Objective: This study investigates the changes in local field potential (LFP) activity during chronic deep brain stimulation (DBS) in patients with Parkinson’s disease (PD) during a 1-hour period with stimulation temporarily turned off. Specifically, the study examines changes in LFP within the hemisphere and assesses the impact of inter-hemispheric communication.

Background: The effects of DBS on the ipsilateral and contralateral hemispheres in PD patients have not been thoroughly explored.

Method: We conducted a longitudinal observational study involving eight PD patients. During data collection, DBS was temporarily turned off for 1 hour. LFP recordings were taken at 5, 10, 15, 30, 45, and 60-minute intervals during this hour, with each recording lasting ~20 seconds.

Results: Our observations revealed notable findings regarding the ipsilateral and contralateral effects of DBS and LFP activity. Specifically, in patients with unilateral DBS implants, worsening clinical symptoms on the non-stimulated side correlated with an increased coefficient of variation (CV) of LFP signals on the stimulated side. Additionally, we observed an interesting phenomenon in some patients during the 1-hour off-stimulation interval. As evidenced by increased bradykinesia, beta power in the LFP progressively decreased over the hour. Typically, reduced beta power is associated with improved motor impairment; however, our findings highlight a discordance between clinical observations and electrophysiological data.

Conclusion: This study suggests that interhemispheric communication influences LFP activity across hemispheres. Additionally, our study demonstrates the inter-hemispheric expression of disease progression, as well as the ipsilateral and contralateral effects of DBS. However, these effects varied among patients, which may imply heterogeneity in interhemispheric neural connectivity among individuals. It would be particularly interesting to further explore whether inter-hemispheric neurophysiological markers of the disease correlate with motor and non-motor symptoms such as gait and cognition and if symptom dominance on the right versus left side affects these relationships. Moreover, this study suggests that beta power alone may not be a fully reliable indicator of clinical motor impairment during short-term stimulation-off intervals, highlighting the complexity of interpreting LFP signals in PD patients undergoing DBS.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/chronic-dbs-stimulations-effects-after-1-hour-off-stimulation/