White Matter Microstructure in Idiopathic Craniocervical Dystonia

Abstract

Background: Dystonias are hyperkinetic movement disorders characterized by involuntary muscle contractions resulting in abnormal torsional movements and postures. Recent neuroimaging studies in idiopathic craniocervical dystonia (CCD) have uncovered the involvement of multiple areas, including cortical ones. Our goal was to evaluate white matter (WM) microstructure in subjects with CCD using diffusion tensor imaging (DTI) analysis. Methods: We compared 40 patients with 40 healthy controls. Patients were then divided into subgroups: cervical dystonia, blepharospasm, blepharospasm + oromandibular dystonia, blepharospasm + oromandibular dystonia + cervical dystonia, using tract-based spatial statistics. We performed a region of interest-based analysis and tractography as confirmatory tests. Results: There was no significant difference in the mean fractional anisotropy (FA) and mean diffusivity (MD) between the groups in any analysis. Discussion: The lack of DTI changes in CCD suggests that the WM tracts are not primarily affected.

Isolated focal dystonia phenotypes are associated with distinct patterns of altered microstructure

“…While our results may at first appear to differ from those reported by Pinheiro et al who found no significant differences in white matter microstructure between groups including BSP patients, CD patients and HC ( Pinheiro et al, 2015 ), their study differed from ours in a few key ways that likely account for the dissimilar findings. First, their dystonia population was more heterogenous division into subgroups resulted in their pure BSP subgroup including only five subjects.…”

“…A strength of this study is that patients included in the imaging analysis were all carefully examined and only those without evidence of dystonia involvement beyond their primary site were included so that only pure phenotypic forms of focal dystonia were included. Enrollment of mixed phenotypes or lack of precise patient selection may have contributed to some of the lack of consistent DTI findings reported thus far in BSP and CD ( Blood et al, 2012 ; Neychev et al, 2011 ; Pinheiro et al, 2015 ; Ramdhani and Simonyan, 2013 ; Yang et al, 2014 ; Zoons et al, 2011 ). One potential limitation to our study is the change of MRI scanners that occurred during conduction of this study.…”

“…To date, only a few DTI studies in dystonia to date have investigated whether changes differ between CD and BSP phenotypes ( Fabbrini et al, 2008 ; Pinheiro et al, 2015 ; Yang et al, 2014 ). None of these prior studies, however, applied probabilistic atlas maps derived using the superior anatomical resolution of a 7 T MRI to investigate gray matter structures including smaller nuclei within the basal ganglia and brainstem.…”

“…Interestingly, Fabbrini et al found no significant DTI changes in a BSP group compared to HC suggesting that microstructural differences may exist between different adult-onset focal dystonia phenotypes. More recently, Pinheiro et al reported finding no differences in DTI measures between HC and patients with either BSP or CD ( Pinheiro et al, 2015 ), however their study focused on evaluating white matter changes and was limited by small numbers of patients in the BSP group.…”

Blepharospasm 40 years later

“…Diffusion tensor imaging is a form of diffusion‐weighted imaging that measures two indices, fractional anisotropy and mean diffusivity. No diffusion tensor imaging changes were observed in 3 studies in which 5 to 16 patients with blepharospasm were compared with healthy controls . However, a more recent study based on 31 patients with blepharospasm revealed fractional anisotropy reductions in the white matter of the left anterior lobe of the cerebellum and in the right precuneus of the parietal lobe (abnormalities that significantly correlated with disease severity and duration) as well as increases in mean diffusivity in the right lentiform nucleus, thalamus, and insula …”