Objective: The goal of this study was to assess the feasibility, safety and efficacy of staged, bilateral, focused ultrasound thalamotomies for essential tremor.

Background: Essential tremor (ET) is a prevalent disorder affecting everyday function and quality of life (QOL). In patients who fail to respond to medications, unilateral thalamotomy improves contralateral tremor and can be performed noninvasively using magnetic resonance-guided focused ultrasound (MRgFUS). This procedure, however, does not address tremor on the second side.

Method: We conducted a prospective, single-arm, single-blinded trial of second-side MRgFUS thalamotomy in patients with ET who had undergone first-side treatment at least 6 months prior. Patients were assessed acutely and at 1 month. The primary outcome was the change in QOL relative to baseline, as well as the answer to the question “Given what you know now, would you treat the second side again?”. Secondary outcomes included additional measures of QOL, tremor, quantitative assessments of gait and speech, as well as adverse effects. A prespecified interim analysis was performed after 10 treatments. Because of the magnitude of the effect observed, we report the results in the first 10 patients now.

Results: The study met both primary outcomes, with the intervention resulting in clinically significant improvement in QOL at 1 month (mean QUEST score difference: 20.9, 95% CI:6.6–35.1, p=0.009) and all patients reporting that they would elect to receive the second-side treatment again. This suggests the benefits outweighed the risks for each subject.Tremor significantly improved in all patients. Seven experienced mild adverse effects, including 2 with gait impairment and a fall, and 1 with dysarthria persisting at 1 month.

Conclusion: Our results suggest that staged, bilateral MRgFUS thalamotomy can be performed with a reasonable safety profile similar to that seen with unilateral thalamotomy, and improves the tremor and QOL of patients with ET. Longer-term follow-up and continued accrual will be required to validate these findings and to assess the duration of the clinical benefits and adverse events.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/bilateral-focused-ultrasound-thalamotomy-for-essential-tremor-best-fus-trial-safety-and-efficacy-proof-of-principle/