As Stan Au's Parkinson's disease symptoms progressed, everyday activities became daily battles. His hands shook so badly that he struggled to hold utensils and couldn't sign his name. He stopped playing pickleball—a sport he once enjoyed—despite taking a widely prescribed medication for managing motor symptoms, such as rigidity or stiffness, slow movement, involuntary muscle movement (dyskinesia) and tremors.
Diagnosed with Parkinson's 12 years ago, Stan Au of Essex Fells, New Jersey, and his wife, Pam, explored other treatments, including deep-brain stimulation, which involves implanting electrodes into brain structures that help control movement. "Stan wasn't singing out of that hymn book—he had no interest in having brain surgery," Pam Au said.
Hope emerged in 2020, when they met Dr. Harini Sarva, associate professor of clinical neurology at Weill Cornell Medicine. The couple felt that Dr. Sarva took their concerns seriously and thoroughly explored existing treatments.
"It was a partnership finding the right treatment for Stan," said Dr. Sarva, who is also a neurologist and chief of the Division of Movement Disorders at NewYork-Presbyterian/Weill Cornell Medical Center. She recommended a clinical trial for magnetic resonance-guided focused ultrasound (MRgFUS). This noninvasive, outpatient treatment focuses ultrasound waves on a tiny pathway deep within the brain to create a precise lesion that interrupts abnormal movement signals.
"Parkinson's affects about one million Americans, and while there is no cure, ultrasound treatments offer patients a better quality of life, reducing some of the most disabling effects of the disease," said Dr. Michael G. Kaplitt, M.D. '95, professor of neurological surgery at Weill Cornell and director of the Neuromodulation Program at NewYork-Presbyterian/Weill Cornell Medical Center, who led the clinical trial.
The procedure starts with shaving the patient's head to help ultrasound energy pass through the scalp efficiently. Next, the patient wears a helmet and lies inside a magnetic resonance imaging (MRI) machine. The helmet directs ultrasound beams through the skull onto the target. MRI images guide the doctor to the precise treatment site, while real-time thermal measurement helps monitor the temperature.
The U.S. Food and Drug Administration (FDA) first approved focused ultrasound in 2016 to treat essential tremor. Researchers later adapted the technology to target different movement-control pathways in Parkinson's disease, leading to approval in 2018 to treat Parkinson's tremors and then expanded approval in 2021 for mobility issues.
However, treatment was limited to one side. Since the body's right and left sides are controlled separately, the procedure needed to be tested on both sides of the brain to address symptoms on both sides of the body.
Clinical trial provides data for FDA approval
Dr. Kaplitt and his colleagues conducted the first multicenter clinical trial of a bilateral approach (treatment on both sides of the brain) for Parkinson's motor complications. The trial findings, published earlier this year in The Lancet Neurology, showed that bilateral MRgFUS could improve motor symptoms and tremors in some patients with Parkinson's, while revealing risks associated with treating the second side of the brain. He co-led the Lancet Neurology study along with corresponding author Dr. Howard Eisenberg in the Department of Neurosurgery at the University of Maryland School of Medicine.
The clinical trial recruited 54 patients with Parkinson's, including Stan Au, who were tested for motor function before the treatment as a baseline assessment. The team first performed MRgFUS on the side of the brain corresponding to each patient's more severely affected side of the body. The study was designed so that patients could then choose to have the procedure on the other side of the brain at least six months later. Ultimately, 40 patients underwent bilateral treatment.
The procedure targeted the pallidothalamic tract, a bundle of nerve fibers that carries signals from the globus pallidus interna (GPi) to the thalamus. These two structures are part of the brain's movement-control network. In Parkinson's disease, abnormal signaling through this pathway contributes to tremor, rigidity, slow movement and dyskinesia. The focused ultrasound creates a tiny lesion in this tract, interrupting abnormal signals involved in movement.
The FDA approved the staged bilateral treatment using this platform in July 2025 based on the results of the clinical trial, and Medicare began covering it in March this year.
By the time a medication is no longer effective, most patients have reached a point where symptoms are prominent on both sides. And now, some patients can choose to treat motor complications on both sides, giving them more control over how they address their disease."
Dr. Michael G. Kaplitt, M.D. '95, professor of neurological surgery, Weill Cornell Medicine
The FDA's review found that 86% of patients reported at least some improvement three months after the second procedure, and 62% of patients reported being satisfied with the bilateral procedure at that time. However, the second treatment provided less additional motor improvement and was associated with a higher risk of speech, walking and balance issues.
As a result, the FDA concluded that bilateral treatment should be reserved for carefully selected patients with disabling symptoms on the untreated side and who have experienced no serious side effects after the first treatment. "It's important to take a holistic view of patients and how their functional limitations are impacting their daily activities," Dr. Sarva said.
Getting back to a more active life
"Stan seemed very happy after his first procedure—his tremors and mobility improved, and he didn't have any serious adverse effects," Dr. Sarva said. "He was in a much better place after a long time, which prompted his decision to have treatment on the second side of the brain nine months later."
While Stan improved more from the initial treatment, the second procedure also had some additional gains. "In his case, the bilateral focused ultrasound treatment and a pump that attaches to his body to deliver fine-tuned amounts of medication every hour have really made a big impact in his daily life," Dr. Sarva explained.
"Every Parkinson's patient has a different combination of symptoms with varying severities, which impacts their lives, so it is critically important for physicians to explain available treatments and how they might fit with each individual's lifestyle and specific symptoms," Dr. Kaplitt said.
Stan Au saw immediate benefits after both outpatient treatments and said he would recommend the procedure as an option for other Parkinson's patients with similar symptoms. "I have less stiffness, better coordination, and I am more active—even playing pickleball again," he said.
The mobility he has regained has also given Stan Au something especially meaningful to look forward to: he plans to walk his daughter down the aisle at her wedding next fall.
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