Abstract
Although conventional structural MRI provides vital information in the evaluation of congenital sensorineural hearing loss (SNHL), it is relatively insensitive to white matter microstructure. Our objective was to evaluate possible changes in microstructure of the auditory pathway in children with congenital sensorineural hearing loss (SNHL), and the possible distinction between good and poor outcome of cochlear implantation (CI) patients by using diffusion tensor imaging (DTI). Twenty-four patients with congenital SNHL and 20 healthy controls underwent conventional MRI and DTI examination using a 1.5T MR scanner. The DTI metrics of fractional anisotropy (FA) and mean diffusivity (MD) of six regions of interest (ROIs) positioned along the auditory pathway—the trapezoid body, superior olivary nucleus, inferior colliculus, medial geniculate body, auditory radiation and white matter of Heschl's gyrus—was measured in all subjects. Among the 24 patients, 8 patients with a categorie of auditory performance (CAP) score over 6 were classified into the good outcome group, and 16 patients with a CAP score below 6 were classified into the poor outcome group. A significant decrease was observed in FA values while MD values remained unchanged at the six ROIs of SNHL patients compared with healthy controls. Compared to good outcome subjects, poor outcome subjects displayed decreased FA values at all of the ROIs. No changes were observed in MD values. Correlation analyses only revealed strong correlations between FA values and CAP scores, and strong correlations between CAP scores and age at implant were also found. No correlations of FA values with age at implant were observed. Our results show that preoperative DTI can be used to evaluate microstructural alterations in the auditory pathway that are not detectable by conventional MR imaging, and may play an important role in evaluating the outcome of CI. Early cochlear implantation might be more effectively to restore hearing in SNHL patients.
Highlights
Imaging modalities, such as CT and magnetic resonance imaging (MRI) have been widely used for the evaluation of congenital sensorineural hearing loss
Student’s t-test evaluation showed that fractional anisotropy (FA) values were decreased (P
FA values measured at the trapezoid body (TB), superior olivary nucleus (SON), inferior colliculus (IC), medial geniculate body (MGB), auditory radiation (AR) and white matter of Heschl's gyrus (WHG) of the SNHL group were compared with the control group
Summary
Imaging modalities, such as CT and MRI have been widely used for the evaluation of congenital sensorineural hearing loss. Preoperative magnetic resonance imaging (MRI) can yield valuable information regarding the status of the inner ear in pediatric cochlear implant (CI) recipients, which may be related to postoperative outcomes [2,3] These complementary modalities can accurately and objectively evaluate sensorineural hearing loss due to morphological abnormalities present [4], the functional change or dysfunction of the central auditory pathway itself cannot be evaluated by conventional imaging [5]. Diffusion tensor imaging (DTI) is a sensitive, noninvasive tool for assessing white matter abnormalities in the central nervous system [7] It detects the orientation of water molecules and yields an index of microstructural integrity through quantification of the directionality of water diffusion [5]. We investigated whether microstructural and functional changes of the central auditory pathway could be detected in SNHL patients by using DTI, and investigated the correlations between the clinical outcomes and indices of DTI, and correlations of the clinical outcomes and indices of DTI with age at implant
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