The study plans to recruit 12 patients with Parkinsonian tremor, essential tremor, or dystonic tremor. After receiving NaviFUS-ctbTUS stimulation, the improvement in their tremor will be recorded.

Inclusion Criteria:

• Age between 18 and 80 years.

• Subjects must belong to one of the following three categories:

  1. Patients with Parkinson's disease tremor who have an inadequate response to medication.
  2. Patients with essential tremor who have an inadequate response to medication.
  3. Patients with dystonic tremor who have an inadequate response to medication.

• Subjects are willing to shave hair over the treatment area for focused ultrasound.

• Stable medication regimen (types and dosages) for at least 4 weeks prior to study enrollment.

• Normal liver and renal function (Creatinine < 1.3 mg/dL, GPT < 41 U/L).

• Female participants of childbearing potential, or male participants with female partners of childbearing potential, must agree to use appropriate contraception from the first study treatment until at least 6 months after the last treatment to prevent pregnancy.

Exclusion Criteria:

• Presence of intracranial implants deemed unsuitable for MRI, such as metal clips, ventriculoperitoneal (VP) shunts, cochlear implants, deep brain stimulation (DBS) devices, pacemakers, or implantable cardioverter- defibrillators (ICDs).

• Any abnormalities along the focused ultrasound beam path through the skull, including scars on the skull, scalp conditions (e.g., eczema), open wounds, calp atrophy, or significant calcification confirmed by imaging along the ultrasound transmission pathway.

• Pregnant or breastfeeding women.

• Use of investigational drugs from other clinical trials.

• Patients with major depressive disorder (Beck Depression Inventory-II score > 30 within the past year) or with suicidal ideation.

• Any condition that, in the opinion of the investigator, may interfere with treatment efficacy or increase risk to the subject.

• Presence of any brain tumors, vascular malformations, or significant traumatic brain injury.

• Presence of significant psychiatric symptoms (Clinical Dementia Rating [CDR]

  • 2).

• Use of anticoagulant medications.

• Use of medications known to exacerbate tremor.

• Tremor due to metabolic or psychogenic causes.

• Coagulopathy or abnormal coagulation profiles, including any of the following:

  1. Platelet count ≤ 100,000/µL
  2. INR ≥ 1.5
  3. PT ≥ 1.5 × upper limit of normal (ULN)
  4. aPTT ≥ 1.5 × ULN
  5. Fibrinogen ≤ 150 mg/dL

• Inability to provide informed consent or comply with study procedures, posing potential safety concerns.

• Insufficient skull density as determined by pre-treatment evaluation, resulting in ultrasound transmission efficiency less than 20%.