Neocortical abnormalities of [C-11]-flumazenil PET in mesial temporal lobeepilepsy

Objective: To characterize abnormalities in neocortical central benzodiazep ine receptor (cBZR) binding in patients with mesial temporal lobe epilepsy (mTLE) with unilateral hippocampal sclerosis (HS) using [C-11]-flumazenil-( FMZ) PET and complementary voxel-based and quantitative volume-of-interest (VOI) methods. Methods: The authors studied 13 control subjects and 15 pati ents with refractory mTLE and unilateral HS with [C-11]-FMZ PET. Data were corrected for partial volume effect in the interactively outlined hippocamp us and in 28 cortical VOI using an individualized template. A voxel-based a nalysis was also performed using statistical parametric mapping (SPM). Resu lts: Fourteen patients with mTLE had reduced [C-11]-FMZ volume distribution (V-d) in the hippocampus ipsilateral to the EEG focus, extending into the amygdala in four. Five patients showed additional significant neocortical a bnormalities of [C-11]-FMZ binding: temporal neocortical increases (1), ext ratemporal decreases (2), extratemporal increases only (1), and temporal an d extratemporal neocortical increases (I). Group VOI analysis revealed sign ificant reductions only in the ipsilateral hippocampus. SPM showed decrease d [C-11]-FMZ-V-d in the ipsilateral hippocampus in 13 of 15 patients, exten ding into the amygdala in eight. Five patients showed additional neocortica l abnormalities: temporal neocortical increases only (3), extratemporal dec reases (1), or both temporal neocortical and extratemporal decreases (I). G roup analysis showed significant reductions in the ipsilateral hippocampus only. Conclusions: A combination of VOI- and voxel-based analysis of [C-11] -FMZ PET detected extrahippocampal changes of cBZR binding in eight of 15 p atients with mTLE due to HS. The finding of abnormalities in patients who w ere thought to have unilateral HS only based on MRI suggests that more wide spread abnormalities are present in HS.