Focused Ultrasound Thalamotomy

What is focused ultrasound thalamotomy?

Focused ultrasound thalamotomy describes the use of focused waves of sound to treat an area deep in your brain called the thalamus. This procedure can reduce or eliminate symptoms of essential tremor.

In focused ultrasound thalamotomy, sounds waves come from different directions and generate heat at the point where the waves converge. The heat ablates a portion of the thalamus. This prevents the firing of the circuits responsible for essential tremor, thus eliminating or reducing the tremor.

What is a thalamotomy?

A thalamotomy is any procedure that ablates a part of the thalamus. In this context, an ablation refers to the intentional destruction tissue for therapeutic purposes. Thalamotomies have been performed using various techniques for over 50 years to treat essential tremor and parkinsonian tremor. Techniques have included inserting a radiofrequency probe through a hole made in the skull, delivering focused radiation (similar to what is used for some tumors), and, more recently, focused ultrasound.

Focused ultrasound thalamotomy does not require incisions or drilling of the scalp or skull. In addition, the sound waves do not have enough energy to cause damage except at the point where they converge. This means that portions of the brain more than a few millimeters from where the ultrasound is being targeted are not at risk of being damaged.

What to Expect During the Procedure

During this procedure, magnetic resonance imaging (MRI) is used to image the brain, guide the targeting of the ultrasonic waves, and monitor the temperature changes caused by the ultrasound energy.

It will be necessary to shave your scalp for this procedure to ensure that your hair does not interfere with the delivery of the sound waves.

Before the procedure, a stereotactic frame is attached to your head. This ensures that your head does not move during the MRI or as the sound waves are being transmitted. The frame is attached by pressure applied at four sites. Numbing medicine is injected to those four sites using a small needle. You will also take Tylenol, a steroid, and an anti-nausea medication before the procedure to control for symptoms during the procedure.

Because the sound waves can cause to you feel a hot sensation, our team will fit you with a cap that will be placed over your head like a headband. This will circulate cold water over your scalp to help you stay comfortable.

You will remain flat on the MRI table for the duration of the procedure, which lasts about two hours. The bed is padded for your comfort. The table will move in and out of the scanner as we image your brain, administer test doses to confirm therapeutic effect and evaluate for side effects, and administer the therapeutic doses.

What to Expect: Side Effects and Recovery

Focused ultrasound thalamotomy is performed without any sedation, meaning you will be awake and alert during the procedure, including the placement of the headframe. Your neurosurgeon will ask you questions and have you perform tasks and movements to ensure the procedure is having the desired effect and to evaluate for side effects.

This is an outpatient procedure, meaning you will go home on the same day as the procedure.

Most people do not report pain during the procedure. Unsteadiness immediately after the procedure is common, and patients are recommended to take precautions not to fall. Many patients bring a walker, cane, or wheelchair to assist with balance after the procedure. Other symptoms may include dizziness, numbness, headache, nausea, or tingling. These effects usually are transient and improve with time.

 A short course of steroids is typically prescribed to help with side effects.

There will be four points on your scalp where the pins from the frame were placed – above the eyebrows and behind the ears. Bandages and ointment will be placed on those areas. You may remove these and shower the day after.

You are required to have a companion drive you home after the procedure. You may not drive for two weeks.