Is Hyperventilation an Effective ‘‘Activating’’ Procedure in Routine Clinical EEG Studies in Children?

Abstract

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.

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“…Another interesting brief communication of Raybarman 20 showed that from 275 recorded pediatric patients with generalized epilepsy, in only a small amount of them (11.6%) the HV maneuver induced an increase of interictal epileptiform discharges, and none of them had clinical seizures induced during HV. The value of hyperventilation as an ‘‘activating’’ procedure in routine clinical EEG studies was questioned in this study even in generalized epilepsies.…”

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“…Hyperventilation is the oldest provocation methods, its efficiency in triggering absence seizures being observed even before the use of EEG, while the effect it has on cerebral electric activity has been observed by Berger in 1934 and further studied by Gibbs et al in 1935. [15][16][17] Over time, its diagnostic value has been certified by several studies and it has become a part of most standard EEG recordings [16][17][18][19][20][21][22][23][24][25] and it is also of use in intracranial EEG recordings 26 .…”

“…As a provocation method, it has proven to be more useful in generalized epilepsy, and especially in absence seizures 16,17,[19][20][21][27][28][29] , but also in Juvenile Myoclonic Epilepsy [29][30][31] . Nevertheless, some studies have shown that it can also trigger focal seizures, especially those with a temporal lobe onset 17,22,23,26,28 while others question its value for focal epilepsy 18,24,27 In addition to epileptiform discharges, HV can also elicit slow activity. Sometimes this is a normal phenomenon, especially in children or young adults, but it can also point to a specific cerebral disease.…”

“…The great variation in these numbers comes both from the design of the study and the selected population (the diagnostic yield is higher in children than in adults, and in generalized epilepsies, particularly in Childhood Absence Epilepsy, than in focal ones) but also from the duration of the HV maneuver. In most of the studies the duration of HV was 3 minutes 16,23,27,28,31,43 , in one it was 4 minutes 41 , in others it was 5 minutes 17,24,41,[44][45][46] , or ranging from 3 to 6 minutes 26 , from 3 to 5 minutes 38 and one of the biggest studies, on 3745 patients has durations of HV ranging from 1 to 7 minutes 21 .…”

“…Guaranha et al17 excluded children under 10 years and only looked at patients with drugresistant focal epilepsy, while Raybarman et al24 only included children with generalized epilepsy), but also in the methods applied and in the duration of HV itself.…”