AVOIDING THE PITFALLS OF EEG INTERPRETATION IN CHILDHOOD EPILEPSY

The accurate interpretation of the electroencephalogram (EEG) of infan ts and children being evaluated for suspected epilepsy is based on the appreciation of normal and expected age-dependent characteristics, an awareness of the significance of both epileptiform and non-epileptifo rm activity, and the correlation of epileptiform abnormalities with cl inical findings. Avoiding the pitfalls of pediatric EEG interpretation include the recognition of such normal EEG features in wakefulness as posterior slow waves of youth, mu rhythm, and lambda waves. In additi on, the understanding of age-dependent characteristics of EEG state-ch anges is essential, such as: monorhythmic and paroxysmal hypnagogic hy persynchrony, special features of vertex transients and sleep spindles , positive occipital sharp transients, initial arousal responses and p ost-arousal hypersynchrony. The EEG response to activation procedures such as hyperventilation and photic stimulation may also be a source o f confusion. Patterns of uncertain diagnostic significance also may be present in children, including 14- and 6-Hz bursts and rhythmic tempo ral theta bursts of drowsiness (the so-called psychomotor variant). So me nonepileptiform EEG abnormalities may also be misinterpreted as epi leptiform. The determination of the clinical significance of spike foc i and generalized abortive spike-and-wave may pose more of a problem a s a potential pitfall than the identification by visual analysis of th ese interictal discharges. Another problem posed to the electroencepha lographer is the determination of the EEG response to antiepileptic dr ug therapy including effect on spike foci, generalized spike-and-wave and electrical seizure activity, and effect on background activity. Th e recognition of the differences between the EEG of children and adult s will provide the basis for more accurate interpretation and assist t he electroencephalographer in avoiding the identification of normal, a ge-dependent features as epileptiform.