Unilateral Focused Ultrasound Thalamotomy in Essential Tremor: 3 year safety and efficacy data (P5.279)

Background: ET is a common disorder. Pharmacologic therapy can be effective, but refractory cases of ET remain. Stimulation and radiofrequency lesioning of the thalamic ventralis intermedius nucleus (ViM) have been shown to be effective treatment options. However, additional procedural treatments are needed and particularly non-incisional modalities. MRgFUS uses acoustic energy induce thermal lesions. This allows for incremental delivery of energy for continuous real-time adjustment of focus based on clinical assessments and MRI monitoring prior to delivery of the final lesion. Methods: Between February and December of 2011, MRgFUS Vim thalamotomy was performed in a pilot study of 15 subjects with ET. Subjects included had failed at least two antitremor agents and had disabling tremor in the upper limb to be treated (as defined by the Clinical Rating Scale for Tremor - CRST). Primary outcome measures were safety and change from baseline of the clinical rating scale for tremor (CRST) at 3 years (n=4). Secondary outcome measure were change from baseline in CRST subscores for treated upper limbs, quality of life in essential tremor (QUEST) score, and Physical Performance Test simulated eating task score at 3 years. Results: ViM ablation was achieved in all subjects. Four have 3 year data available. Adverse effects include sensory, cerebellar, and speech abnormalities and paresthesia in 4. At three years, only one subject had persistent partial index finger paresthesia. Mean CRST at baseline was 50.2 and 29.3 at 3 years. Treated upper limb subscores reduced from 19.2 to 8.5, QUEST scores from 30.3[percnt] to 13.1[percnt], and eating task score time from 32.1s to 14.8s. Conclusion: Here we show safety and tremor reduction at 3 years with MRg-FUS thalamotomy, albeit with a degree of loss of benefit by 3 years. Study Supported by: Focused Ultrasound Foundation, Charlottesville, VA Disclosure: Dr. Shah has nothing to disclose. Dr. Voss has nothing to disclose. Dr. Huss has nothing to disclose. Dr. Elias has nothing to disclose. Dr. Harrison has nothing to disclose. Dr. Loomba has nothing to disclose. Dr. Khaled has nothing to disclose. Dr. Frysinger has nothing to disclose.