Introduction
This page has been written by the Unit of Functional Neurosurgery & the Queen Square Imaging Centre at the National Hospital for Neurology and Neurosurgery, Queen Square, London with help from people who suffer from tremor.
Tremor is a highly disabling movement disorder that can interfere with daily functions such as drinking, eating, cooking, writing, dressing etc. There are many different disorders that can cause in tremor, such as Essential Tremor, Dystonic Tremor and Parkinson’s disease. Medications can be tried to help reduce tremor severity. However, sometimes these are not effective or cause intolerable side effects. In these circumstances a therapy called thalamotomy may help. A thalamotomy can be performed using different techniques, the most recently developed technique is MRI guided Focused Ultrasound Thalamotomy.
This page is intended for patients who suffer from tremor who might benefit from this therapy. It is not intended to replace discussion with your consultant.
If you have any questions about this procedure, please do not hesitate to contact a member of our team. We will be pleased to answer any questions you may have.
Thalamotomy is a procedure where part of the brain circuit that causes tremor is targeted and permanently destroyed. As a result, the symptom of tremor is reduced. Thalamotomy was developed the 1950s and is a well-established surgical procedure. It requires a frame to be placed on the head that allows the surgeon to accurately identify the brain target. Different techniques have been used to destroy the target, including extreme cold, chemicals and heat. Most of these surgical procedures require a surgeon to make an incision in the scalp and to drill a hole in the skull to allow a probe to be introduced to the brain target.
Magnetic Resonance Imaging (MRI) guided Focused Ultrasound is a relatively new technique that has recently been introduced to Queen Square. MRI is used to precisely target ultrasound beams that heat brain tissue to achieve tremor suppression. Although head hair must be shaved, Focused Ultrasound thalamotomy can be performed without the need to make a scalp incision, drill a hole in the skull or pass a probe through the brain and is therefore called “incisionless surgery”.
You can consider Focused Ultrasound when tremor has a significant impact on your Quality of Life and either does not respond to medical treatment or when medication causes intolerable side effects. Certain criteria may make you unsuitable for Focused Ultrasound, such as a diagnosis of dementia, significant memory impairment or mental disorders. Pre-existing problems with balance or speech may become worse after Focused Ultrasound thalamotomy.
In some people, the anatomy of the skull prevents the ultrasound effectively reaching the brain. A CT scan of the skull will be obtained before the procedure and can establish if this is the case.
If you have any permanent brain implants (e.g.: stimulator devices or aneurysm clips) or a cardiac pacemaker, it will not be possible to perform Focused Ultrasound thalamotomy. Focused Ultrasound is performed to reduce tremor on one side of the body (typically your dominant side). The procedure is performed on the side of the brain opposite to the hand being treated since the left side of the brain controls the right side of the body, and vice versa.
Tremor reduction is usually immediate but can recur over time. On average, hand tremor scores are reduced by around 50% one year after the Focused Ultrasound procedure. However, benefit in individuals may be greater or smaller than this. Improvement in tremor can make everyday activities easier to perform, including eating, drinking, cooking, changing clothes and writing.
Problems that may happen straight away
- Headache (in almost half of people).
- Dizziness, nausea and vomiting or a sensation of warmth in the scalp or flushing (in about one quarter of people).
Problems that may persist or be serious
- A change in feeling (e.g., numbness or tingling of the limbs or face) is seen in one of every three people. In half of these people, this resolves within weeks or months of the treatment, but it can be permanent in the other half.
- Problems with balance (e.g., unsteadiness when walking) is seen in one in three people. In two thirds of these people, this resolves within weeks or months of the treatment, but it can be permanent in the other one third.
- Problems with speech (e.g., slurring of speech) is seen as a short-term concern (lasting weeks to months) in one out of 20 patients.
- A change in the sense of taste is reported in around one in 20 people.
Are there driving restrictions after Focused Ultrasound?
At the time of going to print, no driving restrictions are imposed after undergoing Focused Ultrasound. Please contact the DVLA or refer to their website for up-to- date guidance on driving advice.
The choice to have this procedure is entirely yours. If you choose not to have this procedure, we can discuss other options with you or refer you to your GP or local neurological team for further advice.
Most people will have exhausted medical therapies before considering Focused Ultrasound. An increase in medication may not provide the expected improvement or may lead to intolerable side effects. However, other forms of surgery can be considered.
Incisionless surgery with Gamma Knife
This involves using a type of focused radiation called gamma rays (instead of ultrasound) to make the brain lesion. It can be used in people who must take blood thinners for other medical conditions. Surgical targeting can be more challenging with gamma knife thalamotomy as the tremor response is delayed by weeks or months. The risks are very similar to Focused Ultrasound but there has not yet been any head-to-head comparison of the two techniques.
Thalamotomy with radiofrequency ablation
This requires a surgeon to make an incision in the scalp and to drill a hole in the skull to allow a probe to be introduced to the brain target. This surgery can be performed without shaving the head but there is a very small added risk of bleeding in the brain. The other risks are very similar to Focused Ultrasound but there has not yet been any head-to-head comparison of the two techniques.
