Periventricular white matter flumazenil binding and postoperative outcome in hippocampal sclerosis.
OBJECTIVE
In patients with hippocampal sclerosis (HS), anterior temporal lobe resection offers the possibility of a long-lasting suppression of seizures in two thirds of patients. White matter (WM) [11C]flumazenil volume of distribution (FMZ-Vd) reflects the number of neuronal cell bodies in WM. Our objective was to correlate WM FMZ-Vd in patients with unilateral HS and postsurgical outcome.


METHODS
We performed [11C]FMZ-PET in 15 patients with refractory mesial temporal lobe epilepsy (mTLE) and a quantitative MRI diagnosis of unilateral HS subsequently histologically verified in all cases. Median follow-up was 7 years (range, 6-9 years). Metabolite-corrected arterial plasma input functions and spectral analysis were used to generate parametric images of [11C]FMZ-Vd. Statistical parametric mapping (SPM99) with explicit masking was used to investigate the entire brain volume including WM.


RESULTS
Eight patients had Engel class IA outcome (completely seizure free since surgery), and seven were not seizure free. Comparison of seizure-free patients with those who continued to have seizures after surgery revealed areas of increased FMZ binding around the posterior horns of the ipsilateral (z=3.7) and contralateral (z=2.7) ventricles in those with suboptimal outcomes.


CONCLUSIONS
Preoperative [11C]FMZ-PET can detect periventricular increases of WM FMZ binding, implying heterotopic neurons in WM, in patients with mTLE. The presence of such increases correlates with a poorer outcome.
Hammers
Alexander
A
MRC Clinical Sciences Centre and Division of Neuroscience, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Koepp
Matthias J
MJ
Brooks
David J
DJ
Duncan
John S
JS
D000328:Adult; D001921:Brain / Q000378:metabolism*; D002552:Cerebral Ventricles / Q000378:metabolism*; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D005442:Flumazenil / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D012598:Sclerosis
D005442:Flumazenil