Predictive value in memory evaluation of the temporal mesial afterdischarges induced by electrical stimulations in stereoelectroencephalography

Abstract

This study evaluates patients' performances on memory tasks during the afterdischarges (ADs) induced by electrical stimulation (ES) in stereoelectroencephalography (SEEG) and compares the results with those of neuropsychological assessment (NPA) in memory evaluation and their predictive value for postoperative memory decline. We reviewed the SEEGs recorded between 1998 and 2022, with bilateral mesial temporal lobe implantations. During the mesial temporal ADs, the patients were evaluated with: the recall of presented objects, the recognition among other objects, and the presence of disorientation in space or time. These performances were compared to the NPA memory scores. For patients who underwent surgery, we evaluated the predictive value of the performance during unilateral mesial temporal AD on postsurgical memory outcomes and compared it with the prediction based on NPA. A total of 65 patients were included. A correlation approaching significance was observed between the NPA results and the performance during the ADs in the non-dominant hemisphere for a recall threshold of .33 (p = .05) and in the dominant side for a recall threshold of .25 (p = .06). For the operated patients, the predictive value of performance during AD for postoperative memory outcome was significant for AD ipsilateral to the surgery at a threshold of .75 (p = .028). It appears that memory performance during mesial temporal AD tends to correlate with the NPA results and can be an additional tool for pre-operative memory assessment. Further dedicated studies are required to validate its more reliable use in surgery.