Outcome and Complications of MR Guided Focused Ultrasound for Essential Tremor: A Systematic Review and Meta-Analysis

Abstract

Background: Magnetic resonance guided focused ultrasound (MRgFUS) is a relatively novel technique to treat essential tremor (ET). The objective of this review was to analyze the efficacy and the safety profile of MRgFUS for ET. Methods: A systematic literature review was done. The post procedure changes in the Clinical Rating Scale for Tremor (CRST) score, hand score, disability and quality of life scores were analyzed. Results: We found 29 studies evaluating 617 patients. DTI based targeting was utilized in six cohorts. A significant difference was observed in the pooled standard mean difference between the pre and postoperative total CRST score (p-value < 0.001 and 0.0002), hand score (p-value 0.03 and 0.02); and the disability at 12 months (p-value 0.01). Head pain and dizziness were the most in procedure complications. The immediate pooled proportion of ataxia was 50%, while it was 20% for sensory complications, which, respectively, declined to 31 and 13% on long term follow up. A significant reduction (p = 0.03) in immediate ataxia related complications was seen with DTI targeting. Conclusion: MRgFUS for ET seems to be an effective procedure for relieving unilateral tremor. Use of DTI based targeting revealed a significant reduction in post procedure ataxia related complications as compared to traditional targeting techniques. Analysis of other complications further revealed a decreasing trend on follow up.

Keywords: cerebellothalamic tract; diffusion tensor imaging; essential tremor; magnetic resonance guided focused ultrasound; targeting technique comparison; ventral intermediate nucleus.

Figure 1

(A) PRISMA flow diagram outlining the literature search process. (B) Bar chart depicting the type and number of studies with year of publication. (C) Bar chart depicting the country where the study was conducted. (D) Bar chart depicting the trend in targeting technique over the years.

Figure 2

Pooled standard mean difference between preoperative and postoperative total CRST score at 3 months (A), total CRST score at 12 months (B), hand score at 3 months (C) and hand score at 12 months (D).

Figure 3

Pooled standard mean difference between preoperative and postoperative disability scores at 3 months (A), disability scores at 12 months (B), QUEST scores at 3 months (C) and QUEST scores at 6 months (D).

Figure 4

Forest plots depicting pooled proportions of immediate sensory (A), motor (B), ataxia (C) and speech and swallowing (D) related complications.