Cross-Sectional Study to Estimate the Prevalence of Inner-Ear Anomalies in Children With Congenital Sensorineural Hearing Loss by High-Resolution Computed Tomography (HRCT) Temporal Bone Scan

Abstract

Background Congenital sensorineural hearing loss (SNHL) is one of the most common birth defects with an incidence ratio of 1:1000 live births in India. Imaging plays an important role in the evaluation of congenital SNHL. As there is a paucity of studies in the Indian setting to determine the prevalence of inner-ear abnormalities, this study attempts to throw light on the various inner-ear anomalies that are prevalent in our setup in the Northern part of Karnataka using high-resolution computed tomography (HRCT) temporal bone scan. Objectives The objectives of this study are estimation of the prevalence of inner-ear anomalies in children with congenital SNHL by employing a radiologic assessment of HRCT temporal bone scans and determination of the factors associated with the identification of these abnormalities like demographic factors and degree of hearing loss. Methods Children with congenital SNHL underwent clinical evaluation with history taking and general and ear examination. Otoacoustic emission (OAE) and brainstem evoked response audiometry (BERA) measurements were obtained. A radiological assessment by HRCT temporal bone scan was done. Using the classification criteria of inner-ear malformations by Jackler and Sennaroglu as a reference, diagnostic standards were established in studying inner-ear malformations. Data were collected and entered in a Performa, which includes patient's demography, audiological findings, and radiological findings, and the results were analyzed. Data were entered into Microsoft Excel, and statistical analysis was carried out using IBM SPSS Statistics for Windows, Version 27 (Released 2020; IBM Corp., Armonk, New York, United States). Categorical variables were presented as frequency and percentage. Then the prevalence of inner-ear anomaly was estimated. Correlation between inner-ear anomaly and other factors was calculated using the Chi-square test. Results The prevalence of inner-ear anomalies identified in congenital SNHL by HRCT scan was as follows: 26.08% (12/46), 26.1% (24/92) of inner ears was anomalous, 23.9% of the cochlea was anomalous, 6.5% of the vestibule was anomalous, 5.4% of the vestibular aqueduct was anomalous, and 3.2% of the semicircular canal was anomalous. Cochlear aplasia, incomplete partition, common cavity, and cochlear hypoplasia were the anomalies found. Few cochleas had an abnormal cochlear height, though they appeared normal structurally. The dilated vestibule was the most common vestibular abnormality. There was a negative association found between the inner-ear anomaly in children with congenital SNHL who had a history of consanguineous marriage in their parents. Conclusion High-resolution temporal CT scanning could provide detailed information on the pathology of the inner ear in congenital SNHL, which can help in better planning the surgery for cochlear implantation and understanding the prognosis.