Electrode location and domain specific cognitive change following subthalamic nucleus deep brain stimulation for Parkinson’s disease

Introduction: Deep brain stimulation (DBS) is an effective treatment for Parkinson’s disease (PD) associated motor symptoms. Several studies suggest that subthalamic nucleus (STN) DBS may be associated with cognitive changes in some patients. We previously found that overall cognitive decline following STN DBS was associated with more medial electrode position. The goal of the present study is to investigate whether electrode location is associated with decline in specific cognitive domains.

Methods: A single-institution retrospective cohort study was conducted in patients with a diagnosis of PD who underwent STN DBS from 09/2006-07/2020. Patients with preoperative and postoperative neuropsychological testing were included. Standardized norm-referenced test z-scores were categorized into five cognitive domains and change scores were calculated (postoperative minus preoperative scores). Change scores were averaged to create domain specific composite scores. We identified AC/PC coordinates of active electrode contacts in atlas space. We performed simple linear regressions to identify relationships between electrode coordinates and change scores in all domains. We performed multiple linear regressions, controlling for age, gender, and follow-up duration, for domains with significant relationships. Bonferroni correction was used to correct for multiple comparisons.

Results: A total of 92 patients (male:n=66,71.7%) were included with mean age of 63.3±8.7 years, disease duration of 9.3±5.0 years, and follow-up duration of 11.3±8.7 months (range:3-60 months). Simple linear regression demonstrated medial electrode position in right STN was associated with executive function decline, but this was not significant on multiple variable regression (r=-0.31,p=0.113). More superior electrode position in left STN was associated with declines in memory (r=-0.35,p=0.007) on both simple and multiple variable regression.

Conclusion : In our cohort of patients with PD that underwent STN DBS, more superior electrode position related to memory decline. Our study provides insight into the pathophysiology of cognitive decline in patients undergoing STN DBS and may help minimize cognitive symptoms.