The use of magnetic resonance-guided high intensity focused ultrasound to treat essential tremor

Abstract

Advances in ultrasound transducer technology have enabled for transcranial sonication with energy levels adequate to achieve tissue ablation. With MR-guidance and monitoring, precise lesioning is now possible of deep brain targets such as the thalamus and basal ganglia so that stereotactic lesioning is being reconsidered for the treatment of movement disorders. In this phase 1 clinical trial, we investigate the feasibility and safety of MRgFUS for performing a unilateral thalamotomy for medication-refractory essential tremor (ET). According to an FDA-approved protocol, 15 patients with medication-resistant ET underwent unilateral MRgFUS lesioning of the thalamus for dominant limb tremor. Intraprocedural monitoring was conducted with each incremental sonication using MR thermometry and clinical examination. Neurological assessments, validated tremor ratings, MRI, and quality of life data were recorded preoperatively and during a year post treatment. Adverse events were recorded throughout the study duration. Accurate thalamic lesioning was achieved in all cases. Dominant limb tremor subscores improved by nearly 75% while ipsilateral limb tremor was unchanged. Functional activities and quality of life measures improved significantly. Refining of the thalamic target was possible in five cases with subthreshold sonications. Serial MR imaging defined the evolution of the lesioning process.