Whole-course power evolution in childhood absence epilepsy: A multi-frequency magnetoencephalography study

This study explores the whole-course neuromagnetic activity changes in childhood absence epilepsy (CAE) using multifrequency magnetoencephalogram (MEG) analysis. We aim to uncover the underlying neurophysiological mechanisms and identify functional signal targets with potential clinical applications.

We recruited 37 drug-naive children with CAE and collected magnetoencephalography (MEG) data from 62 seizures and interictal periods using a CTF-275 channel MEG system. The seizure course was segmented with temporal unification and subjected to dynamic frequency band analysis. Minimum norm estimation combined with Welch's method was employed for spectral power calculation, followed by correlation analysis between power and seizure duration.

Whole-brain magnetic source power changes in 2-60 Hz largely paralleled the progression of spike and wave discharges (SWDs), while power in 60-90 Hz was suppressed during seizures. Alpha band (8-12 Hz) activity showed a prompt loss of occipital dominance at seizure onset, with concurrent elevation in frontal alpha activity. This frontal alpha dominance persisted throughout the ictal period and reverted to occipital dominance at termination. Beta and gamma1 band (15-59 Hz) activity characteristically declined before SWDs cessation. The power of SWDs during ictal period was negatively correlated with seizure duration.

Spectral power analysis of neuromagnetic signals throughout CAE process identifies specific frequency-dependent characteristic changes, among which, the distribution of alpha band (8-12 Hz) activity is closely related to absence manifestations, beta band (15-29 Hz) power decline induces seizure termination. Additionally, ictal SWDs power can serve as a neuroimaging indicator of epilepsy severity.