Differentiation of specific ripple patterns helps to identify epileptogenic areas for surgical procedures

Karolin Kerber (Corresponding Author), Matthias Dümpelmann, Björn Schelter, Pierre Le Van, Rudolf Korinthenberg, Andreas Schulze-Bonhage, Julia Jacobs

Research output: Contribution to journalArticlepeer-review

106 Citations (Scopus)


Objective: High frequency oscillations (HFOs) at 80-500. Hz are promising markers of epileptic areas. Several retrospective studies reported that surgical removal of areas generating HFOs was associated with a good seizure outcome. Recent reports suggested that ripple (80-200. Hz) HFO patterns co-existed with different background EEG activities. We hypothesized that the coexisting background EEG pattern may distinguish physiological from epileptic ripples. Methods: Rates of HFOs were analyzed in intracranial EEG recordings of 22 patients. Additionally, ripple patterns were classified for each channel depending either as coexisting with a flat or oscillatory background activity. A multi-variate analysis was performed to determine whether removal of areas showing the above EEG markers correlated with seizure outcome. Results: Removal of areas generating high rates of 'fast ripples (>200. Hz)' and 'ripples on a flat background activity' showed a significant correlation with a seizure-free outcome. In contrast, removal of high rates of 'ripples' or 'ripple patterns in a continuously oscillating background' was not significantly associated with seizure outcome. Conclusion: Ripples occurring in an oscillatory background activity may be suggestive of physiological activity, while those on a flat background reflect epileptic activity. Significance: Consideration of coexisting background patterns may improve the delineation of the epileptogenic areas using ripple oscillations.
Original languageEnglish
Pages (from-to)1339-1345
Number of pages7
JournalClinical Neurophysiology
Issue number7
Early online date6 Dec 2013
Publication statusPublished - 1 Jul 2014

Bibliographical note

Acknowledgement: This study has been supported by Grant JA 1725/2-1 of the German Research Foundation.


  • Depth electrodes
  • Epilepsy surgery
  • Fast ripple
  • High frequency oscillation
  • Refractory epilepsy
  • Spikes


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