Einfluss der Elektrodenlage im Nucleus subthalamicus auf den motorischen Stimulationseffekt ein Jahr nach tiefer Hirnstimulation bei Morbus Parkinson

Influence of electrode position in the subthalamic nucleus on the motoric stimulation effect one year after deep brain stimulation in parkinson's disease

by Anna Sophie Julia Dietrich née Rudolph
Doctoral thesis
Date of Examination:2025-07-30
Date of issue:2025-07-15
Advisor:PD Dr. Vesna Malinova
Referee:PD Dr. Vesna Malinova
Referee:Prof. Dr. Claudia Trenkwalder
Persistent Address: http://dx.doi.org/10.53846/goediss-11388

 

 

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Abstract

English

Parkinson’s disease is one of the most common neurodegenerative disorders with a steadily increasing incidence. As the disease progresses, deep brain stimulation of the subthalamic nucleus becomes an established therapeutic option. Since the stimulation effect can only be reliably assessed one year after surgery, the identification of early, directly applicable predictors for motor outcome is of great clinical relevance. Advances in imaging technology have made it possible to precisely assess electrode positioning postoperatively. This study was aimed at examining a correlation between the accuracy of electrode positioning and the one-year motor outcome, including intraoperatively collected data, in PD patients who were treated with deep brain stimulation of the nucleus subthalamicus. The primary goal was to determine whether suboptimal electrode positioning leads to insufficient motor improvement, hence possibly indicating a required revision. A retrospective analysis was conducted on a consecutive cohort of 151 patients who underwent awake deep brain stimulation surgery targeting the subthalamic nucleus between 2010 and 2017 at the University Medical Center Göttingen, Germany. The dataset included clinical records, cranial computed tomography, magnetic resonance imaging scans and intraoperative stimulation protocols. The nucleus subthalamicus was visualized by preoperative magnetic resonance imaging scans and the implanted electrodes were localized through postoperative computed tomography imaging. Image fusion was performed using stereotactic planning software to determine both the actual and an imaging morphology-based “optimal” electrode position, expressed in coordinates relative to the mid-commissural point. The Euclidean distance between the actual and optimal electrode positions was calculated. Patients were divided into six groups based on the anatomical location of the implanted electrodes in relation to the nucleus subthalamicus. Electrode localization was then analyzed based on motor outcome parameters and intraoperative parameters. Complete datasets were available for 87 patients comprising a total of 174 implanted electrodes and were utilized for correlation analyses and intergroup comparisons. Deep brain stimulation was very effective (OP index 1.18 on average, postoperative LEDD reduction by 35,6%). Mean distance to the morphologically defined optimal electrode position was relatively small (right side: 2.85 mm; left side: 3,51 mm). Most electrodes were located in the dorsolateral nucleus subthalamicus (right side: 39/87; left side: 47/87). The correlation analyses and group comparisons revealed no statistically significant results. The one-year motor outcome in Parkinson’s patients treated with deep brain stimulation of the nucleus subthalamicus is not significantly influenced by deviations from the presumed optimal electrode placement. Thus, a suboptimal lead placement does not necessarily result in an insufficient motor outcome at a one-year follow-up.
Keywords: Parkinson’s disease; deep brain stimulation; subthalamic nucleus; long-term outcome; awake surgery
 
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