Quality of Life after Deep Brain Stimulation in Parkinson's Disease: Does the Target Matter?

Abstract

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) is an accepted therapy for Parkinson's disease (PD) with disabling motor complications. For elderly patients with poorer cognition and postural instability, GPi has been proposed as the preferable DBS target based on expert opinion, arguing GPi-DBS may be less complicated by depression, apathy, worsened verbal fluency, and executive dysfunction, resulting in greater improvement in quality of life (QoL). However, data supporting such patient-tailored approach are lacking.

Objectives: The aims were to analyze whether the DBS target influences QoL in a PD cohort and a matched subgroup of frail patients with poor cognitive status and reduced postural stability, and whether other factors affect the QoL outcomes.

Methods: In this retrospective study, we analyzed a single-center cohort of 138 PD patients who received bilateral STN-DBS (117) or GPi-DBS (21) using the mentioned approach for target selection. All patients underwent standardized clinical evaluations of motor- and nonmotor signs as well as QoL before and 1 year after surgery.

Results: DBS of both targets improved motor signs, dyskinesias, and pain. QoL improved without significant difference between the targets, but with a trend for greater improvement across all QoL domains in favor of the STN, even in an STN subgroup matched to the GPi group.

Conclusion: Our results contradict the prevailing belief that GPi-DBS is superior in frail PD patients with cognitive decline and postural instability, questioning the proposed patient-tailored approach of DBS target selection. Further studies are needed for a data-driven approach.

Keywords: Parkinson's disease; deep brain stimulation; globus pallidus; quality of life; subthalamic nucleus.

FIG. 1

Mean percentage change before and 1 year after DBS (deep brain stimulation) implantation of PDQ‐39 SI (Parkinson's Disease Questionnaire Summary Index) and subscores. Results are shown for the whole cohort of 117 STN (blue) and 21 GPi patients (yellow). Positive values indicate an improvement in the respective subscore. GPi, globus pallidus internus; STN, subthalamic nucleus.

FIG. 2

Results of the linear model showing the relationship between improvement in PDQ‐39 SI (Parkinson's Disease Questionnaire Summary Index) and improvement (or change in the target) in the respective variables. (A) Relative importance of the variables. (B) Regression coefficients with 95% CIs (confidence interval). For numeric results of the model see Table S2. GPI, globus pallidus internus; LEDD, levodopa equivalent daily dose; MMSE, Mini‐Mental State Examination; MDS‐UPDRS‐III, Movement Disorder Society Unified Parkinson's Disease Rating Scale, Part III.

FIG. 3

Absolute improvement in (A, B) PDQ‐39 SI, (C) postural stability, and (D) MMSE after DBS (deep brain stimulation). (A) Results for the whole cohort of 117 STN and 21 GPi patients. (B–D) Results of the 21 matched patients. GPI, globus pallidus internus; MMSE, Mini‐Mental State Examination; PDQ‐39 SI, Parkinson's Disease Questionnaire Summary Index; STN, subthalamic nucleus.