Abstracts

Rationale: To evaluate the agreement between MEG and ICEEG results, determine the characteristics that lead to agreement, and assess how these factors relate to subsequent epilepsy surgery success. Methods: Fifty patients who had positive MEG findings and subsequent ICEEG between 2008 and 2010 were retrospectively studied. MEG/ICEEG anatomical agreement and the relationship of the MEG focus to the resection were correlated to epilepsy surgery outcome. Results: Thirty-six of the 50 patients who had positive MEG and ICEEG underwent epilepsy surgery. Twenty-two were temporal lobe epilepsy and 28 were extra-temporal; 13 patients had lesion on MRI, and 37 had not. Of those 50 patients, 33(66%) patients had MEG and ICEEG anatomical agreement, and 17 (34%) did not agree. Of those 36 patients who had surgery, 19(53%) had complete resection of MEG focus and 17(47%) had partial or no resection of the MEG focus. Nineteen (53%) had no seizures after epilepsy surgery ( Favourable Outcome ), and 17(47%) had seizures reoccurrence ( Unfavourable Outcome ). Twenty-Seven (75%) had MEG/ICEEG anatomical agreement; of which 18 (66%) had favourable outcome and 9(34%) had unfavorable outcome (p =0.006). Nineteen had complete resection, of which 15(79%) had favourable outcome and 4(21%) had unfavourable outcome (p <0.001). Conclusions: The outcome of epilepsy surgery is favourable when the MEG focus overlaps the area localized by ICEEG, or when a complete resection of the MEG focus was performed. More specific, sublobar agreement was correlated with seizure freedom. As an adjunct to other test results, the findings of magnetoencephalography are predictive of surgical success, and may in the future even replace ICEEG in properly selected cases.