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Lateralized Subthalamic Stimulation for Axial Dysfunction in Parkinson's Disease: Exploratory Outcomes and Open-Label
Karlo J Lizarraga1,2, Bhairavei Gnanamanogaran1,3, Tameem M Al-Ozzi3,4,5,6
1The Edmond J. Safra Program in Parkinson's Disease and the Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, University Hospital Network and Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada.
Reducing stimulation amplitude in Parkinson's disease may improve axial dysfunction. Left-sided amplitude reduction appears more tolerable, while right-sided stimulation may enhance gait velocity.
Area of Science:
- Neurology
- Neurosurgery
- Biomedical Engineering
Background:
- A prior randomized trial indicated that decreasing left-sided subthalamic stimulation amplitude could alleviate axial dysfunction in Parkinson's disease.
- This study aimed to further investigate the tolerability and outcomes of open-label, lateralized deep brain stimulation settings.
Purpose of the Study:
- To assess the open-label tolerability of unilateral subthalamic stimulation amplitude reduction.
- To explore the relationship between trial outcomes, stimulation laterality, and motor asymmetry in Parkinson's disease patients.
Main Methods:
- Collected adverse events from 17 participants receiving open-label lateralized deep brain stimulation for at least 3 months.
- Analyzed associations between stimulation location (left vs. right), motor asymmetry, and clinical outcomes, including gait velocity and axial motor scores (MDS-UPDRS).
Main Results:
- 14 out of 17 participants tolerated unilateral amplitude reduction, with 10 experiencing left-sided and 4 right-sided reduction.
- A significant number of voxels (284 left, 1113 right) were associated with faster gait velocity, while fewer (81 left, 22 right) were linked to slower gait.
- Amplitude reduction contralateral to shorter step length correlated with a 2.4-point decrease in axial MDS-UPDRS, whereas reduction contralateral to longer step length showed a 10-point increase.
Conclusions:
- Left-sided subthalamic stimulation amplitude reduction may be better tolerated than right-sided reduction.
- Right-sided stimulation appears more strongly associated with improved gait velocity compared to left-sided stimulation.
- Shortened step length could indicate overstimulation on the contralateral side, suggesting a need for careful amplitude adjustment.
