Evaluation of memory in persons with mesial temporal lobe sclerosis: A combined fMRI and VBM study

Persons with drug refractory TLE have the option of being managed by surgery. They may develop memory impairment with specific etiology of mesial temporal sclerosis and anterior temporal lobe resection (ATLR). The study evaluated the semantic verbal memory outcomes in pre- and post-surgery temporal lobe epilepsy (TLE) patients using functional MRI and voxel morphometric methods. Twenty consecutive persons with drug-resistant epilepsy (DRE) and 20 healthy controls were recruited after obtaining the institute ethics approval. The fMRI scans were performed on a 1.5 T MR Scanner using standardized semantic verbal memory tasks using a native Hindi paradigm, before and after an anterior temporal lobectomy (in cases). A task-based functional connectivity (FC) was estimated using a conn toolbox. Data analysis was carried out using the statistical parametric imaging (SPM12) and CAT12 toolbox. Post-surgery TLE group showed increased robust FC in the right middle and posterior temporal regions as compared to pre-surgery session. A significant reduction in grey matter volume was observed in the left temporal lobe post-operatively as compared to presurgery and healthy control groups. In the post-surgery TLE group, neuropsychological scores were reduced in specific PGI domains such as visuospatial, working memory, and executive functioning. Our results may help in understanding of memory reorganization in TLE post-operatively.