Key Points
- The data that led to FDA approval of bilateral focused ultrasound treatment for essential tremor (ET) have now been published.
- The multi-center group of authors concluded that staged, bilateral MR–guided focused ultrasound thalamotomy was safe and effective for patients with ET.
In January 2023, the US Food and Drug Administration (FDA) approved bilateral focused ultrasound treatment for patients with medication-refractory ET. Bilateral means treatment on the other side of the brain – the side that was not originally treated. This option is needed and wanted by patients who have bilateral disease. The FDA approved unilateral treatment for essential tremor in 2016; the newer approval is for a staged bilateral treatment, where the second side can be treated 9 months after the first side.
The data that led to FDA approval of bilateral treatment have now been published in the journal JAMA Neurology. The manuscript, Safety and Efficacy of Staged, Bilateral Focused Ultrasound Thalamotomy in Essential Tremor: An Open-Label Clinical Trial, presents the details from a prospective, open-label, seven-center trial that enrolled 62 participants from July 2020 to October 2021 (NCT04112381). The follow-up period was then 12 months.
Research teams (most included a neurologist and a neurosurgeon) at nationwide academic medical centers enrolled 62 patients (86.3% male) with an average age of 73 years who had undergone unilateral focused ultrasound thalamotomy at least 9 months earlier. After 11 participants were excluded from treatment for a variety of reasons, the remaining 51 received the focused ultrasound treatment on the opposite side of their brain from the initial treatment.
The primary outcome measure was based on the Clinical Rating Scale for Tremor (CRST) assessment at 3 months as compared with the pre-treatment CRST. The mean CRST tremor/motor score improved 66%, from 17.4 to 6.4 at 3 months (lower CRST scores are better). Postural tremor and mean disability scores were also both significantly improved.
Considering all adverse events, 85% were mild (159/188), 13% were moderate (25/188), and 2% were severe (1/188, a severe urinary tract infection related to catheter use during procedure). Participant-reported adverse events included numbness/tingling, speech disorders, loss of muscle control, unsteadiness/imbalance, altered taste, gait disturbance, and difficulty swallowing. Mild loss of muscle control, which was reported by 12 participants, was still present in 6 of them 12 months after treatment.
The authors concluded that staged, bilateral magnetic resonance–guided focused ultrasound thalamotomy was safe and effective for patients with essential tremor. The clinical teams that led this trial included:
- Michael G. Kaplitt, MD, PhD (neurosurgery) at Weill Cornell Medicine and Harini Sarva, MD (neurology) at Cornell University, New York, NY
- Vibhor Krishna, MD (neurosurgery) at the University of North Carolina, Chapel Hill, NC
- Howard M. Eisenberg, MD (neurosurgery) and Paul S. Fishman, MD, PhD (neurology) at the University of Maryland, Baltimore, MD
- W. Jeffrey Elias, MD (neurosurgery) and Shayan Moosa, MD (neurosurgery) at the University of Virginia, Charlottesville, VA
- Pejman Ghanouni, MD, PhD (radiology), and Vivek P. Buch, MD (neurosurgery) at Stanford University in Stanford, CA
- Gordon H. Baltuch, MD, PhD (neurosurgery) at Columbia University, New York, NY
- Ali Rezai, MD (neurosurgery) and Ann Marie Murray, MD (neurology) at West Virginia University in Morgantown, WV
- Casey H. Halpern, MD (neurosurgery) at the University of Pennsylvania, Philadelphia, PA
- Brian Dalm, MD (neurosurgery) at The Ohio State University, Columbus, OH
In an invited editorial comment in the journal, Sheth et al. state, “The authors should be commended on this rigorous study with an admirably low attrition rate (92% retention at 12 months)…this therapy provides a welcome option for individuals who cannot tolerate the brain penetration required for deep brain stimulation (DBS) or radiofrequency (RF) lesioning.”
“This is a major win for patients who have bilateral disease but do not desire a procedure that involves a brain incision,” said Tim Meakem, MD, the co-director of the Research and Education Team at the Focused Ultrasound Foundation. “There were some persistent adverse events, but the vast majority (159/188) were mild and temporary. Each patient must work with their physician to choose the best treatment option for their specific situation.”
This study was funded by Insightec, and patients with essential tremor who are interested in learning more can visit the Insightec patient website.
Press Releases: UNC Health, UNC Patient Stories (Frank and Sally), WVU Medicine
Media Coverage: Physician’s Weekly, Medical Dialogues, Health Day, Medical Xpress
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