Presently available noninvasive methods correctly localize epileptogen
ic regions in only similar to 50% of patients with frontal lobe epilep
sy (FLE). Earlier studies have shown that temporal lobe epileptogenic
regions may be identified readily by positron emission tomography (PET
) measurements of regional benzodiazepine (BZD) receptor binding. We t
ested the specific applicability of this method in patients with FLE.
Six patients with frontal partial seizures and 7 healthy men were inve
stigated with PET and the BZD receptor ligand [C-11]flumazenil. All pa
tients had magnetic resonance (MR) brain scans. The independent assess
ment of seizure-onset region was based on seizure semiology, intra- an
d extracranial EEG and, in 4 cases, also on [F-18]fluorodeoxyglucose (
FDG)-PET. The epileptic focus/seizure-generating region was correctly
identified by [C-11]flumazenil PET in all patients. This region was ch
aracterized by a significant reduction in BZD receptor density. The ar
ea with reduced BZD receptor density was better delimited than the cor
responding hypometabolic region, which was observed in 50% of patients
investigated with [F-18]FDG-PET. MRI was normal in 5 patients. Visual
ization of BZD receptors with [C-11]flumazenil PET appears to be a pro
mising approach for noninvasive identification of frontal lobe epilept
ogenic regions.