Objective: Compare gait kinematics Low and High-Frequency Stimulation of 2 Parkinson’s Disease patients treated with STN-DBS

Background: Subthalamic nucleus (STN) Deep Brain Stimulation (DBS) is a well-established therapy for Parkinson’s Disease (PD) motor symptoms and fluctuations. But, if long term benefit on appendicular symptoms can be obtained with High Frequency Stimulation (HFS,130-185 Hz) a relative lack of effectiveness (or even impairment) in axial symptoms is seen. Low-Frequency Stimulation (LFS, 60-80 Hz) has been proposed as a therapeutic option for patients with HFS-related gait impairment, falls or freezing.

Methods: Lower limb 3D kinematics was reconstructed in real time using 7 skin-mounted inertial sensors and the Kinetikos software (Kinetikos, Portugal) from 2 PD patients after STN-DBS. Patient A was a 48-year-old man with 9 years of disease duration that reported gait impairment and falls with HFS-DBS (130Hz) that improved with 80Hz stimulation. Patient B was a 55-year-old man with 11 years of disease duration that did not reported gait changes with HFS-DBS. Gait 3D kinematics was collected for up to 21 randomized conditions for each subject (limited by stimulation-induced side effects) during a walk of 25 meters. Evaluations were performed in a MED-OFF state using 2 different frequencies (130 and 80Hz), up to 10 different voltages per frequency (0.5 to 5V in 0.5V intervals, limited by side effects) and the OFF state.

Results: From all gait spatiotemporal variables calculated we found that the mean gait cycle time of both lower limbs was remarkably sensitive to the STN-DBS parametrisation. Patient A gait spatiotemporal parameters showed a voltage-dependent trend to normalisation with LFS-DBS (80Hz) but not with HFS. This was accompanied by the observed reduction in axial symptoms, and fall number from >3/week (with 130Hz) to <2/year (with 80Hz). In Patient B no relevant difference was observed in spatiotemporal parameters when 130Hz was compared with 80Hz.

Conclusions: In this multiple case study, real time gait 3D kinematics proved to be a pragmatic, fast and useful tool for clinical use in early DBS parameter optimization in PD. Ongoing studies with a larger number of PD patients, with a larger variety of phenotypes, would clarify its role.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gait-3d-kinematics-for-assessment-of-high-frequency-subthalamic-stimulation-induced-axial-symptoms-in-parkinsons-disease-a-comparison-of-2-subjects/