Brain Topography

, Volume 28, Issue 6, pp 832–837 | Cite as

Localization of Epileptogenic Zone on Pre-surgical Intracranial EEG Recordings: Toward a Validation of Quantitative Signal Analysis Approaches

  • Ralph G. Andrzejak
  • Olivier David
  • Vadym Gnatkovsky
  • Fabrice Wendling
  • Fabrice Bartolomei
  • Stefano Francione
  • Philippe Kahane
  • Kaspar Schindler
  • Marco de Curtis
Brief Communication


In patients diagnosed with pharmaco-resistant epilepsy, cerebral areas responsible for seizure generation can be defined by performing implantation of intracranial electrodes. The identification of the epileptogenic zone (EZ) is based on visual inspection of the intracranial electroencephalogram (IEEG) performed by highly qualified neurophysiologists. New computer-based quantitative EEG analyses have been developed in collaboration with the signal analysis community to expedite EZ detection. The aim of the present report is to compare different signal analysis approaches developed in four different European laboratories working in close collaboration with four European Epilepsy Centers. Computer-based signal analysis methods were retrospectively applied to IEEG recordings performed in four patients undergoing pre-surgical exploration of pharmaco-resistant epilepsy. The four methods elaborated by the different teams to identify the EZ are based either on frequency analysis, on nonlinear signal analysis, on connectivity measures or on statistical parametric mapping of epileptogenicity indices. All methods converge on the identification of EZ in patients that present with fast activity at seizure onset. When traditional visual inspection was not successful in detecting EZ on IEEG, the different signal analysis methods produced highly discordant results. Quantitative analysis of IEEG recordings complement clinical evaluation by contributing to the study of epileptogenic networks during seizures. We demonstrate that the degree of sensitivity of different computer-based methods to detect the EZ in respect to visual EEG inspection depends on the specific seizure pattern.


Computer-based signal analysis Epilepsy surgery Epileptogenic zone Focal epilepsy Intracranial EEG 



Epileptogenicity Index


Epileptogenic zone


Focal cortical dysplasia


Intracranial electroencephalogram


Nonlinear Structure Index


Quantified Frequency Analysis Index


Stereo electroencephalogram


Statistical Parametric Mapping of Epileptogenicity Index



RGA acknowledges grant FIS-2010-18204 of the Spanish Ministry of Education and Science. VG was supported by a Grant of the Italian Health Ministry (RG 151-2012). OD, FW and PK acknowledge Grant ANR 2013-TecSan-FORCE.

Conflict of interest

None of the authors has any conflict of interest to disclose.

Supplementary material

10548_2014_380_MOESM1_ESM.docx (32 kb)
Supplementary material 1 (DOCX 32 kb)


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Ralph G. Andrzejak
    • 1
  • Olivier David
    • 2
  • Vadym Gnatkovsky
    • 3
  • Fabrice Wendling
    • 4
  • Fabrice Bartolomei
    • 5
  • Stefano Francione
    • 6
  • Philippe Kahane
    • 7
  • Kaspar Schindler
    • 8
  • Marco de Curtis
    • 3
  1. 1.Department of Information and Communication TechnologiesUniversitat Pompeu FabraBarcelonaSpain
  2. 2.Brain Function and NeuromodulationUniversité Joseph FourierGrenobleFrance
  3. 3.Unit of Experimental Neurophysiology and EpileptologyFondazione Istituto Neurologico Carlo BestaMilanItaly
  4. 4.INSERM, U1099Université de Rennes 1, LTSIRennesFrance
  5. 5.INSERM, U1106, Clinical Epileptology UnitLa TimoneMarseilleFrance
  6. 6.Claudio Munari Epilepsy Surgery CenterOspedale Niguarda Ca’ GrandaMilanItaly
  7. 7.Epilepsy Unit, Neurology & Psychiatry DepartmentGrenoble University HospitalGrenobleFrance
  8. 8.qEEG Group, Department of Neurology, Inselspital, Bern University HospitalUniversity of BernBernSwitzerland

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