Radiosurgical thalamotomy for essential tremor: state of the art, current challenges and future directions

ABSTRACT

Introduction

Essential tremor (ET) is the most frequent movement disorder, affecting up to 5% of adults > 65 years old. In 30–50% of cases, optimal medical management provides insufficient tremor relief and surgical options are considered. Thalamotomy is a time-honored intervention, which can be performed using radiofrequency (RF), stereotactic radiosurgery (SRS), or magnetic resonance-guided focused ultrasounds (MRgFUS). While the latter has received considerable attention in the last decade, SRS has consistently been demonstrated as an effective and well-tolerated option.

Areas covered

This review discusses the evidence on SRS thalamotomy for ET. Modern workflows and emerging techniques are detailed. Current outcomes are analyzed, with a specific focus on tremor reduction, complications and radiological evolution of the lesions. Challenges for the field are highlighted.

Expert opinion

SRS thalamotomy improves tremor in > 80% patients. The efficacy appears comparable to other modalities, including DBS, RF and MRgFUS. Side effects result mostly from idiosyncratic hyper-responses to radiation, which occur in up to 10% of treatments, are usually self-resolving, and are symptomatic in < 4% of patients. Future research should focus on accumulating more data on bilateral treatments, collecting long-term outcomes, refining targeting, and improving lesion consistency.

KEYWORDS:

• Radiosurgery
• gamma knife
• SRS
• thalamotomy
• tremor

Article highlights

• SRS thalamotomy improves tremor in > 80% of patients, with an efficacy comparable to other modalities (DBS, RF and MRgFUS);

• Side effects result mostly from idiosyncratic hyper-responses to radiation, which are symptomatic in < 4% of patients;

• Advantages of SRS include hair preservation, ability to continue antithrombotic medication during the procedure, and overall tolerability of the intervention compared to other modalities;

• Disadvantages of SRS include a 4 month latency period before observing the clinical benefit, as well as inconsistencies in the final size of the lesions.

• Future research should focus on accumulating more data on bilateral treatments, collecting long-term (>5-10 years) outcomes, refining targeting, improving lesion consistency, and better predicting tremor response.

Declaration of interest

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.

Additional information

Funding

This work was supported by a Clinicien-Chercheur grant from the Fonds de Recherche du Québec–Santé (CIM).