Deep Brain Stimulation and Levodopa Affect Gait Variability in Parkinson Disease Differently

Area of Science:

• Neuroscience
• Movement Disorders
• Biomedical Engineering

Background:

• Parkinson disease (PD) affects gait speed and amplitude with both dopaminergic medication and subthalamic nucleus (STN) deep brain stimulation (DBS).
• Gait variability, a measure of gait irregularity, is linked to pedunculopontine nucleus (PPN) cholinergic neuron degeneration in PD.
• The STN and PPN have reciprocal connections, suggesting STN DBS may influence PPN function.

Purpose of the Study:

• To compare the effects of STN DBS versus dopaminergic medication on gait variability in Parkinson disease (PD).
• To investigate if STN DBS improves gait variability by modulating PPN function.
• To differentiate between short-term (irregularity) and long-term gait variability.

Main Methods:

• Studied 11 patients with STN DBS (on/off) and 15 PD patients without DBS (on/off medication).
• Utilized six inertial measurement units for gait data collection during two-minute walking trials.
• Employed Poincaré analysis to distinguish short-term gait variability from long-term variability.

Main Results:

• STN DBS significantly decreased short-term gait variability in lower limb parameters.
• Dopaminergic medication did not improve short-term gait variability.
• STN DBS did not affect arm swing or trunk motion variability, while medication increased them.

Conclusions:

• STN DBS reduces gait variability through a nondopaminergic mechanism, likely involving retrograde activation of cholinergic PPN neurons.
• Dopaminergic medication does not impact gait variability in the same manner as STN DBS.
• Findings suggest STN DBS offers a distinct therapeutic pathway for gait irregularity in Parkinson disease.