Science Times: Development of a Clinically Useful Algorithm for Tractography-Based Ventral Intermediate Nucleus Targeting

Essential tremor, characterized by a persistent, bilateral kinetic and postural tremor, is a common neurological disorder with a prevalence of 0.9% in the general population, and up to 4.6% in those over age 65. Deep brain stimulation (DBS) and thalamotomy of the ventral intermediate nucleus (Vim) of the thalamus can successfully control upper limb tremor. Treatment efficacy depends on precise targeting of the Vim, particularly areas with a high degree of connectivity among regions implicated in the “tremor network,” including the ipsilateral motor cortex and contralateral cerebellum. Indirect targeting is a common method used to locate the Vim target that superimposes atlas-derived coordinates onto a patient’s unique magnetic resonance imaging (MRI) scan. Unfortunately, this approach does not account for interindividual anatomic variability, and MRI limits visualization of individual thalamic nuclei. Individualized tractography may provide more robust anatomic data for targeting thalamic nuclei. A recent study by Sammartino et al1 presents a novel method for determining the tractography-based Vim target (T-Vim) for ultimate use in the clinical treatment of essential tremor.

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