Abstracts

Rationale: We aimed to explore the structural and functional alterations of contralateral hippocampus after anterior temporal lobectomy (ATL) in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure-free for two years. Methods: High-resolution T1-weighted MRI and resting-state functional MRI were obtained in 29 unilateral mTLE patients and 29 matched healthy controls. Patients were scanned before and after surgery, at most, five time points (before surgery, three months, six months, 12 months and 24 months after surgery). Gray matter volume (GMV) and functional connectivity (FC) of bilateral hippocampus were assessed before and after surgery. Their dynamic changes in contralateral hippocampus were confirmed by comparisons among pre- and post-operative data. Results: Before surgery, ipsilateral hippocampus in patients was significantly smaller than that in healthy controls, while there was no statistical difference in contralateral hippocampus between patients and controls group. After successful ATL, significant GMV decrease was observed in contralateral hippocampus at three months follow-up when compared with healthy controls, however, without differences between five scans. Before surgery, ipsilateral rostral hippocampus (rosHIP) and caudal hippocampus (cauHIP) consistently showed increased FC with ipsilateral insula (INS) and temporoparietal junction (TPJ), while ipsilateral cauHIP showed decreased FC with bilateral superior frontal gyrus (SFG) and medial prefrontal cortex (MPFC). After surgery, contralateral cauHIP showed decreased FC with ipsilateral INS and TPJ, and increased FC with bilateral SFG and MPFC. Conclusions: Patients with unilateral mTLE presented obvious structural and functional changes in bilateral hippocampus before and after surgery. Contralateral hippocampus played an important role in structural and functional plasticity after successful ATL. Funding: No funding