Characterizing Thalamo-Cortical Structural Connectivity in Essential Tremor with Diffusional Kurtosis Imaging Tractography. (2nd September 2019)

• Record Type: Journal Article
• Authors: Revuelta, Gonzalo; McGill, Corinne; Jensen, Jens H.; Bonilha, Leonardo
• Is Part Of: Tremor and other hyperkinetic movements. Volume 9(2019)
• Publication Date: 2019-09-02
• Subjects: Essential tremor -- structural connectivity -- thalamus -- thalamo-cortical -- kurtosis -- tractography; Tremor -- Periodicals; Hyperkinesia -- Periodicals; 616.8
• DOI: 10.7916/tohm.v0.690
• Languages: English
• ISSNs: 2160-8288

Abstract

Background: Neuromodulation of the cerebello-thalamo-cortical (CTC) circuit via thalamic stimulation is an effective therapy for essential tremor (ET). In order to develop non-invasive neuromodulation approaches, clinically relevant thalamo-cortical connections must be elucidated. Methods: Twenty-eight subjects (18 ET patients and 10 controls) underwent MRI diffusional kurtosis imaging (DKI). A deterministic fiber-tracking algorithm based on DKI was used, with a seeding region placed at the ventral intermediate nucleus (Vim—located based on intraoperative physiology) to the ending regions at the supplementary motor area (SMA), pre-SMA, or primary motor cortex. One-tailed t -tests were performed to compare groups, and associations with tremor severity were determined by Pearson correlations. All p-values were adjusted for multiple comparisons using Bonferroni correction. Results: There was a decrease in the mean diffusivity (MD) in patients compared to controls in all three tracts: Vim-M1 (ET 0.87, control 0.96, p < 0.01), Vim-SMA (ET 0.86, control 0.96, p < 0.05), and Vim-pre-SMA (ET 0.87, control 0.95, p < 0.05). There was a significant positive correlation between Tremor Rating Scale score and MK ( r = 0.471, p = 0.033) and mean FA ( r = 0.438, p = 0.045) for the Vim-SMA tract, and no significant correlation for the Vim-pre-SMA or Vim-M1 tracts was found. Discussion: Patients with ET demonstrated a reinforcement of Vim-cortical connectivity, with higher Vim-SMA connectivity being associated with greater tremor severity. This finding suggests that the Vim-SMA connection is relevant to the underlying pathophysiology of ET, and inhibition of the SMA may be an effective therapeutic approach.