Directional Versus Nondirectional DBS for ET

Directional Versus Nondirectional Deep Brain Stimulation of the VIM Thalamic Nucleus for Essential Tremor: Assessment of Therapeutic Window, Speech, Gait and Balance

This will be a single center (OHSU) proof of concept trial to demonstrate that directional deep brain stimulation (DBS) creates a larger therapeutic window for the treatment of essential tremor (ET), effectively treats ET, and minimizes effects on speech, gait and balance compared to nondirectional DBS.

Specific Aims:

1. To compare the therapeutic window (TW) of directional versus nondirectional deep brain stimulation for treatment of tremor.

   Hypothesis: directional DBS will result in a wider TW than nondirectional DBS.

2. To compare the effects of directional versus nondirectional DBS on speech Hypothesis: Objective and subjective speech impairment will occur to a greater extent in nondirectional DBS versus directional DBS optimized for tremor control.

3. To compare the effects of directional versus nondirectional DBS on balance and gait Hypothesis: Objective and subjective balance and gait impairment will occur to a greater extent in nondirectional DBS versus directional DBS optimized for tremor control.

4. To assess efficacy for tremor of nondirectional and directional DBS in an optimized programming configuration Hypothesis: both directional and nondirectional DBS will significantly improve tremor compared to baseline.

Inclusion Criteria:

• A tremor syndrome of bilateral upper limb action tremor with at least 3 years' duration

Exclusion Criteria:

• Patients who have decided not to receive DBS for control of their medication-refractory essential tremor.
• Patients with secondary tremor (ie not Essential Tremor), such as side effects from medications, secondary to another identified neurologic disease (eg multiple sclerosis, -----Parkinson's disease, dystonia).
• Prior history of deep brain stimulation.
• Prior history of thalamotomy.
• A history or signs of dystonia, ataxia or parkinsonism.
• Task specific tremor.
• Orthostatic tremor.
• Patients with cardiac pacemakers, defibrillators, or neurostimulators.
• Patients who require MRI, ECT, rTMS, or diathermy.
• Subjects with other type of neurological disease or injury.