Delayed clinical response to focused ultrasound thalamotomy in essential tremor in a patient with suboptimal skull density ratio - A case report.
Authors: Chowdhury EA, Sivan V, Kumar RP, Ruzicka Iv FF, Azmi H
Magnetic resonance imaging-guided focused ultrasound (MRgFUS) thalamotomy offers incisionless treatment for essential tremor or tremor-dominant Parkinson's disease, gaining acceptance as an alternative to deep brain stimulation. Compared to other methods, it offers real-time efficacy assessment without ionizing radiation. A 63-year-old male underwent MRgFUS, initially yielding subtle results due to skull limitations. However, significant tremor relief emerged 6 hours post-procedure, sustained for 5 days. Imaging confirmed thalamotomy effect. A second treatment was delivered at day five for longevity. For patients with challenging skull characteristics and initial suboptimal outcomes, staged procedures may be considered, with potential delayed benefits and the need for lesion expansion for long-term relief.
Introduction
Purpose
Thermal ablation
Study Objective
To report a case demonstrating that staged MRgFUS thalamotomy can produce delayed and sustained tremor relief in a patient with skull characteristics limiting initial treatment efficacy.
Animal model / Human subject
Homo sapiens, strain N/A, 63 years, male
Disease model
Essential tremor / tremor-dominant Parkinson's disease
MRI or image guidance method
MRI-guided (MRgFUS)
Targeted brain region(s)
Thalamus
Outcomes and Safety
Summary of Outcomes
In a patient with unfavorable skull characteristics, MRgFUS thalamotomy produced delayed tremor arrest (~6 hours post-procedure) with radiologic lesion formation and sustained benefit after a staged repeat treatment despite requiring higher-energy sonications to reach target temperatures; no multiple ultrasound-parameter comparisons were performed.
Duration of biological effect
> 9 months
Safety-related matter
The procedure is described as having a relatively low-risk profile, but subthreshold sonication 'mapping' is important to assess side effects such as paresthesias from proximity to the sensory ventral caudal nucleus; challenging skull characteristics and the need for higher energy can limit mapping and complicate management.
Brain Region
Ultrasound Parameters
Ultrasound instrument
MRI-guided FUS
Focal Characteristics
Focal depth: None; Focal length: None; Aperture size: None
Treatment frequency
multiple
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