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Updated: Jun 2, 2026
MRI-guided Focused Ultrasound Thalamotomy for Patients with Medically-refractory Essential Tremor
Published on: December 13, 2017
Objective Quantification of Tremor and Gait After Focused Ultrasound Thalamotomy: Outcome Variability and Adverse
Katy A Cross1, Emily Koenig2, Wenxin Wei3
1Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA.
Background And Objectives:
MRI-guided focused ultrasound (MRgFUS) thalamotomy is an effective therapy for contralateral upper extremity tremor, but outcomes are variable across patients. In addition, speech, sensory, motor, and gait side effects can be more common acutely after MRgFUS thalamotomy than after deep brain stimulation to the same target. Using objective quantification with inertial measurement units and a digitizing tablet, we performed an observational cohort study to identify sources of outcome variability, relationships between efficacy and side effects, and objective measures of gait dysfunction after MRgFUS.
Methods:
Gait, static balance, and tremor were assessed in 54 patients (7 with Parkinson disease, 47 with essential tremor) immediately before and within 48 hours after MRgFUS therapy.
Results:
Tremor efficacy was robust for contralateral tremor, with postural, rest, and spiral-drawing demonstrating greater improvement than finger-to-nose task. Patients with more severe tremor had greater reduction but also greater residual tremor. Ipsilateral postural but not kinetic tremor improved, albeit to a small degree. Side effects were unrelated to tremor benefits. Gait asymmetry increased after the procedure on average; however, no specific gait features explained the subjective gait imbalance that was reported by 70% of patients.
Conclusion:
Tremor efficacy depends on task and pretreatment severity. A lack of relationship between efficacy and side effects suggests that robust tremor reduction may be achieved without side effects and that improved targeting has potential to improve the safety of MRgFUS.
