Focused ultrasound therapy: Back to the future

The surgical treatment of movement disorders, primarily for tremor, started with radiofrequency lesioning of the globus pallidus and thalamus in the 1950s [1]. While this became a state-of-the-art treatment over the following decades, bilateral lesions were associated with significant side effects such as gait, balance, and speech disturbances [2]. In the 70's, radiosurgery with the gamma knife showed promise because the procedure was incisionless. However, it used ionizing radiation, and the target could not be confirmed in real-time, because the effect was delayed by around six months.