When you hear the word ultrasound, you might think of a sonogram that shows a baby in the womb or an injury or illness under the skin. These scans use high-frequency sound waves to create an image of the body’s internal organs.
But ultrasounds can do more than that. When ultrasound beams are turned down to lower frequencies, combined and aimed at a target, they can treat illnesses including cancer, uterine fibroids and now Parkinson’s disease. The technique, called focused ultrasound ablation (also known as high-intensity focused ultrasound, or HIFU), harnesses the power of these beams to kill targeted tissue. It is an incisionless outpatient procedure.
UNC Health neurosurgeon Vibhor Krishna, MD, explains what you need to know about the treatment if you are considering it for yourself or a loved one with Parkinson’s disease.
Who Is a Candidate for Focused Ultrasound Ablation for Parkinson’s Disease?
To understand who could be a candidate for focused ultrasound ablation, it’s helpful to know a little about its history. While the therapy isn’t new, it has just recently started to be used in patients with Parkinson’s disease, a brain disorder linked to reduced levels of dopamine, the brain’s feel-good chemical that also plays a major role in movement.
In 2018, the U.S. Food and Drug Administration approved focused ultrasound ablation to treat Parkinson’s patients experiencing tremor (shaking) as the main symptom. In 2021, it was also approved to treat motor impairment and dyskinesia. Dyskinesia, or involuntary movement, and motor impairment, marked by restricted movement such as stiffness or slowness, are the most common symptoms that people with Parkinson’s disease develop when they take medications designed to restore dopamine levels.
These symptoms worsen patients’ quality of life and often pose a safety risk because they can be unpredictable and may result in a fall or injury, Dr. Krishna says.
People with Parkinson’s who may be candidates for focused ultrasound ablation include those who experience tremor as their main symptom or patients who have been on medication and are experiencing dyskinesia or motor impairment.
How Focused Ultrasound Ablation Works in Parkinson’s Disease Patients
In Parkinson’s disease, patients experience a progressive loss of brain tissue that produces dopamine. As a result, certain areas in their brains develop abnormal activity that is responsible for symptoms such as tremor, dyskinesia and motor impairment. Focused ultrasound ablation harnesses the power of sound waves to target brain tissue with abnormal activity while leaving the surrounding tissue unharmed. The sound beams are delivered through a device called a transducer, which resembles a helmet. The transducer’s circular shape makes it possible for a neurosurgeon to aim the ultrasound beams where they need to go to destroy the target tissue.
“The shape of the ultrasound transducer allows us to focus the beams like a lens or a magnifying glass does to sunlight,” Dr. Krishna says. “One sound beam alone is harmless in the same way that a ray of sun hitting the paper is harmless. But if you have a lens that can combine the rays, the sunlight can burn the paper.”
Focused ultrasound ablation is a one-time treatment. A patient will start the appointment with a multidisciplinary assessment followed by MRI to take pictures of the brain. Then the neurosurgeon will use ultrasound at low intensity to evaluate whether ablation would improve the patient’s symptoms.
“If the neurosurgeon becomes confident that the targeted tissue is safe to ablate and would be effective, they can then increase the energy input of the ultrasound beams and permanently ablate the targeted brain tissue,” Dr. Krishna says. “This is what allows the procedure to make long-lasting improvement in patient symptoms.”
Patients who undergo this treatment must shave their heads before the procedure so the beams can better reach the tissue. Medications are available in case of procedure-related discomfort and nausea.
Pros and Cons of Focused Ultrasound Ablation for Parkinson’s Disease
Focused ultrasound ablation is an outpatient procedure, and patients can be awake the whole time. The procedure is minimally invasive, meaning no incisions are made, and the recovery period is about two to three weeks. This is different from the conventional surgery that treats Parkinson’s disease with deep brain stimulation, in which electrodes are placed inside the brain to modulate the activity of targeted brain tissue.
The results of focused ultrasound ablation can be immediate and long-lasting. New research co-led by Dr. Krishna shows that patients who received the therapy saw significant improvement in dyskinesia and motor impairment. Importantly, the study showed that improvements were sustained in 75 percent of patients one year after the treatment. Dr. Krishna’s research paved the way for FDA approval of focused ultrasound ablation for Parkinson’s disease.
“We’re excited to have a minimally invasive option that can offer immediate results,” Dr. Krishna says.
Of the 65 people in the study who received the treatment, a handful experienced procedure-related side effects including speech difficulty, facial weakness, trouble walking and loss of taste. Many experienced transient headaches that resolved in all patients.
“Our research aims to optimize focused ultrasound treatment to make it safer and highly effective for our patients,” Dr. Krishna says.
He and his team plan to continue to refine the technique as a personalized approach to treating Parkinson’s disease. They will also evaluate whether focused ultrasound ablation could be used to treat other neurological disorders, such as epilepsy.