Seizures

Overview

Children with epilepsy, particularly infants, differ from adults not only in the clinical manifestations of their seizures, but also in the presence of unique electroencephalogram (EEG) patterns, etiologies, and response to antiseizure drugs. The immature brain, particularly in the neonate and young infant, differs from the adult brain in the basic mechanisms of epileptogenesis and propagation of seizures (. It is more prone to seizures, but seizures are more apt to disappear as the child grows.

This topic provides an overview of the classification and etiology of seizures and epilepsy in children. The clinical diagnosis and management of new-onset seizures and epilepsy in children are presented separately.

DEFINITIONS

Seizure — A seizure represents the clinical expression of abnormal, excessive, synchronous discharges of neurons residing primarily in the cerebral cortex. This abnormal paroxysmal activity is intermittent and usually self-limited, lasting seconds to a few minutes.

When the seizure is prolonged or immediately recurrent without a return of consciousness, this is status epilepticus.

Epilepsy — An individual is considered to have epilepsy when any of the following exists:

• At least two unprovoked (or reflex) seizures occurring more than 24 hours apart.
• One unprovoked (or reflex) seizures and a probability of further seizures similar to the general recurrence risk after two unprovoked seizures (eg, ≥60 percent), occurring over the next 10 years. This may be the case with remote structural lesions such as stroke, central nervous system infection, or certain types of traumatic brain injury.
• Diagnosis of an epilepsy syndrome.

Epilepsy is considered to be a disease associated with lasting derangement of normal brain function. It may arise from a variety of genetic, structural, metabolic, immune, infectious, or unknown causes. Acute symptomatic seizures (also referred to as provoked or reactive seizures) caused by hyponatremia, hypocalcemia, high fever, toxic exposure, intracranial bleeding, or bacterial meningitis are not classified as epilepsy unless they become a recurrent process beyond the acute illness.