Abstract
ABSTRACTBackgroundThe ventral intermediate nucleus of the thalamus is not readily visible on structural magnetic resonance imaging. Therefore, a method for its visualization for stereotactic targeting is desirable.ObjectiveThe objective of this study was to define a tractography‐based methodology for the stereotactic targeting of the ventral intermediate nucleus.MethodsThe lateral and posterior borders of the ventral intermediate nucleus were defined by tracking the pyramidal tract and medial lemniscus, respectively. A thalamic seed was then created 3 mm medial and anterior to these borders, and its structural connections were analyzed. The application of this method was assessed in an imaging cohort of 14 tremor patients and 15 healthy controls, in which we compared the tractography‐based targeting to conventional targeting. In a separate surgical cohort (3 tremor and 3 tremor‐dominant Parkinson's disease patients), we analyzed the accuracy of this method by correlating it with intraoperative neurophysiology.ResultsTractography of the thalamic seed revealed the tracts corresponding to cerebellar input and motor cortical output fibers. The tractography‐based target was more lateral (12.5 [1.2] mm vs 11.5 mm for conventional targeting) and anterior (8.5 [1.1] mm vs 6.7 [0.3] mm, anterior to the posterior commissure). In the surgical cohort, the Euclidian distance between the ventral intermediate nucleus identified by tractography and the surgical target was 1.6 [1.1] mm. The locations of the sensory thalamus, lemniscus, and pyramidal tracts were concordant within <1 mm between tractography and neurophysiology.InterpretationThe tractography‐based methodology for identification of the ventral intermediate nucleus is accurate and useful. This method may be used to improve stereotactic targeting in functional neurosurgery procedures. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society
Highlights
IntroductionEssential tremor (ET) is a common movement disorder with a prevalence of between 0.4% to 4%.1
The distance from the midline was similar for each method for the Essential tremor (ET) patients (15-mm conventional coordinate vs 15.03 [1.3] mm, P 5 .99), but significantly different for controls (15-mm conventional coordinate vs 13.5 [1.4] mm for T-ventral intermediate nucleus (VIM), P 5 .00005)
Using the pyramidal tract (PT) and the medial lemniscus (ML) as internal landmarks, an Region of Interest (ROI) for the T-VIM was created similar to the anatomical size of this thalamic subnucleus and identified its structural connectivity with the cerebellum and the motor cortex
Summary
Essential tremor (ET) is a common movement disorder with a prevalence of between 0.4% to 4%.1. It can significantly compromise a patient’s ability to perform activities of daily living.[2] Effective medications for tremor control are limited.[3] Surgical treatment for advanced refractory tremor includes lesioning of the ventral intermediate nucleus (VIM) with radiofrequency,[4] gamma knife,[5] magnetic resonance–guided focused ultrasound (MRgFUS),[6,7] and VIM deep brain stimulation (DBS).[3,4] The precise stereotactic targeting of VIM is associated with improved surgical outcomes.[8] Image-based target identification is becoming important for radiosurgery and MRgFUS because little or no intraoperative mapping is possible. This approach is computationally intensive and ideally suited for research investigations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Movement disorders : official journal of the Movement Disorder Society
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
