# Accurate Repositioning of Deep Brain Stimulation Electrodes May Preserve Clinical Efficacy

## TL;DR

Repositioning deep brain stimulation electrodes during surgery can achieve high accuracy and similar clinical benefits as non-repositioned cases in Parkinson’s patients.

## Contribution

Demonstrates that intraoperative repositioning of DBS electrodes in an 'asleep' workflow preserves clinical efficacy.

## Key findings

- Repositioned electrodes achieved sub-millimeter accuracy similar to non-repositioned electrodes.
- Clinical improvement in Parkinson’s symptoms was comparable between repositioned and non-repositioned groups.
- The study was underpowered to confirm non-inferiority due to a small sample size.

## Abstract

Background and objectives

Accurate placement of deep brain stimulation (DBS) electrodes is critical for therapeutic efficacy. Repositioning during the initial surgery is common and can achieve sub-millimeter accuracy. The impact of repositioning on clinical outcomes is not well studied, especially in an imaging-guided, imaging-verified (“asleep”) workflow. This study evaluates the effect of repositioning on clinical outcomes for people with Parkinson’s disease (PD), comparing clinical outcomes in cases where electrodes required repositioning to those where repositioning was not required.

Methods

We performed a retrospective analysis for PD patients undergoing DBS implantation between July 2018 and November 2024 at a single institution using an “asleep” technique. Electrodes were repositioned if radial error exceeded 1.5 mm or if adverse effects were anticipated based on anatomical electrode location. Radial error and final radial error were measured using the intraoperative O-arm. Clinical outcomes were assessed by percentage improvement in the Movement Disorders Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III score.

Results

Of 172 PD cases, 20 had complete preoperative and postoperative MDS-UPDRS III data, six of which required electrode repositioning. The revision group had a final radial error of 0.86 ± 0.29 mm, similar to 0.91 ± 0.43 mm in the non-revision group (p = 0.44). MDS-UPDRS III improvement was 38 ± 17% in the revision group and 40 ± 26% in the non-revision group (p = 0.44). Patient demographics (age, time since diagnosis, levodopa response) were similar between groups, except for a lower preoperative MDS-UPDRS part III score in the non-revision group (p = 0.04). The study was underpowered to formally detect non-inferiority.

Conclusion

This data suggests that repositioning sub-optimally placed DBS electrodes during initial asleep DBS surgery can achieve sub-millimeter accuracy and MDS-UPDRS part III improvement comparable to cases that did not require repositioning. However, our small sample size limits definitive conclusions, demonstrating a need for larger studies to confirm these findings that support intraoperative imaging-based verification of electrode location.