Four-year follow-up results of magnetic resonance-guided focused ultrasound thalamotomy for essential tremor

Background Following the emergence of magnetic resonance-guided focused ultrasound as a promising tool for movement disorder surgery, thalamotomy for essential tremor using this technique has become a useful tool based on its efficacy and lack of adverse effects. Here, we summarize the 4-year results of previous reports focusing on the durability of effectiveness of magnetic resonance-guided focused ultrasound thalamotomy for essential tremor. Methods From October 2013 to August 2014, 15 patients with intractable essential tremor were enrolled. Twelve of them completed clinical assessment through 4 years of postoperative follow-up. Tremor severity, task performance, and disability were measured using the Clinical Rating Scale of Tremor. Results The mean age of the 12 patients was 61.7 +/- 8.1 years. Maximally delivered energy was 15,552.4 +/- 6574.1 joules. The mean number of sonications was 17.3 +/- 1.6. The mean postoperative lesion volume was 82.6 +/- 29.023 mm(3) and in 1 year was a mean of 9.667 +/- 8.573 mm(3). Four years postoperatively, improvement of the hand tremor score was 56%, that of the disability score was 63%, that of the postural score was 70%, and that of the action score was 63% compared with baseline; all improvements were significant and sustained over the 4-year period after thalamotomy. There was no permanent adverse effect throughout the 4-year follow-up period. Conclusions Magnetic resonance-guided focused ultrasound thalamotomy exhibits sustained clinical efficacy 4 years after the treatment of intractable essential tremor. Adverse events are generally transient. A large cohort of patients who have undergone magnetic resonance-guided focused ultrasound thalamotomy with longer follow-up is needed to confirm our findings. (c) 2019 International Parkinson and Movement Disorder Society