When it comes to treating Parkinson's movement symptoms, patients and doctors have a variety of options, including exercise regimens, medications and surgical therapies such as deep brain stimulation (DBS). And researchers are working to improve and expand treatments to cover more symptoms in broader populations of people with Parkinson's. In recent years, focused ultrasound has entered clinical trials for Parkinson's.
What Is Focused Ultrasound?
Focused ultrasound is a non-invasive procedure that uses ultrasound waves to destroy brain cells that cause movement problems. (It's sort of like using a magnifying glass to focus sunlight rays on a leaf to make a tiny hole.) The targeted brain cells are part of the basal ganglia, the circuit that controls normal movement and is affected in Parkinson's.
What Can It Treat?
Clinical trials are testing focused ultrasound for Parkinson's tremor that doesn't respond to medication and for dyskinesia: uncontrolled, involuntary movements that can develop with long-term use of levodopa and many years of Parkinson's. (MJFF funded an early study of focused ultrasound for dyskinesia.) Depending on what they're treating (tremor or dyskinesia), researchers direct the ultrasound waves at a different set of cells within the basal ganglia. MRI brain imaging guides ultrasound beams to the right location.
The therapy is U.S. Food and Drug Administration (FDA)-approved to treat essential tremor, a movement disorder that typically causes shaking of the hands with activity.
What Are the Possible Pros and Cons?
Focused ultrasound does not require surgical incisions or general anesthesia. It's typically a one-time procedure that produces immediate symptomatic benefit. Like all currently available therapies, it is not a cure.
Right now, the procedure is usually only performed on one side of the brain (can be either the right or the left) because of possible speech, swallowing and cognitive problems when done on both sides. This means it eases symptoms only on one side of the body. Also, infection and bleeding can occur, but these are somewhat uncommon side effects.
How Does It Differ from Deep Brain Stimulation?
The two procedures target the same brain areas. Unlike deep brain stimulation, focused ultrasound does not require placement of wires in the brain, batteries that need recharging or replacement, or devices that entail doctor appointments for programming. However, focused ultrasound also is irreversible because it involves destruction of cells.
What Trials Are Ongoing?
Current studies are evaluating whether focused ultrasound could ease dyskinesia and motor fluctuations: alterations between "on" time, when symptoms are controlled, and "off" time, when symptoms return. Read more about a recruiting study.
Researchers also are looking at focused ultrasound for Parkinson's tremor, and early indications suggest the therapy may be safe and beneficial.
Who Might Benefit from This Therapy?
If approved for Parkinson's, focused ultrasound may be an option to treat symptoms in those who can't or don't want to undergo deep brain stimulation. Some people are unable to undergo surgical procedures because of heart or bleeding problems. Others aren't DBS candidates because of cognitive problems. Still others don't want to manage the logistics of DBS programming and future battery replacements. Focused ultrasound could expand the choices of available treatments for patients and doctors.