Multimodal Quantitative MRI Reveals No Evidence for Tissue Pathology in Idiopathic Cervical Dystonia

Abstract

Background: While in symptomatic forms of dystonia cerebral pathology is by definition present, it is unclear so far whether disease is associated with microstructural cerebral changes in idiopathic dystonia. Previous quantitative MRI (qMRI) studies assessing cerebral tissue composition in idiopathic dystonia revealed conflicting results. Objective: Using multimodal qMRI, the presented study aimed to investigate alterations in different cerebral microstructural compartments associated with idiopathic cervical dystonia in vivo. Methods: Mapping of T₁, T₂, ${\text{T}}_2^{*}$ , and proton density (PD) was performed in 17 patients with idiopathic cervical dystonia and 29 matched healthy control subjects. Statistical comparisons of the parametric maps between groups were conducted for various regions of interest (ROI), including major basal ganglia nuclei, the thalamus, white matter, and the cerebellum, and voxel-wise for the whole brain. Results: Neither whole brain voxel-wise statistics nor ROI-based analyses revealed significant group differences for any qMRI parameter under investigation. Conclusions: The negative findings of this qMRI study argue against the presence of overt microstructural tissue change in patients with idiopathic cervical dystonia. The results seem to support a common view that idiopathic cervical dystonia might primarily resemble a functional network disease.

Keywords: idiopathic dystonia; movement disorders; proton density; quantitative MRI; relaxometry.

Figure 1

Regions of interest used for the evaluation of qMRI data demonstrated for a representative subject in MNI 152 standard space (z = 8). Blue: pallidum; red: putamen; green: caudate nucleus; violet: white matter; yellow: thalamus.

Figure 2

Quantitative T₁, T₂, ${\text{T}}_2^{*}$, and proton density maps shown for the same subject presented in Figure 1 (z = 8).

Figure 3

Region of interest-based analysis of T₁, T₂, and ${\text{T}}_2^{*}$ relaxation times and proton density. qMRI values were averaged across bilateral ROIs and presented as boxplots (median, upper, and lower quartile and 90% CI) for the patients with idiopathic cervical dystonia (DT) and healthy control subjects (HC). P-values for between-group comparisons are inserted into the diagram below the corresponding boxplots. Ncl., nucleus; cerebel., cerebellum.