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Research paper
EEG correlated functional MRI and postoperative outcome in focal epilepsy
  1. Rachel Thornton1,2,
  2. Helmut Laufs1,2,3,
  3. Roman Rodionov1,2,
  4. Sajitha Cannadathu1,2,
  5. David W Carmichael1,2,
  6. Serge Vulliemoz1,2,
  7. Afraim Salek-Haddadi1,2,
  8. Andrew W McEvoy1,2,
  9. Shelagh M Smith1,2,
  10. Samden Lhatoo4,
  11. Robert D C Elwes5,
  12. Maxime Guye6,
  13. Matthew C Walker1,2,
  14. Louis Lemieux1,2,
  15. John S Duncan1,2
  1. 1Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
  2. 2National Hospital for Neurology and Neurosurgery, UCL Hospitals NHS Trust, London, UK
  3. 3Department of Neurology and Brain Imaging Centre, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
  4. 4Department of Neurology, North Bristol NHS Trust, Frenchay Hospital, Bristol, UK
  5. 5Department of Neurophysiology, Kings College Hospital, London, UK
  6. 6Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR CNRS 6612 and Service de Neurophysiologie Clinique, INSERM U 751,CHU Timone, AP-HM, Faculté de Médecine de Marseille, Université de la Méditerranée, Marseille, France
  1. Correspondence to Dr R Thornton, UCL, Institute of Neurology, MRI Unit, National Society for Epilepsy, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK; r.thornton{at}ion.ucl.ac.uk

Abstract

Background The main challenge in assessing patients with epilepsy for resective surgery is localising seizure onset. Frequently, identification of the irritative and seizure onset zones requires invasive EEG. EEG correlated functional MRI (EEG-fMRI) is a novel imaging technique which may provide localising information with regard to these regions. In patients with focal epilepsy, interictal epileptiform discharge (IED) correlated blood oxygen dependent level (BOLD) signal changes were observed in approximately 50% of patients in whom IEDs are recorded. In 70%, these are concordant with expected seizure onset defined by non-invasive electroclinical information. Assessment of clinical validity requires post-surgical outcome studies which have, to date, been limited to case reports of correlation with intracranial EEG. The value of EEG-fMRI was assessed in patients with focal epilepsy who subsequently underwent epilepsy surgery, and IED correlated fMRI signal changes were related to the resection area and clinical outcome.

Methods Simultaneous EEG-fMRI was recorded in 76 patients undergoing presurgical evaluation and the locations of IED correlated preoperative BOLD signal change were compared with the resected area and postoperative outcome.

Results 21 patients had activations with epileptic activity on EEG-fMRI and 10 underwent surgical resection. Seven of 10 patients were seizure free following surgery and the area of maximal BOLD signal change was concordant with resection in six of seven patients. In the remaining three patients, with reduced seizure frequency post-surgically, areas of significant IED correlated BOLD signal change lay outside the resection. 42 of 55 patients who had no IED related activation underwent resection.

Conclusion These results show the potential value of EEG-fMRI in presurgical evaluation.

  • Eeg
  • Epilepsy
  • Epilepsy, Surgery
  • Functional Imaging

https://doi.org/10.1136/jnnp.2009.196253

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    Footnotes

    • Funding This work was funded by the Medical Research Council (G0301067). This work was undertaken at UCLH/UCL who received a proportion of funding from the Department of Health's NIHR Biomedical Research Centres funding scheme and supported by a grant from the UK Medical Research Council No. G0301067. We are grateful to the Big Lottery Fund, Wolfson Trust and National Society for Epilepsy for supporting the NSE MRI scanner. HL was supported by the Deutsche Forschungsgemeinschaft (LA 1452/3-1) and the Bundesministerium für Bildung und Forshung (BMBF 01 EV 0703). SV was supported by the “Fonds de Perfectionnement” of the University Hospital of Geneva, Switzerland. JD receives funding from the Wellcome Trust (067176) and the Medical Research Council (G9805089) and the National Society for Epilepsy.

    • Competing interests None.

    • Ethics approval This study was conducted with the approval of the National Hospital for Neurology and Neurosurgery and the Institute of Neurology Joint Research Ethics Committee.

    • Provenance and peer review Not commissioned; externally peer reviewed.