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What happens during MR-Guided Focused Ultrasound treatment?

When compared to other surgical procedures used to treat essential tremor (such as deep brain stimulation or radio frequency ablation), MR-guided focused ultrasound is relatively fast, simple and comfortable for patients. The procedure does not involve any incisions, and takes place in an MRI scanning unit, rather than an operating theatre. This means that the majority of patients will be able to go home immediately after their focused ultrasound treatment, and will not need a hospital stay to recover.

Despite its relative simplicity, there are some specific preparations for patient’s having focused ultrasound treatment to undergo. When a patient arrives for treatment, the first thing we need to do is completely shave the head. This might sound quite dramatic, but it’s a very important part of the process. This is because the air trapped by hair follicles can prevent the ultrasound energy from getting to the right target. Therefore, the head needs to be completely shaved. Patients can rest assured however, that their hair will regrow.

The next stage of preparation for treatment is that the head needs to be placed in a frame. This is important because the head needs to be kept very still during treatment. Otherwise the focus of the ultrasound won’t be as precise as we need it to be. We apply local anaesthetic to the scalp when we attach the frame, so this should not be painful. Patients often describe a feeling of pressure when the frame is being fitted. However, this quickly goes away.

Next, we place a rubber diaphragm around the frame and head. This diaphragm is designed to hold cool water that we will pump around the head during treatment. This is because the skull actually absorbs some of the ultrasound energy as it’s going through, which can cause heating. It is important to cool that down to prevent discomfort and any injury to the skull. At this point, we also give some painkillers and some anti-nausea agents. These will help to minimise any side effects that might happen during the therapy.

Once the patient has their frame and diaphragm in position, we will then take the patient into the MRI scanning room. Here, they lay flat on a comfortable table that is attached to the MRI scanner. We use pads and pillows to make sure the patient is well supported and as comfortable as possible. A piece of equipment is then moved into position, so that the frame and the head of the patient goes inside a dome. This dome contains hundreds of ultrasound transducers which are the generators that produce the energy that is required to create the lesion.

Once in position, the treatment can then start. Typically, the procedure is performed with patients awake. This is really important because as we perform the therapy, we actually want to see that the tremor disappears. We also want to make sure that we’re not damaging important parts of the brain that could be important for producing speech, providing sensation and feeling or for providing power. To make sure we avoid this, a neurologist will ask the patient to perform simple tasks. This allows us to monitor any side effects and adjust the therapy as needed. With this, we can safely create a lesion to treat the essential tremor whilst avoiding side effects in ‘real time’.

Typically, the treatment itself takes about an hour. Magnetic resonance imaging (MRI) will be used throughout to pinpoint the target we want to ablate to reduce the tremor. We then use feedback from the patient, looking at symptom improvement and side effects, to make sure we are treating the right spot.

Once treatment is complete, the patient is taken out from the MRI scanner and the frame removed. At this stage, the patient should be able to see the difference after their treatment compared to before. Patients who couldn’t drink from a glass of water or sign their name, are typically able to once more. All without having to perform a traditional surgical operation and without a single drop of blood. The immediate nature of the results never fails to be astounding to those involved!

After treatment, we advise people to be a little cautious on the first day or two after surgery. This is because balance can be slightly affected. This is a recognised and normally temporary side effect. A walking stick or frame may be needed for a few days or weeks. This is particularly important if the patient already had some problems with balance before their surgery.

The day after surgery, we review patients to make sure that the tremor really has gone. We also sometimes perform an MRI scan to look at the lesion. We then like to speak to patients again one week, one month and then three months post treatment. We will then plan to see them in person six months after the surgery to assess the tremor.

Where can I find further information about focused ultrasound treatment of essential tremor?

MR-guided focused ultrasound treatment for medication-refractory essential tremor is now available in Queen Square to private patients. If you are interested in treatment and would like to find out more, please contact our treatment coordinators at

Additional information is also available at

Zrinzo Ludvic

Professor Ludvic Zrinzo
Consultant Neurosurgeon
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