Beta-triggered adaptive deep brain stimulation during reaching movement in Parkinson’s disease

Abstract

Subthalamic nucleus (STN) beta-triggered adaptive deep brain stimulation (ADBS) has been shown to provide clinical improvement comparable to conventional continuous DBS (CDBS) with less energy delivered to the brain and less stimulation induced side-effects. However, several questions remain unanswered. First, there is a normal physiological reduction of STN beta band power just prior to and during voluntary movement. ADBS systems will therefore reduce or cease stimulation during movement in people with Parkinson’s disease (PD) and could therefore compromise motor performance compared to CDBS. Second, beta power was smoothed and estimated over a time period of 400 ms in most previous ADBS studies, but a shorter smoothing period could have the advantage of being more sensitive to changes in beta power which could enhance motor performance. In this study, we addressed these two questions by evaluating the effectiveness of STN beta-triggered ADBS using a standard 400 ms and a shorter 200 ms smoothing window during reaching movements. Results from 13 people with PD showed that reducing the smoothing window for quantifying beta did lead to shortened beta burst durations by increasing the number of beta bursts shorter than 200 ms and more frequent switching on/off of the stimulator but had no behavioural effects. Both ADBS and CDBS improved motor performance to an equivalent extent compared to no DBS. Secondary analysis revealed that there were independent effects of a decrease in beta power and an increase in gamma power in predicting faster movement speed, while a decrease in beta event related desynchronization (ERD) predicted quicker movement initiation. CDBS suppressed both beta and gamma more than ADBS, whereas beta ERD was reduced to a similar level during CDBS and ADBS compared with no DBS, which together explained the achieved similar performance improvement in reaching movements during CDBS and ADBS. In addition, ADBS significantly improved tremor compared with no DBS but was not as effective as CDBS. These results suggest that STN beta-triggered ADBS is effective in improving motor performance during reaching movements in people with PD, and that shortening of the smoothing window does not result in any additional behavioural benefit. When developing ADBS systems for PD, it might not be necessary to track very fast beta dynamics; combining beta, gamma, and information from motor decoding might be more beneficial with additional biomarkers needed for optimal treatment of tremor.

Beta Burst-Driven Adaptive Deep Brain Stimulation Improves Gait Impairment and Freezing of Gait in Parkinson’s Disease

“…The operation of aDBS has also differed across studies, with some employing rapid on/off fluctuations of stimulation in response to beta power using a single threshold 33,40 , slower adaptation in response to beta power using a dual threshold 10,23 , proportional-control 39 , or inverse algorithms based on either subcortical or cortical gamma power 37,38,41 . Here, we implemented a single-threshold algorithm where stimulation was incremented or decremented based on the duration of the most recent ongoing beta burst.…”

Proceedings of the 11th Annual Deep Brain Stimulation Think Tank: pushing the forefront of neuromodulation with functional network mapping, biomarkers for adaptive DBS, bioethical dilemmas, AI-guided neuromodulation, and translational advancements

“…Continuous high frequency STN DBS over-suppresses gamma oscillations during voluntary movements, which helps invigorate the movements, compared to beta-triggered aDBS. Therefore, even though beta-triggered aDBS led to less stimulation during reaching movements, it improves the movement performance to the same level as continuous DBS (He et al, 2023 ). Meanwhile, the ERNA reduced in frequency and amplitude with time during cDBS indicating synaptic depletion, whereas ERNA remained high during aDBS due to the bursting nature of the DBS, indicating a different synaptic status (Wiest et al, 2023a ).…”

Dopaminergic reinforcement in the motor system: Implications for Parkinson's disease and deep brain stimulation

“…In theory, it could even counteract purposeful weakening of unwanted activity patterns, potentially associated with side‐effects like dyskinesia. In practice, however, high‐beta adaptive STN‐DBS has been reported to improve motor performance in PD patients (He et al, 2023). Thus, more studies are needed that clarify the relationship between subthalamic beta activity and phasic dopaminergic release in the motor striatum.…”