Objective This prospective, bicentre, blinded, intention to treat study assessed the clinical added value of magnetic source imaging (MSI) in the presurgical evaluation of patients with refractory focal epilepsy (RFE).
Methods 70 consecutive patients with RFE (42 men; mean age 31.5 years, range 3–63) from two Belgian centres were prospectively included. All patients underwent conventional non-invasive presurgical evaluation (CNIPE) and a whole head magnetoencephalography recording (Elekta Neuromag). Equivalent current dipoles corresponding to interictal epileptiform discharges (IED) were fitted in the patients' spherical head model and coregistered on their MRI to produce MSI results. Results of CNIPE were first discussed blinded to the MSI results in respective multidisciplinary epilepsy surgery meetings to determine the presumed localisation of the epileptogenic zone and to set surgical or additional presurgical plans. MSI results were then discussed multidisciplinarily. MSI influence on the initial management plan was assessed.
Results Based on CNIPE, 21 patients had presumed extratemporal epilepsy, 38 had presumed temporal epilepsy and 11 had undetermined localisation epilepsy. MSI showed IED in 52 patients (74.5%) and changed the initial management in 15 patients (21%). MSI related changes were significantly more frequent in patients with presumed extratemporal or undetermined localisation epilepsy compared with patients with presumed temporal epilepsy (p≤0.001). These changes had a clear impact on clinical management in 13% of all patients.
Conclusion MSI is a clinically relevant, non-invasive neuroimaging technique for the presurgical evaluation of patients with refractory focal epilepsy and, particularly, in patients with presumed extratemporal and undetermined localisation epilepsy.
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Funding This work was supported by research grants from Elekta (Elekta Oy, Helsinki, Finland), the ‘Fonds de la Recherche Scientifique’ (FRS-FNRS, 3.4604.07, Belgium), the ‘Service Public Fédéral, Politique Scientifique’ (Belgium) and the ‘Instituut voor de Aanmoediging van Innovatie voor Wetenschap en Technologie in Vlaanderen (IWT-Vlaanderen)’ (Belgium).
Competing interests The Laboratoire de Cartographie Fonctionnelle du Cerveau benefit from a research grant from Elekta Neuromag. XDT is ‘Clinicien Chercheur Spécialiste’ at the ‘Fonds de la Recherche Scientifique’ (FRS-FNRS, Brussels, Belgium). XDT received consulting fees from Elekta for consulting activities in 2010 and 2011. EC benefited from financial support from Elekta to participate at the annual congress of the American Epilepsy Society 2009. MB benefits from a research grant of the ‘Fonds pour la Recherche Industrielle et Agricole’ (FRIA, Brussels, Belgium).
Patient consent All patients signed informed consent forms which were approved by the respective ethics committees at the time of the study, after having read the study information sheets also approved by the respective ethics committees. These information sheets clearly stated that the data of the study will be published in international scientific journals and presented at international scientific conferences, and as far as possible the data have been fully anonymised. In addition, regarding BMJ policy for patient confidentiality (http://group.bmj.com/products/journals/patient-consent-forms): (1) none of the clinical data presented in this manuscript allows patient identification. The only demographic information provided is age and enrolment period in two Belgian medical centres. These personal data are not sufficient to identify the included patients; (2) patient information has been sufficiently anonymised (see above); (3) all included patients are still alive; (4) patient data are grouped and there are no case reports, anecdotes or photographs of any patient; (5–7) this manuscript does not include any patient photographs. Images of patient brain MRI are completely anonymised.
Ethics approval The study was approved by the ULB-Hôpital Erasme and Ghent University Hospital ethics committees.
Provenance and peer review Not commissioned; externally peer reviewed.