Objectives: This study was performed to evaluate the frequency of bony cochlear nerve canal (BCNC) stenosis and its clinical significance in pediatric patients with unilateral sensorineural hearing loss (SNHL) of unknown etiology.
Materials and methods: We analyzed the medical records and temporal bone computed tomography (CT) results of patients less than 13 years of age with a diagnosis of unilateral SNHL of unknown etiology between July 2007 and July 2017. We compared the BCNC diameter between both sides and analyzed the age at diagnosis, degree of hearing loss, and accompanying inner ear anomalies.
Results: In 42 patients, the mean age at diagnosis was 7.4 ± 3.6 years, and the average hearing level in the affected ear was 87.9 ± 20.0 dB HL (decibels hearing level). The average diameter of the BCNC was 1.22 ± 0.75 mm on the affected side and 1.96 ± 0.52 mm on the normal side. The most suitable criterion for BCNC stenosis appeared to be a diameter of 1.2 mm by the recursive partitioning procedure. With application of this criterion, the rate of BCNC stenosis was significantly greater on the affected side than on the normal side (52.4% vs. 4.8%, respectively; P < 0.05). A narrow internal acoustic canal was found in two patients, and vestibular and cochlear anomalies were found in three patients each.
Conclusions: Our results suggest that it is reasonable to set a diameter of 1.2 mm as a cutoff for BCNC stenosis, and also that BCNC stenosis is a common cause of unilateral SNHL of unknown etiology in childhood.
Keywords: Bony cochlear nerve canal; Inner ear anomaly; Temporal bone computed tomography; Unilateral sensorineural hearing loss.
Copyright © 2018. Published by Elsevier B.V.