MRgFUS (Magnetic Resonance–guided Focused Ultrasound) is an advanced noninvasive therapeutic modality used particularly for the treatment of tremor disorders that are insufficiently controlled by pharmacotherapy. The procedure is performed without any surgical incision and without implantation of a medical device.

So,  who is eligible for MRgFUS? Why are patients typically awake during the procedure? When is clinical efficacy expected to manifest? And can tremor recur after treatment? The most commonly asked questions regarding MRgFUS are summarized for you below.

What is MRgFUS?

MRgFUS is a non-invasive treatment method that combines Magnetic Resonance Imaging (MRI) technology with high-intensity ultrasound waves.

In the system, 1,024 ultrasound transducer elements/waves are directed from outside the skull to a small target in the brain—specifically the “thalamus” area which is believed to be responsible for tremor—or to any desired point in the brain. Using MRI, the target location and the temperature changes occurring during the procedure are tracked in real time throughout the treatment.

For which conditions can MRgFUS be used?

MRgFUS can be evaluated especially for people with essential tremor who either do not get enough benefit from medication or experience significant side effects from intensive drug therapy.

It may also be considered for some Parkinson’s disease patients when tremor is the main symptom and when the patient meets the required criteria. However, MRgFUS does not eliminate all symptoms of Parkinson’s disease and does not stop the disease from progressing; its primary goal is to reduce tremor on the targeted side.

For that reason, the underlying cause of the tremor must first be determined, and clinicians should assess whether tremor is indeed the symptom that most strongly affects the patient’s quality of life.

Is MRgFUS used only for patients who have tremor?

In addition to these interventions, MRgFUS can also be used to improve other findings such as Parkinson’s rigidity, slowness, and involuntary movements through lesions performed in specific regions of the brain outside the tremor center. However, in a patient planned for treatment, it is necessary for physicians who are experts in this field and who are knowledgeable about both treatments to evaluate whether deep brain stimulation surgery (DBS) or MRgFUS method is more appropriate for improving the disease symptoms, and to select the most suitable treatment.

Are all patients with tremor suitable for MRgFUS?

No. Not every tremor has the same cause, and not every type of tremor is suitable for MRgFUS treatment.

The patient’s diagnosis, the type and severity of the tremor, the response to medication, losses/impairments in daily life, overall health status, and suitability for MR imaging are assessed together. The decision for MRgFUS is not made based solely on the presence of tremor.

Why is a Computed Tomography (CT) scan taken before treatment?

In MRgFUS, ultrasound waves must pass through the skull bone and reach the targeted area of the brain. However, the structure and density of the skull bones vary from patient to patient.

Therefore, a Computed Tomography (CT) scan is taken before the procedure to measure the skull’s capacity to transmit ultrasound waves. In some patients whose skull density is not suitable, it may not be possible to deliver sufficient energy to the target area safely.

How is the MRgFUS procedure performed?

To prevent ultrasound waves from being affected, the patient’s hair is shaved/cut before the procedure. Under local anesthesia, a fixed frame is placed on the patient’s head to prevent head movement and to determine the target coordinates accurately.

After the patient is placed on the MRI table, the ultrasound energy is started at low levels and gradually increased. Once sufficient temperature is reached in the target area, a small, controlled thermal lesion is created with the aim of reducing the transmission of abnormal signals that cause the tremor.

Why is the patient awake during the procedure?

Keeping the patient awake plays an important role in ensuring the treatment proceeds safely and with control.

During the procedure, the patient is asked to open and close their hand, hold the hand in a specific position, write, draw a spiral, or speak. This allows the changes in the tremor and the patient’s neurological functions to be evaluated in real time. The patient remains in communication with the treatment team throughout the procedure.

Is the MRgFUS procedure painful, and how long does it take?

General anesthesia is not used during the procedure. Local anesthesia is applied at the points where the head frame is attached. Some patients may experience pressure, a sensation of heat, headache, nausea, or dizziness.

With preparation, targeting, and neurological checks, the procedure typically takes about two to three hours. The duration may vary depending on the patient’s characteristics and the assessments made during the procedure.

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