This study evaluates the effectiveness of tremor control using various strategies for implementing demand-driven thalamic deep brain stimulation (DBS) for essential tremor. Therapeutic stimulation at the Vim nucleus of the thalamus will be initiated and modulated using signals derived from external sensors (e.g. EMG, accelerometer) and cortical or thalamic electrodes.

Essential tremor is effectively treated with deep brain stimulation of the ventralis intermedius nucleus of the thalamus, presumably because high-frequency stimulation disrupts aberrant cerebellar-thalamic input. For the most part, patients with essential tremor have a kinetic tremor that is present or worsened with movement. However, DBS therapy is currently continuous, and thus, stimulation occurs when the patient will not benefit symptomatically from treatment. This exposes the patient to unnecessary stimulation, which can lead to unnecessary usage of battery, unnecessary exposure to stimulation side-effects, and can possibly contribute to tolerance to DBS therapy.

One possible solution is selective stimulation when movement is required. This study will determine signals predictive of motor activity using external sensors such as EMG, and cortical biomarkers of real and imaginary movement that are well-characterized.

The primary aim is to demonstrate successful initiation and modulation of DBS therapy using the Activa PC+S system and implanted cortical or thalamic electrodes. Putative improvements in battery usage related to stimulation on-time and definition of coupling signals between thalamus and cortex that characterize tremor state are secondary outcomes.

Inclusion Criteria:

• Appropriate candidates for DBS with essential tremor

Exclusion Criteria:

• Not meeting inclusion criteria based on tremor amplitude, neuropsychological testing, etc.
• Prior trauma to the brain on side of putative implantation of stimulator