With focused ultrasound (FUS), doctors use ultrasound beams 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.) Doctors target different brain cells depending on what symptoms they are treating.
In 2018, the FDA approved focused ultrasound (FUS) for Parkinson's tremor. (FUS also is approved for essential tremor, another movement disorder.) Clinical trials are testing FUS for other PD symptoms and complications, such as dyskinesia (uncontrolled, involuntary movement). And MJFF funded an early study of focused ultrasound for dyskinesia.
Focused Ultrasound Surgery
During the FUS procedure, a patient is awake. No general anesthesia or surgical incisions are involved. Doctors use MRI brain scans to direct ultrasound beams to the target brain location.
Focused ultrasound typically decreases symptoms immediately. It does not require adjustment, programming or additional procedures. But it is irreversible and permanent.
When done on both sides of the brain, FUS may cause speech, swallowing or memory problems. So doctors only do the procedure on either the right or the left. (This means it only helps symptoms on one side of the body.) Other potential side effects include rare bleeding or skin infection.
Focused Ultrasound vs. Deep Brain Stimulation
Focused ultrasound and deep brain stimulation (DBS) are both surgical procedures for Parkinson’s. Both are FDA-approved to treat tremor that does not benefit from medication. DBS also is approved for Parkinson’s movement symptoms and dyskinesia, and clinical trials are evaluating FUS for these same indications.
Focused ultrasound and DBS work in the same brain areas but in different ways. FUS destroys cells, and DBS delivers small electrical pulses to those same cells to interrupt abnormal signaling. FUS is permanent and irreversible, while DBS may be reversed by removing the system or turning it off. Focused ultrasound is non-invasive — there are no incisions and no hardware is placed in the body. For DBS surgery, doctors make incisions in the skull to insert wires in the brain and in the chest to place a battery below the collarbone. FUS is a one-time procedure that does not require adjustment. DBS needs programming to find the right electrical stimulation settings to maximize benefit and limit side effects.
Focused ultrasound may be an option in people who can't or don't want to pursue deep brain stimulation. Some are unable to undergo invasive surgery because of heart or bleeding problems. Others aren't DBS candidates because of memory and thinking 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.
Research into Focused Ultrasound
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. Researchers also are looking at how ultrasound could help other Parkinson’s treatments, such as antibodies against alpha-synuclein or gene therapies, get into the brain more easily and efficiently.