SEIZURE RELATED SHORT TERM PLASTICITY OF BENZODIAZEPINE RECEPTORS IN PARTIAL EPILEPSY
Abstract number :
3.176
Submission category :
Year :
2002
Submission ID :
859
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Sandrine Bouvard, Nicolas Costes, Frédéric Bonnefoi, Christian Pierre, Jacques Delforge, Fran[ccedil]ois Maugui[egrave]re, Philippe Ryvlin. Functional Neurology and Epileptology, Neurological Hospital, Lyon, France; CERMEP, Neurological Hospital, Lyon, Fr
RATIONALE: We have previously reported that patients with temporal lobe epilepsy (TLE) undergoing repeated 11C-flumazenil positron emission tomography (FMZ-PET) could demonstrate focal test-retest variatons of FMZ binding (Ryvlin et al, 1999, Neurology;53:1882-1885), and benzodiazepine (BZD) receptor B[scquote]max (Bouvard et al, 1999, Epilepsia, 40(7):250). We have now extended our study in order to evaluate the relationship of such focal variations to the epileptic activity.
METHODS: Six TLE patients underwent a test-retest 11C-FMZ study at one week interval, while undergoing a long-term video-EEG monitoring. The latter started one week prior to the first PET study, allowing to precisely count the number of seizures occuring during the week preceding each of the two PET studies, and to define which of the two was the closest to the last previously occuring seizure. FMZ-PET was performed using a validated partial-saturation protocol which allowed the calculation of B[scquote]max (receptor density) parametric images.MRI-based regions of interest (ROIs) were placed over the hippocampus and transfered to the PET images, in order to look for the test-retest hippocampal B[scquote]max variation as a function of seizure occurence (paired t-test). In addition, we performed a SPM analysis, where the dummy covariate represented the delay between PET studies and the last previously occuring seizure.
RESULTS: Hippocampal B[scquote]max significantly differed between the two PET studies. This difference pointed to more severe decreased B[scquote]max in the epileptogenic hippocampus for PET studies associated with the shortest delay from the last previously occuring seizure (p=0,005). This result was confirmed by the SPM analysis as illustrated below.
CONCLUSIONS: BZD receptor B[scquote]max, as quantified through 11C-FMZ-PET imaging, proved to significantly vary during a one week period in patients with TLE, in particular over the epileptogenic hippocampus. This variation appears to be partly related to seizure occurence, with the closest the last seizure to the PET study, the greater the decreased hippocampal B[scquote]max. This phenomenom might reflect a seizure-related release of endozepines, and should be taken into account when using FMZ-PET in a clinical setting.[figure1]
[Supported by: Université Claude Bernard Lyon I]
