Scottish Deep Brain Stimulation
You have been referred for consideration of MRI guided Focused Ultrasound (MRgFUS) Thalamotomy for Essential Tremor (ET). The aim of this information leaflet is to provide further details on the assessments required to establish if you are suitable for the treatment and what this procedure involves.
Thalamotomy for Essential Tremor
In Scotland there are 2 principal types of brain surgery that may be suitable for patients with essential tremor, either Deep Brain Stimulation or Ultrasound Thalamotomy (Magnetic Resonance Guided Focussed Ultrasound). There are pros and cons to each technique, and not everyone is suitable for them. The DBS team in Glasgow works together with the Ultrasound Thalamotomy team in Dundee to make sure each patient is getting the treatment that is best for them. Rarely, a third type called radiofrequency lesioning is also employed. The following information specifically relates to Ultrasound Thalamotomy for Essential Tremor.
Transcranial MR-guided Focused Ultrasound
During your assessment for Focused Ultrasound Thalamotomy you will meet several
members of the clinical team:
| Dr Tom Gilbertson | Consultant Neurologist |
| Mr Sadaquate Khan | Consultant Neurosurgeon |
| Professor Douglas Steele | Consultant Neuropsychiatrist |
| Mrs Baljit Jagpal | Senior MRI Radiographer |
Contact Details
Miss Laurie Anderson
TcMRgFUS Administrator
Department of Neurology
Ninewells Hospital & Medical School
Dundee, DD1 9SY
Tel: 01382 632910
Email: Laurie.Anderson@nhs.scot
Thalamotomy is a procedure where the brain circuits which cause tremor are heated so that they are permanently destroyed and the symptoms of tremor are reduced.
MRgFUS uses MRI (Magnetic Resonance Imaging) to precisely target ultrasound beams which heat the brain tissue to achieve tremor suppression. MRgFUS 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.
On the day of the procedure, the head is shaved to prevent heating of the scalp by the ultrasound beam. Under local anaesthetic, the surgeon attaches a metal headframe which is worn throughout the treatment.
During the procedure, ultrasound treatments (lasting approximately 10 seconds) are delivered which produce short lasting effects on tremor and allow assessment of potential side effects. The intensity of these ultrasound treatments is increased gradually to achieve permanent tremor relief. During and after each ultrasound treatment, a neurologist will assess you and additional pictures of the brain will be taken with the MRI scanner.
A typical MRgFUS Thalamotomy takes 3 hours and requires between 10 – 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. The clinical team will be able to provide you with pain relief, anti-sickness medication or mild sedation during the treatment. The procedure is performed without general anaesthetic. You will be able to have a relative or friend present with you during the procedure.
| Suitable for TcMRgFUS | Unsuitable |
| A diagnosis of Essential tremor by a movement disorder specialist |
A diagnosis of dementia or memory impairment |
| Your tremor should significantly impact on your Quality of life | History of significant mental health illness |
|
You must have tried both propranolol and (with either lack of sufficient clinical benefit or unacceptable side-effects). |
In some patients, the anatomy of the skull prevents the ultrasound effectively reaching the brain. A CT scan of the skull can establish if this is the case or not. |
| If you are unsteady or have a tendency to fall | |
| If you have pre-existing difficulties with your speech | |
| You must not have any permanent metal implants within the brain (e.g. stimulator devices, aneurysm clips). |
|
| If you have a cardiac pacemaker and even if this is compatible with MRI scanning, then you cannot have the procedure. |
The aim for surgery is to reduce the tremor on one side of the body by around 50% (typically your dominant side)
MRgFUS Thalamotomy cannot be used to treat both sides of the body. Tremor in your
non-dominant side will remain the same.
The procedure is unlikely to improve head or voice tremor.
Sensory disturbance (e.g. numbness or tingling of the limbs or face) is seen in 1 in 3 patients.
- In half of these patients, this resolves within weeks or months of the treatment, but it can be permanent in the other half.
Balance disturbance (e.g. unsteadiness when walking) is seen in 1 in 3 patients.
- In two thirds of these patients, this resolves within weeks or months of the treatment, but it can be permanent in the other one third.
Speech disturbance (e.g. slurring of speech) is seen as a short term complication (lasting weeks to months) in 1 out of 20 patients1
Deep Brain Stimulation (DBS) uses electricity to suppress tremor. Any side effects following DBS can be improved by changing the properties of the electrical stimulation. Side effects following MRgFUS Thalamotomy may improve with time but can be permanent.
