STN and Gpi DBS for Parkinson's Disease Tremor Result in Comparable Tremor Reduction: A Single-center Retrospective Study

Introduction: Tremor is observed in approximately 65% of Parkinson’s disease (PD) patients at disease onset. 26% of PD patients without tremor at disease onset develop it with PD progression. Deep Brain Stimulation (DBS) is a highly effective treatment for PD patients whose tremor is unresponsive to medication or who develop dose-dependent side effects limiting pharmacological treatment. The subthalamic nucleus (STN) and the globus pallidus internus (GPi) are common DBS targets for managing PD motor symptoms, including tremor. However, STN DBS may offer superior tremor control.

Methods: In this retrospective single-center experience of 187 PD patients (133 male, 54 female) who underwent DBS between 2009 and 2017, we compare outcomes of GPi vs STN stimulation on tremor and medication outcomes. Patients received unilateral DBS, bilateral DBS, or staged bilateral DBS.

Results: 109 patients underwent STN DBS and 78 underwent GPi DBS, with target selection determined from a multidisciplinary conference. Average time to follow-up was 16.4 months. Changes in Unified Parkinson's Disease Rating Score (UPDRS), tremor UPDRS subscore, contralateral tremor UPDRS subscore, and L-dopa equivalent daily dosage (LEDD) were analyzed using a linear mixed effects model. Mean preoperative on-medication UPDRS score was 17.34. Mean preoperative LEDD was 1249.5 mg. UPDRS scores were reduced by 4.83 points with STN DBS compared to 2.43 points with GPi DBS (p < 0.048). UPDRS tremor subscores were reduced by 1.75 points with STN DBS compared to 1.23 with GPi DBS (non-significant). UPDRS contralateral tremor scores were decreased by 1.98 with STN and 1.29 points with GPi (p < 0.044). STN DBS reduced LEDD by 483 mg (p < 0.001) compared to 200 mg with GPi DBS.

Conclusion : While STN and GPi DBS lead to similar tremor reduction with respect to USPDR tremor subscore, STN DBS is associated with greater LEDD decrease LEDD. STN DBS also leads to a greater overall USPDR score reduction and contralateral tremor scores. Our findings have implications for DBS target selection in PD patients, particularly when tremor control is a key consideration.