Duke University Durham, North Carolina, United States
Introduction: The subthalamic region consists of a complex intersection of many different axonal pathways. The concepts of connectomic deep brain stimulation (DBS) suggest that this merging of multiple pathways into a focal area is advantageous because direct stimulation of specific axonal pathways has been linked to the control of specific motor symptoms in Parkinson’s disease (PD) (e.g. cerebellothalamic (CT) – tremor; pallidothalamic (PT) – rigidity; motor hyperdirect (mHD) – bradykinesia). However, the typical coronal DBS lead trajectory limits opportunities to preferentially target the different pathways.
Methods: We used advanced computational models to evaluate the theoretical utility of posterior DBS lead trajectories in facilitating preferential activation of the CT, PT, and mHD pathways during subthalamic DBS. We compared the typical coronal DBS lead trajectory to the posterior alternative for general surgical safety and pathway activation selectivity considerations. Simulations were performed with a 16 contact directional DBS lead within the context of the CIT168 human atlas brain populated with the Petersen axonal pathway models. Subthalamic DBS pathway recruitment curves were calculated with driving force algorithms and realistic accounting of electrode localization precision.
Results: PT, mHD, and CBT fibers are distributed in an anterior-to-posterior fashion within the subthalamic region. Given this anatomical feature, the span of DBS contacts along a posterior lead trajectory can provide better opportunities for selective activation of each pathway of interest, while avoiding unwanted activation of the internal capsule fibers of passage. Alternatively, coronal trajectories limit opportunities for pathway-targeted DBS because the electrode contacts are primarily aligned dorsal-ventrally.
Conclusion: Posterior DBS trajectories warrant consideration in PD as the research concepts of pathway-targeted DBS begin migrating into clinical practice.
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