The Effectiveness of Alternating Stimulation in Preventing Tolerance in Essential Tremor Patients

The Effectiveness of Alternating Ventral Intermediate Nucleus Deep Brain Stimulation Parameters in Preventing Tolerance in Essential Tremor Patients

The purpose of this study is to investigate the hypothesis that alternating DBS parameters on a weekly basis will prevent tolerance to stimulation and thus waning of benefit, compared with non-alternating stimulation. The primary endpoint will be preserved tremor control with the alternating group compared with standard treatment using the Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS). Key secondary endpoints will be preserved activities of daily living measures as well as preserved tremor control as quantified by motion sensor data.

This study has one primary aim: To determine if alternating DBS stimulation parameters on a weekly basis will be superior at preserving tremor control compared with usual stimulation (non-alternating stimulation) in ET patients with VIM DBS.

Inclusion Criteria:

1. Patients with clinically diagnosed ET who have had placement of VIM DBS and are willing to undergo a baseline programming visit and 12-week follow-up assessment
2. At least initial benefit from VIM DBS as judged by patient report and clinician exam
3. VIM DBS placement no less than three months from entry into study
4. Patients must demonstrate ability to use patient programmer to switch between group settings on a weekly basis
5. Ability to wear wrist monitor for 2 week intervals, twice during the study 6. Patients with the following IPG types: Activa PC, SC or RC

Exclusion Criteria:

1. Atypical tremor disorder including but not limited to tremor due to multiple sclerosis, medication-induced tremor, Parkinson's disease or parkinsonian syndrome
2. DBS placement complicated by infection, hemorrhage or stroke
3. Previous thalamotomy (either stereotactic, gamma knife or focused ultrasound) or previous DBS surgery resulting in explantation and reimplantation
4. Known incorrect or poor lead placement
5. Inability to change group settings on a weekly basis at least 75% of the time
6. Inability to tolerate 12-week period without additional programming changes, including voltage stimulation adjustment
7. Inability to tolerate 12-week period without adjustment of anti-tremor medications, including primidone, beta-blockers, gabapentin, topiramate and/or benzodiazepines
8. Battery voltage < or equal to 2.70V
9. Patient with the following IPG types: Soletra, Kinetra or Itrel
10. Inability to tolerate two group settings due to side effects or lack of efficacy