Objective: To explore neurophysiological markers of intentional executed and imagined movement in both Globus Pallidus Internus (Gpi) and Pedunculopontine Nucleus (PPN) in patients with Parkinson’s Disease (PD) and Freezing of Gait symptoms (FoG).

Background: Freezing of Gait (FoG) is a unique and poorly understood clinical phenomenon affecting ~53% of the patients with Parkinson’s Disease (PD), and it is characterized by a sporadic inability to step forward. Although the pathophysiological basis of PD and FoG remain unknown, it has been shown that Deep Brain Stimulation (DBS) in the Gpi can decrease the FoG episodes and alleviate other PD phenotypes. There is pressing need to reach a better understanding of the network involved in gait initiation, to be able to shed light on the pathology and potentially use newfound biomarkers as control features for responsive DBS therapies.

Methods: Two patients were implanted in both Gpi and PPN regions as part of an explorative closed-loop DBS cohort with Medtronic PC+S neurostimulators. The patients were asked to “walk” by moving their feet with a simulated gait motion while intermittently touching a pad that was acting as ground. Leveraging the inertial and EMG sensors data, it was possible to explore neurocorrelates with movement intention/execution. The absence of movement during the cued motor imagery task (imagine walking/rest) allow us to evaluate intention without the peripheral feedback as confounding factor.

Results: The simulations executed on intraoperatively collected data from PD patients shows that is possible to reliably detect movement execution in both Gpi and PPN. Furthermore, it appears that during the motor imagery task only the Gpi shows reliable and significant modulation that correlates with the cues.

Conclusions: Our results suggest that gait initiation modulates Gpi activity during both imagined and executed gait task. PPN instead seems to have significant modulation only during executed tasks, suggesting an involvement with the execution but not the planning of movement, or a feedback evoked activity. The results suggest that it would be possible to use gait onsets as feature to modulate a responsive DBS activation, to stimulate only during gait, decreasing stimulation evoked side effects and battery depletion.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/globus-pallidus-and-pedunculopontine-nucleus-oscillations-during-executed-and-imagined-gait-in-patient-with-parkinsons-disease-and-freezing-of-gait-symptoms/