Localizing value of ictal déjà vu, déjà vécu, dreamy state and reminiscence: A systematic review

We performed a systematic review of the literature regarding the localization value of déjà vu (DV), déjà vécu, dreamy state and reminiscence in focal epilepsy, with the aim to summarize the state-of-the-art anatomo-electroclinical correlations in the field and help guide interpretation of ictal semiology within the framework of pre-surgical evaluation of focal drug-resistant epilepsy (DRE). The review was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Patient series were included if they provided sufficient anatomo-electroclinical correlation to allow determination of the epileptogenic zone (EZ) and assessment of the level of confidence in each report. We evaluated the risk of bias and the diagnostic accuracy quality of each publication using the Quality of Diagnostic Accuracy Studies (QUADAS-2) and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tools. For search terms déjà, dreamy state and reminiscence, we identified 22 eligible publications containing a total of 597 patients. The reports with the highest level of confidence suggest that ictal DV or dreamy state reflect an EZ located in both anterior and posterior mesial temporal structures; however, lateral temporal and insulo-opercular EZs have also been described. The anatomo-electroclinical correlation of ictal DV and related phenomena points most commonly to the mesial temporal structures; however, due to the heterogeneous quality of reports and the pooling and overlap of these related symptoms, our findings are regarded with moderate degree of reliability. Future reports should adopt a more refined classification and clinical description of these experiential memory-related ictal phenomena. The use of advanced imaging modalities and a broader implementation of stereoelectroencephalography should facilitate the accumulation of cases with higher level of evidence, which would result in a more robust anatomo-electroclinical correlations of these fascinating epileptic semiologies.