Hippocampal intracerebral evoked potentials as a marker of its functionality in drug-resistant epilepsy - 19/08/22

Doi : 10.1016/j.neucli.2022.07.001

Daniela de Andrade Morange ^a,^b, Virginie Laguitton ^c, Romain Carron ^a,^d, Daniele Schön ^a, Christian-George Bénar ^a,^c, Bernard Giusiano ^a, Fabrice Bartolomei ^a,^c, Agnès Trébuchon ^a,^c,^⁎
^a Aix Marseille Univ, INSERM, INS, Inst Neurosci Syst, Marseille, France
^b University Hospital Professor Edgard Santos (HUPES), Clinical Neurophysiology, Brazil
^c AP-HM, Hôpital de la Timone, Service de Neurophysiologie Clinique, Marseille, France
^d AP-HM, Timone Hospital, Stereotactic and Functional Neurosurgery, France

^⁎Corresponding author at: INSERM UMR1106, Institut des Neurosciences des Systèmes, Aix-Marseille Université, Faculté de Médecine Timone, 27, Bd Jean-Moulin – 13385 Marseille CEDEX 05, Service de Neurophysiologie Clinique, Hôpital de la Timone, 13005 Marseille, France.INSERM UMR1106Institut des Neurosciences des SystèmesAix-Marseille UniversitéFaculté de Médecine Timone,Service de Neurophysiologie Clinique, Hôpital de la Timone27, Bd Jean-Moulin – 13385 Marseille CEDEX 05, France.Marseille13005France.

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Abstract

Objectives

To assess hippocampal function during stereoelectroencephalography (SEEG) investigations through the study of the medial temporal lobe event-related potential (ERP) MTL-P300.

Methods

We recorded the MTL-P300 during a visual oddball task, using hippocampal electrodes implanted for SEEG in 71 patients, in a preoperative epilepsy investigation. The presence of an MTL-P300 and its amplitude were correlated with hippocampal involvement during seizures and memory function.

Results

Analysis using ROC curves revealed that an MTL-P300 amplitude below -46 µV, has a specificity of 93.3% in detecting the epileptogenic zone, and absence of the MTL-P300 in the left hippocampus of patients with typical language organization was associated with marked alteration of verbal memory scores. There was a significant correlation between performance in non-verbal memory tests and the amplitude of the MTL-P300 in the right hippocampus of patients with left hemispheric seizures (immediate visual recall: r = 0.67, p = 0.005; delayed visual recall: r = 0.56, p = 0.025). Using a linear regression, we confirmed that the absence of the MTL-P300 in the left hippocampus, the involvement of the left hippocampus during seizures, and the duration of epilepsy were predictors of verbal memory deficits.

Conclusion

Analysis of the MTL-P300 during SEEG recording provides relevant information for the analysis of hippocampal functionality and can help to localize the epileptogenic zone.

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Keywords : Event-related potentials, iEEG, Marker, MTL-P300, Oddball, Temporal lobe epilepsy