An exploratory study on surgical planning of single trajectory deep brain stimulation of ventral intermediate nucleus...

Tremor-dominant Parkinson's disease (td-PD) patients experience insufficient tremor relief following subthalamic nucleus (STN) deep brain stimulation (DBS). While ventral intermediate nucleus (VIM) DBS offers tremor benefit, it is generally less effective for broader motor symptoms. Recent advances, including DBS leads with more than four traditional contacts, are expected to enable stimulation of both targets. Although dual-targeting of STN and VIM has been reported via frontal or parietal approaches, no direct technical comparison exists between these strategies. This exploratory study aims to assess the feasibility of each approach and to compare the two approaches in the planning of DBS targeting both VIM and STN.

We analyzed 70 hemispheres with PD. Tentative targets for STN and VIM were established using direct and indirect methods. When the straight trajectory between the two targets (tentative trajectory, TT) intersected critical structures (e.g., ventricles, sulci, blood vessels), an adjusted trajectory was planned via either a frontal or parietal approach. STN was prioritized as the primary target, accepting deviations within 2 mm from the tentative STN (tSTN).

All 70 TTs required adjustment to avoid critical structures. The mean distance from the adjusted STN target to tSTN was 1.63 mm (frontal) vs. 0.52 mm (parietal, p = 5.03 × 10⁻²⁷). The distance from the adjusted VIM target to the tentative VIM was 2.68 mm (frontal) vs. 1.53 mm (parietal, p = 2.32 × 10⁻²³).

Single-trajectory dual-target DBS is technically feasible via both approaches. The parietal approach yields significantly closer alignment with both tentative targets.