MR-Guided Focused Ultrasound for Treatment of Tremor
What is MR-guided focused ultrasound?
MR-guided focused ultrasound is a treatment method that combines two technologies.
Magnetic resonance (MR) imaging aids vision and planning – the images provide surgeons with clear and highly detailed pictures, which helps pinpoint the area to treat and monitors treatment progress.
Ultrasound (sound waves) is a form of energy that can pass through various types of tissues – skin, fat, bone, and muscle. Highly focused ultrasound is the method of treatment. Guided by the MR images, over 1,000 beams of ultrasound are concentrated and focused on a specific target in the body. The beams raise the temperature of the targeted spot of tissue. The heat causes a burn that destroys the targeted tissue but does not damage the surrounding tissue.
What neurologic conditions can be treated with MR-guided focused ultrasound?
The U.S. Food and Drug Administration has approved focused ultrasound for the following conditions:
- Essential tremor. MR-guided focused ultrasound is approved for the treatment of essential tremor that cannot be controlled with medication. Approval is for treatment of one side of the brain only. Patients must be at least 22 years of age.
- Tremor-dominant Parkinson’s disease. MR-guided focused ultrasound is approved to treat patients with Parkinson’s disease whose main symptom is tremor. Patients must be at least 30 years of age.
Use of MR-guided focused ultrasound is being explored for other neurologic conditions including the tremors associated with multiple sclerosis, epileptic seizures that cannot be controlled by other treatment approaches, other movement disorders, stroke, brain tumors and neuropathic pain. Treating these other conditions is considered experimental at this time.
How does the focused ultrasound reduce tremor?
For essential tremor and Parkinson’s disease, over 1,000 highly focused beams of ultrasound are concentrated on a specific area in the brain’s thalamus. The thalamus in the brain is a relay station of motor and sensory signals. Essential tremor and Parkinson’s disease cause the thalamic circuitry to become abnormal, which results in tremors. The heat from the ultrasound causes a tiny burn or lesion on the targeted spot on the thalamus. Creating the tiny burn or lesion interrupts the abnormal activity, which relieves the tremors associated with these diseases.