Essential tremor (ET) and Parkinson disease (PD) are the most prevalent tremor disorders. ET, considered as a pure tremor disease, is characterized by upper limb intention or postural tremor, while PD is characterized by a variety of motor and nonmotor symptoms, among them rest tremor. Tremor suppression can be achieved by lesioning or stimulating a relay nucleus of the thalamus, known as the ventral intermediate nucleus (VIM). One emerging and promising approach to lesion VIM is magnetic resonance-guided focused ultrasound (MRgFUS). This technique allows delivery of spherical phased converging beams to a specific brain target using MR imaging (MRI) for guidance. A number of studies have demonstrated the effectiveness and safety of ExAblate MRgFUS thalamotomy for medication-refractory tremor in patients with ET/PD. MRgFUS thalamotomy has been approved for ET/PD patients in late 2020.~Magnetic resonance imaging (MRI) is a technique for measuring structural features and mapping brain activity that is noninvasive and safe. It is being used in many studies to better understand how the healthy brain works, and in a growing number of studies it is being applied to understand how that normal function is disrupted in disease. The analysis of the imaging data related to MRgFUS thalamotomy may help us to further understand the neuroplasticity characteristics of patients around treatment and the altered brain network dynamics. It would also further help us grasp the advantages and disadvantages of such brain lesion therapy techniques and serves guidance for the next clinical studies. Therefore, we registered this new study for our current prospective study.~Brief summary of retrospective data：~- Medication-refractory ET and PD Patients subjected with MRgFUS thalamotomy were recruited for multimodal MR scanning, including T2; T2 Flair; DWI; ESWAN; MRS; 3D ASL 2.0s; 3D-T1; DTI; rs-functional MRI at baseline, postoperative 1-day, postoperative 1-week, postoperative 1-month, postoperative 3-months, postoperative 6-months, postoperative 1-year, postoperative 2-year, postoperative 3-year, postoperative 4-year, postoperative 5-year. Extra baseline info were also collected, as well as ultrasound parameters (energy, power, duration time, temperature, target location), clinical assessment (clinical rating scale for tremor (CRST), Unified Parkinson Disease Rating Scale (UPDRS), associated adverse effects and so on.
The technological advance of magnetic resonance-guided focused ultrasound (MRgFUS) has once again brought lesion therapy back to the clinical frontline for the treatment of movement disorder. Thus far, the safety of MRgFUS has been widely proven and has just been made available in China in late 2020. We attempted to analyze the neuroplasticity characteristics and altered neural circuit activity in patients subjected with MRgFUS thalamotomy via Multiple MR Imaging study, and to explore potential biomarkers that could be used to predict the treatment outcome.