Objective: To retrospectively analyze the accuracy of the preoperative Deep Brain Stimulation (DBS) trajectory planning based on final trajectories chosen with intraoperative neurophysiological testing and to  determine the change in the success rate of the preoperative trajectory planning with yearly experience.

Background: Intraoperative neurophysiological testing in patients treated with DBS provides crucial information for the optimal choice of final electrode  placement and patients’ clinical outcome. Preoperatively, an optimal (central) trajectory for microelectrode placement is chosen by a neurosurgeon. During intraoperative testing four additional trajectories (anterior, posterior, lateral, medial) are tested and compared in effect. Discontinuation of intraoperative testing may follow successful preoperative planning.

Method: We gathered data on final trajectories chosen from 25 patients treated with DBS in our center between Jan. 2014 and Dec. 2018. Indications for DBS were Parkinson’s disease (PD), Essential tremor (ET) and Dystonia (DYS). The DBS target for all PD patients was the Subthalamic Nucleus (STN), the Ventral Intermedian Nucleus (VIM) for ET patients and Globus Pallidus internus (GPi) for DYS patients. Trajectories were analyzed for each individual target (n= 50). Separate analyses for STN (n= 40), GPi (n=2) and VIM (n= 8) trajectories were conducted. Additionally, we analyzed final trajectories chosen for each year separately.

Results: Analysis of all targets (n=50) showed that the central trajectory was finally chosen in 24 (48%) cases. Trajectory analysis for STN target (n=40) showed that the central trajectory was finally chosen in 19 (47.5%) cases. The central trajectory was chosen in both GPi targets (100%). Among 8 VIM targets, the central trajectory was chosen in 3 (37.5%), and the posterior in 5 (62.5%). Yearly analysis showed that the central trajectory was chosen  in 37.5 % cases in 2015 (n=8), 14.2% in 2016 (n=6), 83% in 2017 and 63% in 2018 (n=22).

Conclusion: Our results show an important role of the intraoperative neurophysiological monitoring for the final lead placement. GPi trajectory planning showed best success, while VIM showed poorest. Preliminary results suggest a trend in higher success of preoperative planning with each following year. We predict further improvement with more experience.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/accuracy-of-preoperative-microelectrode-trajectory-planning-in-patients-treated-with-dbs-an-ongoing-study/