Evaluation of Cerebral White Matter in Prelingually Deaf Children Using Diffusion Tensor Imaging

Abstract

This study compared white matter development in prelingually deaf and normal-hearing children using a tract-based spatial statistics (TBSS) method. Diffusion tensor imaging (DTI) was performed in 21 prelingually deaf (DEAF group) and 20 normal-hearing (HEAR group) subjects aged from 1.7 to 7.7 years. Using TBSS, we evaluated the regions of significant difference in fractional anisotropy (FA) between the groups. Correlations between FA values and age in each group were also analyzed using voxel-wise correlation analyses on the TBSS skeleton. Lower FA values of the white matter tract of Heschl's gyrus, the inferior frontooccipital fasciculus, the uncinate fasciculus, the superior longitudinal fasciculus, and the forceps major were evident in the DEAF group compared with those in the HEAR group below 4 years of age, while the difference was not significant in older subjects. We also found that age-related development of the white matter tracts may continue until 8 years of age in deaf children. These results imply that development of the cerebral white matter tracts is delayed in prelingually deaf children.

Figure 1

The tracts of interest of the FSL JHU White Matter Tractography Atlas Tool. SLF, superior longitudinal fasciculus; UF, uncinate fasciculus; IFOF, inferior frontooccipital fasciculus; FM, forceps major; HG, Heschl's gyrus.

Figure 2

Voxel-wise statistical analyses of skeleton-space FA images. (a) Effects of age on regional FA in both groups. White matter tracts in red-yellow reveal a significant age-related increase in FA. In the DEAF group, significant correlations with age appear for nearly every white matter tract. (b) White matter structures exhibiting significantly lower FAs in the DEAF4 group (P < 0.05, corrected for multiple comparisons). The background image is a group-specific brain template. Green voxels are the FA white matter skeleton. Red to yellow voxels show regions of lower FA values in the DEAF4− group compared with the HEAR4− group. Axial sections with z-values ranging from −12 to 30 (the MNI coordinates) are shown.

Figure 3

The mean FA values in tracts of interest [the superior longitudinal fasciculus (SLF); the uncinate fasciculus (UF); the inferior frontooccipital fasciculus (IFOF); the forceps major (FM); and the white matter tracts leading to Heschl's gyrus (HG)]. In the DEAF group, DEAF4− subjects (compared with DEAF4+ subjects) exhibited significantly lower FA values in each tract of interest. However, in the HEAR group, no significant difference was apparent between HEAR 4− and HEAR4+ subjects except in the right UF. Of subjects aged <4 years, those in the DEAF4− group exhibited significantly lower FA values in all tracts of interest (except the UF) than did HEAR4− subjects. However, in subjects aged >4 years, no significant difference was apparent between the DEAF4+ and HEAR4+ groups.