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

Shenghong He,Erlick Pereira,Huiling Tan,Fahd Baig,Tipu Z Aziz,Abteen Mostofi,Alek Pogosyan,Peter Brown,Alexander L Green,Jean Debarros

doi:10.1002/mds.28513

Abstract

BackgroundHigh‐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.ObjectiveWe 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.MethodsEight 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.ResultsUsing the proposed method, stimulation was switched on for 80.37 ± 7.06% of the time when tremor‐evoking 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.ConclusionsThe results suggest that responsive thalamic stimulation for essential tremor based on tremor‐provoking 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. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Highlights

Essential tremor (ET) is one of the most common neurological movement disorders, in which the symptom is typically intermittent, predominantly occurring during voluntary movement and/or sustained posture.[1,2,3] Severe
On average, A-deep brain stimulation (DBS) using the proposed method suppressed the tremor by 52.62 ± 13.12% compared with no DBS, similar to the level of tremor suppression achieved by continuous DBS (53.02 ± 12.59% for C-DBS, t5 = −0.0267, P = 0.9798, paired t-test)
In this study we demonstrated that both voluntary movement and postural actions provoking tremor can be detected using thalamic Local field potentials (LFPs) despite stimulation artefact when the DBS was switched on, and verified the effectiveness of the proposed closed-loop DBS system with real-time stimulation testing in patients with essential tremor

Summary

Introduction

Essential tremor (ET) is one of the most common neurological movement disorders, in which the symptom is typically intermittent, predominantly occurring during voluntary movement and/or sustained posture.[1,2,3] Severe. ET can be functionally disabling and up to 50% of patients do not respond adequately to drug therapy.[4]. Continuous deep brain stimulation (DBS) is an effective therapy for ET.[5,6] a gradual increase of stimulation intensity is often required due to disease progression or habituation to stimulation.[7,8,9] High-intensity stimulation may induce unpleasant side effects including postural instability and speech impairment.[10,11,12]

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