Early Ictal Dynamics in Childhood Absence Epilepsy: Scalp EEG Detection of Direct Current Shifts and High-Frequency Oscillations.
Keisuke Maeda, Shunta Yamaguchi, Himari Tsuboi et al.
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Case in brief
Two children with childhood absence epilepsy had typical absence seizures during hyperventilation-provoked scalp EEG. Wide-band recordings captured both direct-current (DC) shifts and high-frequency oscillations (HFOs) in the same seizure epochs. Across three seizures, a negative DC shift began several hundred milliseconds before the first generalized spike-and-wave complex (SWC), deepened toward onset, and was followed shortly after onset by discrete, spike-locked HFOs. The sequence was consistent across the seizures and both patients despite differences in seizure duration and clinical background. The authors interpret the signals as reflecting slow network changes before thalamocortical hypersynchrony and faster dynamics associated with SWC generation.
What made this case unusual
Scalp wide-band EEG captured both a pre-SWC negative DC shift and post-onset spike-locked HFOs within the same seizure epochs, revealing a reproducible temporal sequence across the two children.
Diagnostic / clinical pearl
In childhood absence seizures, wide-band scalp EEG may reveal a negative DC shift several hundred milliseconds before the first SWC, followed by spike-locked HFOs after onset; conventional SWC-focused review may not show these early dynamics.
Why it matters
The authors suggest that noninvasive detection of both slow and fast ictal components could provide a basis for developing early ictal biomarkers in childhood absence epilepsy.