Assessing systematic spatial differences between intraoperative and postoperative Probabilistic Sweet Spots in Deep Brain Stimulation for Essential Tremor

Inroduction Deep Brain Stimulation (DBS) is an established therapy for movement disorders such as Essential Tremor (ET). While electrode displacement across intraoperative and postoperative stages has been studied, Probabilistic Sweet Spot (PSS) analyses rarely account for temporal evolution. Consequently, it remains unclear whether intraoperatively identified optimal stimulation sites are spatially stable over time and can reliably inform postoperative programming. This study investigated systematic differences between intraoperative and postoperative PSS locations, both at cohort and individual patient levels. Methods Intraoperative ( N = 324) and postoperative ( N = 566) stimulation tests were retrospectively analyzed from 14 ET patients. Electric field simulations were performed for all tested stimulation settings. Voxel-wise statistical testing was applied to compute intraoperative and postoperative PSSs at both the group and patient-specific levels. PSSs volumes and centroid locations were compared between time points using spatial overlap metrics and displacement analyses. Results A partial spatial concordance between intraoperative and postoperative PSSs at different symptom improvement thresholds was observed at the group level, with a maximum Dice coefficient of 0.75. Overlap decreased between regions associated with higher tremor suppression. At the individual level, a consistent anterior–posterior displacement was identified in the left hemisphere, with intraoperative PSSs located more posteriorly than postoperative PSSs (mean displacement ≈1.5 mm). Discussion Modest but systematic spatial differences exist between intraoperative and postoperative PSS; however, their magnitude remains within a few millimeters, and a considerable spatial overlap is observed. These findings suggest that intraoperative PSS may inform early postoperative DBS programming which could support and streamline early postoperative screening.