Is hyperventilation an effective ''activating'' procedure in routine clinical EEG studies in children?

Electroencephalography (EEG) records of consecutive 275 children (ages 3-18 years; average 11 years; 34.5% females), with generalized epilepsy, consistent with epileptiform discharges in baseline EEG, who underwent 5 minutes of voluntary hyperventilation during standard EEG recordings were reviewed in this study to determine the actual value of the voluntary hyperventilation in routine clinical EEG in provoking epileptiform EEG abnormalities. Of the 275 EEG records, only in 11.6% hyperventilation revealed increased interictal epileptiform discharges as evidenced by increase in frequency during hyperventilation when compared with the baseline EEG and in 0.7% ictal epileptiform discharges without clinical seizure. None of the 275 children elicited clinical seizure during hyperventilation. The value of voluntary hyperventilation as an ''activating'' procedure in routine clinical EEG studies even in children with generalized epilepsy was questioned in this study.