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Updated: Jan 26, 2026

Brain Source Imaging in Preclinical Rat Models of Focal Epilepsy using High-Resolution EEG Recordings
Published on: June 6, 2015
Postictal EEG changes following focal seizures: Interrater agreement and comparison to frequency analysis
Ivan C Zibrandtsen1, Sigge Weisdorf1, Martin Ballegaard1
1Department of Neurophysiology, Zealand University Hospital, Roskilde, Denmark.
Objectives:
To compare frequency analysis to human raters and determine the interrater agreement of postictal EEG changes after focal seizures.
Methods:
24 focal seizures with and without impaired awareness recorded with scalp-EEG in the epilepsy monitoring unit were selected. Five board-certified neurophysiologists annotated seizure termination and end of postictal changes for all seizures. We assessed agreement using intraclass correlation, described the band-power changes by time-frequency analysis, and correlated these measures with the rater annotations.
Results:
Interrater agreement on the duration of the postictal changes was moderate (0.64, 95% confidence interval: 0.36-0.82). The interrater agreement for seizure termination was excellent (1.00). Median duration of the postictal interval of seizures with impaired awareness was significantly shorter than for seizures with retained awareness (p = 0.0004). Mean postictal duration was 16.4 min. Seizure duration did not predict duration of the postictal changes. We found a strong correlation of 0.8 between the median human rater and the duration of the decrease in spectral edge frequency.
Conclusions:
The agreement of neurophysiologists is moderate for duration of postictal changes and high for seizure termination. Rater determination of postictal duration is correlated with measures of EEG slowing.
Significance:
Disagreement between neurophysiologists on postictal duration need to be considered.
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