Inner ear computed tomography findings among children with audiometry proven sensorineural hearing loss in a special needs school in South-West, Nigeria

Abstract

Background: Hearing loss is a major problem in children because of its devastating effect on education and cognitive development. Clinicians rely on pure-tone audiometry (PTA) to determine the types and degrees of hearing loss; however, the test is subjective and cannot determine the cause of the hearing loss. Computed tomography (CT) of the temporal bone is important for evaluating hearing loss, due to its ability to identify bony ear malformations and to examine pathologies of the middle and the inner ear. The objective of this study was to determine bony labyrinthine anomalies in a group of children with profound and severe hearing loss. Materials and Methods: This was a descriptive cross-sectional study conducted among students from a school with special needs in Osogbo, Osun State, Nigeria. One hundred and twenty students with hearing loss selected by stratified systematic random sampling participated in this study. There were 66 (55%) males and 54 (45%) females. Demographic data were collected from the participants and from the school records. All the participants went through audiometry so as to determine and confirm their thresholds and a high-resolution CT scan of the temporal bone to determine bony labyrinthine abnormalities. Results: One hundred and twenty participants making 240 ears were studied, with a mean age of 12.1 ± 2.3 years. Ninety-five participants (79.2%) had prelingual hearing loss while 25 (20.8%) had acquired postlingual hearing loss. Nine participants (7.5%) had abnormalities of the bony labyrinth; seven of which had bilateral and two unilateral bony abnormalities, and thus 16 (6.7%) out of 240 ears had such abnormalities. The most common cochlear abnormality was hypoplasia 6 ears (37.5%), followed by type I incomplete cochlear partitions 3 ears (18.7%). Conclusion: This study found that the bony labyrinth was normal in 93.3% of ears, and the most common bony anomaly was cochlear hypoplasia.