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Magnetic resonance-guided focused ultrasound thalamotomy as a viable option for essential tremor after deep brain stimulation explantation: illustrative case.

Authors: Souza DN, Folz CC, Seas A, Michael A, Todd L, Harward SC

Essential tremor (ET) has limited pharmacological treatments, and deep brain stimulation (DBS) has emerged as an effective surgical intervention. DBS, although effective and safe, is inherently invasive. Patients at high risk for surgery or who experience complications with DBS are left with limited treatments for medically refractory ET. Magnetic resonance-guided focused ultrasound (MRgFUS) is a less invasive and effective option for these patients. A 67-year-old right-handed male with a 37-year history of refractory ET underwent DBS of the bilateral ventral intermediate nuclei. His postoperative course was complicated by infection requiring device explantation and tremor recurrence. The patient subsequently elected to undergo left MRgFUS thalamotomy. Postoperative imaging illustrated overlap of the left thalamic MRgFUS lesion with the decussating and nondecussating dentato-rubro-thalamic tracts, while avoiding the medial lemniscus and corticospinal tract. The postoperative lesion was slightly posterior and superior to the original DBS lead trajectory. The patient reported 90% tremor reduction 3 months posttreatment, and his Clinical Rating Scale for Tremor score dropped from 47 to 11 with significant quality of life improvement. While MRgFUS is not a replacement for DBS, it is an effective and less invasive option for patients with medically refractory ET at high risk for surgery or who fail treatment with DBS. https://thejns.org/doi/10.3171/CASE25240.

Introduction

Purpose Thermal Ablation
Study Objective To report a case demonstrating the safety and efficacy of MR-guided focused ultrasound thalamotomy as a less invasive treatment for medically refractory essential tremor in a patient who experienced tremor recurrence after DBS explantation.
Animal model / Human subject Homo sapiens (human), strain: N/A, 67-year-old, male
Disease model Essential tremor
MRI or image guidance method Magnetic resonance–guided focused ultrasound (MRgFUS)
Targeted brain region(s) Thalamus
Target coordinates Not provided
Cargo name and characteristics Not Provided
Route of administration not provided

Outcomes and Safety

Summary of Outcomes Unilateral MRgFUS thalamotomy produced an 85-90% reduction in contralateral tremor (Clinical Rating Scale for Tremor 47→11) with significant quality-of-life improvement and only mild transient adverse effects at 3 months; no different focused ultrasound parameters were tested.
Duration of biological effect 3 months
Safety-related matter DBS carries an approximate 4% complication rate, most commonly electrode malfunction and infection — this patient experienced recurrent hardware infections requiring device explantation. MRgFUS is described as a less invasive alternative with essentially no infection risk and only mild transient adverse effects in this case, with staged bilateral safety supported by recent trials, although long-term durability and possible tremor recurrence remain undercharacterized.

Brain Region

Ultrasound Parameters

Ultrasound instrument Not provided
FUS Frequency Not provided
FUS Intensity Not provided
FUS Pressure Not provided
FUS Mode Not provided
Pulse duration Not provided
Duration of a single FUS session Not provided
Focal Characteristics Not provided
Treatment frequency Single session

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