Cortical vs Subcortical Recordings to Drive Closed-Loop Deep Brain Stimulation in Essential Tremor

Essential tremor (ET) is a hyperkinetic disorder presenting most commonly with postural and action-kinetic tremor. For patients with ET, conventional deep brain stimulation might not be the optimal stimulating paradigm. Closed-loop deep brain stimulation (CL-DBS) aims to deliver stimulation in response to symptom presence, detected by neuro-markers from brain signals, to increase battery life, decrease stimulation-induced side effects, and potentially reduce tolerance to stimulation.

We aimed to establish patient-specific desynchronization in subcortical and cortical motor regions as a surrogate marker for tremor that tracks movement, allowing stimulation modulation.

Using a long-term embedded implantable pulse generator, CL-DBS was successfully implemented in 4 participants, with clinical efficacy maintained up to 18 months postimplantation.

Sensorimotor cortical regions had higher performance than thalamic nuclei, with more consistent performance over time. Patient-reported experiences using a closed-loop paradigm at home for months at a time were mostly positive, with distinct negative experiences related to stimulation cessation providing necessary feedback in a real-world environment to guide the next generation of therapies.

The use of a cortical strip to record neural activity remote from a site of stimulation was, in our experience, the optimal solution for closed-in ET when using movement signatures as a surrogate biomarker, rather than biomarkers of the presence of symptoms.

The Clinicaltrials.gov registration number for the study is NCT02649166.