A randomized trial was designed to evaluate the effect of focused ultrasound subthalamotomy for Parkinson disease. Researchers randomized patients with clearly asymmetric Parkinson disease who had motor signs not fully controlled by medication or who were ineligible for deep-brain stimulation surgery in a 2:1 ratio to undergo focused ultrasound subthalamotomy on the side opposite their main motor signs or a sham procedure. Twenty-seven were assigned to focused ultrasound subthalamotomy (active treatment) and 13 to the sham procedure (control) among 40 enrolled patients. In selected patients with asymmetric signs, focused ultrasound subthalamotomy in one hemisphere improved motor features of Parkinson disease. Speech and gait disturbances, weakness on the treated side, and dyskinesia were adverse events. The mean MDS-UPDRS III score for the more affected side decreased from 19.9 at baseline to 9.9 at 4 months in the active-treatment group and from 18.7 to 17.1 in the control group; the between-group difference was 8.1 points Source