Selective Alterations of White Matter Associated with Visuospatial and Sensorimotor Dysfunction in Turner Syndrome

Abstract

Turner syndrome (TS) is a neurogenetic disorder characterized by impaired spatial, numerical, and motor functioning but relatively spared verbal ability. Results from previous neuroimaging studies suggest that gray matter alterations in parietal and frontal regions may contribute to atypical visuospatial and executive functioning in TS. Recent findings in TS also indicate variations in the shape of parietal gyri and white matter microstructural anomalies of the temporal lobe. Diffusion tensor imaging and structural imaging methods were used to determine whether 10 females with TS and 10 age-and gender-matched control subjects exhibited differences in fractional anisotropy, white matter density, and local brain shape. Relative to controls, females with TS had lower fractional anisotropy (FA) values in the deep white matter of the left parietal-occipital region extending anteriorly along the superior longitudinal fasciculus into the deep white matter of the frontal lobe. In addition, decreased FA values were located bilaterally in the internal capsule extending into the globus pallidus and in the right prefrontal region. Voxel-based morphometry (VBM) analysis showed corresponding white matter density differences in the internal capsules and left centrum semiovale. Tensor-based morphometry analysis indicated that the FA and VBM results were not attributable to differences in the local shape of brain structures. Compared with controls, females with TS had increases in FA values and white matter density in language-related areas of the inferior parietal and temporal lobes. These complementary analyses provide evidence for alterations in white matter pathways that subserve affected and preserved cognitive functions in TS.

More Is Not Always Better: Increased Fractional Anisotropy of Superior Longitudinal Fasciculus Associated with Poor Visuospatial Abilities in Williams Syndrome

“…This hypothesis would be consistent with findings of reduced brain activation in the parietal region during visuospatial processing (MeyerLindenberg et al, 2004). These interpretations remain to be tested in future studies, because previous studies showed increased FA as potentially reflecting both compensatory mechanisms (Holzapfel et al, 2006) and poor cognitive functioning (Tuch et al, 2005).…”

“…Among the DD individuals, seven had idiopathic DD, and three had a diagnosis of fragile X syndrome, Turner syndrome, or velocardiofacial syndrome, and were diagnosed as in previous publications from our group Gothelf et al, 2005Gothelf et al, , 2007aThompson et al, 2005;Holzapfel et al, 2006;Kesler et al, 2006;Hoeft et al, 2007).…”

Cortical anatomy in human X monosomy

“…These regions are notable in that (i) they are known to be connected to the IPS by white matter tracts which are thought to be disrupted in TS (e.g. inferior and superior longitudinal fasciculus) based on diffusion tensor imaging (DTI) and sMRI data (Cutter et al, 2006; Holzapfel et al, 2006; Molko et al, 2004), and (ii) simultaneous functional abnormalities within many of these regions have been previously documented in TS during fMRI studies [(Kesler et al, 2006; Molko et al, 2003) - left intra-parietal sulcus, left supramarginal gyrus, superior and middle temporal cortices, cingulate and right inferior and middle frontal cortices during numerical reasoning].…”

Estrogen and hearing from a clinical point of view; characteristics of auditory function in women with Turner syndrome

“…Holzapfel et al performed neuroimaging on females with Turner syndrome in search of altered areas causing the visuo-spatial and sensorimotor dysfunction in these women (Holzapfel et al, 2006). They report changes in the left parieto-occipital region extending into the frontal lobe and bilaterally in the internal capsule extending into the globus pallidus and in the right prefrontal region.…”