gms | German Medical Science

Objective: Despite its application for several decades, it is still not fully understood which cerebral structures are responsible for the therapeutical effects indeep brain stimulation (DBS). Although targeting mainly includes grey matter stuctures such as the subthalamic nucleus (STN), the role of white matter tracts has been featured lately. Diffusion tensor based tractography serves as a valuable tool to depict white matter connections. The goal of this study was to analyze structural connections involved in rigor reduction in STN DBS.

Methods: We retrospectively analyzed diffusion tensor data of 21 patients with Parkinson’s disease, who had received STN DBS. Probabilistic tractography was performed based on seeds on each individual electrode contact. In addition, we evaluated each contact concerning the proportional effect on rigor reduction. Based on this data, effective and ineffective contacts were compared regarding the structural connections and fiber tracts affected by stimulation.

Results: Imaging and clinical data of 21 patients (42 hemispheres, 168 contacts) could be analyzed retrospectively. Reduction of rigor (> 50%) compared to base line was observed in 83.8% of the electrode contacts. The following fiber bundles were significantly more frequently associated with clinically effective rigor reduction: connections to the brainstem (fasciculus anterolateralis), connections to the thalamus (fasciculus thalamicus, fibers to the lamina medialis thalami) and connections to the globus pallidus pars interna and to Brodmann areas 45 and 46. Interestingly, the localization of contacts relative to STN anatomy did not show significant differences in terms of rigor reduction.

Conclusion: Our data suggest that brainstem-, thalamic- and frontal connections might be involved in rigor reduction. This information could be useful in target planning for deep brain stimulation and also in post-operative programming of the stimulation parameters.