Brain cells called neurons normally communicate, in part, by short bursts of electrical activity. Some of these discharges may be abnormally intense, to a degree that normal brain function is disrupted. The result may be symptoms such as atypical body movements, altered or lost consciousness, hallucinations, or changes in emotion and behavior. This association of abnormal brain electrical activity with such symptoms is called a seizure.

Many acute medical problems--infection, low blood sugar, poisoning, and others--can cause seizures. If a child has recurrent seizures in the absence of any of these factors, he or she is said to have a seizure disorder, or epilepsy. The nature of a seizure depends on which brain structures are affected.

Partial Seizures

A seizure in which the abnormal discharge is limited to part of the brain is defined as a partial seizure. A partial seizure can spread to the rest of the brain, triggering a generalized seizure. A wide range of clinically distinct partial seizure disorders exists, but consciousness is at least partially maintained in each one.

Generalized Seizures

A seizure that involves the entire brain is termed a generalized seizure. Several kinds of generalized seizures exist. By definition, all generalized seizures are accompanied by a complete loss of consciousness.

An electroencephalogram (EEG) provides a record of the brain's electrical activity. It is typically part of the evaluation of a young child referred for seizures. An EEG may point to cerebral structures where seizure activity begins and propagates. The test may also reveal abnormal firing patterns that suggest epilepsy.

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