Assessing Cerebral White Matter Microstructure in Children With Congenital Sensorineural Hearing Loss: A Tract-Based Spatial Statistics Study

Abstract

Objectives: To assess the microstructural properties of cerebral white matter in children with congenital sensorineural hearing loss (CSNHL).

Methods: Children (>4 years of age) with profound CSNHL and healthy controls with normal hearing (the control group) were enrolled and underwent brain magnetic resonance imaging (MRI) scans with diffusion tensor imaging (DTI). DTI parameters including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were obtained from a whole-brain tract-based spatial statistics analysis and were compared between the two groups. In addition, a region of interest (ROI) approach focusing on auditory cortex, i.e., Heschl's gyrus, using visual cortex, i.e., forceps major as an internal control, was performed. Correlations between mean DTI values and age were obtained with the ROI method.

Results: The study cohort consisted of 23 children with CSHNL (11 boys and 12 girls; mean age ± SD: 7.21 ± 2.67 years; range: 4.1-13.5 years) and 18 children in the control group (11 boys and 7 girls; mean age ± SD: 10.86 ± 3.56 years; range: 4.5-15.3 years). We found the axial diffusivity values being significantly greater in the left anterior thalamic radiation, right corticospinal tract, and corpus callosum in the CSHNL group than in the control group (p < 0.05). Significantly higher radial diffusivity values in the white matter tracts were noted in the CSHNL group as compared to the control group (p < 0.05). The fractional anisotropy values in the Heschl's gyrus in the CSNHL group were lower compared to the control group (p = 0.0015). There was significant negative correlation between the mean fractional anisotropy values in Heschl's gyrus and age in the CSNHL group < 7 years of age (r = -0.59, p = 0.004).

Conclusion: Our study showed higher axial and radial diffusivities in the children affected by CNHNL as compared to the hearing children. We also found lower fractional anisotropy values in the Heschl's gyrus in the CSNHL group. Furthermore, we identified negative correlation between the fractional anisotropy values and age up to 7 years in the children born deaf. Our study findings suggest that myelination and axonal structure may be affected due to acoustic deprivation. This information may help to monitor hearing rehabilitation in the deaf children.

Keywords: congenital sensorineural hearing loss; diffusion tensor imaging; diffusivity; magnetic resonance imaging; tract-based spatial statistics; white matter.

FIGURE 1

Axial diffusivity (AD) map showing significantly higher AD values in the CSHNL group as compared to the control group. The red–yellow highlighted areas indicate higher AD values in the right corticospinal tract, left anterior thalamic radiation, and left corpus callosum. The background image consists of the standard MNI T1-weighted template at 1-mm thickness and the FA skeleton (green). The images at the bottom row from the left side to the right side indicate sagittal, coronal, and axial images for one representative axial level.

FIGURE 2

Radial diffusivity (RD) map showing significantly higher RD values in the CSHNL group as compared to the control group. The red–yellow highlighted areas indicate higher RD values in left inferior fronto-occipital fasciculus (IFOF) and left anterior thalamic radiation. The background image consists of the standard MNI T1-weighted template at 1-mm thickness and the fractional anisotropy (FA) skeleton (green). The images at the bottom row from the left side to the right side indicate sagittal, coronal, and axial images for one representative axial level.

FIGURE 3

The white matter (WM) tracts of interest selected for region of interest (ROI) analysis. (A) Axial, (B) sagittal, and (C) coronal images of the selected brain regions.

FIGURE 4

The mean FA values for the HG and the FM in both the CSNHL group and the control group.

FIGURE 5

Correlation analysis between the mean FA values and age. The mean FA values on the Y-axis indicate the differences between the Heschl’s gyrus (HG) and the forceps major (FM). (A) Correlation between the mean FA values and age in the CSNHL group < 7 years of age. (B) Correlation between the mean FA values and age in the CSNHL group ≥ 7 years of age.