Abstracts

Rationale: To compare MEG findings with intracranial EEG (ICEEG) and to assess MEG's predicitive abilities regarding subsequent epilepsy surgery outcome. Methods: This is a retrospective study of 36 patients who had positive MEG findings and subsequent epilepsy surgery based on intracranial EEG findings between 2008 and 2010. Medical reports were used to compare the hemisphere implicated by MEG to the SPECT scan, PET scan, and side of surgical resection. Resection of the site localized by MEG was correlated to epilepsy surgery outcome. Results: Thirty six patients had positive MEG and epilepsy surgery, of which 31 were lateralized to the side of epilepsy surgery and 5 were not. Of those 31 patients, 18 (58%) had no seizures on follow up and 13(42%) had seizures reoccur (P=0.105). Among the 31 patients, the MEG and at least one other test (PET/SPECT) agreed on lateralizing to the side of surgery in 25, and five did not. Of those 25 patients, 15(60%) had no seizures on follow up and 10(40%) had seizures reoccur (P=0.283). The epileptogenic region identified by MEG was resected in 26, while in 10 there was no overlap. Of those 26 patients, 17(65%) had no seizures on follow up and 9(35%) had seizures reoccur (P=0.014) Conclusions: MEG predicts seizure outcome better than SPECT or PET independently. Seizure freedom was higher when lateralizing MEG was overlapping the surgical resection or was in agreement with at least one other functional imaging test.