When it comes to treating Parkinson's movement symptoms, such as tremor, patients and doctors have several options: exercise, medication and surgical therapies such as deep brain stimulation (DBS). Recently, the U.S Food and Drug Administration (FDA) approved focused ultrasound — a non-invasive procedure — for Parkinson's tremor that does not benefit from medication.
What Is Focused Ultrasound?
Focused ultrasound is a non-invasive surgical procedure that uses ultrasound waves to destroy brain cells that cause movement problems. (It's a bit 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?
Focused ultrasound is FDA-approved to treat Parkinson's tremor that does not benefit from medication. Clinical trials also are testing the therapy 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.)
Focused ultrasound also is FDA-approved to treat essential tremor, a movement disorder that typically causes shaking of the hands with activity.
How Is It Done?
Depending on whether they're treating tremor or dyskinesia, researchers direct the ultrasound waves at a different group of brain cells. MRI brain imaging guides ultrasound beams to the right location.
What Are the 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 repeated 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.
Who Might Benefit from This Therapy?
Focused ultrasound may be an option 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 memory and thinking (cognitive) problems. Still others don't want to manage the logistics of DBS programming and future battery replacements. Focused ultrasound expands the available treatment choices for patients and doctors.