5 - Sensitivity of the immature central nervous system to epileptogenic stimuli

Summary

Introduction

During the last ten years, there has been an increased interest in investigating the basic mechanisms of epilepsy in the immature brain. It was already known that the behavioral manifestations of seizures were age dependent but it was widely believed that in the immature central nervous system (CNS) inhibitory events predominated (Purpura & Housepian, 1961; Purpura, 1969, 1972). Therefore, it was assumed that the immature brain was not prone to seizures. However, the preponderance of recently acquired data indicates that the developing CNS is more susceptible to seizures than is the adult CNS. This concept is based on both epidemiological (Gibbs & Gibbs, 1963; Vernadakis & Woodbury, 1969; Hauser & Kurland, 1975; Woodbury, 1977) and experimental (Moshé et al., 1983; Albala et al., 1984; Schwartzkroin, 1984; Swann & Brady, 1984; Cavalheiro et al., 1987; Sperber & Moshé, 1988; Moshé, 1989) studies. Additional data have revealed that epileptogenesis during development may not be a linear event. There appear to be periods of increased seizure susceptibility, followed by relatively more resistant ‘developmental windows’ (Schwartzkroin, 1984; Moshé 1989; Moshé et al., 1992). Furthermore, since brain areas do not mature at the same time, epileptogenesis may differ from site to site.