EEG-correlated fMRI and Post-Operative Outcome in Focal Epilepsy

Rachel Thornton (1) , Helmut Laufs (2) , Serge Vulliemoz (3) , David W Carmichael (3) , Sajitha Cannadathu (3) , Afraim Salek-Haddadi (1) , Roman Rodionov (3) , Andrew W Mcevoy (1) , Shelagh Smith (4) , Robert Elwes (5) , Samden Lhatoo (6) , Matthew C Walker (3) , Louis Lemieux (3) , John S Duncan (7)

1 UCL, Institute of Neurology
2 University Hospital Frankfurt
3 Institute of Neurology
4 UCL Queen Square Institute of Neurology
5 King‘s College London
6 Department of Neurology, Frenchay Hospital, North Bristol NHS Trust, Bristol
7 Natl Hosp for Neurology & Neurosurgery

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 fMRI (EEG-fMRI) is a novel imaging technique which may provide localising information with regard to these regions. In patients with focal epilepsy, interictal epileptiform discharges (IED) correlated BOLD (blood oxygen dependent level) signal changes are observed in approximately 50% of patients in whom IEDs were 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. We assessed the value of EEG- fMRI in patients with focal epilepsy who subsequently underwent epilepsy surgery and related IED-correlated fMRI signal changes to the resection area and clinical outcome Methods: We recorded simultaneous EEG-fMRI in 76 patients undergoing presurgical evaluation and compared the locations of IED-correlated pre-operative BOLD signal change with the resected area and post-operative outcome. Results : 21 patients had activations with epileptic activity on EEG fMRI and 10 underwent surgical resection. 7/10 patients are seizure free following surgery and the area of maximal BOLD signal change was concordant with resection in 6/7. In the remaining 3, with reduced seizure frequency post-surgically, areas of significant IED correlated BOLD signal change lay outside the resection. 42/55 patients who had no IED related activation underwent resection. Conclusion: These results show potential value for EEG-fMRI in pre-surgical evaluation.

Mots clés: EEG; EPILEPSY; SURGERY; FUNCTIONAL IMAGING

Rachel Thornton, Helmut Laufs, Serge Vulliemoz, David W Carmichael, Sajitha Cannadathu, et al.. EEG-correlated fMRI and Post-Operative Outcome in Focal Epilepsy. Journal of Neurology, Neurosurgery and Psychiatry, 2010, 81 (8), pp.922. ⟨10.1136/jnnp.2009.196253⟩. ⟨hal-00557429⟩