36th Annual Meeting of the International Society for Paediatric Neurosurgery, Cape Town, South Africa, 12-16 October 2008

摘要

A comparison of in vitro electrophysiologic differences between focal and parafocal tissue resected from pediatric epilepsy patients: moving towards a greater understanding of the nature of epilepsyPediatric epilepsy in humans typically arises from the neocortex. The underlying mechanisms involved in the generation of epileptiform activity remain poorly defined. Despite a large amount of electrophysiological data obtained from human brain " slices resected from patients with intractable epilepsy, e!ectrophys-iological differences between focal and parafocal tissue have not been identified. In this study, human brain slice preparations were prepared from tissue resected in pediatric patients undergoing resective brain surgery for the treatment of intractable epilepsy. We made simultaneous recordings of extracellular neural network activity and rntracellular activity from individual neurons. Seizure-like activity was induced in vitro by enhancing excitatory (with NMDA) and suppressing inhibitory synaptictransmission (with bicuculline). Electrophyiological recordings from focal and parafocal resected tissue (as defined by intracranial EEG recordings) were then compared. In patients without cortical dysplasia, focal neurons were found to be more likely to engage in paroxysmal depolarization shifts (PDS), an intracellular correlate of epileptiform activity, when compared to parafocal neurons. In patients with widespread cortical dysplasias this difference was not observed, suggesting that patients with cortical dysplasia have widely distributed rather than focal hyperexcitabiliry. Further study in this area will lead to a greater understanding of the nature of epileptogenic networks and ideally lead to an in vitro functional assay to guide resection.