Seizures, Epilepsy, and Status Epilepticus

A seizure is a transient occurrence of signs or symptoms caused by abnormal excessive or synchronous neuronal activity in the brain. Normal brain function depends on a balance between excitation, largely mediated by glutamate, and inhibition, largely mediated by GABA. When that balance shifts toward excessive excitation, groups of neurons can discharge together in a hypersynchronous pattern. The activity may stay within one network, producing a focal seizure, or spread through both hemispheres, producing a generalized seizure. A seizure is an event; epilepsy is a disorder with an enduring tendency to have epileptic seizures. Epilepsy is diagnosed when any one of these criteria is met: - Two unprovoked, or reflex, seizures occurring more than 24 hours apart. - One unprovoked or reflex seizure plus a predicted probability of further seizures of at least 60% over the next 10 years. - An epilepsy syndrome is diagnosed. A seizure provoked by a correctable acute problem—such as severe hypoglycemia, acute intoxication, or an acute metabolic disturbance—does not automatically establish epilepsy. The cause and the probability of recurrence must be assessed. The International League...