HIFU treatment: Focused ultrasound helps treat debilitating essential tremor

High-intensity focused ultrasound, or HIFU treatment, effectively tames essential tremor, a movement disorder that affects 1% of people.
Dec. 1, 2023
Bob Horvat visits Fairyland Canyon in Utah. He plans to enjoy his frequent road trips even more since a focused ultrasound procedure vastly improved the essential tremor in his right hand. Photo courtesy of Bob Horvat.
Bob Horvat visits Fairyland Canyon in Utah. He plans to enjoy his frequent road trips even more since a focused ultrasound procedure vastly improved the essential tremor in his right hand. Photo courtesy of Bob Horvat.

As a project manager for a multimillion-dollar construction company, Bob Horvat was frequently called on to make presentations to clients, board members and colleagues.

“I had to stand in front of people on a regular basis to talk about work, bids and finances,” Horvat said. He never worried about lacking details or being able to answer questions about the company’s work. But at a certain point in his career, Horvat did have one big worry when he stood up to speak.

The talks required gesturing, wielding a pointer, jotting notes on a whiteboard and other staples of public speaking. Over time, that presented a big obstacle for Horvat. His hands, particularly the right one, shook. He couldn’t control it. He told the owner of the company he had a problem, but not the one that trembling in front of audiences might suggest.

“I have no fear,” Hovat told the owner, assuring him he wasn’t bothered by regularly speaking to groups. “It was the perception of weakness that you can’t portray.”

Dr. Drew Kern performed the high-intensity focused ultrasound (HIFU) procedure that stilled most of the essential tremor in Horvat’s hand. Photo by the University of Colorado.
Dr. Drew Kern performed the high-intensity focused ultrasound (HIFU) procedure that stilled most of the essential tremor in Horvat’s hand. Photo: University of Colorado School of Medicine.

The essentials of essential tremor

Horvat did not have Parkinson’s disease, which can cause limb trembling when a person is at rest. Nor was he nervous. Instead, the source of his increasingly severe shaking was essential tremor, a movement disorder that causes hands and other limbs to waver when a person holds them out in space or performs everyday tasks like holding a cup, bringing a spoon to the lips – or holding a pointer during an office meeting, as Horvat experienced. The condition can be debilitating.

“An individual can have such a degree of tremor that it renders the limb essentially useless,” said Dr. Drew Kern, associate professor of Neurology at the University of Colorado School of Medicine.

Kern noted that essential tremor affects about 1% of the general population, making it one of the most common movement disorders. In people 65 or older, that percentage spikes to 5%, he said.

The physical and emotional trials of essential tremor – and a ray of hope

Horvat has dealt with his essential tremor, which he inherited from his father, for decades. He treated it with a host of medications with varying success. But over time, the disorder cut his career short. It also robbed him of many things he loved and disrupted routines he had taken for granted.

Fishing will also be easier for Horvat, thanks to the ultrasound procedure. Photo courtesy of Bob Horvat.
Fishing will also be easier for Horvat, thanks to the ultrasound procedure. Photo courtesy of Bob Horvat.

Now 71, the disorder forced him into retirement in Pueblo at 62. The company owner had given him a “sidekick” to assist him during meetings by using a pointer and taking notes. But by 60, the shaking in both hands had worsened considerably, and he knew he couldn’t hang on much longer.

“I was a burden to myself and to the company,” Horvat said. “I couldn’t do my job functions. It was time to move on.”

However, the relentless trembling also meant he had to abandon leisure activities he’d loved, including woodworking, welding, fishing and cooking. Simple daily activities – shaving, brushing teeth, clipping nails, putting pills in a box, writing, eating and drinking – became “almost impossible,” Horvat said. “You fight your way through them.”

In a remarkably short period of time recently, all of that changed, thanks to an improbable connection a desperate Horvat made with Kern. Horvat’s essential tremor is not entirely gone, but it’s been mostly tamed in his dominant right hand by an FDA-approved minimally invasive procedure called high-intensity focused ultrasound (HIFU). Kern and neurosurgeon Dr. Steven Ojemann directed the procedure through the Advanced Therapies in Movement Disorders program at the University of Colorado.

