ChronosDirectional Bilateral Thalamic Patterned Stimulation (Chronos)

Inclusion Criteria:

1. Phase 1: 5 to 10 tremor patients already treated with VIM-DBS but not doing well due to early and/or late loss of benefits (i.e. tremor scores ON stimulation identical or greater than before surgery in absence of stimulation).
2. Phase 2: 10 Essential Tremor patients in need of DBS surgery.
3. Written and signed Informed Consent.
4. Age 18 to 85 years old.
5. Subject must have Essential Tremor, as defined by all the following criteria: (a) isolated tremor syndrome consisting of bilateral action tremor; (b) at least three years duration; and (c) with or without tremor in other locations (e.g., head, voice, or low limbs) \[1\].
6. Soft signs (categorizing patients as Essential Tremor-plus) will be allowed and noted in the patient's chart.
7. Subject must be on stable dose of anti-tremor medication for at least 4 weeks prior to screening.
8. Subject had no botulinum injection for at least three months prior to screening.
9. Subject does not have a significant other medical condition biasing the study finding in investigator's opinion.

Exclusion Criteria:

1. Unwilling or inability to follow the procedures specified by the protocol.
2. Presence of significant psychiatric or cognitive condition likely to compromise the subject's ability to comply with requirements of the study protocol.
3. Untreated clinically significant depression.
4. Any current drug or alcohol abuse, as determined by the investigator.
5. History of suicidal attempt within the last 1 year prior to consent or current active suicidal ideation as determined by the investigator.
6. Any significant medical condition that is likely to interfere with study procedures or likely to confound evaluation of study endpoints.
7. Any terminal illness with life expectancy of < 12 months.
8. Participation in any other interventional clinical trial (e.g. drug, device).