No progressive or delayed complications of treatment were recorded after 3 years in patients with essential tremor who underwent focused ultrasound.
The benefits of focused ultrasound (FUS) thalamotomy in patients with essential tremor (ET), including vast improvements in hand tremor, disability, postural tremor, and quality in life, are still realized 3 years after treatment, according to findings published in Neurology.
The randomized, double-blind, crossover, multi-site, 2-arm study included 75 participants and examined the efficacy, durability, and safety of FUS for medication-refractory ET. Each patient was assessed on the Clinical Rating Scale of Tremor, which includes 3 subsection categories: tremor-motor (scale of 0-32), functional disability (scale of 0-32), and postural tremor (scale of 0-4), as well as total scores from the Quality of Life in Essential Tremor Questionnaire (QUEST; scale of 0-100) which focuses on 5 key domains, including speech, work and finance, hobbies and leisure activities, physical activity, and psychological factors. Scores for all endpoints were recorded at baseline, 6 months, and 36 months to compare efficacy and durability.
Overall, all measured scores showed consistent improvement from baseline to 36 months (all P <.0001). Results showed a range of improvement from baseline of 38% to 50% in hand tremor, 43% to 56% in disability, 50% to 75% in postural tremor, and 27% to 42% in quality of life. Total QUEST scores improved from 42 at baseline to 18 at 36 months. Notably, median scores for hand tremor and disability were increased at 36 months compared to scores at 6 months (95% CI, 0-2, P = .0098; 95% CI, 1-4, P = .0001).
All previously recorded adverse events (AE) remained mild or moderate. No AE worsened, 2 were resolved, and no new AEs occurred. Among the 75 patients enrolled, 21 chose to exit the study, including 4 patients who elected to have deep brain stimulation.
“We expected focused ultrasound to be a safer and more precise way to do this treatment as we can visualize the lesion with MRI heat maps. Thus, the overall durability of the effect and relative safety were not surprising,” said Casey Halpern, assistant professor of Neurosurgery and, by courtesy, of Neurology and Neurological Sciences, and Psychiatry and Behavioral Sciences, and is also director of epilepsy surgery at Stanford University Medical Center, in an interview with NeurologyLive.
The 3-year follow up results after unilateral FUS thalamotomy exemplify significant tremor reduction all while retaining a positive safety profile. The overall durability of the treatment effects over time remained strong, with only slight increases in hand tremor and disability noted at 3 years.
Given the results, FUS has strong potential to become a central therapy for refractory ET, “particularly for unilateral treatment,” Halpern said. “Bilateral treatment at the moment is off-label but is likely relatively safe and effective with focused ultrasound. Over time we hope to be able to offer this therapy bilaterally.”
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Halpern CH, Santini V, Lipsman N, et al. Three-year follow-up of prospective trial of focused ultrasound thalamotomy for essential tremor. Neurology. 2019;93(1-10). doi: 10.1212/WNL.0000000000008561.