Objectives Deep brain stimulation (DBS), targeting the subthalamic nucleus (STN) and globus pallidus interna, is a surgical therapy with class 1 evidence for Parkinson’s disease (PD). Bilateral DBS electrodes may be implanted within a single operation or in separate staged surgeries with an interval of time that varies patient by patient. In this study, we used the variation in the timing of implantation from the first to the second implantation allowing for examination of potential volumetric changes of the basal ganglia in patients with PD who underwent staged STN DBS.
Methods Thirty-two patients with a mean time interval between implantations of 141.8 (±209.1; range: 7–700) days and mean duration of unilateral stimulation of 244.7 (±227.7; range: 20–672) days were included in this study. Using volumetric analysis of whole hemisphere and subcortical structures, we observed whether implantation or stimulation affected structural volume.
Results We observed that DBS implantation, but not the duration of stimulation, induced a significant reduction of volume in the caudate, pallidum, putamen and thalamus ipsilateral to the implanted hemisphere. These findings were not dependent on the trajectory of the implanted electrode nor on first surgery pneumocephalus (0.07%: %Δ for intracranial volume between first and second surgery). In addition, unique regional atrophy differences were evident in each of the structures.
Conclusion Our results demonstrate that DBS implantation surgery may affect hemisphere volume at the level of subcortical structures connected to the surgical target.
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Contributors JAT, AA and DSK planned the study. JAT, AA and SO collected the data. DSK, DU and RR organised the data. JAT and DSK conducted the statistical analysis. JAT and DU created initial figures. JAT and DSK created final figures and tables. DSK, JAT and DU wrote initial draft of the manuscript. JAT, DSK, AA and SO reviewed and critiqued revised drafts of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All protocols and procedures for this study were approved by the Colorado Multi-Institutional Review Board (COMIRB protocol # 16-1060).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.
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