Neonatal Seizures and EEG

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After completing this article, readers should be able to: 1. Distinguish between epileptiform activity and an electrographic seizure. 2. List clinical events that are most likely and least likely to be associated with electrographic seizures. 3. Define electroclinical dissociation and uncoupling. 4. List interictal EEG abnormalities associated with epileptic seizures. The current terminology used to define a seizure is confusing. Using strict terminology, a “seizure” is a sudden clinical event that has an outward change in neurologic function. (1) Pathophysiologically, a “seizure” may or may not have an epileptic basis, with electroencephalography (EEG) used primarily to differentiate these. An epileptic event is caused by a hypersynchronous neuronal discharge that is seen on EEG as an electrographic seizure. In newborns, however, many clinicians use the term neonatal seizure synonymously with epileptic seizure, thus assuming an epileptic mechanism. The International League Against Epilepsy glossary for seizure classification now uses the descriptor “epileptic” with seizure, (2) which specifically assigns an epileptic mechanism to the clinical event. In older children and adults, determining whether a seizure has an epileptic basis is more straightforward because of a greater association between epilepsy and EEG readings. In the older child, there also is a greater realization that nonepileptic events exist, with specific terminology used, including nonepileptic paroxysmal events and paroxysmal nonepileptic events. (3) The distinction between an epileptic event and a nonepileptic event is not so straightforward in the newborn. Neonates exhibit a broad repertoire of clinical behaviors (events) that are termed seizures. (4) In the article on movement disorders that also appears in this issue of NeoReviews , it is noted that tremor, myoclonus, or dyskinesias may represent seizures, and EEG is used for the evaluation. Determining whether neonatal seizures have an epileptic basis is, therefore, critical for management and determination of whether an antiepileptic drug (AED) is needed. …