Objective: To evaluate the safety and efficacy outcomes of bilateral staged magnetic resonance guided focused ultrasound (MRgFUS) thalamotomy for medication-refractory essential tremor (ET) and ET plus one year after the second MRgFUS thalamotomy.

Background: Unilateral MRgFUS thalamotomy showed long-lasting therapeutic efficacy in medication-refractory ET with a reasonable safety profile. However, this unilateral treatment only improves contralateral tremor, and ipsilateral tremor in bilaterally affected ET patients continues to affect quality of life. To improve the quality of life of patients with severe bilateral tremor, bilateral thalamotomy is being considered. So far, only short-term results up to six months after the second thalamotomy with significant tremor improvement and without relevant permanent side effects have been described.

Method: Data from patients with medication-refractory ET or ET plus who underwent bilateral MRgFUS thalamotomy at the University Hospital Zurich, Switzerland, were retrospectively collected. We describe the efficacy and safety outcomes one year after the second thalamotomy. Relative tremor improvement was defined as change in Whiget Tremor Rating Scale score from baseline to one year after the second thalamotomy. Safety outcomes were described as mild (no impact on quality of life), moderate (moderately disturbing) and severe (clear impact on quality of life), depending on the impact on quality of life.

Results: Fifteen patients underwent bilateral MRgFUS thalamotomy between January 2019 and February 2022. In most patients, the right side was treated first. The interval between the first and second thalamotomy was at least six months. The mean age of the patients was 66.8 ± 13.58 years at the time of the second thalamotomy. The mean skull density Ratio (SDR) was 0.49 ± 0.13. The mean Whiget score decreased by 53.25% (±25.82) from baseline to one year after the second thalamotomy. Three patients reported no adverse events one year after the second thalamotomy, 7 patients reported mild adverse events, 4 patients moderate adverse events, and 1 patient severe adverse events.

Conclusion: Our results show that bilateral staged MRgFUS thalamotomy is feasible and that one year after the second thalamotomy, the tremor response persists and the safety profile is adequate. However, larger prospective studies are needed.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/bilateral-staged-mr-guided-focused-ultrasound-thalamotomy-for-essential-tremor-one-year-follow-up-results/