Abstracts

Rationale: p { margin-bottom: 0.25cm; direction: ltr; line-height: 120%; text-align: left; }Background: Patients with focal epilepsy who have failed two antiepileptic drug trials should be considered for epilepsy surgery. Successful outcome (ie seizure free) is strongly dependent on the exact localization of the seizure onset zone. The presugical evaluation differs to some degree between epilepsy centers and Magnetoenchephalography (MEG) is used by some hospitals as a supplement in the evaluation. Norway has no MEG facilities but some difficult surgical cases are referred to MEG at Helsinki University Central Hospital in Finland. The benefit of MEG in epilepsy surgery work up is still unclarified; hence we wanted to investigate the benefit of this tool in our patients. Methods: In Norway epilepsy surgery is centralized to one center at Oslo University hospital, Norway. The patients follow well-defined pre- and post-surgical procedures. All patients sent to MEG investigations from 01.02.09 -30.11.16 were identified and included in the study. Results: Seventy patients (60 adults and 10 children) were investigated with MEG. Seventeen were excluded because of ongoing surgical evaluation. Seventeen (32%) had an epileptic lesion on MRI. The other cases were MRI negative. Twenty two (42%) had temporal semiology and the others had semiology consistent with extra temporal epilepsy or were not clearly classifiable. Interictal epileptiform activity was found in 91% of all MEG evaluations performed. In twenty four (45 %) the MEG was ictal. Eighteen patients underwent resective epilepsy surgery after the MEG investigation and one had a functional hemispherotomy. Thirteen of these 18 patients had an Engel I outcome one year after surgery. Conclusions: Nineteen of 53 patients (36%) could be offered surgery after a work up including MEG. Thirty eight % were classified as Engel I one year after surgery. MEG can be of benefit in the pre surgical evaluation in selected epilepsy surgery cases. Funding: Nothing to declare