Objective: To evaluate the impact of patient-specific structural connectivity between VTA in STN targeting and SMA/preSMA on functional mobility improvements in PD patients undergoing DBS.

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established treatment for Parkinson’s disease (PD). However, individual variability in stimulation outcomes highlights the importance of patient-specific structural connectivity¹. This study investigates the relationship between volume of activated tissue (VTA) in STN-DBS and its structural connectivity to the supplementary motor area (SMA) and pre-supplementary motor area (preSMA) in relation to functional mobility changes assessed by the Timed Up and Go (TUG) and Sit-to-Stand (STS) tests.

Method: Patient-specific tractography was performed in nine PD patients using preoperative 3T MRI. Tractography processing included motion artifact correction via QSIRecon and visualization in DSI Studio with native space alignment using patient-specific T1 imaging. SMA and preSMA regions were extracted from the HMAT atlas and transformed into native space, while VTA was reconstructed using Lead-DBS based on stimulation parameters three months postoperatively (SimBio model). No further changes in stimulation settings or medication were made before the six-month follow-up. Connectivity between VTA and SMA/preSMA was quantified, and correlation analyses were conducted with changes in TUG and STS test results, defined as the difference between preoperative (Med ON) and six-month postoperative (DBS ON, Med ON) assessments.

Results: A significant positive correlation was found between VTA-SMA connectivity and TUG improvement (r = 0.71, p = 0.047). A similar trend was observed between VTA-preSMA and TUG improvement (r = 0.67, p = 0.071), though it did not reach statistical significance. The correlation between VTA-preSMA and overall STS performance was weak (r = 0.14, p > 0.05). 

Conclusion: Our findings suggest that structural connectivity between VTA in STN-DBS and SMA may influence mobility outcomes. This underscores the importance of personalized DBS programming based on individual connectivity profiles. Larger studies are needed to validate these results and refine patient-specific targeting strategies.

Correlation graph: VTA-SMA v.s TUG

Pipeline of patient-specific tractography.

References: 1. Wang, Q. et al. Normative vs. patient-specific brain connectivity in deep brain stimulation. NeuroImage 224, 117307 (2021).

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MDS Abstracts - https://www.mdsabstracts.org/abstract/impact-of-patient-specific-structural-connectivity-of-stn-dbs-on-balance-and-mobility-pilot-study/