Magnetic resonance imaging-guided focused ultrasound thalamotomy for essential tremor: 5-year follow-up results

Abstract

Objective: The objective of this study was to evaluate, at 4 and 5 years posttreatment, the long-term safety and efficacy of unilateral MRI-guided focused ultrasound (MRgFUS) thalamotomy for medication-refractory essential tremor in a cohort of patients from a prospective, controlled, multicenter clinical trial.

Methods: Outcomes per the Clinical Rating Scale for Tremor (CRST), including postural tremor scores (CRST Part A), combined hand tremor/motor scores (CRST Parts A and B), and functional disability scores (CRST Part C), were measured by a qualified neurologist. The Quality of Life in Essential Tremor Questionnaire (QUEST) was used to assess quality of life. CRST and QUEST scores at 48 and 60 months post-MRgFUS were compared to those at baseline to assess treatment efficacy and durability. All adverse events (AEs) were reported.

Results: Forty-five and 40 patients completed the 4- and 5-year follow-ups, respectively. CRST scores for postural tremor (Part A) for the treated hand remained significantly improved by 73.3% and 73.1% from baseline at both 48 and 60 months posttreatment, respectively (both p < 0.0001). Combined hand tremor/motor scores (Parts A and B) also improved by 49.5% and 40.4% (p < 0.0001) at each respective time point. Functional disability scores (Part C) increased slightly over time but remained significantly improved through the 5 years (p < 0.0001). Similarly, QUEST scores remained significantly improved from baseline at year 4 (p < 0.0001) and year 5 (p < 0.0003). All previously reported AEs remained mild or moderate, and no new AEs were reported.

Conclusions: Unilateral MRgFUS thalamotomy demonstrates sustained and significant tremor improvement at 5 years with an overall improvement in quality-of-life measures and without any progressive or delayed complications. Clinical trial registration no.: NCT01827904 (ClinicalTrials.gov).

Keywords: MRI; essential tremor; focused ultrasound; functional neurosurgery; thalamotomy.

Conflict of interest statement

Drs. Cosgrove, Ghanouni, Eisenberg, and Santini received clinical or research support from InSightec for the study described. Dr. Lozano is a consultant for Medtronic, Abbott, Boston Scientific, and Insightec and the scientific director for Functional Neuromodulation. Dr. Ghanouni is a consultant for InSightec and SonALASense. Dr. Taira is a consultant for and receives honoraria from InSightec Japan. Dr. Santini receives support from Biogen and Genentech for non–study-related clinical or research effort and receives honoraria from the American Academy of Neurology and International Parkinson and Movement Disorder Society. Dr. Hynynen receives royalties from InSightec. Dr. Elias is a consultant for InSightec.

Figures

FIG. 1.

A: Observed change in CRST Part A (postural tremor) scores from baseline (BL) at the annual follow-up, calculated by separate t-tests per visit. Boxes indicate medians with interquartile ranges; whiskers, ranges; and plus signs, means. The mean score values (standard deviations) are noted in blue type. B: Mean observed change in CRST Part A (postural tremor) scores from baseline at the annual follow-up. Mo = month. Figure is available in color online only.

FIG. 2.

A: Observed change in CRST Parts A and B (tremor/motor) scores from baseline at the annual follow-up, calculated by separate t-tests per visit. Boxes indicate medians with interquartile ranges; whiskers, ranges; and plus signs, means. The mean score values (standard deviations) are noted in blue type. B: Mean observed change in CRST Parts A and B (tremor/motor) scores from baseline at the annual follow-up. Figure is available in color online only.

FIG. 3.

A: Observed change in CRST Part C (disability) scores from baseline at the annual follow-up, calculated by separate t-tests per visit. Boxes indicate medians with interquartile ranges; whiskers, ranges; and plus signs, means. The mean score values (standard deviations) are noted in blue type. B: Mean observed change in CRST Part C (disability) scores from baseline at the annual follow-up. Figure is available in color online only.

FIG. 4.

Observed change in total QUEST scores from baseline at the annual follow-up, calculated by separate t-tests per visit. Boxes indicate medians with interquartile ranges; whiskers, ranges; and plus signs, means. The mean score values (standard deviations) are noted in blue type. Figure is available in color online only.

FIG. 5.

Observed change in QUEST dimension subscores from baseline at the annual follow-up, calculated by separate t-tests per visit. Boxes indicate medians with interquartile ranges; whiskers, ranges; and plus signs, means. The mean score values (standard deviations) are noted in blue type. Graphs are shown only for the significant dimension outcomes. Figure is available in color online only.