Objective: Determining the relevance of subthalamic (STN) beta peaks in Parkinson’s disease (PD) patients with deep brain stimulation (DBS) in relation to the best possible clinical outcome.

Background: STN beta band activity is pathologically increased in PD patients and comprises a patient-specific peak [1]. In addition, beta activity correlates with severity of motor symptoms and can be attenuated by DBS [2, 3]. Since both the beta activity and the effectiveness of STN-DBS depend on the location of applied contacts, STN beta peaks may serve as a biomarker to optimize DBS settings.

Method: We recorded local field potentials (LFP) in 27 PD patients (8 female, 59.0 ± 8.7 years) 1-3 days after STN-DBS surgery at rest for 30 min with (ON) and without (OFF) dopaminergic medication and inactive DBS. Furthermore, we determined part three of the MDS-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS-III), the contact’s therapeutic window (TW) and the best clinical contact (BCC; the stimulated contact 6-24 months after implantation). Peaks in the power spectral density were determined for the low beta band (LBB; 12-20 Hz) and the high beta band (HBB; 21-35 Hz) using the fitting oscillations & one over f (FOOOF) toolbox [4, 5]. Binary logistic and linear regression models were calculated and, in the case of multiple comparisons, the p-values were Bonferroni corrected [6].

Results: 25 patients OFF and 24 patients ON medication had at least one beta peak in the STN. Over 72 % of the highest beta peaks occurred in the LBB (OFF: 227 of 312; ON: 216 of 288) [figure 1, 2]. The ratio of the highest peak amplitude in the LBB (ON vs. OFF) positively correlated with the TW. In regressions, this quotient significantly predicted the TW (R² = .237; F (1.52) = 16, b = 0,756, p < .001) [figure 3] and the MDS-UPDRS-III values ON medication 6-24 months after DBS surgery (R² = .075; F (1,149) = 12, b = -5,600, p = .004) but not the BCC (R² = .075, b = 1,575, p = .063).

Conclusion: Beta peaks are mainly present in the LBB but not in all STN-LFPs. These peaks are to some extent predictive of the TW and MDS-UPDRS-III, which in turn are related to the clinical outcome. These findings further highlight the clinical relevance of pathological beta activity in the STN.

[figure1]

[figure2]

[figure3]

References: [1] Tinkhauser, G., et al., The modulatory effect of adaptive deep brain stimulation on beta bursts in Parkinson’s disease. Brain, 2017. 140(4): p. 1053-1067.
[2] Brittain, J.S. and P. Brown, Oscillations and the basal ganglia: motor control and beyond. Neuroimage, 2014. 85 Pt 2(Pt 2): p. 637-47.
[3] Oswal, A., et al., Deep brain stimulation modulates synchrony within spatially and spectrally distinct resting state networks in Parkinson’s disease. Brain, 2016. 139(Pt 5): p. 1482-96.
[4] Donoghue, T., et al., Parameterizing neural power spectra into periodic and aperiodic components. Nat Neurosci, 2020. 23(12): p. 1655-1665.
[5] Tadel, F., et al., Brainstorm: a user-friendly application for MEG/EEG analysis. Comput Intell Neurosci, 2011. 2011: p. 879716.
[6] Curtin, F. and P. Schulz, Multiple correlations and Bonferroni’s correction. Biol Psychiatry, 1998. 44(8): p. 775-7.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/beta-peaks-as-predictor-for-dbs-outcome-in-parkinsons-disease/