Objective: Since the understanding of electrophysiological biomarker dynamics during every-day activities is crucial for adaptive deep brain stimulation (aDBS), this study aims to investigate characteristics of long-term subthalamic beta band recordings regarding medication and motor performance in chronically implanted Parkinson’s disease (PD) patients.

Background: Subthalamic beta band activity has been investigated as a biomarker in PD reflecting motor states and therapy effects.^1-3 With novel implantable pulse generators (IPGs), electrophysiological biomarker activity can be recorded chronically and will be used for aDBS. In a previous studies, we observed strong circadian periodicity that may influence therapy quality, e.g. during sleep.⁴ However, to date it has not yet been characterized how different every-day activities, motor states and medication responses are reflected in chronic electrophysiological biomarkers.

Method: 23 PD patients with bilateral subthalamic DBS were included in the study. Subthalamic electrophysiological chronic peak biomarker data, clinical notes on medication times and motor self-scoring were collected during a post-operative optimization inpatient stay of 15.9±3.1 days at the Movement Disorders Hospital Beelitz. Electrophysiological data were inspected for ECG-artifact contamination, normalized and analyzed regarding medication-intake dependent power-fluctuations.

Results: Of the 21 patients included in the final analysis, data from 84% of recording configurations were included after ECG-artifact inspection. In the overall cohort of 19 patients with consistent medication documentation and beta biomarker recordings, peak beta band activity 1.5 hours pre-medication intake and post-medication reflected the expected trend of beta band suppression by medication.

Conclusion: Peak beta band activity seems to reflect biomarker changes during DBS ON related to medication intake. More detailed analysis of the present data set will include subgroup analysis regarding reported motor scores, and movement artifact contamination. However, further investigation with better objective measures, e.g. wearables including accelerometers, will be necessary to disentangle activity-related changes in biomarker dynamics for future aDBS implementation.

References: 1. Feldmann LK, Lofredi R, Neumann WJ, et al. Toward therapeutic electrophysiology: beta-band suppression as a biomarker in chronic local field potential recordings. NPJ Parkinsons Dis 2022;8(1):44.
2. Lofredi R, Okudzhava L, Irmen F, et al. Subthalamic beta bursts correlate with dopamine-dependent motor symptoms in 106 Parkinson’s patients. NPJ Parkinsons Dis 2023;9(1):2.
3. Kuhn AA, Kupsch A, Schneider GH, Brown P. Reduction in subthalamic 8-35 Hz oscillatory activity correlates with clinical improvement in Parkinson’s disease. Eur J Neurosci 2006;23(7):1956-1960.
4. van Rheede JJ, Feldmann LK, Busch JL, et al. Diurnal modulation of subthalamic beta oscillatory power in Parkinson’s disease patients during deep brain stimulation. NPJ Parkinsons Dis 2022;8(1):88.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/detecting-clinical-fluctuations-in-chronic-biomarker-recordings-experiences-with-chronic-subthalamic-peak-beta-band-recordings-in-a-large-parkinsons-disease-patient-cohort/