Neuropsychological Outcome in Subthalamic Nucleus Stimulation Surgeries with Electrodes Passing through the Caudate Nucleus

Abstract

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson disease (PD) is associated with postoperative cognitive decline. One of the proposed underlying mechanisms is the surgical procedure with the lead trajectory penetrating the caudate nucleus. Objective: To study whether penetration of the caudate nucleus affects neuropsychological outcome. Methods: Neuropsychological and imaging data of 30 PD patients who underwent bilateral STN DBS were analysed. Lead trajectories were evaluated leading to a group with (n = 10) and a group without penetration of the caudate nucleus (n = 20). The neuropsychological performance of each group was compared to baseline, both at 3 and 12 months postoperatively. Results: Only the Trail-Making Test part B (TMT-B) showed an interaction effect within the groups over time at 3 months postoperatively. At 12 months postoperatively, there was only a main effect of time with a decrease in performance in TMT-B for both groups. Also verbal fluency showed a significant decrease over time for both groups at 3 and 12 months postoperatively. Conclusion: Caudate nucleus penetration affects cognitive flexibility only in the short term after surgery.

Electrode Penetration of the Caudate Nucleus in Deep Brain Stimulation Surgery for Parkinson’s Disease

“…They concluded that there was no influence on cognitive outcomes due to CN penetration. Isler et al [11] evaluated 30 cases (all bilateral) of STN DBS for PD with usage of postoperative MRI and CT and noted 10 patients with CN penetration. They found a significant difference in the Trail Making Test Part B after 3 months of follow-up; however, they found no influence on cognitive outcomes due to CN penetration after 12 months of follow-up.…”

“…Normalization of the data was applied, which facilitated comparisons between subjects; however, the individual interrelationship between DBS trajectory and CN was lost [9, 17]. Taking the findings of Isler et al [11] into account, these differences are possibly due to short-term follow-up.…”

“…Morishita et al [10] analyzed predominantly unilateral DBS procedures and Isler et al [11] noted unilateral caudate penetration in the majority of cases. Witt et al [9] noted CN penetration in the majority of their patients, leaving almost none with no penetration.…”

“…Finally, penetration of the head itself (apart from lesion volume) may have contributed to the cognitive decline found by the Witt et al [9]. Isler et al [11] did not report on the location of caudate penetration. Differences in the location of CN penetration could be due to differences in the trajectory angles chosen; however, these were not reported by any of the 3 groups.…”

“…By complying with these conditions, the periventricular CN could occasionally be traversed by the course of the optimal trajectory. Recently, the relation between penetration of the CN and postoperative cognitive decline was studied, with contradictory conclusions [9-11]. …”