Abstracts

Rationale: The identification of epileptogenic zone (EA) has a crucial role for the epilepsy surgery and for the seizure freedom. Electrophysiology, functional and structural neuroimaging and neuropsychological evaluation helps the EZ to be delineated correctly. In this study, we sought to investigate the role of FDG-PET findings to define EZ in MRI negative patients. Methods: Out of 182 patients who were evaluated according to a standart protocol for epilepsy surgery including FDG-PET as well as EEG, neuropsychology and MRI, 45 patients (16 male, 29 female) without a structural lesion on MRI were included in the study. Mean age was 31.4 and mean age at seizure onset was 10,8. Seven patients were operated. EEG findings were grouped as lateralized, localized or indefinitive and PET findings were grouped as temporal, extratemporal or diffuse hypometabolism. Results: PET showed hypometabolism in 27 patients (5 extratemporal, 22 temporal). In 5 patients hypometabolism involve more than one lobe where EEG localized to temporal lobe in one. In 17 patients with temporal hypometabolism on PET, 9 had EEG localized to temporal lobe. From 7 patients who underwent surgery, 3 had temporal, 3 had frontal and 1 had parietal resections. In 5 of them PET was positive and guided for placement of intracranial electrodes. Histopathology revealed cortical displasia in 6, gliosis in 1 patient. Conclusions: FDG-PET may be useful in MRI negative patients to decide about the placement of electrodes and further description of EZ to be resected.