“It was a blessing,” Horvat said simply.

Thwarting essential tremor’s scrambled signals using HIFU treatment

It’s not known what causes essential tremor, although many people inherit the trait from a parent, as Horvat did. The condition causes scrambled signals at a critical juncture in the cerebellum, the area of the brain that is responsible for regulating movement and coordination. The disruption produces uncontrolled shaking and trembling, Kern explained.

The HIFU treatment essentially disrupts the disruption with powerful ultrasound waves delivered through the patient’s skull to the problem area. The high-intensity waves obliterate the tiny patch of brain tissue that conveyed the rogue brain signaling and prompted the tremors.

Kern said some people can control their essential tremor with first-line medications like propranolol and primidone or secondary options, such as gabapentin. If these treatments do not deliver relief – Horvat took a number of different medications over years while his symptoms worsened – patients have very effective surgical options in deep brain stimulation (DBS) or HIFU, Kern said. DBS involves implanting a device under the skin that delivers electrical stimulation through wires to electrodes strategically placed in the brain.

The ”clinical benefit” of DBS can be as high as 90%, Kern said – roughly double over what can be expected from moving to secondary medications. But DBS also carries with it surgical risk, such as infection and brain bleeds. For patients like Horvat, HIFU offers an outpatient alternative that produces benefits similar to DBS immediately and with no incisions, Kern said.

Focused ultrasound for essential tremor

The HIFU procedure requires careful planning. The first step is patient selection “to determine if we should move forward,” Kern said. He explained that the team might exclude a patient for a number of reasons, including an incorrect diagnosis; unrealistic expectations, such as an artist who has relied on fine movements to paint; problems with balance that might be worsened by HIFU tissue damage; and previous brain surgery. The procedure also requires MRIs, so patients with metal in their bodies and those with severe claustrophobia are not candidates, Kern added.

A viable HIFU candidate also has to have a hard head – literally. That is, the individual cannot have a “low skull density ratio,” or a relatively soft or spongy skull that will absorb the ultrasound waves, which generates pain.

“The patient must have the skull hardness to allow the ultrasound waves to go through and reach the targeted area of the brain,” Kern said.

The patient selection process also includes a patient care conference attended by specialists in movement disorder neurology, neurosurgery, neuroradiology, neuropsychology, and neuropalliative care, Kern said. The team jointly determines if a patient is a candidate for HIFU.

Finding the way in the brain

Kern said the planning for HIFU aims at “ensuring we are performing the procedure in the ideal region of the brain.” That relies on an MRI-generated, computerized “atlas,” which is a patient-specific map of the landscape of the brain. In addition, tractography produces 3D images of the specific signaling pathways, or tracts, in the cerebellum that regulate movement. With that imaging, providers can identify the specific pathway that is responsible for the tremor while visualizing other tracts to avoid, Kern said.

Kern gets the MRI a week before the HIFU procedure and evaluates it to pinpoint the targeted tissue area that will receive the ultrasound waves. He reviews the plan with Ojemann and Dr. John Thompson of the Department of Neurosurgery to reach agreement on the targeting.

On the day of the procedure, the team shaves the patient’s head completely and then attaches a head frame and a rubber diaphragm. The patient enters the MRI machine, where the frame is anchored to the table to prevent movement. The membrane is attached to a transducer, which resembles a helmet or an old-fashioned salon hair dryer, and will deliver the ultrasound saves. The transducer contains a space for cold circulating water to improve the transmission of the waves.

Kern takes a new MRI, merges the current image with his targeting plan, and marks areas of the brain to protect from the ultrasound waves. He aligns the transducer with the targeted area and delivers the ultrasound waves, or sonications, first to ensure they are hitting their target. These “alignment sonications,” which Kern said “stun the tissue,” arrive at less than 52 degrees Celsius (about 120 to 125 degrees Fahrenheit).

