Neocortical seizure foci localization by means of a directed transfer function method

Christopher Wilke, Wim Van Drongelen, Michael Kohrman, Bin He

Research output: Contribution to journalArticlepeer-review

100 Scopus citations


Purpose: Determination of the origin of extratemporal neocortical onset seizures is often challenging due to the rapid speed at which they propagate throughout the cortex. Typically, these patients are poor surgical candidates and many times experience recurrences of seizure activity following resection of the assumed seizure focus. Methods: We applied a causal measurement technique - the directed transfer function (DTF) - in an effort to determine the cortical location responsible for the propagation of the seizure activity. Intracranial seizure recordings were obtained from a group of 11 pediatric patients with medically intractable neocorticalonset epilepsy. Time windows were selected from the recordings following onset of the ictal activity. The DTF was applied to the selected time windows, and the frequency-specific statistically significant source activity arising from each cortical recording site was quantified. The DTF-estimated source activity was then compared with the seizure-onset zone(s) identified by the epileptologists. Results: In an analysis of the 11 pediatric patients, the DTF was shown to identify estimated ictal sources that were highly correlated with the clinically identified foci. In addition, it was observed that in the patients with multiple ictal foci, the topography of the casual source activity from the analyzed seizures was associated with the separate clinically identified seizure-onset zones. Discussion: Although localization of neocortical-onset seizures is typically challenging, the causal measures employed in this study - namely the directed transfer function - identified generators of the ictal activity that were highly correlated with the cortical regions identified as the seizure-onset zones by the epileptologists. This technique could prove useful in the identification of seizure-specific propagation pathways in the presurgical evaluation of patients with epilepsy.

Original languageEnglish (US)
Pages (from-to)564-572
Number of pages9
Issue number4
StatePublished - Apr 2010


  • Directed transfer function
  • Epilepsy
  • Functional connectivity
  • Seizure localization


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