Safety and efficacy of bilateral staged focused ultrasound thalamotomy in refractory essential tremor

Abstract

Essential Tremor is a common movement disorder characterized by postural and kinetic tremor, primarily affecting the upper limbs, head and voice. For patients who fail medical therapy, neurosurgical interventions such as thalamotomy have been explored. This study evaluates the efficacy and safety of bilateral staged Magnetic Resonance Imaging-guided High-Intensity Focused Ultrasound thalamotomy for the treatment of medication-refractory Essential Tremor. From January 2022 to January 2024, 20 patients who had previously undergone successful unilateral focused ultrasound thalamotomy were enrolled. The primary outcome was the change in tremor severity, using the Clinical Rating Scale for Tremor at 6 months post-second side thalamotomy. Secondary outcomes included functional disability, quality of life and adverse events, particularly balance and gait impairments. Results demonstrated significant tremor reduction, with a 59.98% decrease in Clinical Rating Scale for Tremor A + B score from baseline to 6 months after the second thalamotomy. Quality of life also improved markedly, with an 84.91% reduction in disability and significant enhancement in physical and psychosocial aspects of quality of life. Adverse events were predominantly mild; with subjective gait instability and paresthaesia being the most common. Notably, no cases of severe ataxia or cognitive impairment were observed. Bilateral staged Magnetic Resonance Imaging-guided High-Intensity Focused Ultrasound thalamotomy is an effective and safe treatment for medication-refractory Essential Tremor, providing substantial tremor relief and improved quality of life with manageable side effects. These findings support its use as an alternative to more invasive neurosurgical procedures, especially in carefully selected patients.

Keywords: bilateral; essential tremor; focused ultrasound; staged; thalamotomy.

Graphical Abstract

Figure 1

CRST A + B CRST: clinical rating tremor scale. CRST A + B at Baseline, FUS1 (6 months after the first MRgFUS) and FUS2 (6 months after the second MRgFUS). CRST A + B was calculated from the CRST Part A (3 items: resting, postural and action components of hand tremor) and Part B (5 tasks involving handwriting, drawing and pouring). N = 20. ANOVA F = 76.8; P < 0.001. Bonferroni´s post hoc test (all P < 0.001). ***P value < 0.001.

Figure 2

CRST C. CRST: Clinical Rating Tremor Scale. CRST C at Baseline, FUS1 (6 months after the first MRgFUS) and FUS2 (6 months after the second MRgFUS). N = 20. ANOVA F = 103.9; P < 0.001. Bonferroni´s post hoc test: Baseline versus FUS1 P < 0.001; FUS1 versus FUS2 P = 0.308; Baseline versus FUS2 P < 0.001. ***P value < 0.001. NS, no significance.

Figure 3

QUEST. QUEST: Quality of Life in Essential Tremor Questionnaire (QUEST). QUEST outcomes at Baseline, FUS1 (6 months after the first MRgFUS) and FUS2 (6 months after the second MRgFUS). N = 20. Overall score: ANOVA F = 16.9; P < 0.001. Bonferroni´s post hoc test: Baseline versus FUS1 P = 0.398; FUS1 versus FUS2 P = 0.005; Baseline versus FUS2 P < 0.001. Communication score: Friedman´s test Chi2 = 0.20; P = 0.905. Wilcoxon´s test corrected by Bonferroni: Baseline versus FUS1 z = 0 P = 1; FUS1 versus FUS2 z = 1.07 P = 0.855; Baseline versus FUS2 z = 0.27 P = 1. Work and finances score: Friedman´s test Chi2 = 6.74; P = 0.034. Wilcoxon´s test: Baseline versus FUS1 z = 0.74 P = 1; FUS1 versus FUS2 z = 1.56 P = 0.357; Baseline versus FUS2 z = 1.68 P = 0.276. Hobbies score: Friedman´s test Chi2 = 11.31; P = 0.003. Wilcoxon´s test: Baseline versus FUS1 z = 2.53 P = 0.033; FUS1 versus FUS2 z = 1.69 P = 0.273; Baseline versus FUS2 z = 1.99 P = 0.046. Physical score: N = 14, 20, 19. Friedman´s test Chi2 = 10.32; P = 0.006. Wilcoxon´s test: Baseline versus FUS1 z = 0.49 P = 1; FUS1 versus FUS2 z = 3.15 P = 0.006; Baseline versus FUS2 z = 3.11 P = 0.006. Psychosocial score: Friedman´s test Chi2 = 8.98; P = 0.011. Wilcoxon’s test: Baseline versus FUS1 z = 2.14 P = 0.099; FUS1 versus FUS2 z = 2.84 P = 0.012; Baseline versus FUS2 z = 2.08 P = 0.015.