The patient is awake during the entire procedure. After delivering the alignment sonications, Kern examines the patient for any adverse effects, including weakness, changes in the senses or coordination problems. He also checks for the crucial benefit: lessening of the tremor. If there are issues, he adjusts his target.

The final stage, or treatment sonication, boosts the wave temperature to 56 to 58 degrees Celsius (130 to 135 degrees Fahrenheit). The aim: create a permanent hole in the tissue of the targeted area and disable the tremor-creating signaling. With the therapy completed, Kern performs another MRI to verify that he has created the hole and watches the patient for an hour or two to check for movement problems – and again for improvement of the tremor.

“There should be an immediate response,” Kern said. “If not, either the wrong diagnosis was made or our targeting was off.”

A surprising discovery of HIFU

Bob Horvat described Kern’s attention to detail as exhaustive and his HIFU experience as exhausting. But his battle with essential tremor had amply prepared him to try something new. By the time he saw Kern for his evaluation in mid-August, his attempts to draw concentric circles veered into abstract art. His signature was little more than a flat line across a page. Horvat also worried about the stress for his wife, Jeanni, every time his shaking hands scattered food from his dinner plate or spilled coffee.

Horvat and his wife Jeanni. Photo courtesy of Bob Horvat.
Horvat and his wife Jeanni. Photo courtesy of Bob Horvat.

He’d also taken an alphabet soup of medications with only temporary relief and a variety of side effects. “At some point, they didn’t work, and I wouldn’t take them half the time,” Horvat said. He’d heard about DBS from providers but wasn’t yet willing to go through the surgery.

His frustration was high one day last spring when he sat down to surf the Internet for ideas. He was suddenly surprised when an ad for Insightec, a company that developed HIFU treatment for essential tremor, popped up.

“I had not known I had other options,” Horvat said.

He sent an inquiring email to the company, where a representative promptly “started the ball rolling” toward the eventual pivotal meeting with Kern. Less than six months after the ad appeared on his computer screen, he was on the MRI table at UCHealth University of Colorado Hospital.

Surprising results for a grateful patient

Following the HIFU procedure, Horvat said he was “emotionally drained,” so much so that the improved stability in his hand and ability to control his movements didn’t immediately register.

“I looked at my hand not shaking and thought, ‘That’s kind of cool,’” he remembers, but without dwelling on it any further, he went back to his hotel with Jeanni and fell asleep. He woke up later to a new world with a virtually tremor-free right hand.

“The elation I felt was unbelievable,” Horvat said. “I made coffee and carried the cup out [without spilling it]. I don’t think I even drank it.”

More than a month after the HIFU procedure, Horvat said the tremors in his right hand are about 90% gone. His left hand continues to tremble, and he is contemplating a second procedure but must wait at least nine months before doing so (an advantage of the DBS surgery is that it can be performed on both sides of the brain simultaneously).

Focused ultrasound is another tool to treat essential tremor

Kern emphasized that HIFU is not a replacement for DBS, and patients must balance the benefits and risks of both. But HIFU does offer an additional source of hope and relief for people suffering from essential tremor, he said.

“It’s a wonder to have an option for patients who are not good candidates for DBS and not getting any significant benefit with medications,” Kern said.

Because of that HIFU option, Horvat today concentrates on his new lease on life. He can once again eat out, write legibly, surf easily on his tablet, groom himself and barbecue. Welding is still “touch-and-go” because of his shaky left hand, but during a conversation from his motor home parked in the coastal town of Port Aransas, Texas, he said he was planning to fish in the Gulf of Mexico.

“I do these things just because I can,” Horvat said. “The frustration I had was unbelievable, and now it’s gone.”

About the author

Tyler Smith has been a health care writer, with a focus on hospitals, since 1996. He served as a writer and editor for the Marketing and Communications team at University of Colorado Hospital and UCHealth from 2007 to 2017. More recently, he has reported for and contributed stories to the University of Colorado School of Medicine, the Colorado School of Public Health and the Colorado Bioscience Association.