EEG features of absence seizures in idiopathic generalized epilepsy: impact of syndrome, age, and state.
OBJECTIVE
Factors influencing the electroencephalography (EEG) features of absence seizures in newly presenting children with idiopathic generalized epilepsy (IGE) have not been rigorously studied. We examined how specific factors such as state, provocation, age, and epilepsy syndrome affect the EEG features of absence seizures.


METHODS
Children with untreated absence seizures were studied using video-EEG recording. The influence of state of arousal, provocation (hyperventilation, photic stimulation), age, and epilepsy syndrome on specific EEG features was analyzed.


RESULTS
Five hundred nine seizures were evaluated in 70 children with the following syndromes: childhood absence epilepsy (CAE) 37, CAE+ photoparoxysmal response (PPR) 10, juvenile absence epilepsy (JAE) 8, juvenile myoclonic epilepsy (JME) 6, and unclassified 9. Polyspikes occurred in all syndromes but were more common in JME. They were brought out by drowsiness and sleep in fragments of generalized spike and wave (GSW). Polyspikes were more likely to occur during photic stimulation, but were not influenced by age independently. GSW was more likely to be disorganized in JME than JAE, and in JAE than CAE. Increasing age and levels of arousal were more likely to result in organized GSW. Factors specific to each child independently influenced EEG features; the nature of these factors has not been identified.


CONCLUSIONS
The EEG features of absence seizures are influenced by a complex interaction of age, epilepsy syndrome, level of arousal, provoking factors, and other intrinsic factors. Epilepsy syndrome alone cannot predict specific features of GSW; however, JME is more frequently associated with polyspikes and disorganization of the paroxysm.
Sadleir
Lynette Grant
LG
Department of Paediatrics, Wellington School of Medicine, University of Otago, Wellington, New Zealand. lynette.sadleir@otago.ac.nz
Scheffer
Ingrid E
IE
Smith
Sherry
S
Carstensen
Bendix
B
Farrell
Kevin
K
Connolly
Mary B
MB
D000293:Adolescent; D000367:Age Factors; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000209:etiology* / Q000473:pathology*; D004829:Epilepsy, Generalized / Q000150:complications*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D012189:Retrospective Studies; D012890:Sleep / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology