Basic mechanisms of seizure expression.

While there are many types of seizures, our understanding of their pathophysiology is limited to a few types. On the basis of the behavior of neurons during a seizure, two fundamental types of paroxysms are recognized--spike-wave electrographic seizures and tonic-clonic electrographic seizures. When the former type of paroxysm takes place throughout the forebrain, an absence seizure ensues. When the latter type of paroxysm takes place within a limited set of neurons, a simple partial or complex partial seizure takes place, depending on the functional anatomy. When the latter type of paroxysm takes place throughout the forebrain, a generalized convulsion takes place. The basic cellular and synaptic processes that underlie electrographic spike-wave and tonic-clonic paroxysms are complex and dissimilar between the two types of discharges. This paper reviews these multiple processes. The diverse pathophysiological mechanisms presented provide a theoretical substrate for rational polypharmacy directed to seizure suppression.