Magnetic resonance-guided focused ultrasound for the treatment of tremor

ABSTRACT

Introduction

Magnetic resonance-guided focused ultrasound (MRgFUS) is an emerging treatment for tremor and other movement disorders. An incisionless therapy, it is becoming increasingly common worldwide. However, given MRgFUS’ relative novelty, there remain limited data on its benefits and adverse effects.

Areas covered

We review the current state of evidence of MRgFUS for tremor, highlight its challenges, and discuss future perspectives.

Expert opinion

Essential tremor (ET) has been the major indication for MRgFUS since a milestone randomized controlled trial (RCT) in 2016, with substantial evidence attesting to the efficacy and acceptable safety profile of this treatment. Patients with other tremor etiologies are also being treated with MRgFUS, with studies – including an RCT – suggesting parkinsonian tremor in particular responds well to this intervention. Additionally, targets other than the ventral intermediate nucleus, such as the subthalamic nucleus and internal segment of the globus pallidus, have been reported to improve parkinsonian symptoms beyond tremor, including rigidity and bradykinesia. Although MRgFUS is encumbered by certain unique technical challenges, it nevertheless offers significant advantages compared to alternative neurosurgical interventions for tremor. The fast-growing interest in this treatment modality will likely lead to further scientific and technological advancements that could optimize and expand its therapeutic potential.

KEYWORDS:

• Basal ganglia
• essential tremor
• magnetic resonance-guided focused ultrasound
• pallidotomy
• Parkinson’s disease
• subthalamotomy
• thalamotomy
• ventral intermediate nucleus

Article highlights

• MRgFUS is a novel stereotactic modality to treat tremor.

• Its incisionless nature and real-time temperature feedback constitute unique advantages compared to alternative tremor treatments in use today.

• An increasing number of people will suffer from tremor in the future, and there will be greater demands for surgical management of tremors.

• While some evidence has been established for ET and PD, many questions and issues remain unsolved.

• MRgFUS for multiple indications and targets are under investigation.

• The rapid increase in the number of publications of MRgFUS for tremors in the last several years suggests an increased level of interest in this treatment.

• Given the fast-growing interest in this treatment, scientific and technological advancements will be enhanced to solve the current issues in the coming decade.

Abbreviations

CI, confidence interval; CRST, Clinical Rating Scale for Tremor; CTT, cerebellothalamic tract; cZI, caudal zona incerta;DBS, deep brain stimulation; ET, essential tremor; FDA, Food and Drug Administration; GA, general anesthesia; GPi, globus pallidus internus; MDS, Movement Disorder Society; MR, magnetic resonance; MRgFUS, magnetic resonance-guided focused ultrasound; MS, multiple sclerosis; PD, Parkinson’s disease; PDQ-39, 39-item Parkinson’s Disease Questionnaire; PPN, pedunculopontine nucleus; PSA, posterior subthalamic area; PTT, pallidothalamic tract; QUEST, Quality of Life in Essential Tremor; RCT, randomized controlled trial; RF, radiofrequency; SDR, skull density ratio; STN, subthalamic nucleus; TDPD, tremor-dominant Parkinson’s disease; UPDRS, Unified Parkinson’s Disease Rating Scale; VIM, ventral intermediate; VOP, ventralis oralis posterior.

Declaration of interest

C Sarica has been receiving fellowship grants from Michael and Amira Dan Foundation and Turkish Neurosurgical Society. AM Lozano is Scientific Director for Functional Neuromodulation Ltd. and a consultant to Medtronic, Abbott, Boston Scientific, Insightec, and Focused Ultrasound Foundation. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/14737175.2022.2147826

Additional information

Funding

This paper was not funded