Using Ultrasound to Stop Tremors in Parkinson and Dyskinesia

Howard M. Eisenberg, MD

A magnetic resonance imaging (MRI)-guided focused ultrasound on the brain used to treat Parkinson's disease (PD) may also prove promising for dyskinesia treatment, results from a phase 3 study suggest.

Researchers from the University of Maryland Medical Center are testing the noninvasive technique as a final step before the US Food and Drug Administration (FDA) may consider approval for the technology. This study is just the second clinical trial of its kind.

“The goal of the focused ultrasound treatment is to both lessen the main symptoms of Parkinson’s disease, which include tremors, rigidity and slow movement, as well as treat the dyskinesia that is a medication side effect, so that less medication is needed,” principal investigator Howard M. Eisenberg, MD, said in a statement.

Medication or deep brain stimulation are both options for PD treatment, but can lead to dyskinesia and other complications. Patients with Parkinson's who develop dyskinesia often see their quality of life drastically affected.

The patients remain awake through the entire procedure, which is performed at an outpatient setting. The patient is fitted with a type of helmet to stabilize their head inside the MRI scanner. The doctors use the MRI to create a heat map and learn exactly where to aim inside the brain. Then, the focused ultrasound is aimed at the brain structure (globus pallidus).

Doctors raise the temperature to the area to ablate the tissue while the patient still awake, alert, and able to provide feedback. The doctors can monitor the immediate effects of the treatment and make adjustments in real time.

“For people with Parkinson’s disease and other movement disorders such as essential tremor, focused ultrasound is an appealing alternative to deep brain stimulation because it does not involve more invasive surgery,” Paul S. Fishman, MD, PhD, professor of neurology at UMSOM and a neurologist at UMMC, said.

A 2015 pilot study examining this process showed promising result which Eisenberg considered to be "very encouraging."

The pilot study involved dyskinesia patients who received a focused ultrasound. Most of the 20 total patients showed significant improvement in their tremors.

The new study, which expects to include between 80 and 100 patients, kicked off in February. The researchers loosened the exclusion criteria in order to make the study more inclusive, though patients do have to be over 30 years of age.

A July 2016 FDA document evaluated the ExAblate Model 4000 system used in the study. The paper concluded that the study supported a "reasonable assurance of safety and effectiveness of this device when used in accordance with the indications for use.”

“The ExAblate Neuro treatment is a reasonable alternative to existing treatments,” researchers wrote. “The treatment benefits of the device for the target population outweigh the risks when used in accordance with the directions for use."

InSightec, the company funding the study, plans to market the device as Exablate Neuro and has a short video describing how the device works on their website, advertising that it requires "no anesthesia, no incisions, [and] no implanted hardware."

More information about the study, "A Pivotal Clinical Trial of the Management of the Medically-Refractory Dyskinesia Symptoms or Motor Fluctuations of Advanced Idiopathic Parkinson's Disease," can be found here.