Generalized convulsive epilepsy: possible mechanisms.

Neuronal mechanisms underlying focal convulsions and secondary generalized convulsions continue to be intensively investigated and many important pathophysiological processes are now recognized. Our understanding of primary generalized convulsions remains limited in spite of a variety of approaches. While there are well known clinical situations offering insights into some aspects of the pathophysiology, studies in animal models of generalized convulsions offer a deeper understanding of some of the processes likely to be occurring. Animal studies have indicated that generalized convulsive epilepsies are likely to be comprised of several types of convulsion and that these arise from more than one neuronal network. In particular, the cortex and brain stem can interact in various ways to lead to convulsions and may even act independently. Pharmacological agents can produce specific changes in the excitability of neurons and cause generalized convulsions, so providing models of the possible neurophysiological defects in humans. Based on electrophysiological recordings of generalized convulsions in these animal models, we also suggest that the convulsion involves subcortical mechanisms and raise the idea that primary generalized convulsive epilepsy arises out of intensified (synchronized) normal brain rhythms. Copyright 1999 Harcourt Publishers Ltd.