Stimulation related artifacts and a multipurpose template-based offline removal solution for a novel sensing-enabled deep brain stimulation device

Abstract

Background: The Medtronic "Percept" is the first FDA approved deep brain stimulation (DBS) device with sensing capabilities during active stimulation. Its real-world signal recording properties have yet to be fully described. Objective: This study details sources of artifact (and potential mitigations) in local field potential (LFP) signals collected by the Percept, and assesses the potential impact of artifact on the future development of adaptive DBS (aDBS) using this device. Methods: LFP signals were collected from seven subjects in both experimental and clinical settings. The presence of artifacts and their effect on the spectral content of neural signals were evaluated in both the stimulation ON and OFF states using three distinct offline artifact removal techniques. Results: Template subtraction successfully removed multiple sources of artifact, including 1) electrocardiogram (ECG), 2) non-physiologic polyphasic artifacts, and 3) ramping related artifacts seen when changing stimulation amplitudes. ECG removal from stimulation ON (at 0 mA) signals recovered the spectral shape seen when OFF stimulation (averaged difference in normalized power in theta, alpha, and beta bands ≤ 3.5%). ECG removal using singular value decomposition was similarly successful, though required subjective researcher input. QRS interpolation produced similar recovery of beta-band signal, but resulted in residual low-frequency artifact. Conclusions: Artifacts present when stimulation is enabled notably affected the spectral properties of sensed signals using the Percept. Multiple discrete artifacts could be successfully removed offline using an automated template subtraction method. The presence of unrejected artifact likely influences online power estimates, with the potential to affect aDBS algorithm performance.

Concurrent stimulation and sensing in bi-directional brain interfaces: a multi-site translational experience

“…In addition to stimulation artifacts, cardiac artifacts may preclude application of adaptive stimulation algorithms by corrupting signal spectral information in the low frequency biomarker bands [ 50 , 51 ]. The presence of an ECG artifact is only observed in the subcortical channels, and is not present in cortical channels.…”

“…Other studies have opted for pulse generators placed farther away from the chest, for example skull based implants [1,5,7,30]. A mitigation strategy during 'off-line' (post processing) has been proposed by [51] using template-based extraction, but this implementation is not applicable to closed-loop (real-time) DBS.…”

Diurnal modulation of subthalamic beta oscillatory power in Parkinson’s disease patients during deep brain stimulation

“…This may lead to physiological modulation of beta in response to movements (Jenkinson & Brown, 2011; Kühn et al, 2004; Lofredi et al, 2019; Neuville et al, 2021; Quinn et al, 2015), but will also increase potential artifact sources. It is already known that the heartbeat can affect measures of beta power in certain DBS devices (Neumann et al, 2021; Sorkhabi et al, 2020), and movements themselves present another potential source of transient artifacts in LFP recordings (Hammer et al, 2021; Swann, Hemptinne, Miocinovic, et al, 2018). As the parameters for aDBS are currently set under controlled conditions during clinician working hours, both physiological and artifactual diurnal changes in beta measurement could impact aDBS effectiveness outside of the clinic.…”