Imaging memory and predicting postoperative memory decline in temporal lobe epilepsy: Insights from functional imaging.
After medial temporal lobe epilepsy (MTLE) surgery, there is considerable individual variation in the extent, nature and direction of postoperative memory change. Before surgery, epileptic patients who are surgery candidates need precise information about the potential cognitive after effects, and particularly in temporal lobe epilepsy, postoperative memory changes. Clinical and neuropsychological data may bring useful information to predict the postoperative memory outcome, but, these data are not always sufficient to replace the Wada test, considered for a long time, as the gold standard to predict postoperative decline following surgery. In any case, numerous studies demonstrate that the Wada procedure can be nowadays reliably replaced by functional MRI (fMRI) activation studies. A vast majority of fMRI studies suggest that it is the functional adequacy of the resected hippocampus rather than the functional reserve of the contralateral hippocampus that determines the extent of postoperative memory decline. In addition, new functional neuroimaging procedures that explore more widespread network disruptions commonly found in MTLE such as diffusion-tensor imaging (DTI) or connectivity studies could in the future constitute a reliable approach combined with fMRI activation studies to significantly improve the prediction of postsurgical memory decline.
Epilepsy unit and rehabilitation unit, hôpital de la Salpêtrière, 47, boulevard de l'Hôpital, 75651 Paris cedex 13, France; Rehabilitation unit, hôpital de la Salpêtrière, 47, boulevard de l'Hôpital, 75651 Paris cedex 13, France; Centre de recherche de l'institut du cerveau et de la moëlle épinière (ICM), UMPC-UMR 7225 CNRS-UMRS 975 Inserm, bâtiment ICM, 47, boulevard de l'Hôpital, 75651 Paris cedex 13, France; Université Pierre et Marie Curie, 4, place Jussieu, 75005 Paris, France. Electronic address: sophie.dupont@psl.aphp.fr.
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D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000523:psychology* / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008569:Memory Disorders / Q000209:etiology* / Q000523:psychology*; D009483:Neuropsychological Tests; D011183:Postoperative Complications / Q000209:etiology* / Q000473:pathology / Q000523:psychology*; D011237:Predictive Value of Tests; D016896:Treatment Outcome
Connectivity; Connectivité; DTI; Devenir mnésique; IRM de diffusion; Medial temporal lobe epilepsy; Memory outcome; Test de Wada; Wada test; fMRI; Épilepsie temporale médiale