Abstract
Objective: Language acquisition was assumed to proceed normally in children with unilateral hearing loss (UHL) since they have one functioning ear. However, children with UHL score poorly on speech-language tests and have higher rates of educational problems compared to normal hearing (NH) peers. Diffusion tensor imaging (DTI) is an imaging modality used to measure microstructural integrity of brain white matter. The purpose of this pilot study was to investigate differences in fractional anisotropy (FA) and mean diffusivity (MD) in hearing- and non-hearing-related structures in the brain between children with UHL and their NH siblings.Study Design: Prospective observational cohort.Setting: Academic medical center.Subjects and Methods: Sixty one children were recruited, tested and imaged. Twenty nine children with severe-to-profound UHL were compared to 20 siblings with NH using IQ and oral language testing, and MRI with DTI. Twelve children had inadequate MRI data. Parents provided demographic data and indicated whether children had a need for an individualized educational program (IEP) or speech therapy (ST). DTI parameters were measured in auditory and non-auditory regions of interest (ROIs). Between-group comparisons were evaluated with non-parametric tests.Results: Lower FA of left lateral lemniscus was observed for children with UHL compared to their NH siblings, as well as trends toward differences in other auditory and non-auditory regions. Correlation analyses showed associations between several DTI parameters and outcomes in children with UHL. Regression analyses revealed relationships between educational outcome variables and several DTI parameters, which may provide clinically useful information for guidance of speech therapy.Discussion/Conclusion: Our data suggests that white matter microstructural patterns in several brain regions are preserved despite unilateral rather than bilateral auditory input which contrasts with findings in patients with bilateral hearing loss.
Highlights
Unilateral hearing loss (UHL) often goes undetected until children begin school, prevalence rates of unilateral hearing loss (UHL) in newborns range from 0.04 to 3.4% (Mehl and Thomson, 1998; Widen et al, 2000)
Lower fractional anisotropy (FA) of left lateral lemniscus was observed for children with UHL compared to their normal hearing (NH) siblings, as well as trends toward differences in other auditory and non-auditory regions
There were no significant differences in gender, age, racial composition, handedness or rates of prematurity between the NH and UHL groups
Summary
Unilateral hearing loss (UHL) often goes undetected until children begin school, prevalence rates of UHL in newborns range from 0.04 to 3.4% (Mehl and Thomson, 1998; Widen et al, 2000). Studies have estimated the prevalence of UHL in schoolaged children (ages 6–19 years) as high as 5% (Niskar et al, 1998). In one study, when compared with their normal hearing (NH) siblings, children (ages 6–12 years) with UHL had substantially worse oral language scores (Lieu et al, 2010). Other investigators have found evidence of increased rates of behavioral problems, a greater need for intensive educational plans and worse performance in school amongst children with UHL (Bess, 1982; Bess and Tharpe, 1984; Davis et al, 2002)
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