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

Brain Topography volume 28, pages 832–837 (2015)Cite this article

Abstract

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.

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Fig. 1

Abbreviations

EI:

Epileptogenicity Index

EZ:

Epileptogenic zone

FCD:

Focal cortical dysplasia

IEEG:

Intracranial electroencephalogram

NLSI:

Nonlinear Structure Index

QFAI:

Quantified Frequency Analysis Index

SEEG:

Stereo electroencephalogram

SPMEI:

Statistical Parametric Mapping of Epileptogenicity Index

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Acknowledgments

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.

Author information

Affiliations

  1. Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain

    Ralph G. Andrzejak

  2. Brain Function and Neuromodulation, Université Joseph Fourier, Grenoble, France

    Olivier David

  3. Unit of Experimental Neurophysiology and Epileptology, Fondazione Istituto Neurologico Carlo Besta, Milan, Italy

    Vadym Gnatkovsky & Marco de Curtis

  4. INSERM, U1099, Université de Rennes 1, LTSI, 35000, Rennes, France

    Fabrice Wendling

  5. INSERM, U1106, Clinical Epileptology Unit, La Timone, 13000, Marseille, France

    Fabrice Bartolomei

  6. Claudio Munari Epilepsy Surgery Center, Ospedale Niguarda Ca’ Granda, Milan, Italy

    Stefano Francione

  7. Epilepsy Unit, Neurology & Psychiatry Department, Grenoble University Hospital, Grenoble, France

    Philippe Kahane

  8. qEEG Group, Department of Neurology, Inselspital, Bern University Hospital, University of Bern, 3010, Bern, Switzerland

    Kaspar Schindler

Authors
  1. Ralph G. Andrzejak
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  2. Olivier David
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  3. Vadym Gnatkovsky
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  4. Fabrice Wendling
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  5. Fabrice Bartolomei
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  6. Stefano Francione
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  7. Philippe Kahane
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  8. Kaspar Schindler
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  9. Marco de Curtis
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Corresponding author

Correspondence to Marco de Curtis.

Additional information

Ralph G. Andrzejak, Olivier David, Vadym Gnatkovsky and Fabrice Wendling have equally contributed to this study.

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Andrzejak, R.G., David, O., Gnatkovsky, V. et al. Localization of Epileptogenic Zone on Pre-surgical Intracranial EEG Recordings: Toward a Validation of Quantitative Signal Analysis Approaches. Brain Topogr 28, 832–837 (2015). https://doi.org/10.1007/s10548-014-0380-8

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  • DOI: https://doi.org/10.1007/s10548-014-0380-8

Keywords

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