Abigail Rao, MD, uses deep brain stimulation and high-frequency focused ultrasound to treat essential tremor and Parkinson’s disease at Norton Neuroscience Institute
LOUISVILLE A new treatment procedure that uses high-frequency ultrasound technology can help essential tremor and Parkinson’s patients control their tremors, says Abigail Rao, MD, a neurosurgeon with the Norton Neuroscience Institute (NNI), which is the first in Kentucky to use high-frequency, focused ultrasound waves (HiFU) to target specific areas of the brain to treat essential tremor and tremor-dominant Parkinson’s disease.
Starting this year, NNI is the first and only facility in Kentucky to offer the procedure. The treatment uses MRI-guided high-frequency focused ultrasound to create a lesion in the specific part of the brain important for hand tremors. Using pinpoint accuracy, neurosurgeons can target areas, within millimeters, to give immediate relief to a patient’s symptoms and provide them better movement control.
“It’s a new delivery system to create a precise and focused lesion in the brain without needing to put anything into the brain. These aren’t life-saving procedures, but they’re massively life altering.” — Abigail Rao, MD
During the procedure, patients wear a helmet-like device filled with water that has more than 1,000 ultrasound transmitters while the surgeon tests the patient’s neurological and tremor function. “It’s a procedure where we very much want to see the patient’s tremors that we’re treating right then and there,” says Rao. “We need to be able to test their tremor so that we know if our treatment has been adequately efficacious, then we also need to be able to test their side effects.”
Choosing Functional Neurosurgery
From a Wisconsin family of physicians, Rao came to Norton Neuroscience Institute in 2018 after completing her undergraduate work at the University of Wisconsin-Madison and a year of research at the National Institute of Health (NIH). During medical school at Warren Alpert Medical School at Brown University, Rao was mentored by Kim Burchiel, MD, during her neurosurgery residency. It was during Rao’s neurosurgery residency at Oregon Health & Science University in Portland, Oregon, that she developed her interest in functional neurosurgery as a sub-specialty.
“I think the nervous system is massively fascinating. So much is known, but so much is unknown, so the specialty has major potential for growth and change,” she says. “I trained under the chairmanship of one of the major pioneers in the field of functional neurosurgery, Dr. Kim Burchiel. Many trainees who come in contact with him are inevitably influenced by seeing what he does. It was during my residency that I first came to understand what the subspecialty is about.”
While other specialties may focus on surgeries that are life-saving, functional neurosurgery focuses on procedures that improve a patient’s quality of life. Using surgical techniques like deep brain electrical stimulation (DBS), neuromodulation, and now focused ultrasound, Rao treats epilepsy, essential tremor, movement disorders, and chronic pain.
The specialty provides her with a broad range of patients in terms of both age and acuity and types of disorders. Rao says the combination of the patient profile and surgery on all parts of the nervous system drew her to the specialty.
“My medical practice involves taking care of patients who are acutely ill and are dying; and those who are not acutely ill, but impaired. It also involves taking care of patients who are about as healthy as they could possibly be, but they are still seeing me for some reason,” Rao says. “Sometimes, we may meet a patient once. Sometimes we may meet them many times over the course of years or decades, or effectively, their whole life.”
She says that she is also drawn to the subspecialty of functional neurosurgery because of its constantly changing nature. “The subspecialty is one of the most fascinating specialties of neurosurgery because it is one of the most rapidly expanding in terms of what we
LOUISVILLE Dr. Abigail Rao performed the HiFU procedure on multiple patients on November 21, 2024, at the Norton Neuroscience Institute. Her observations were as follows:
MDU Did the procedures go as expected? Anything unexpected?
Dr. Rao We did four surgeries today, and they went great! Nothing really unexpected. There will always be unexpected medical and workflow/ technical snafus periodically, in any process, but all four patients had smooth treatments, a great team to support them, and excellent clinical outcomes. All patients are very happy.
MDU What were the immediate observed results?
Dr. Rao As expected, we could immediately notice, test, and quantify the clinical relief of tremor and also assess for side effects. The tremor relief in all patients was vast, and there were minimal side effects that were within what is expected.
MDU Any feedback from the patients?
Dr. Rao They are all very happy and grateful. They immediately started talking about all the activities they would do, like painting their nails, drinking coffee, writing a signature. Many were showing off to family and looking at their treated hand in disbelief. Many also starting already plotting to have the other side treated.
can do—the indications, the types of things we treat, how we treat them,” Rao says. “It’s ever changing, and it’s also very satisfying because the focus of it, from the patient care standpoint, is to improve their quality of life.”
