Objective: To investigate the impact of active electrode contact location on non-motor outcomes in patients with Parkinson’s disease (PD) and subthalamic nucleus (STN) deep brain stimulation (DBS).

Background: In PD patients STN-DBS improves motor and non-motor symptoms (NMS) with a considerable degree of inter-subject variance, possibly due to individual variability of active contact location. Although STN was targeted visually, we hypothesized that an atlas-based approach could elucidate the relationship between location of neurostimulation and non-motor effects of DBS.

Methods: In this prospective, open-label, multicenter study including 50 PD patients undergoing bilateral STN-DBS, we collected NMSScale (NMSS, clinician-rated), NMSQuestionnaire (NMSQ, patient-rated), and SCOPA-motor examination at preoperative baseline and on 6 months follow-up (6MFU). Significant changes were detected with Wilcoxon signed-rank/t-test and Bonferroni-correction for multiple comparisons. Post-hoc, based on fused MRI/CT images (OPTIVISE software), we explored the influence of active contact location, using their Cartesian coordinates referenced to the midcomissural point with standardization to Mai-atlas. To this end, we computed Spearman-correlations between change scores and x-/y-/z-coordinates respectively and, subsequently, linear regressions integrating information of all axes into one model using coordinate blocks as independent and change scores as dependent variables.

Results: NMSS, NMSQ and SCOPA-motor examination improved significantly on 6MFU (all p<0.01). Mean active contact coordinates were for x-/y-/z-axis: 12.12mm/-0.52mm/-3.09mm. NMSQ improvement was significantly correlated to anterior (p<0.001) and ventral (p=0.049) active contact location, correlation between NMSS and lateral localization trended (p<0.1). Confirming these results, linear regressions, integrating all axes into one model, were significant for NMSQ and NMSS (both p<0.02).

Conclusions: Our results support the concept that DBS outcomes may depend on the location of neurostimulation. DBS in more anterior and ventral STN parts (“non-motor STN”) was associated with bigger improvement of non-motor outcomes. This study provides information for DBS programming/lead positioning in patients with clinically relevant NMS and encourages further studies to investigate non-motor effects of DBS.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/non-motor-outcomes-of-subthalamic-stimulation-in-parkinsons-disease-depend-on-the-location-of-active-contacts/