SOURCE LOCALIZATION DETERMINED BY MAGNETOENCEPHALOGRAPHY AND ELECTROENCEPHALOGRAPHY IN TEMPORAL-LOBE EPILEPSY - COMPARISON WITH ELECTROCORTICOGRAPHY - TECHNICAL CASE-REPORT

OBJECTIVE AND IMPORTANCE: Source modeling by magnetoencephalography (M EG) and electroencephalography (EEG) may be useful techniques for noni nvasive localization of epileptogenic zones for surgery in patients wi th partial seizures. CLINICAL PRESENTATION: Simultaneous recordings of MEG and EEC, obtained in two patients, were coregistered on each pati ent's magnetic resonance image for direct comparison of these two meth ods with intracranial electrocorticography, TECHNIQUE: The average dif ference between MEG and EEG for localization of the same interictal sp ikes was approximately 2 cm in one patient and 3.8 cm in the other pat ient. One patient experienced a complex partial seizure during testing , which permitted comparison between interictal and ictal source local ization by both MEG and EEG, The EEG ictal localization differed from the interictal one, whereas the MEG ictal and interictal localizations were more similar. In this patient, the MEG interictal source seemed to localize close to the ictal source, whereas EEG did not. The patien ts underwent temporal lobectomy after electrocorticography, and the re sults were compared with the findings of MEG and EEG. Although the res ults of both techniques agreed with the findings of electrocorticograp hy, in one patient the MEG localization seemed to be more accurate. Bo th patients experienced good surgical outcomes. CONCLUSION: Both MEG a nd EEC source localization can add useful and complementary informatio n for epilepsy surgery evaluation, MEG seemed to be more accurate than EEG, especially when comparing interictal versus ictal localization. Further study is needed to evaluate the validity of source localizatio n as useful noninvasive techniques to localize the epileptogenic zone.