Presurgical evaluation of epilepsy by brain diffusion: MR-detected effects of flumazenil on the epileptogenic focus.
OBJECTIVE
After focal status epilepticus, focal alterations of the apparent diffusion coefficient (ADC) have been demonstrated in the epileptogenic zone by using diffusion-weighted magnetic resonance (MR)imaging (DWI). Effects of flumazenil on an epileptogenic focus have been demonstrated by EEG recordings, but not by functional MRI. We hypothesized that dynamic spatiotemporal alterations of brain diffusion of the epileptogenic focus after application of flumazenil will be detectable by DWI and correlate with the epileptogenic zone.


METHODS
Twelve adult patients considered for epilepsy surgery with medically intractable temporal lobe epilepsy (TLE; n = 7), extratemporal lobe epilepsy (ETE; n = 2), and TLE+ETE (n = 3) were prospectively examined with DWI interictally (serving as baseline) and 10 min after application of 1 mg flumazenil i.v.


RESULTS
The baseline interictal ADC was significantly elevated in the hippocampus on the ictogenic side in the patients with TLE (p = 0.002) as compared with healthy volunteers. The following changes of the mean ADC were seen in different regions of interest (ROIs) after injection of flumazenil: decreases in the hippocampus on the seizure-onset side by 14.8% (p = 0.005); decreases in the parahippocampal gyrus on both sides by 6.8% (epileptogenic side; p = 0.044) or 7.9% (nonepileptogenic side; NS), respectively; decreases in the cortex on the nonictogenic side by 7.9% (p = 0.047); and no significant changes of the ADC in the other ROIs.


CONCLUSIONS
ADC decreases measured after application of flumazenil were seen in the seizure-onset zone as revealed by EEG and structural MRI and are an indicator of focus localization in patients with TLE.
Konermann
Stefan
S
Department of Neurology, University of Essen, Essen, Germany. stefan.konermann@uni-essen.de
Marks
Sonja
S
Ludwig
Tanja
T
Weber
Johannes
J
de Greiff
Armin
A
Dörfler
Arnd
A
Leonhardt
Georg
G
Wiedemayer
Helmut
H
Diener
Hans-Christoph
HC
Hufnagel
Andreas
A
D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004827:Epilepsy / Q000139:chemically induced* / Q000175:diagnosis* / Q000378:metabolism; D004833:Epilepsy, Temporal Lobe / Q000139:chemically induced / Q000175:diagnosis / Q000378:metabolism; D005260:Female; D005442:Flumazenil / Q000494:pharmacology; D007839:Functional Laterality / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D020534:Parahippocampal Gyrus / Q000187:drug effects / Q000378:metabolism; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D013702:Temporal Lobe / Q000187:drug effects / Q000378:metabolism / Q000601:surgery
D005442:Flumazenil