Clinical utility of 11C-flumazenil positron emission tomography in intractable temporal lobe epilepsy

BACKGROUND: 11C-flumazenil (FMZ) positron emission tomography (PET) is a new entrant into the armamentarium for pre-surgical evaluation of patients with intractable temporal lobe epilepsy (TLE). AIMS: To analyze the clinical utility of FMZ PET to detect lesional and remote cortical areas of abnormal benzodiazepine receptor binding in relation to magnetic resonance imaging (MRI), 2-Deoxy-2 18F] fluoro-D-glucose, (18F FDG) PET, electrophysiological findings and semiology of epilepsy in patients with intractable TLE. MATERIALS AND METHODS: Patients underwent a high resolution MRI, prolonged Video-EEG monitoring before 18F FDG and 11C FMZ PET studies. Regional cortical FMZ PET abnormalities were defined on co-registered PET images using an objective method based on definition of areas of abnormal asymmetry (asymmetry index {AI}>10%). SETTINGS AND DESIGN: Prospective. STATISTICAL ANALYSIS: Student's "t" test. RESULTS: Twenty patients (Mean age: 35.2 years 20-51]; M:F=12:8) completed the study. Mean age at seizure onset was 10.3 years (birth-38 years); mean duration, 23.9 years (6-50 years). Concordance with the MRI lesion was seen in 10 patients (nine with hippocampal sclerosis and one with tuberous sclerosis). In the other 10, with either normal or ambiguous MRI findings, FMZ and FDG uptake were abnormal in all, concordant with the electrophysiological localization of the epileptic foci. Remote FMZ PET abnormalities (n=18) were associated with early age of seizure onset (P=0.005) and long duration of epilepsy (P=0.01). CONCLUSIONS: FMZ-binding asymmetry is a sensitive method to detect regions of epileptic foci in patients with intractable TLE.