Short-term cerebral activity alterations after surgery in patients with unilateral mesial temporal lobe epilepsy associated with hippocampal sclerosis: A longitudinal resting-state fMRI study

PURPOSE Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), as a brain network disorder, has given increased importance to resective surgery. We aimed to examine the short-term postoperative functional network reorganization in patients with unilateral MTLE-HS using resting-state functional magnetic resonance imaging (Rs-fMRI) data with a longitudinal design. METHOD Seventeen (10 right-side and 7 left-side) patients with unilateral MTLE-HS were recruited. Rs-fMRI data were recorded from each subject before surgery and at an average of 4.5 months after surgery. Preoperative and postoperative amplitude of low-frequency fluctuations (ALFF) values as well as regions of interesting (ROI)-wise functional connectivity (FC) were compared to characterize the dynamic alterations of cerebral activity. RESULTS After surgery, patients with unilateral MTLE-HS presented bilateral diffuse ALFF value changes, which were more widespread in the left-side resection group. Regarding the postoperative Rs-FC alterations, the left MTLE-HS patients presented an interhemispheric FC alteration in a relatively symmetric manner between the bilateral frontal lobe and putamen; the right MTLE-HS patients exhibited an intrahemispheric FC reduction in the basal ganglia-thalamocortical circuit. CONCLUSION Patients with unilateral MTLE-HS presented bilateral diffuse regional and interregional neural activity alteration after surgery, even over a short period, which exhibited a divergent pattern between the different sides of resection. This finding may contribute to the understanding of the effect and the mechanisms of surgery on the whole brain network in patients with unilateral MTLE-HS.