Reduction of benzodiazepine receptor binding is related to the seizure onset zone in extratemporal focal cortical dysplasia

Purpose: Comparison of regional reduction of GABA receptor binding and seiz ure onset zone in patients with extratemporal epilepsy due to focal cortica l dysplasia. Methods: Two patients with frontal lobe epilepsy who remained seizure free after partial frontal lobe resection were investigated with magnetic resona nce imaging, positron emission tomography (PET) with F-18-fluoro-deoxy-gluc ose (FDG) and C-11-flumazenil, subdural EEG-video recordings, and postopera tive benzodiazepine (BDZ)-receptor autoradiography. Results: The area of reduced BDZ-receptor binding as documented by preopera tive flumazenil-PET and postoperative BDZ-receptor autoradiography correspo nded to the seizure on-set zone and was smaller than the interictal hypomet abolism documented by FDG-PET. Conclusion: Flumazenil-PET is a useful tool for localization of the epilept ogenic zone in patients with extratemporal epilepsy caused by focal cortica l dysplasia. Neuronal distribution of BDZ-receptor density confirms in vivo flumazenil-PET findings. The regional reduction of BDZ-receptor binding in focal cortical dysplasia seems to be confined to the seizure onset zone an d not to the extent of dysplastic cortex.