MR-guided focused ultrasound surgery (MRgFUS) represents a new treatment paradigm available to stereotactic surgeons.

     With the advent of phased array transducers, precise noninvasive transcranial ultrasound lesioning is now feasible. Furthermore, MR thermometry allows for real-time monitoring of the treatment location and intensity.

     Fifteen medication-refractory essential tremor patients receiving a unilateral MRgFUS Vim thalamotomy are being investigated under an FDA-approved protocol. .

     Pre and post assessments with a validated rating scale for tremor and MRI were obtained throughout the study period at time points of one day, one week, one month, and three months. Adverse events were recorded throughout the study period

     Substantial reductions in contralateral appendicular tremor were noted in subjects throughout the three month study period. The adverse event profile was comparable to stereotactic thalamic procedures and included paresthesia, ataxia and subjective unsteadiness. Transient device-related adverse effects include headache, warm sensations, dizziness and nausea. The full spectrum of outcomes and adverse events from the study will be presented. Neuromodulation at low power sonications was performed in a few patients based on their intraprocedural clinical testing.

     This is a retrospective study.

     This initial investigation of MRgFUS thalamotomy seems safe and effective in alleviating contralateral appendicular tremor.

     This noninvasive technique, in combination with neuromodulation acoustic parameters, may prove to be very effective for people with tremor and other movement disorders.