Objective: To identify neurophysiologic markers of intention tremor in the ventral intermediate thalamic nucleus (Vim) and hand motor cortex to develop closed-loop deep brain stimulation (DBS) systems for the treatment of essential tremor (ET).

Background: Intention tremor in ET is a slow oscillation (∼5-10 Hz) of the hands and arms, experienced during the initiation and execution of goal-directed reaching motions, while absent at rest. Although the pathophysiological basis of ET remains unknown, a pathological synchronous oscillation in a neuronal network involving the thalamic Vim, the premotor (PM) and primary motor (M1) cortices, and the cerebellum has been suggested. Our goal is to study local field potentials in the thalamocortical network in order to improve DBS therapies.

Methods: Patients will be implanted with next generation Medtronic Activa PC+S neurostimulators (Medtronic, Minnesota, USA) capable of recording brain signals from electrode arrays in the Vim and over the hand motor cortex. Leveraging the presence of specific biomarkers such as movement intention (mu rhythms in the Vim, PM and M1), presence of tremor (rhythms in Vim and wearable accelerometers), and coherence between brain signals and accelerometers, it is possible to responsively deliver DBS and to modulate its stimulation parameters.

Results: Our analyses with intraoperative data from ET patients and with data collected postoperatively from implanted PC+S units demonstrate the presence of reliable biomarkers that can be used for initiating and terminating DBS therapy.

Conclusions: Our results suggest the feasibility of closed-loop DBS for the treatment of intention tremor in ET. We hypothesize that such a system would decrease the side effects experienced with DBS, decrease tolerance build up towards DBS and prolong the battery life of the DBS implant (in turn reducing the number of replacement surgeries patients need to undergo). In our future work we will investigate the clinical efficacy of these systems.

Presented at SFN.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/towards-a-responsive-deep-brain-stimulation-for-the-treatment-of-essential-tremor/