Deep Brain Stimulation of the Deep Cerebellar Nuclei for Refractory Tremor

Inclusion Criteria: * Age 21 years and older; * Ability to give informed consent; * Diagnosis of ET, cerebellar tremor, or MS-related tremor with a failed a prior intervention (VIM DBS or HIFU thalamotomy) or determined to not be suitable candidates for VIM DBS or HIFU thalamotomy because they have a cerebellar outflow or MS-related tremor. * Tremor history of at least three years; * Tremor that is refractory to medical management; * A score of ≥24 on the Mini Mental State Examination; * Inability to successfully perform ADLs without assistance or has lost interest in social, professional, or personal activities due to tremor Exclusion Criteria: * Any other neurological condition that could reduce the safety of study participation including central nervous system vasculitis and intracranial malignancy * A condition that, in the opinion of the clinical investigator, would significantly increase the risk or interfere with study compliance, safety, or outcome; * A diagnosis of dementia; * Tremors due to other neurological conditions such as Parkinson's disease, dystonia, or other conditions not consistent with ET, cerebellar outflow tremor, or MS-related tremor. * Diagnosis of epilepsy; * Major active and untreated psychiatric illness that may interfere with study, such as psychotic disorders or severe personality disorders; * Untreated or inadequately treated depression defined by a score of 20 or greater on the Beck Depression Inventory-II at the time of enrollment; * At risk for suicide defined by a score greater or equal to 3 on the Columbia Suicide Severity Rating Scale (C-SSRS); * Pregnancy; * Unable to communicate with investigators or staff; * Surgical contraindications to DN DBS; * Contraindication to magnetic resonance (MRI) imaging, e.g., weight incompatible with scanner, implanted metallic devices or electrical devices (pacemaker, defibrillator, spinal cord stimulator, prior DBS) or intolerance to MRI contrast agent; * Enrolled in another device, biologic or pharmaceutical study within 30 days of consent in the current study, (i.e., patient cannot be enrolled if participation in another study was not completed at least 30 days prior to consent.); * Evidence of behavior(s) consistent with alcohol or substance abuse/dependence as defined by the criteria outlined in the DSM-V within the preceding six months; * Injection of botulinum toxins into the arm, neck or face within six months prior to baseline;