Deep Brain Stimulation (DBS) can be used to treat symptoms on both side of the body, MRgFUS Thalamotomy is currently only licenced for one sided treatments.
The assessment process for MRgFUS-Thalamotomy relies upon three outpatient appointments. The first appointment is an initial screening consultation and is performed via NHS NearMe video-consultation or telephone. If we think that treatment should be considered, we will organise two further outpatient appointments which will help confirm your eligibility. At the second appointment, you will receive the following assessments:
Neuropsychiatry
At your second appointment, you will be seen by a consultant neuropsychiatrist who will assess your memory and mood. This will involve an interview and answering a series of questionnaires. The effectiveness of surgery for Essential Tremor is reduced and the complication rate increased in patients with significant memory or mood disorder. If these are identified, this may make you less appropriate for MRgFUS-Thalamotomy.
Brain imaging
In order for us to plan the treatment and confirm if your skull anatomy is suitable for ultrasound treatment, we will perform a CT scan of your head. An MRI scan will also be performed to identify the precise target for the Thalamotomy. Depending upon availability, both of these scans will be performed on the same day as your second appointment or organised at a subsequent visit. If the neurological or neuropsychiatric assessment performed at your second appointment suggests that you are not suitable for the treatment, brain imaging will not be performed..
Video recording
With your consent, a video of your examination will be obtained so that this can be reviewed with other members of the clinical team not present at the physical consultation.
Multidisciplinary Team meetings
Once all of the necessary assessments are obtained, the clinical team will meet to make the final decision on whether we will offer you an operation. These meetings take place once a month. In the event that the clinical team or you are uncertain as to whether you would benefit from alternative treatments such as Deep Brain Stimulation (DBS), we will discuss your case in the National Tremor Multidisciplinary (MDT) meeting. This occurs every 6 months and includes both the DBS and MRgFUS clinical teams. Patients can be referred to the National Tremor MDT at any point during the process of assessment for MRgFUS Thalamotomy if you or the clinical team are uncertain as to if the treatment is right for you.
Tremor electrical recording
We will perform a short recording of the tremor electrical activity. This is used to further confirm the diagnosis of Essential Tremor and helps eliminate other causes of tremor which may not respond to Thalamotomy.
Blood tests
Routine blood tests of your clotting, blood counts, liver and kidney function will be taken at the appointment. If there are unexpected abnormalities, these results will be relayed to you and your GP. At the third and final consultation, the outcome of the assessment process will be fed back to you. In the event that you are suitable, you will be consented by a consultant Neurosurgeon and a date for the treatment will be confirmed.
You will be given contact details of our Movement Disorder specialist nurse who you will be able to contact within working hours if you have any questions or concerns.
You will attend four further outpatient clinics (1 month, 3 months, 1 year and 2 years) after the treatment. The purpose of these assessments is to document your tremor response to the treatment, monitor for any unexpected signs of memory or mood disturbance, and to document any side-effects of the treatment.
We would advise you contact the DVLA or refer to their website for up-to-date guidance on driving advice following this procedure.
- Most patients receive a significant reduction in tremor and improvement in quality of life following the procedure. In a small number of patients the improvement may not be as much as you might have expected.
- A small number of patients have had the procedure repeated. This decision would require further re-assessment and discussion between you and the clinical team regarding whether or not this should be considered.
- MRgFUS is a new treatment and long term information about its effectiveness over many years is limited. The natural course for some patients with Essential Tremor is for it to progress slowly over time. We do not know if MRgFUS reduces or delays this progression.
- A very small number of patients around the world have had DBS after MRgFUS Thalamotomy. DBS has been performed in these patients when the response to MRgFUS Thalamotomy has not been as good as expected. Due to this limited experience, it is currently unknown how safe or effective DBS is in patients who have had MRgFUS Thalamotomy. Due to this uncertainty, if you have MRgFUS Thalamotomy, this may make you less eligible for DBS in the future, however re-assessment for this would be considered on a case-by-case basis.
1. Giordano, M., Caccavella, V. M., Zaed, I., Manzillo, L. F., Montano, N., Olivi, A., & Polli, F. M. (2020). Comparison between deep brain stimulation and magnetic resonance guided focused ultrasound in the treatment of essential tremor: a systematic review and pooled analysis of functional outcomes. Journal of Neurology, Neurosurgery & Psychiatry, 91(12), 1270-1278.
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