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Brain Topography

, Volume 28, Issue 2, pp 305–317 | Cite as

Detecting Functional Hubs of Ictogenic Networks

  • Frederic Zubler
  • Heidemarie Gast
  • Eugenio Abela
  • Christian Rummel
  • Martinus Hauf
  • Roland Wiest
  • Claudio Pollo
  • Kaspar Schindler
Original Paper

Abstract

Quantitative EEG (qEEG) has modified our understanding of epileptic seizures, shifting our view from the traditionally accepted hyper-synchrony paradigm toward more complex models based on re-organization of functional networks. However, qEEG measurements are so far rarely considered during the clinical decision-making process. To better understand the dynamics of intracranial EEG signals, we examine a functional network derived from the quantification of information flow between intracranial EEG signals. Using transfer entropy, we analyzed 198 seizures from 27 patients undergoing pre-surgical evaluation for pharmaco-resistant epilepsy. During each seizure we considered for each network the in-, out- and total “hubs”, defined respectively as the time and the EEG channels with the maximal incoming, outgoing or total (bidirectional) information flow. In the majority of cases we found that the hubs occur around the middle of seizures, and interestingly not at the beginning or end, where the most dramatic EEG signal changes are found by visual inspection. For the patients who then underwent surgery, good postoperative clinical outcome was on average associated with a higher percentage of out- or total-hubs located in the resected area (for out-hubs p = 0.01, for total-hubs p = 0.04). The location of in-hubs showed no clear predictive value. We conclude that the study of functional networks based on qEEG measurements may help to identify brain areas that are critical for seizure generation and are thus potential targets for focused therapeutic interventions.

Keywords

Quantitative EEG Functional brain networks Epilepsy surgery Symbolic transfer entropy 

Supplementary material

10548_2014_370_MOESM1_ESM.pdf (177 kb)
Supplementary material 1 (PDF 176 kb)

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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Frederic Zubler
    • 1
  • Heidemarie Gast
    • 1
  • Eugenio Abela
    • 2
  • Christian Rummel
    • 2
  • Martinus Hauf
    • 2
  • Roland Wiest
    • 2
  • Claudio Pollo
    • 3
  • Kaspar Schindler
    • 1
  1. 1.Department of Neurology, Inselspital Bern, Bern University HospitalUniversity of BernBernSwitzerland
  2. 2.Support center for advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, Inselspital Bern, Bern University HospitalUniversity of BernBernSwitzerland
  3. 3.Department of Neurosurgery, Inselspital Bern, Bern University HospitalUniversity of BernBernSwitzerland

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