Structural white matter abnormalities in patients with idiopathic dystonia

Abstract

We investigated whether structural white matter abnormalities, in the form of disruption of axonal coherence and integrity as measured with diffusion tensor imaging (DTI), constitute an underlying pathological mechanism of idiopathic dystonia (ID), independent of genotype status. We studied seven subjects with ID: all had cervical dystonia as their main symptom (one patient also had spasmodic dysphonia and two patients had concurrent generalized dystonia, both DYT1-negative). We compared DTI MR images of patients with 10 controls, evaluating differences in mean diffusivity (MD) and fractional anisotropy (FA). ID was associated with increased FA values in the thalamus and adjacent white matter, and in the white matter underlying the middle frontal gyrus. ID was also associated with increase in MD in adjacent white matter to the pallidum and putamen bilaterally, left caudate, and in subcortical hemispheric regions, including the postcentral gyrus. Abnormal FA and MD in patients with ID indicate that abnormal axonal coherence and integrity contribute to the pathophysiology of dystonia. These findings suggest that ID is not only a functional disorder, but also associated with structural brain changes. Impaired connectivity and disrupted flow of information may contribute to the impairment of motor planning and regulation in dystonia.

Structural, functional and molecular imaging of the brain in primary focal dystonia—A review

“…Besides, it suggests loss of neurons in the prefrontal cortex, SMA and the corpus callosum (Fabbrini et al, 2008). In contrast to this, Bonilha et al (2007) found an increase in FA in the thalamus, basal ganglia and adjacent white matter and significant decreased FA in the frontal projections in 7 patients suffering mainly from CD. In a later study, the same group found disrupted thalamic-prefrontal pathways in 7 patients with mainly CD compared to controls (Bonilha et al, 2009).…”

A Transverse and Longitudinal MR Imaging Voxel-Based Morphometry Study in Patients with Primary Cervical Dystonia

“…In CD, DTI abnormalities in the putamen, caudate head, pallidum, prefrontal cortex, SMA, and corpus callosum have been previously demonstrated. [19][20][21][22] In patients with focal hand dystonia, VBM data receive support from the recent finding of DTI abnormalities in the fiber tracts connecting the primary sensorimotor areas with subcortical structures. 23 The reduced connectivity reported in the subcortical white matter of the sensorimotor area in DYT1 mutation carriers 24 further supports the axonal loss in this subcortical white matter region and abnormalities in the neuronal density in the overlying cortex, which may contribute to the development of dystonia.…”

Structural brain abnormalities in cervical dystonia

“…Diffusivity was enhanced in the prefrontal cortex and decreased in the caudate nucleus and putamen [9]. In contrast, in another ROI study, diffusivity in the pallidum, putamen and caudate nucleus was increased in patients with cervical dystonia [6,10]. …”