Editor’s note: The Parkinson’s News Today team is providing in-depth coverage of the 2021 Virtual AAN Annual Meeting, held April 17–22. Go here to read stories from the conference.
Deep brain stimulation (DBS) can lessen motor function impairments and reduce the need for medication for up to 10 years in people with Parkinson’s disease (PD), a new study shows.
Moreover, the effectiveness of DBS was maintained and independent of the brain region stimulated — either the subthalamic nucleus or the globus pallidus interna, both involved in motor control.
The results were presented in the poster “10 Year Clinical Outcomes of Subthalamic Nucleus versus Pallidal Deep Brain Stimulation for Parkinson’s Disease: VA/NINDS CSP #468F” at the 2021 Virtual American Academy of Neurology Annual Meeting, which ran through April 22.
DBS is a well-established surgical treatment for Parkinson’s disease that involves implanting a device in the brain to stimulate with electrical impulses the subthalamic nucleus (STN) or the globus pallidus interna (GPi).
Previous studies have reported the effectiveness of DBS in improving motor function of people with Parkinson’s disease after three years, but longer-term follow-up studies were lacking, especially comparing the effectiveness of stimulating STN versus GPi.
“This is the longest follow up describing DBS outcomes comparing the two targets in a randomized cohort,” the researchers wrote.
The study, led by led by Jill Ostrem, MD, of the University of California, San Francisco, assessed the outcomes — after years of follow-up — of 155 patients who enrolled the Phase 3 trial (NCT00056563), during which they were assigned randomly to undergo either STN-DBS or GPi-DBS.
Patients were evaluated after two years (70 patients in the STN-DBS group and 85 patients in GPi-DBS group), seven years (49 patients STN-DBS and 68 patients GPi-DBS), or 10 years (28 patients STN-DBS and 49 patients GPi-DBS).
The main goal was to assess changes in the motor score of the Unified Parkinson’s Disease Rating Scale (UPDRS) in the off medication/on stimulation state. The UPDRS is a four-part scale that assesses signs and symptoms of the disease, in which higher scores indicate more severe impairments. At the start of the trial (baseline) the scores were 43.2 in both groups.
Additional parameters included tremor and bradykinesia (slowness or difficulty in movement) scores, as well as behavior and mood (UPDRS-I), activities of daily living (UPDRS-II) and complications linked with therapy (UPDRS-IV).
In both groups, the motor scores in UPDRS declined significantly across all times analyzed. In the group of STN-DBS, the scores declined from 43.2 to 27.7 after two years, to 34.4 after seven years, and to 28.3 after 10 years. In the group of GPi-DBS, the scores declined to 25.8 after two years, to 35.4 after seven years, and to 34 after 10 years.
While improvements were similar between both groups, researchers observed a trend favoring STN-DBS.
During the years of follow-up, tremor scores showed the greatest reduction, followed by rigidit. Improvements in bradykinesia were significantly greater after seven and 10-years of follow-up, specifically with STN-DBS.
Significant long-term improvements also were seen for mood and behavior (UPDRS-I), activities of daily living (UPDRS-II), as well as fewer complications linked with therapy (UPDRS-IV), regardless of the type of DBS.
Patients’ reported outcomes on quality of life, measured using the Parkinson’s Disease Questionnaire (PDQ-39), stopped showing improvement after seven years in both groups.
The use of medication was reduced significantly over time in both STN-DBS and GPi-DBS, with no differences between both types of DBS stimulation.
Overall, these findings show that “DBS therapy had a significant and stable effect on motor function regardless of target over 10 years,” the researchers wrote.
“This is remarkable, given that [Parkinson’s disease] is a progressive neurodegenerative disease,” they added.
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