June 2025

NEUROSCIENCES

QUICK READ: MR-GUIDED FOCUSED ULTRASOUND FOR ESSENTIAL TREMOR AND PARKINSON'S DISEASE

2-minute read

Northwestern Medicine is one of only a few health systems in Illinois offering magnetic resonance-guided focused ultrasound (MRgFUS) for patients with essential tremor (ET) and tremor-dominant Parkinson’s disease.
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Jason K. Hsieh, MD, shares insights on the procedure below.

What Is MRgFUS?
  • MRgFUS is an incisionless treatment for ET and tremor-dominant Parkinson’s disease patients who aren’t responding to medication.
  • It uses MRI-guided ultrasound waves to target a small area within the thalamus, creating a localized ablation for a therapeutic effect.
  • Patients are awake during the procedure, allowing real-time evaluation of tremor improvement and monitoring for side effects.

Why Consider MRgFUS for Your Patients?
  • Treatment available on both sides (nine months separation between sides) for ET patients
  • No incisions, no implanted hardware
  • Patients can return home on the same day
  • Immediate tremor improvement, usually with durable and lasting effects

Deep Brain Stimulation vs. MRgFUS
When you’re deciding between deep brain stimulation (DBS) and MRgFUS, consider:
  • Evaluating the patient's symptom profile (voice, head or trunk symptoms, for example) and treatment goals.
  • Whether the patient would benefit more from a one-time treatment with durable effects (MRgFUS) or an implanted device that may require future procedures (such as battery changes, for DBS) but also allows for future titration of therapy.
  • Reviewing the patient’s individual risk profile, including their tolerance for surgical risks and preferences on head shaving and implants.
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Clinical Evidence
  • First side treatment:
    • In clinical trials, 56 patients received focused ultrasound treatment, and 19 patients received a sham procedure before crossing over to the treatment group.
    • Among the 75 treated patients, 54 were analyzed at the three-year follow-up:
      • Tremor severity improved by 76.5%.
      • Motor function/quality of life improved by 53%.
      • Functional disability decreased by 56.9%.
  • Second side treatment:
    • Another trial involved 51 subjects who had their first side treated at least nine months earlier:
      • Tremor severity improved by 80.2% at six months.
      • Motor function improved by 64.3%.
      • Functional disability decreased by 74.3% at six months.

Referral Criteria
Consider referring patients for MRgFUS if all the following apply:
  • They have medication-refractory essential tremor or tremor-predominant Parkinson’s disease.
  • They’re not achieving adequate control with current tremor medications.
  • They can tolerate the awake procedure and MRI without sedation.
  • They have no contraindications to MRI (such as size or implants).
  • They can activate the stop button during the procedure.
  • They believe their quality of life will improve with tremor reduction.

​Important Considerations
  • Patients must have their heads completely shaved on the procedure day.
  • A small number of patients may be ineligible based on their skull density ratio, which will be assessed via a head CT scan.
  • Certain health conditions, like excessive scalp scarring, may also render a patient ineligible.

To learn more or to refer a patient, visit nm.org/FUS.
​Jason K. Hsieh, MD, Assistant Professor of Neurological Surgery at Northwestern Medicine

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Northwestern Medicine welcomes the opportunity to partner with you in caring for your patients. ​

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