Focused ultrasound: focused on tremor

Magnetic resonance-guided focused ultrasound (MRgFUS) has emerged as a leading noninvasive therapy for tremor, offering a precise, lesion-based alternative to deep brain stimulation (DBS) and traditional lesioning techniques. By using phased ultrasound arrays to focus energy at intracranial targets, MRgFUS allows for real-time visualization and monitoring, improving safety and efficacy. Initially developed for essential tremor (ET), MRgFUS-VIM-thalamotomy has gained widespread acceptance and is now a first-line option for tremor-dominant Parkinson's disease (TDPD) and other tremor syndromes.

This review discusses the fundamental physics of focused ultrasound, key anatomical targets, and the clinical application of MRgFUS thalamotomy, pallidotomy, and subthalamotomy. Skull density ratio (SDR) and energy efficiency are highlighted as crucial factors affecting treatment outcomes. The evolution of MRgFUS as a bilateral treatment, along with the exploration of novel targets such as the pallidothalamic tract, is examined. Additionally, we discuss advancements in FUS neuromodulation, which could complement lesioning by providing temporary or reversible symptom relief.

MRgFUS is poised to further revolutionize tremor treatment with frameless technology, staged bilateral procedures, and the integration of neuromodulation. Future developments may allow for precise, adaptive therapies that enhance both efficacy and patient experience.