Smart brain device zaps tremors only when needed

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. You provide informed consent. 2. You are over 21 years of age. 3. You are diagnosed with a postural-intention (essential) tremor for at least 3 years and meet strict diagnostic criteria and have been seen and examined by a movement disorders fellowship trained neurologist. 4. You have had a significant disabling medical-refractory upper extremity tremor with no evidence of supraspinal central nervous system disease or injury (tremor not adequately controlled by medications for at least three (3) months before implant). 5. You have had a postural or kinetic tremor severity score of at least 2 out of 4 in the extremity intended for treatment on the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (CRST). 6. You have had a CRST score of 2 or above in any one of the items 16-23 from the Disability subsection of the CRST: speaking, feeding other than liquids, bringing liquids to mouth, hygiene, dressing, writing, working and social activities. 7. Your tremor is refractory adequate trials of at least two medications, one of which should be either propranolol or primidone. An adequate medication trial is defined as a therapeutic dose of each medication or the development of side effects as the medication dose is titrated. 8. You are available for appropriate follow-up times for the length of the study. Exclusion Criteria: 1. Any previous neurosurgical intervention including deep brain stimulation or ablative brain lesions. 2. Medication related movement disorders. 3. Any suspicion of Parkinsonian tremor, including presence of Parkinsonian features such as bradykinesia, rigidity, or postural instability. 4. Any behaviors consistent with ethanol or substance abuse as defined by the criteria outlined in DSM-V. 5. Severe medical co-morbidity including cardiovascular disorder, lung disorder, kidney disease, continuous neurological disease, hematological disease, or frailty that impact tolerability of the surgery as judged by the screening physicians. 6. Abnormal brain MRI including hydrocephalus, stroke, structural lesions, demyelinating lesions, or infectious lesions. Also excluded will be subjects with severe atrophy. 7. Any uncontrolled symptoms or signs of increased intracranial pressure (e.g., headache, nausea, vomiting, lethargy, papilledema). 8. A history of seizures within the past year. 9. A dementia rating scale score (DRS) \<130 signifying significant cognitive dysfunction and a potential for inability to cooperate with tasks involved in the study. 10. Any attempt or intent of suicide in the last six months. 11. Presence or history of psychosis. 12. Significant or active mood disorders including depression. For the purpose of this study, we consider a significant mood disorder to include any subject who has: 1. Scores ≥ 20 on the Patient Health Questionnaire - 9 (PHQ-9). 2. Currently under the care of a psychiatrist 3. Currently participating in cognitive-behavioral therapy 4. Been hospitalized for the treatment of a psychiatric illness within 12 months 5. Ever received transcranial magnetic stimulation 6. Ever received electroconvulsive therapy n. In addition, patients who are pregnant or plan to become pregnant will be excluded from this study.