Electroclinical features of absence seizures in childhood absence epilepsy.

OBJECTIVE: To accurately define the electroclinical features of absence seizures in children with newly diagnosed, untreated childhood absence epilepsy (CAE).
METHODS: The authors searched an EEG database for absence seizures in normal children with new onset untreated absence epilepsy. Seventy consecutive children were classified into IGE syndromes. The clinical and EEG features of the seizures in the children with CAE were analyzed using video-EEG recordings.
RESULTS: The authors analyzed 339 absence seizures in 47 children with CAE. The average seizure duration was 9.4 seconds and clinical features consisted of arrest of activity, loss of awareness, staring, and 3-Hz eyelid movements, but there was individual variation. Ictal EEG predominantly showed regular 3-Hz generalized spike and wave (GSW) with one or two spikes per wave; however, disorganization of discharges was common and three or more spikes per wave occurred rarely. Postictal slowing was frequent. Interictal abnormalities included fragments of GSW, posterior bilateral delta activity, and focal discharges. Although all 47 children met the current criteria for CAE, only 5 fulfilled the recently proposed criteria for CAE.
CONCLUSION: The heterogeneous nature of each clinical and EEG feature of untreated absence seizures is of critical importance when determining criteria for childhood absence epilepsy.