

Abnormalities of auditory event-related potentials in students with schizotypal personality disorder

Biological, phenomenological and cognitive similarities are known to exist between schizophrenia and schizotypal personality disorder (SPD). This study examined whether, and to what extent, abnormalities in event-related potentials (ERPs) already extensively reported in schizophrenia can also be observed in persons psychometrically identified with SPD. Event-related potentials were examined in nine SPD subjects and nine controls recruited from among 1693 college students, using the Schizotypal Personality Questionnaire (SPQ) and the Structured Clinical Interview for DSM-III-R (SCID I and II). Event-related potentials were recorded during an auditory oddball task. Smaller P300 amplitude and prolonged P300 latency were found in SPD subjects as compared with controls. Our findings indicate that such individuals do have deficits in information processing similar to that found in schizophrenia. We can conclude that P300 abnormalities may not be specific for SPD but that abnormalities shown in SPD are possibly a vulnerability marker for developing schizophrenia.

Epileptic seizures and event-related potentials (P300) in childhood partial epilepsies

To clarify the relationship between cognitive function and clinical seizures, auditory event-related potentials (P300) were examined in 72 patients (185 trials) with partial epilepsy. Twenty-six patients (67 trials) had idiopathic partial epilepsies (IPE), and 46 (118 trials) symptomatic or cryptogenic partial epilepsies (SPE). In this study, to rule out the effects of epileptogenesis and other factors, we only examined patients with partial epilepsies undergoing carbamazepine (CBZ) monotherapy at doses of less than 16 mg/kg/day. The results were: 1) the mean age-corrected P300 latency in the patients with SPE (394 +/- 38 msec) was significantly prolonged compared with that in the patients with IPE (378 +/- 28). 2) The prolongation of the P300 latency had no relationship to the seizure frequency, seizure type or seizure duration. 3) In both epileptic groups, there was no significant correlation between the seizure-free period and the age-corrected P300 latency. Our results suggest that the effect of clinical seizures on the cognitive function may be relatively little, and that the cognitive dysfunction in partial epilepsies may mainly originate from epileptogenesis or other factors.