Sonication-based OCD Neurosurgical Intervention Via Capsulotomy

The goal of this clinical trial is to determine if ExAblate MR-guided Focused Ultrasound (MRgFUS) bilateral anterior capsulotomy can be used safely and effectively to relieve symptoms of moderate to severe obsessive compulsive disorder (OCD) in individuals who have not benefited from psychotherapy and medications. The main questions it aims to answer are: 1. Can ExAblate MRgFUS capsulotomy be safely delivered to individuals suffering from treatment-refractory OCD through an intact skull with a risk and side-effect profile that is comparable to other neurosurgical approaches for capsulotomy? 2. Will ExAblate MRgFUS capsulotomy result in improvement in clinical symptoms and quality of life metrics that are similar to those seen with other surgical approaches for capsulotomy? In the first stage of the study, participants with severe, treatment resistant OCD (n=10) will be recruited in two centers (Harvard and Stanford) and treated with best medical care (BMT) for 6 months. Thereafter, they will receive the ExAblate MRgFUS procedure and then another BMT for 12 months. In the second stage of the study, participants with moderate to severe OCD (n=56) will be recruited in a multi-center study and treated with BMT plus real or sham MRgFUS for 12 months. Thereafter, those who received sham MRgFUS and did not improve will receive real MRgFUS and then treated with BMT for another 12 months.