Closed‐Loop Deep Brain Stimulation for Essential Tremor Based on Thalamic Local Field Potentials

Abstract

A BS TRACT: Background: High-frequency thalamic stimulation is an effective therapy for essential tremor, which mainly affects voluntary movements and/or sustained postures. However, continuous stimulation may deliver unnecessary current to the brain due to the intermittent nature of the tremor. Objective: We proposed to close the loop of thalamic stimulation by detecting tremor-provoking movement states using local field potentials recorded from the same electrodes implanted for stimulation, so that the stimulation is only delivered when necessary. Methods: Eight patients with essential tremor participated in this study. Patient-specific support vector machine classifiers were first trained using data recorded while the patient performed tremor-provoking movements. Then, the trained models were applied in real-time to detect these movements and triggered the delivery of stimulation. Results: Using the proposed method, stimulation was switched on for 80.37 ± 7.06% of the time when tremorevoking movements were present. In comparison, the stimulation was switched on for 12.71 ± 7.06% of the time when the patients were at rest and tremor-free. Compared with continuous stimulation, a similar amount of tremor suppression was achieved while only delivering 36.62 ± 13.49% of the energy used in continuous stimulation. Conclusions: The results suggest that responsive thalamic stimulation for essential tremor based on tremorprovoking movement detection can be achieved without any requirement for external sensors or additional electrocorticography strips. Further research is required to investigate whether the decoding model is stable across time and generalizable to the variety of activities patients may engage with in everyday life.

Wearable sensor-driven responsive deep brain stimulation for essential tremor

“…To overcome these and other limitations of cDBS, responsive DBS (rDBS) has been introduced and relies on one or more feedback signals to modulate stimulation amplitude [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. The rationale for rDBS is to provide stimulation only when necessary (i.e., when a patient is or would be experiencing symptoms).…”

Implantable Pulse Generators for Deep Brain Stimulation: Challenges, Complications, and Strategies for Practicality and Longevity

“…Transitioning from continuous stimulation to the responsive stimulation of aDBS is also expected to decrease the amount of energy consumption. Furthermore, several human clinical trials (Little et al, 2013(Little et al, , 2016Rosa et al, 2017;Swann et al, 2018b;Velisar et al, 2019;Opri et al, 2020;He et al, 2021) have assessed the average energy saving associated with aDBS compared to continuous DBS in a similar time period and showed a range of energysaving percentage of 38-73%. The characteristics and energy consumption percentages of these trials are given in Table 2.…”

The Expanding Horizon of Neural Stimulation for Hyperkinetic Movement Disorders

“…Twelve features of the LFP are used to train four classifiers for two stimulator states (off/on) and two movement states (movement/posture detection). The presence (1) or absence (0) or the movement states dictates whether the stimulator state is changed [adapted from (57)].…”

“…In a follow-up work, the group therefore studied the use of thalamic LFPs for real-time closed-loop DBS in ET (Figure 1B). DBS electrodes were inserted into the VIM and zona incerta (ZI), and stimulation and LFPs recordings occurred simultaneously (57). Twelve features in time and frequency domains were extracted from the bipolar LFPs recorded from VIM-ZI thalamus.…”

“…The performance of several classification methods was tested and linear methods outperformed other methods that take into account non-linear relationships (advantageous as linear models tend to require less data to train models and have a less demanding processing requirement for online decoding). Compared with continuous stimulation, a similar amount of tremor suppression was achieved whilst delivering <40% of the energy required for continuous stimulation (57). Such approaches are enormously exciting as devices with the capacity for chronic sensing and bidirectional communication become available.…”