Postictal EEG changes following focal seizures: Interrater agreement and comparison to frequency analysis

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  • Ivan C. Zibrandtsen, University of Copenhagen
  • ,
  • Sigge Weisdorf, University of Copenhagen
  • ,
  • Martin Ballegaard, University of Copenhagen
  • ,
  • Sándor Beniczky
  • Troels W. Kjaer, University of Copenhagen

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.

Original languageEnglish
JournalClinical Neurophysiology
Pages (from-to)879-885
Number of pages7
Publication statusPublished - 1 Jun 2019

    Research areas

  • Clinical neurophysiologist, EEG, Epilepsy, Focal seizures, Interrater agreement, Time-frequency analysis

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