CNN —
Undergoing clinical trials around the world is a brain surgery that requires no incision or blood production, but dramatically improves the lives of people with essential tremor, depression, and more. The procedure, known as focused ultrasound, directs sound waves at parts of the brain to disrupt faulty brain circuits causing symptoms.
“Focused ultrasound is a non-invasive therapeutic technology,” said Dr. Neil Cassell, founder and chairman of the Focused Ultrasound Foundation. “We said that focused ultrasound is the most powerful sound you’ll ever hear, but a sound that could someday save your life.”
Cassell describes the way it works as “analogous to using a magnifying glass to focus beams of light on a point and burn a hole in a leaf.”
“With focused ultrasound, instead of using an optical lens to focus light beams,” he added, “an acoustic lens is used to focus multiple beams of ultrasound energy on targets deep in the body with a high degree of precision and accuracy, sparing adjacent normal tissue .”
The procedure has been significantly beneficial for people with essential tremor, a neurological disorder that causes involuntary and rhythmic shaking. The disorder can affect almost any part of the body, but tremors usually occur in the hands — even during simple tasks like eating, drinking or writing.
Essential tremor is usually more noticeable on one side of the body and may worsen with movement. It’s most common in people 40 and older and affects nearly 25 million worldwide, according to a 2021 study.
Such was the case for 80-year-old Brenda Hrick, who recently underwent a focused ultrasound at the University of Virginia, an institution that pioneered the procedure.
Hrick’s tremors made her uncomfortable in social situations because she was afraid of spilling or knocking something over, she told CNN.
But just 44 seconds of focused ultrasound waves got rid of her tremors.
“I looked at my hand and it wasn’t moving, and it was the first time I’d been able to see my fingers still in about 20 years,” Hrick said. “I think it’s definitely a miracle and I thank God for it.”
Focused ultrasound is a form of functional neurosurgery, targeting precise structures deep in the brain to change it, restore function or, in this case, stop a tumor. It’s an alternative treatment for those like Hrick who don’t respond or stop responding to conventional drug treatment, experts said.
“In a simplistic sense, you can imagine that there are a bunch of abnormal neurons in this single target that are firing uncontrollably, causing a tremor, a tremor,” Cassell said.
Focused ultrasound technology uses a transducer to force beams of sound waves to converge on a single point to raise the temperature and destroy the tissue.
Before receiving the high-intensity focused ultrasound needed to treat essential tremor, patients must shave their heads because air can sometimes get trapped in the hair follicles.
The patient then undergoes an MRI and CT scan so doctors can use the resulting images to map the structure of the brain and the target.
The Insightec Exablate Neuro, a focused ultrasound platform, instructs how many beams should be used to perform the treatment, after which neurosurgeons can take what Dr. Jeff Elias calls “test shots, just to make sure we’re focused right in the bull’s eye.”
A UVA Health neurosurgeon who treated Hric, Elias pioneered the treatment of essential tremors using ultrasound waves. In 2011, he led the clinical trials critical to obtaining regulatory approval for this procedure in the United States.
“These (test shots) are really low energy, but we want to see if our treatment is exactly where we want it,” he said. “This is our chance to see the rifle.”
Four 11-second treatment doses significantly improved Hric’s tremors. The entire procedure lasted less than two hours, with most of it spent mapping the brain and testing the target.
Previously, Hrik had problems drawing inside the circles. Focused ultrasound helped her color the lines.
In general, anyone diagnosed with essential tremor that doesn’t respond to medication will be eligible for focused ultrasound treatment, said Dr. Nir Lipsman, a scientist at Sunnybrook Health Sciences Center in Toronto and director of Sunnybrook’s Harquail Center for Neuromodulation.
People who can’t undergo an MRI because of claustrophobia or the presence of metal in their body are not eligible for focused ultrasound, said Dr. Noah Philip, professor of psychiatry and human behavior at the university’s Alpert School of Medicine. Brown. Philip also directs mental health research at VA RR&D’s Center for Neuroregeneration and Neurotechnology.
Ideally, the benefits of focused ultrasound are permanent, Lipsman said. “If you can destroy the part of the brain responsible for tremors, it should be a permanent effect,” he said. “After a year, however, some of these patients will have a rebound or recurrence of their tremor, and we don’t know why that is.”
However, such a return can also occur with medical treatment—which is why some essential tremor patients turn to focused ultrasound in the first place.
But some patients experienced benefits five years after undergoing focused ultrasound, according to a 2022 Elias study.
The potential side effects of focused ultrasound are why the mapping and testing parts of the procedure are so important. If the wrong area is targeted or treated excessively, the patient’s balance and stability can be damaged in the long term.
“The most common risks we experience with patients is temporary numbness or tingling, which can sometimes occur in the treated arm or in the lip area,” Lipsman said. “Most of the time it goes away with time.”
Other common but usually temporary risks include mild leg unsteadiness after the procedure. But doctors don’t use general anesthesia or hospitalize patients for this procedure, he added.
Today, focused ultrasound technology is used worldwide in various stages, including clinical trials and approved regulatory use. There are more than 170 clinical applications — including for neurodegenerative diseases and tumors of the brain, breast, lung, prostate and others — and the field is growing, Cassell said.
“You can watch the effect of the ultrasound treatment in real time while the treatment is being administered, whereas with radiation the effect of the treatment is invisible while it is being administered,” Cassel said. “And it takes weeks or months for the effects of the radiation to become apparent.”
Use in depression and OCD is on the table, according to a small 2020 study by Lipsman and a team of researchers. They found that focused ultrasound was safe and effective in improving symptoms in people with major depression and OCD. But further studies are needed.
One limitation of focused ultrasound is that every person’s skull is not the same, Lipsman said.
“The density of the skull has a big impact on the ability of ultrasound to pass through it,” he added. “It’s rare, but there are some patients where, no matter how hard we try, we can’t make an effective lesion in the brain. The skull does not allow the passage of ultrasound. So that’s a technical limitation of the technology, something we’re actively working on.”
Focused ultrasound is not available for every condition, but experts said they hope “medicine’s best-kept secret” will one day become a standard treatment.
“My belief is that in 10 years,” Cassel said, “focused ultrasound will be a mainstream therapy affecting millions of patients each year around the world. It will be widely accepted.”
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