Abstracts

Although all patterns and frequencies of seizure onset were recorded in both temporal and extratemporal locations, some specific ictal patterns during intracranial recordings may help to predict surgical outcome. The purpose of this study is to compare the intracranial ictal EEG (ictal EEG) patterns in patients with temporal lobe epilepsy (TLE) to find the ictal patterns suggesting good surgical outcome., We analyzed total 128 seizures in 33 TLE patient underwent invasive intracranial study using bilateral temporal depth and subdural electrodes. Of the 33 patents, 26 were underwent temporal lobectmy with amygdallohippocampectomy, in whom 21 were [apos]seizure-free[apos] and 5 were [apos]not seizure-free[apos] with minimum 1 year follow-up. Seven were not operated. We divided the patients into 3 groups as [apos]seizure-free[apos], [apos]not seizure-free[apos] and [apos]non-operation[apos]. We analyzed each ictal EEG charicteristics based on presence or absence of peri-ictal discharges, ictal distribution, involved number of electrodes, waveform pattern, onset frequency and interhemispheric propagation time (IHPT). Statistical analysis used chai-squre, Fisher[apos]s exact test and ANOVA test using SPSS 12.0 version., There are no differences in dermographic data including sex, onset age, duration of epilepsy, risk factor and hippocampal atrophy on MRI among 3 groups. But all analyzed ictal EEG charicteristics have statistically significant difference among 3 groups. The presence of peri-ictal discharges was exclusively observed in [apos]seizure-free[apos]. The lesser number of involved elcetrodes with ictal distribution of [apos]depth only[apos] or [apos]depth and medial strip electrode[apos] were associated with [apos]seizure-free[apos] but [apos]non-operation[apos] had spatially wider distribution of ictal onset involving [apos]diffuse strip and depth[apos] or [apos]strip only[apos]. Higher onset frequency above beta range more correlated to [apos]seizure-free[apos] while slow onset frequency lesser than alpha in others. Ictal onset patterns with fast spike trains were exclusively observed in [apos]seizure-free[apos], whereas pattern with rhythmic activity was common in [apos]not-seizure-free[apos] and [apos]non-operation[apos]. IHPT was 22. 46[plusmn]19.44 seconds(s) in [apos]seizure-free[apos], 18.56 [plusmn]16.74 s in [apos]not seizure-free[apos], but 5.96 [plusmn]8.04 s in [apos]non-operation. IHPT was signifiantly shorter in [apos]non-operation[apos]., Intracranial ictal EEG patterns are significantly different among [apos]seizure-free[apos],[apos] [apos]not seizure-free[apos] and [apos]non-operation[apos]. These findings suggest that analysis of ictal EEG patterns help to predict surgical outcome.,