EEG FEATURES OF CORTICAL DYSPLASIA IN CHILDREN

Two distinctive electroencephalographic abnormalities, very high ampli tude rhythmic activity or prominent fast activity, have been described in children with extensive cortical dysplasia. Cases with cortical dy splasia identified on computerised tomography or magnetic resonance im aging, or a characteristic EEG were selected. One hundred and forty el ectroencephalograms from 94 cases were reviewed and related to the ima ging findings. An EEG with very high amplitude rhythmic activity was f ound to have high specificity for severe cortical dysplasia but low se nsitivity (< 50% cases). Abnormal fast activity was not specific and w as seen with very diverse pathologies. The EEG features of most cases with localised cortical dysplasia were very variable. The EEG could be normal even when the cortical dysplasia was extensive. These differen ces emphasise the need for both detailed neuroimaging and neurophysiol ogical investigations when assessing children with neurological proble ms.