Comparison of Functional Deficit Zone Defined by FDG PET to the Epileptogenic Zones Described in Stereo-Electroencephalograph in Drug-Resistant Epileptic Patients Treated by Surgery.

Introduction The purpose of presurgical assessment is to delimit the epileptogenic zone and the functional deficit zone with a brain MRI, an electroencephalograph or even a stereo-electroencephalograph (SEEG), neuropsychological evaluation, and a cerebral FDG PET. Several studies concur that the hypometabolism of FDG PET seems to be consistent with epileptogenic zones. We compared the functional deficit zone defined by FDG PET with the results of the SEEG, for each cluster electrode contact (CEC) located in the gray matter. Methods The electrode diagram of the 15 patients (486 CECs) operated on for drug-resistant epilepsy was merged with MRI and FDG PET. The metabolisms of FDG PET and SEEG were compared using a logistic regression test. Results The presence of hypometabolism resulted in a significantly higher risk of being in the seizure onset zone and the irritative zone, particularly when it was intense. Of the deeply hypometabolic CECs, 47% were in the seizure onset zone and 76% in the irritative zone. Normal metabolism resulted in a significantly higher probability of being in the healthy zone. Conclusions This study demonstrated an association between the presence of normal metabolism and the location of CECs in the healthy zone, and between the presence of pathological metabolism and the location of CECs in the seizure onset zone and the irritative zone, with metabolism abnormalities progressively more present and more intense near the seizure onset zone.