Combining tract‐ and atlas‐based analysis reveals microstructural abnormalities in early Tourette syndrome children

Abstract

Tourette syndrome (TS) is a neurological disorder that causes uncontrolled repetitive motor and vocal tics in children. Examining the neural basis of TS churned out different research studies that advanced our understanding of the brain pathways involved in its development. Particularly, growing evidence points to abnormalities within the fronto-striato-thalamic pathways. In this study, we combined Tract-Based Spatial Statistics (TBSS) and Atlas-based regions of interest (ROI) analysis approach, to investigate the microstructural diffusion changes in both deep and superficial white matter (SWM) in TS children. We then characterized the altered microstructure of white matter in 27 TS children in comparison with 27 age- and gender-matched healthy controls. We found that fractional anisotropy (FA) decreases and radial diffusivity (RD) increases in deep white matter (DWM) tracts in cortico-striato-thalamo-cortical (CSTC) circuit as well as SWM. Furthermore, we found that lower FA values and higher RD values in white matter regions are correlated with more severe tics, but not tics duration. Besides, we also found both axial diffusivity and mean diffusivity increase using Atlas-based ROI analysis. Our work may suggest that microstructural diffusion changes in white matter is not only restricted to the gray matter of CSTC circuit but also affects SWM within the primary motor and somatosensory cortex, commissural and association fibers. Hum Brain Mapp 37:1903-1919, 2016. © 2016 Wiley Periodicals, Inc.

Disrupted topological organization of structural networks revealed by probabilistic diffusion tractography in Tourette syndrome children

“…Furthermore, our result showed that the precuneus is also a structural hub and its structural connection with parietal regions is significantly disrupted in TS children. The previous study [Wen et al, ] also reported significantly reduced FA value or increased RD value in precuneus WM, which reveals microstructural abnormalities in this region and is in line with our finding.…”

“…Evidence from a magnetization transfer ratio (MTR) study also showed WM reductions in the inferior frontal gyrus and cingulate gyrus in TS patients [Muller‐Vahl et al, ], and previous postmortem study [Thomas et al, ] proved MTR reductions correlate with myelin and axonal loss in the WM. So, our results showed that reduced white matter integrity is associated with TS children [Plessen et al, ; Wen et al, ] from a network perspective, and the reduced global and local efficiencies in TS group may indicate a disturbance of the normal balance in their structural brain network, which tends to have a more randomized configuration [Peng et al, ].…”

“…In addition to volumetric approaches, DTI has also been used to investigate, indirectly, the microstructural properties of the regions in TS. The previous diffusion MRI studies found decreased FA and increased MD in superficial WM regions of parieto‐occipital cortex in TS children [Wen et al, ] and suggested that a disrupted myelination mechanism underlie the abnormalities. Increased MD value or decreased FA values could reflect reduced myelination, fewer axons, or atypical organization of axons within the WM tract.…”

“…Following DTI acquisition, we used the FMRIB's Diffusion Toolbox (FDT2.0) within FSL v4.1 (http://www.fmrib.ox.ac.uk/fsl) for DTI processing. As differences in head motion between groups can induce spurious group differences [Yendiki et al, ], prior to the estimation of diffusion, we used the same preprocessing pipeline as in the previous TS study [Wen et al, ] to perform corrections for distortions due to eddy currents and head motion. In detail, we used the eddy tool in FDT, which is a tool to correct for eddy current‐induced distortions and subject movements in diffusion data.…”

Short-range connections in the developmental connectome during typical and atypical brain maturation

“…Philips et al, 2016b) and Tourette’s syndrome (e.g. Wen et al, 2016). It is beyond the scope of this review to discuss all brain disconnectivity in greater depth (for review on disconnection syndromes, see e.g.…”