Unilateral and Staged Bilateral Pallidothalamic Tractotomy Using Exablate MRgFUS in Advanced Parkinson's Disease.

This study is a randomized clinical trial evaluating a focused ultrasound treatment for people with advanced Parkinson's disease (PD) who have disabling motor complications and symptoms. The study uses the Exablate Neuro System, which delivers MR-guided Focused Ultrasound (MRgFUS). This technology focuses ultrasound energy on a specific brain target and generates heat to create a small lesion (ablation) without making a surgical incision. The target in this study is the Pallidothalamic Tract (PTT), a pathway involved in the abnormal brain circuits that contribute to Parkinson's symptoms and complications. This study is evaluating whether treating one side of the brain or treating both sides (in separate procedures) provides better outcomes for people with advanced Parkinson's disease who have motor complications and symptoms. The main outcome measure is the change in the MDS-UPDRS Part III Upper/Lower Extremity (ULE) score at 3 months after first and second side treatment, compared with the respective control groups. MDS-UPDRS Part III is a standard clinical scale used to assess Parkinson's motor symptoms. ULE score focuses on motor function in the arms and legs. Assessments are performed in the OFF-medication state, meaning Parkinson's medications are temporarily withheld so that the treatment effect can be measured more accurately. In addition improvement in motor complications will be assessed with MDS-UPDRS Part IV and Patient diaries.