AUTHOR: Anushka Garg
Introduction
Parkinson’s disease is a progressive neurological disorder affecting mainly the basal ganglia. This study aimed to determine the effects of a treatment for Parkinson’s disease called deep brain stimulation (DBS) by comparing the Unified Parkinson’s Disease Rating Scale-III (UPDRS-III) scores of patients who underwent treatment versus patients who did not receive any treatment. This study relates to current research about how symptoms of Parkinson’s disease may manifest differently in different patients and how DBS and other treatment methods can be improved to be more impactful overall, as well as cater to the needs of individual patients. DBS is a surgical therapy for mid to late stage Parkinson’s disease, aimed to improve motor symptoms and quality of life for patients, as well as reducing side effects of pharmacological treatments such as Levadopa. The proven effectiveness of DBS in late-stage cases of Parkinson’s leads to warrant trials to evaluate the effects of DBS in the early stages of the disease. Vanderbilt University ran a trial that evaluated STN (subthalamic nucleus) DBS in early-stage Parkinson’s for 30 patients, which included week-long “wash-outs” at baseline every 6 months during the trial, which helped the researchers conclude the underlying state of the symptoms without medications. These “off” states were when the patients’ DBS scores were collected. This study proved that DBS + ODT was a more effective treatment as compared to ODT, but their evidence was not substantial. It’s goal was to evaluate whether progression of motor features was influenced by early DBS.
Methods
The study included 28 patients aged 50–75 who had been on Parkinson’s medications for 6 months to 4 years. UPDRS scores (excluding rigidity) were assessed via videotape during “on” therapy at the start of washout and “off” therapy at the end. Evaluations occurred at baseline and every 6 months thereafter. After the first round, patients were randomized to receive ODT or DBS + ODT. All patients continued standard treatment under set guidelines, with experimental treatments titrated accordingly. Surveys assessed patient experiences, with additional questions for DBS participants. Statistical analysis was performed to measure the results. A change of 0.0038 in UPDRS from baseline to 24 months was considered significant. Linear regression models compared treatment effects over time, with separate models for “on” and “off” states (four groups total). A Cox proportional hazards model accounted for errors. Additional outcomes included the number of limbs affected by tremor and development of rest tremor.
Results
Over the 24 months, movement symptoms got worse in both groups when patients were in the “off” state (when medication was not working). However, the group that received DBS along with standard medication did better overall. Specifically, their scores were 3.1 points better than the group that received medication alone. This was the only result that clearly showed a significant benefit of DBS in early-stage Parkinson’s disease. Tremor frequency at a resting position slightly worsened in the medication-only group, but the change was small. In contrast, tremor frequency improved in the DBS group.10 out of 14 medication-only patients experienced worsening rest tremors, while fewer patients in the DBS group (4 out of 13) did. At the start of the study, patients in both groups had tremors in about one to two limbs on average. After 24 months, the number of affected limbs doubled in the medication-only group, but slightly decreased in the DBS group. When looking at the “on” state (when medication was working), tremors improved in the DBS group but worsened in the medication-only group. In surveys, most patients said the biggest benefit of being in the study was improvement in their tremors. Many also reported a better overall quality of life.
Discussion
The aim of this study was to analyze the effects of DBS on tremor progression in early-stage Parkinson’s disease. The main result was that DBS is beneficial for rest tremors, as a common trend was that the rest tremor levels of the ODT group progressively worsened over 2 years, while the DBS + ODT group experienced some improvements. While additional research is still necessary to support these findings, it can be concluded that DBS is an effective treatment for Parkinson’s patients. These results back up the idea that DBS could potentially, in the future, become a more common treatment for early-stage Parkinson’s disease as an improved quality of life was often reported by patients. This study also adds to a growing body of evidence on the topic, and as more research continues to be established about the effects of deep brain stimulation, these findings will be important to note. This future research may include studies about tremor progression, side effects of deep brain stimulation, quality of patient life, and other improvements to be made so that more reliable conclusions are able to be drawn.
Journal Article: https://doi.org/10.1212/WNL.0000000000005903
