Deep Brain Stimulation of the Subthalamic Nucleus vs. Globus Pallidus Internus in the Treatment of Parkinson’s Disease: A Systematic Review
Authors: Naguib Al Shehaby Amr Mohamed , Kotb Mohamed Mostafa , Abdel-Latif Assem Mounir M , Mohamed Abdelaziz Abdelaziz Mahdy 
Published: July 2024

Abstract

Background
Parkinson’s disease (PD) is a very common debilitating disease especially in the elderly population. Bilateral stimulation of the subthalamic nucleus or the globus pallidus internus provides significant motor benefits for patients with advanced Parkinson’s disease, while reducing dyskinesia and motor fluctuation. High frequency stimulation of the STN and the GPi is relatively safe. The effects are stable even after 1 year of stimulation.

Aim of the Work
The primary goal of the current review is to compare the efficacy of using the Subthalamic Nucleus (STN) vs. the Globus Pallidus Internus (GPi) as the primary target for Deep Brain Stimulation (DBS) in the treatment of Parkinson disease (PD); in terms of improved motor function measured using the Unified Parkinson's Disease Rating Scale (UPDRS), psychiatric symptoms, rate of reduction of medication, and complications. This will be done through a systematic review of literature addressing this research question.

Patients and Methods
In this Review, the authors are aiming at the analysis of the collective outcomes from studies comparing bilateral deep brain stimulation of the Subthalamic Nucleus and the Globus Pallidus Internus in the management of idiopathic Parkinson’s disease. The following electronic databases were searched for included articles: PubMed, Google Scholar, EMBASE, Science Direct, Cochrane database of systematic reviews, using the keywords “Parkinson’s disease – treatment – management – deep brain stimulation – subthalamic – globus pallidus internus” in different combinations. Also, manual search were conducted for reference lists of included articles. Limiting the search in English. The information sources previously mentioned were searched from 2000 to 2021.

Results
A total of 594 patients underwent STN-DBS, with a mean change in total UPDRSIII score of 3.26 on medication and 25.04 off medication. A total of 446 patients underwent GPi-DBS, with a mean change in total UPDRSIII score of 4.75 on medication and 19.31 off medication. There was a higher change for GPi on medication that was statistically significant with a p value (˂0.001), while off medication STN caused a higher change that was also statistically significant with a p value (˂0.001). We observed a statistically significant higher average improvement in ADLs after STN-DBS than GPi, however, non- motor function improvements were greater after GPi DBS than STN DBS.

Conclusion
Based on our systematic review and other available data in the literature, the STN may be the preferred target for DBS in consideration of motor function improvement, medication reduction, and economic efficiency, although GPI stimulation has some advantages in terms of mood and cognition. Treatment decisions should be individualized and based on patients’ specific symptoms and expectations. Additional well-designed multicenter clinical trials that can minimize bias are needed, especially for evaluation of the long-term outcomes of the two stimulation targets.