Factors affecting targeting accuracy in minimally invasive twist drill deep brain stimulation

The efficacy of deep brain stimulation (DBS) relies on accurate stereotactic electrode placement. Post-implantation imaging enables assessment of electrode positioning and quantification of targeting accuracy. While DBS is typically performed through burr hole, this study examines targeting accuracy factors using a minimally invasive twist drill technique.

We retrospectively analyzed 86 patients (171 electrodes) who underwent DBS at our institution. Different measures of targeting error were defined and compared. Analysis focused on trajectory error (TE), the closest perpendicular distance between the electrode's center and target locus. Seventeen demographic, clinical, and procedural variables were assessed for potential impact on accuracy. Multivariate mixed effects models were applied to identify significant associations.

Mean (±standard deviation) TE was 1.4 (0.7) mm. Electrodes tended to lie medial (0.3 ± 0.1 mm; mean ± 95% confidence interval), posterior (0.6 ± 0.1 mm), and superior (0.5 ± 0.1 mm) to targets. Three variables were independently and significantly associated with greater TE: use of one of two stereotactic frames (effect size 0.4 ± 0.2 mm), second-side implantation in bilateral surgery (0.3 ± 0.2 mm), and decreasing coronal approach angle (0.04 ± 0.03 mm/°). All three factors were associated with significantly more posterior implantation, while second-side and decreasing coronal angle also yielded a more superiorly located point of closest approach of the electrode.

We present a thorough multivariate analysis of targeting accuracy in DBS, identifying significant factors associated with accuracy within our workflow. We suggest that such targeting error analysis should be performed routinely by neurosurgeons undertaking DBS to audit targeting accuracy and identify error sources within their workflows.