Focused ultrasound resolves persistent radiosurgery related change in a patient with tremor.

We report on a patient who underwent magnetic resonance guided focused ultrasound (MRgFUS) thalamotomy to treat tremor 3 years after a stereotactic radiosurgery (SRS) thalamotomy. The SRS produced only limited and transient improvements and was associated with a persistent hyperintensity on T2-FLAIR MR images. The MRgFUS thalamotomy was successful, with tremor improvement at 3 months, no adverse effects, and radiological appearance of the MRgFUS lesion similar to other patients undergoing this therapy. We also observed that the SRS-related T2-FLAIR hyperintensity had increased signal intensity 1 day post-MRgFUS, but appeared completely resolved 3 months post-MRgFUS. In conclusion, the case demonstrates that MRgFUS thalamotomy may effectively control tremor in patients with a history of SRS thalamotomy. We also speculate on the potential mechanisms of the apparent resolution of radiation-related change, and discuss possible applications of MRgFUS to reduce persistent SRS-related inflammation.