A New Way to Treat Tremors
Focused ultrasound goes by many names: fUS, MRI-guided focused ultrasound (MRgFUS), and high frequency focused ultrasound (HiFU). The treatment was first FDA approved in 2016 for essential tremor, followed by FDA approval in 2018 for Parkinson’s tremor. That approval was expanded in 2021 to treat other symptoms of Parkinson’s such as stiffness or slowness, as well as dyskinesia, uncontrolled, involuntary movement.
At NNI, the treatment was initiated with the purchase of technology and equipment thanks to a $2.8 million grant from the Norton Healthcare Foundation. The high-frequency focused ultrasound treatment procedure became available and operational in fall 2024.
“This procedure is a game changer for our ability to treat patients with essential tremor and tremor-dominant Parkinson’s disease,” says Rao. “Acquiring this technology advances our mission of giving patients the best possible outcomes, while further establishing Norton Neuroscience Institute as the regional leader in advanced neurological care.”
Since its approval, the treatment has spread rapidly.
“Roughly about 75 treatment centers exist in the country,” says Rao. “It’s rapidly expanding, but It’s not just about buying a new instrument, it’s really about starting a whole new clinical program, because even though we, and other centers, have been treating patients with these diagnoses for a while, the work-flow and the surgery itself and the management are all very different for HiFU.
Choosing the Right Patient for HiFU or DBS
“One aspect of candidacy is, can the patient participate with the testing? Do they have the cognitive capacity and willingness to do that?”
she says. “High-frequency focused ultrasound is MRI-guided, so MRI images and heat maps are used during the procedure to guide the treatment. That means the patient has to be willing and able to get an MRI.”
Rao said HiFU and other treatments, like deep brain stimulation where wires implanted into each side of the brain deliver electrical pulses to change the movement circuitry of the brain to regulate control over movement, are similar in their results for essential tremor. Which treatment is right for a patient is between the patient and their doctor, Rao says.
“It’s not necessarily that there’s always clearcut candidacy, or that there’s a flow chart that says, ‘If this, do this, and if this, do the other,’ Rao says. “One big difference is that deep brain stimulation is programmable or modifiable, while in high-frequency focused ultrasound, we’re using the ultrasound to create a specific lesion in the brain.”
With DBS, doctors can use external controls of the implants to manage the treatment. With HiFU, that treatment is targeted and permanent. And while HiFU is all external, DBS does require anesthesia and a short hospital stay to implant the devices. If a patient is not capable of undergoing the MRI treatment, they may be a good candidate for DBS, while someone who doesn’t want to undergo traditional surgery may be a better candidate for HiFU.
“For an individual patient, a lot of it boils down to understanding their goals, what they
want to accomplish from the treatment, and what they want to see get better,” she says. “Understanding that and talking about undergoing anesthesia, having an incision, having an implanted device that does require some maintenance over time, can help us narrow down what we might recommend.”
Rao expects HiFU use will be expanded in the future. “High-frequency focused ultrasound is a surgical system, a very technologically advanced surgical tool,” she says. “It’s presently indicated for medically refractory essential tremor and medically refractory tremor-dominant Parkinson’s disease. Based on the growth we’ve seen in the past few years, we’ll continue to see those indications grow. In a few years’ time, we’ll see it can be used for other diseases.”
As an example, HiFU has been used to treat prostate cancer for years.
While the effects of the procedure are immediate, the side effects are generally mild, Rao says. They can range from effects on walking or balance, to adverse effects on taste. Other side effects can include feeling foggy or mentally slower, headaches, nausea, and dizziness, but those effects are not typically long-lasting, she says.
A New Treatment Option for Patients
The first HiFU treatment for essential tremor at NNI took place in mid-November 2024. Rao and others at the NNI screened several potential patients to be that first HiFU treatment recipient. Their stories show just how impactful the treatment can be.
One patient, a woman in her late 70s, is very active, healthy, and independent, and wants to stay that way. Rao says the patient is “cognitively able to live on her own, but her tremors are preventing her from continuing to do so. The tremors are so strong she can no longer legibly write checks to pay bills. The ability to use HiFU to change a patient’s quality of life, without having to open up their head, is a game changer.”
“It’s a new delivery system to create a precise and focused lesion in the brain without needing to put anything into the brain,” Rao says. “These aren’t life-saving procedures, but they’re massively life altering.”