Abstracts

RATIONALE: Cortical dysplasias (CD) are increasingly recognized as pathological substrates in patients with medically intractable epilepsy. A rat model for multifocal cortical dysplasia characterized using in uteroirradiation was previously described. The purpose of the present study is to characterize the in vivoelectroencephalographic (EEG) patterns in this model using continuous epidural and hippocampal depth electrode recordings. METHODS: Time pregnant Sprague-Dawley rats were radiated (145 Grays) at E17. The offspring of the radiated rats (n=5) and those of age-matched controls (n=4) were implanted with bilateral epidural and depth hippocampal electrodes at postnatal day (PND) 60. Continuous EEG recordings were performed and analyzed for the occurrence of interictal spikes and spontaneous seizures. At the end of the monitoring rats were sacrificedand their brains processed for histopathological characterization. RESULTS: All irradiated rats showed evidence of microscopic CD and hippocampal subfields neuronal dispersion. Spontaneous interictal spikes and EEG documented seizure patterns were only seen in irradiated rats. No epileptic activity was recorded from any of the control rats at least 24 hours after the electrode implantation. Interictal and ictal activities were recorded independently from the right and left frontal cortical areas, and from both hippocampal formations. CONCLUSIONS: Our current study shows in vivo evidence of the presence of spontaneous epileptogenicity in a chronic epilepsy model of CD. This model may be used for the studying of the mechanisms of epileptogenicity of CD and to test novel pharmacological and other medical/surgical treatment modalities.