Three-year follow-up of prospective trial of focused ultrasound thalamotomy for essential tremor

Abstract

ObjectiveTo test the hypothesis that transcranial magnetic resonance–guided focused ultrasound (tcMRgFUS) thalamotomy is effective, durable, and safe for patients with medication-refractory essential tremor (ET), we assessed clinical outcomes at 3-year follow-up of a controlled multicenter prospective trial.MethodsOutcomes were based on the Clinical Rating Scale for Tremor, including hand combined tremor–motor (scale of 0–32), functional disability (scale of 0–32), and postural tremor (scale of 0–4) scores, and total scores from the Quality of Life in Essential Tremor Questionnaire (scale of 0–100). Scores at 36 months were compared with baseline and at 6 months after treatment to assess for efficacy and durability. Adverse events were also reported.ResultsMeasured scores remained improved from baseline to 36 months (all p < 0.0001). Range of improvement from baseline was 38%–50% in hand tremor, 43%–56% in disability, 50%–75% in postural tremor, and 27%–42% in quality of life. When compared to scores at 6 months, median scores increased for hand tremor (95% confidence interval [CI] 0–2, p = 0.0098) and disability (95% CI 1–4, p = 0.0001). During the third follow-up year, all previously noted adverse events remained mild or moderate, none worsened, 2 resolved, and no new adverse events occurred.ConclusionsResults at 3 years after unilateral tcMRgFUS thalamotomy for ET show continued benefit, and no progressive or delayed complications. Patients may experience mild degradation in some treatment metrics by 3 years, though improvement from baseline remains significant.Clinicaltrials.gov identifierNCT01827904.Classification of evidenceThis study provides Class IV evidence that for patients with severe ET, unilateral tcMRgFUS thalamotomy provides durable benefit after 3 years.