Using Theia Markerless Motion capture to measure the impact of adjusting deep brain stimulation parameters on gait in a Parkinson’s Disease case study

The way one swings their arms, turns their torso, and moves their feet, are gait parameters that are commonly disturbed in patients with Parkinson’s Disease (PD).1 Deep brain stimulation in the subthalamic nucleus (STN-DBS) has proven to be an effective long-term therapy for reducing cardinal motor symptoms and improving quality of life, compared to standard medical treatments like levodopa-based therapies.2-4 However, optimizing STN-DBS settings for individual needs can be a complex process, as standard clinical tools for PD progression, such as the Unified Parkinson's Disease Rating Scale, may be subjective and have limitations.5,6 This project aimed to explore markerless motion capture as a novel, objective measurement of gait progression in PD. The study used an n=1 case design to investigate how gait metrics change with adjustments to DBS settings. The participant, a PD patient with STN-DBS, underwent five randomized, double-blind trials in which their DBS frequency (Hz) and current strength (mA) were adjusted. The following combinations of left and right ventral electrode settings were used: Left: 179 Hz, 3.1 mA; Right: 179 Hz, 2.9mA (Baseline) Left: 149 Hz, 3.1 mA; Right: 149 Hz, 2.9mA (149 low) Left: 149 Hz, 3.4 mA; Right: 149 Hz, 3.2 mA (149 high) Left: 104 Hz, 3.1 mA; Right: 104 Hz, 2.9mA (104 low) Left: 104 Hz, 3.3 mA; Right: 104 Hz, 3.2 mA (104 high) During each 5-minute trial, the participant walked on a treadmill at a comfortable speed while being recorded using a Theia3D markerless motion capture system. The recordings were analyzed using Visual3D software, which quantified gait metrics including cadence, step length, stride length, posture, and arm swing. Notably, differences in the participant’s arm swing between the left and right sides were observed across the various DBS settings. This technology provided objective, measurable data on gait, offering a potential tool for future gait assessments in PD. Its applicability extends to long-term tracking of patient progress, with the potential for markerless motion capture to transform how clinicians evaluate the efficacy of DBS in patients with PD.