Deep brain stimulation (DBS)
DBS also requires a surgeon to make an incision in the scalp and to drill a hole in the skull. Electrodes (wires) are permanently implanted in the brain target and connected by cables to a battery or pacemaker that is implanted under the skin, usually on the front of the upper chest. A general anaesthetic is needed for part of this procedure. DBS surgery can be performed without having to shave the head but there is a very small added risk of bleeding in the brain. There are also added risks of infection or malfunction of the implanted DBS device requiring further surgery. The other risks are very similar to Focused Ultrasound but there has not been any head-to-head comparison of the two techniques.
The main advantage of DBS is that tremor can be treated on both sides of the body at the same time in many people. In addition, any side effects that do occur are usually reversible and the DBS therapy can be adjusted over time to minimise these. However, this approach also requires numerous appointments after surgery to “programme” the neural pacemaker.
The first appointment is an initial screening consultation and can be via video- consultation or face-to-face. If Focused Ultrasound thalamotomy should be considered, several investigations will be organised and may include formal assessment of tremor severity, brain and skull imaging, blood tests and neuropsychology tests. At the next consultation you will meet members of the team that will review you and your test results. They will explain the advantages and disadvantages of the various surgical treatments for tremor, including Focused Ultrasound thalamotomy, and how they pertain to your specific situation. You will then have the necessary information to help you decide as to what you wish to do.
Patients undergoing Focused Ultrasound thalamotomy should not be taking medications that thin the blood such as warfarin or apixaban. You should avoid taking Aspirin and non-steroidal anti-inflammatory drugs (such as Ibuprofen or diclofenac) for a week prior to and following surgery to reduce the risk of bleeding.
You should continue taking your other medications as normal unless the team tells you otherwise. If you are unsure whether you should take a new type of medicine, please contact us before you do so.
On the day of the procedure, you should bring an overnight bag and any medications that you take routinely. Our staff will be in touch with you to provide detailed instructions on where and when to arrive. You should not have anything to eat or drink other than sips of water from midnight before the procedure. The procedure usually takes around three to four hours. We would advise you to have a friend of family member with you when going home.
We want to involve you in all the decisions about your care and treatment. If you decide to go ahead with treatment, by law we must ask for your consent and will ask you to sign a consent form. This confirms that you agree to have the procedure and understand what it involves. Staff will explain all the risks, benefits, and alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please don’t hesitate to speak with a senior member of staff again.
The procedure is performed without general anaesthetic. Focused Ultrasound Thalamotomy is performed whilst you are awake. Most patients do not need to stay in hospital following the procedure, but in some cases, overnight stay is required for observation.
You may wish to come to the hospital with a friend or relative, but they will not be able to be with you during the procedure. On the day of the procedure, the whole of the head is shaved. An intravenous cannula (drip) will be placed to allow the team to give you medication if needed. Under local anaesthetic, the surgeon uses screws to attach a stereotactic frame to the head. This is worn throughout the treatment.
The head is positioned inside a 'helmet' with a flexible membrane within an MRI machine. The flexible membrane provides a tight seal against your head and is filled with cold water. The cold water circulates between the scalp and the helmet to keep your scalp cool during the ultrasound procedure. MRI scans allow the surgeon to visualise the brain target. During the procedure, ultrasound treatments (lasting approximately 10 seconds) are delivered to the brain. A member of the team will be next to you and will interact with you to examine your movements, asses the tremor and ask whether there are any side effects such as tingling. It is important that you are awake so that you can interact with the team and help them optimise the treatment.
The intensity of these ultrasound treatments is gradually increased to achieve maximum tremor relief. During and after each ultrasound treatment, the team will assess you and additional pictures of the brain will be taken with the MRI scanner.
A typical focused ultrasound thalamotomy takes three to four hours and requires between 10 and 20 ultrasound treatments. During each of these, it is common to feel heating and discomfort around the headframe. You may also feel dizzy and/or nauseous. You will be given an emergency stop button during the procedure that can be used at any time if you are feeling unwell. The clinical team will be able to provide you with pain relief, anti-sickness medication or mild sedation through the intravenous cannula during the treatment.
Figure: equipment used to deliver MR-guided focused ultrasound (courtesy of Insightec)
After the procedure, the stereotactic frame is removed, and you will be escorted to the ward. Pain relief and anti-sickness medication will be prescribed should you need it. You will be examined to assess the tremor and any numbness or balance problems before you go home, usually the day after the procedure. Follow up appointments will be arranged within 6-12 weeks, six months and one year after the procedure to assess your progress. However, if you have any concerns outside these times, please contact our team (details below) or the on call neurosurgery registrar via UCLH switchboard.
You may find these websites useful:
UCLH cannot accept responsibility for information provided by other organisations.
Elias, W. J. et al. A Randomized Trial of Focused Ultrasound Thalamotomy for Essential Tremor. New England Journal of Medicine 375, 730–739 (2016).
Zrinzo, L. Thalamotomy using MRI-guided focused ultrasound significantly improves contralateral symptoms and quality of life in essential tremor. Évid Based Medicine 22, 64–64 (2017).
Mohammed, N., Patra, D. & Nanda, A. A meta-analysis of outcomes and complications of magnetic resonance–guided focused ultrasound in the treatment of essential tremor. Neurosurg Focus 44, E4 (2018).
Your Consultant Functional Neurosurgeon and Clinical Nurse Specialist can be reached via:
Queen Square Imaging Centre
8-11 Queen Square
London WC1N 3AR
Tel: 020 3280 2472
Fax: 020 7837 8074
Email: treatment
Website: www.
Page last updated: 31 July 2024
Review due: 01 July 2026