With focused ultrasound (FUS), doctors guide ultrasound beams toward tiny areas of cells that cause Parkinson’s motor symptoms. Each beam is harmless on its own, but when focused together, they can create enough heat to eliminate neurons in the brain that contribute to Parkinson’s symptoms. Doctors target different brain areas for different symptoms.
As of 2025, FUS can now be used on both sides of the brain (bilateral) through two procedures that are performed months apart. This bilateral process treats motor symptoms and dyskinesia on both sides of the body. The bilateral treatment builds on FUS’ earlier approvals as a one-sided, or unilateral, treatment for Parkinson's-related tremor, stiffness or slowness and dyskinesia (uncontrolled, involuntary movement). In each case, however, unilateral FUS was approved to treat only one side of the brain and therefore only treated symptoms on one side of the body. The bilateral technique allows for symptom control on both sides of the body.
Not everyone is a candidate for focused ultrasound. The procedure may be considered for people who continue to have movement symptoms despite medication and who cannot or do not want to have deep brain stimulation (DBS). Eligibility depends on many factors, including symptom severity, brain anatomy, response to levodopa, skull density and overall health.
Focused Ultrasound Surgery
During the FUS procedure, no general anesthesia, surgical incisions or implanted hardware is involved. While the patient is sedated yet awake, doctors use MRI brain scans to direct ultrasound beams to clumps of brain cells, called neurons, that cause symptoms. The area of the brain targeted for treatment varies based on what symptoms are being addressed and whether the procedure is one- or both-sided. The bilateral procedure is carried out one side at a time, with at least six months between treatments.
Focused ultrasound typically decreases symptoms immediately. It does not require adjustment, programming or additional procedures. But it is irreversible and permanent. Possible side effects may include speech changes, headache, numbness and tingling, imbalance or gait changes, and others.
Difference Between Focused Ultrasound and Deep Brain Stimulation
Focused ultrasound and deep brain stimulation (DBS) are both surgical procedures that aim to ease Parkinson’s movement symptoms or dyskinesia, as well as “off time” and motor fluctuations (when symptoms are not well controlled). These therapies may be options for people who get a good response to levodopa but have complications, such as dyskinesia or “off” time. Or they may be a consideration for people who have tremor that cannot be controlled with medication.
FUS and DBS both work in brain areas that contribute to movement symptoms. FUS destroys cells and DBS delivers small electrical pulses to those same cells to interrupt abnormal signaling. Bilateral focused ultrasound targets a slightly different part of the brain, damaging the “wiring” that carries the signals, rather than the part of the brain that produces those signals.
FUS is permanent and irreversible, while DBS may be reversed by removing the system or turning it off. Focused ultrasound has no incisions and there is no hardware placed in the body. In DBS surgery, doctors insert thin wires into the brain and a battery. For both FUS and DBS, a patient typically is awake, but some centers do offer asleep DBS. FUS is a one-time procedure (or two-time if bilateral) that does not require ongoing adjustment. DBS needs regular programming to find the right electrical stimulation settings to maximize benefit and limit side effects.
Focused ultrasound may be an option for people who can't or don't want to pursue deep brain stimulation. Some are unable to undergo invasive surgery because of other medical problems. Others may not want to manage the logistics of DBS programming and future battery replacements.
Research into Focused Ultrasound
The Michael J. Fox Foundation has supported research into focused ultrasound since its early days, even funding an early study of focused ultrasound for dyskinesia. Ongoing research on focused ultrasound for Parkinson’s is evaluating the procedure in different brain areas affected by Parkinson’s, such as the subthalamic nucleus, aiming to expand the symptoms treated (potentially extending to stiffness and slowness).
Researchers also are studying 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 by temporarily opening the brain’s protective barrier. FUS is even being studied as a tool to collect difficult-to-gather biomarker measurements from the brain, that could be used for screening in clinical trials and potentially even diagnosis.