title: How important is the seizure onset zone for seizure dynamics?
abstract: OBJECTIVE
  Research into epileptic networks has recently allowed deeper insights into the epileptic process. Here we investigated the importance of individual network nodes for seizure dynamics.
  
  
  METHODS
  We analysed intracranial electroencephalographic recordings of 86 focal seizures with different anatomical onset locations. With time-resolved correlation analyses, we derived a sequence of weighted epileptic networks spanning the pre-ictal, ictal, and post-ictal period, and each recording site represents a network node. We assessed node importance with commonly used centrality indices that take into account different network properties.
  
  
  RESULTS
  A high variability of temporal evolution of node importance was observed, both intra- and interindividually. Nevertheless, nodes near and far off the seizure onset zone (SOZ) were rated as most important for seizure dynamics more often (65% of cases) than nodes from within the SOZ (35% of cases).
  
  
  CONCLUSIONS
  Our findings underline the high relevance of brain outside of the SOZ but within the large-scale epileptic network for seizure dynamics. Knowledge about these network constituents may elucidate targets for individualised therapeutic interventions that aim at preventing seizure generation and spread.
authors.affiliation: Department of Epileptology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn, Germany; Helmholtz Institute for Radiation and Nuclear Physics, University of Bonn, Nussallee 14-16, 53115 Bonn, Germany. Electronic address: geier@uni-bonn.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Geier
authors.affiliation: Max Planck Institute for the Physics of Complex Systems, Nöthnizer Straße 38, 01187 Dresden, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Bialonski
authors.affiliation: Department of Epileptology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn, Germany.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Elger
authors.affiliation: Department of Epileptology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn, Germany; Helmholtz Institute for Radiation and Nuclear Physics, University of Bonn, Nussallee 14-16, 53115 Bonn, Germany; Interdisciplinary Center for Complex Systems, University of Bonn, Brühler Straße 7, 53175 Bonn, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Lehnertz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D002648:Child; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D012189:Retrospective Studies; D012640:Seizures / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: Centrality; Epileptic networks; Graph analysis; Node importance; Seizure onset zone