EEG IN TYPE-I AND TYPE-II LISSENCEPHALY

Lissencephaly syndromes are rare disturbances of the neuronal migratio n with agyria and/or pachygyria. Typical patterns in the EEG of 5 chil dren with lissencephaly are presented. Rhythmic alpha- or beta-waves w ith high amplitudes of diffuse or fronto-precentral localisation are c haracteristic in type I lissencephaly. In type II lissencephaly initia lly theta- or delta-waves of somewhat lower amplitude are observed. Sh arp and slow wave-complexes of very high amplitude are found more ofte n in type I lissencephaly. They seem to correlate with the severity of the brain malformation and the epilepsy. In both types of lissencepha ly the spatial organisation of the background activity and the sleep-w ake differenciation are absent. The EEG of most type I lissencephalies show no reactivity to intravenous benzodiazepines. With increasing ag e the frequency of the background activity and of the high amplitude r hythmic waves decrease in type I and increase in type II lissencephaly . A complete dedifferenciation of the EEG tracings has been observed i n the course of type I lissencepahly. Lissencephaly is diagnosed by im aging techniques. However, with a high probability lissencephaly can b e suspected already by its EEG.