[Electroencephalographic normal variants or with uncertain significance].

Electroencephalography is an important tool in the diagnosis of primary or secondary disorders of central nervous system, epilepsy is one of the most important. Sometimes normal electroencephalographic activity simulates epileptiform activity. This activity does not have pathological value and is considered a variant of normal brain activity. The main groups based on the classification proposed by Blum and Cervone are: rhythmic patterns; epileptiform patterns; lambda waves, and age dependent changes. These changes are frequently seen during drowsiness, sleep and during activation maneuvers and more common in children and adolescents. The aim of this review is to present the most important characteristics of each of these variants, in order to prevent them being confused with abnormal brain activity.