How focused ultrasound works
Multiple ultrasound beams pass through the skull and converge on a planned target involved in tremor. Heating at that focus creates a small permanent lesion that interrupts abnormal activity in the tremor circuit. MRI helps the team identify anatomy and monitor temperature during treatment. This is an acoustic treatment, not ionizing radiation. [1]
For tremor, the procedure commonly targets part of the thalamus and is called thalamotomy. It does not require an incision into the skull or an implanted brain electrode. However, “incisionless” does not mean that it leaves brain tissue unchanged or carries no neurological risk. [1]
Who may be considered
A common indication is essential tremor that substantially interferes with activities such as eating, drinking or writing despite appropriate medication trials, or when medicines are not tolerated. Selected people with tremor-dominant Parkinson’s disease may also be assessed. The diagnosis, target and authorized indications vary with the treatment system and jurisdiction. [1, 2]
A movement-disorders specialist should establish the cause of tremor and agree on realistic goals with you. Treating tremor does not necessarily improve other symptoms or prevent disease progression. Treating one side of the brain mainly addresses tremor on the opposite side of the body. [1]
Assessment before a decision
Assessment usually includes neurological examination, medication history and a review of everyday function, balance, speech and relevant medical conditions. MRI is used to assess brain anatomy, while CT helps evaluate the skull’s ability to transmit ultrasound. Skull characteristics can limit whether a suitable target can be heated effectively. [1]
The team also checks MRI compatibility, including any implanted devices, and whether you can lie still in the scanner and communicate during testing. Claustrophobia, bleeding or clotting problems and medicines affecting bleeding require discussion. Follow the treating team’s instructions about medication; do not stop prescribed treatment on your own. [1, 2]
What happens during treatment
The usual process includes scalp preparation, a head frame to keep the target aligned and a cooling system around the head. For tremor procedures, patients are generally awake so that the team can assess movement and symptoms. Low-energy test exposures and repeated neurological checks help confirm the target before higher-energy treatment creates a permanent lesion. [1, 4]
MRI temperature monitoring continues during treatment. The team may ask you to draw, move your hands or speak, and checks for unwanted effects such as tingling, weakness or speech changes. Report discomfort or new symptoms promptly. The clinical response guides adjustments and whether treatment should continue. Monitoring and discharge arrangements depend on individual recovery and the centre’s protocol. [1, 4]
Benefits, limits and possible risks
Selected patients may experience meaningful improvement in hand tremor and daily activities without implanted hardware. Long-term follow-up has shown sustained benefit in some patients, but the amount and duration of improvement vary; tremor can persist or return. The lesion is irreversible and cannot be reprogrammed like deep brain stimulation (DBS). [1, 3]
Possible effects include headache, nausea, dizziness, numbness or tingling, weakness, and problems with walking, balance or coordination. Some neurological effects persist. Speech or swallowing difficulties are also possible, including after staged treatment on both sides. A second-side procedure requires its own careful assessment; evidence from selected patients does not establish suitability for everyone. Discuss both temporary and lasting effects before deciding. [1, 3, 4]
Alternatives and continuing care
Alternatives may include medication adjustment, practical aids, botulinum toxin in selected situations, DBS or another lesioning procedure. DBS offers adjustable stimulation but requires implanted equipment, surgery and ongoing programming. The choice depends on your diagnosis, treatment goals, symptoms on both sides, general health and preferences. [1–3]
Follow-up should review tremor, daily function, walking, sensation and any speech or swallowing changes, as well as medicines and rehabilitation needs. Before proceeding, ask which symptom and side are being targeted, what benefit is realistic, which effects could last, and how follow-up would be arranged after you return home.
Sources and further reading
- Techniques, Indications, and Outcomes in Magnetic Resonance-guided Focused Ultrasound Thalamotomy for Tremor
- Essential Tremor — Cleveland Clinic
- Magnetic resonance imaging–guided focused ultrasound thalamotomy for essential tremor: 5-year follow-up results
- Safety and Efficacy of Staged, Bilateral Focused Ultrasound Thalamotomy in Essential Tremor