Abstracts

RATIONALE: Ictal EEG of cortical dysplasia(CD) was not elucidated well. To investigate the characteristics of ictal and interictal discharges on CD, we analyzed and compared intracranial EEG recordings in CD and with non-dysplastic lesions(ND). METHODS: 18 patients had CD and 15 patients had ND(tumor, infarction, atrophy). They had undergone epilepsy surgery after intracranial EEG monitoring with subdural grids and pathologically proven. The distribution, shape, ahd rhythmicity of ictal and interictal discharges were analyzed. RESULTS: Ictal discharges of repetitive rhythmic discharges were seen in 90.5% of CD and 20% of ND. The remaining 80% of ND showed ictal irregular fast and sharp waves. The distributions of ictal discharges were regional(56%), multiregional(22%), focal(11%), multifocal(11%) in CD and focal(40.5%), regional(40%), multiregional(19.5%)in ND. The mean frequencies of interictal spikes between CD and ND were 2750 per hour and 398 per hour in ND. There was no difference in distribution of interictal spikes between CD and ND. CONCLUSIONS: The main ictal EEG feature of CD was repetitive rhythmic discharges. CD showed more extensive ictal discharge and frequent interictal spikes.