Willing and able to give consent and attend all study visits
A confirmed diagnosis of medication-refractory, MS-related hand tremor
No clinical evidence of relapse over 12 months or more before enrollment
No MRI activity over 3 months or more before enrollment
Presence of disabling postural or kinetic tremor
Unsatisfactory tremor response to adequate trials of at least two medications
Able to communicate sensations during the treatment
Stable doses of all medications for 30 days prior to and during study
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Severe cerebellar dysfunction measured by Scale for the Assessment and Rating of Ataxia (\>35 out of 40)
Severe weakness or sensory loss in arm contralateral to the side of the brain considered for MRgFUS
Evidence of a superimposed or atypical movement disorder
Unstable cardiac status such as angina pectoris, congestive heart failure, etc.
Severe hypertension
Patients with standard contraindications for MR imaging
History of abnormal bleeding and/or coagulopathy
Ischemic or hemorrhagic stroke within 6 months
Symptoms and signs of increased intracranial pressure (e.g. headache, nausea, vomiting, lethargy, and papilledema)
Untreated, uncontrolled sleep apnea
Active or suspected acute or chronic uncontrolled infection
Receiving anticoagulant or antiplatelet therapy within one week of focused ultrasound procedure or drugs known to increase risk or hemorrhage within one month of MRgFUS surgery
Not able or willing to tolerate the required prolonged stationary supine position during treatment
Participating or have participated in another clinical trial in the last 30 days
Unable to communicate with the investigator and staff
Presence of neurodegenerative disease or significant cognitive impairment
Presence of significant cognitive impairment (≤24 on MMSE)
Uncontrolled major psychiatric disorder or suicidal ideation
Risk factors for intraoperative or postoperative bleeding or documented coagulopathy
Presence of brain tumours
Any illness that in the investigator's opinion preclude participation in this study
Pregnancy or lactation
Legal incapacity or limited legal capacity
Deep Brain Stimulation or a prior stereotactic ablation of the basal ganglia
