Unilateral Sensorineural Hearing Loss in Children: The Importance of Temporal Bone Computed Tomography and Audiometric Follow-Up

Abstract

Objectives: The first objective of this study was to identify rates, types, and laterality of clinically relevant inner ear malformations in children with unilateral sensorineural hearing loss (USNHL). The second objective was to assess the change of the ipsilesional and contralesional hearing thresholds of the patients with USNHL and the association between hearing change with time and the findings on high-resolution temporal bone computed tomography (TBCT). Study Design: Retrospective case review. Setting: Tertiary referral center. Patients: A total of 322 children diagnosed with USNHL on initial audiometry were included. Interventions: Otologic examination, pure-tone audiometry or auditory brainstem response, and high-resolution TBCT. Main Outcome Measures: Radiologic findings demonstrating clinically relevant bony or soft tissue malformations of the inner ear. Audiologic findings of change in thresholds. Results: In a series of 322 consecutively investigated children with USNHL, 93 TBCT scans (28.9%) were identified as abnormal. The abnormal CT findings included cochleovestibular malformations (49 cases; 52.7%), vestibular malformations (27 cases; 29.0%), and malformations of vestibular or cochlear aqueducts (17 cases; 18.3%). Of these abnormal CT findings, 18 cases (19.4%) showed bilateral malformations. Incomplete partition type II was the most common type of malformation (28 cases), followed by narrow internal auditory canal (23 cases) and subsequently followed by enlarged vestibular aqueduct syndrome (17 cases). Of 244 patients, 77 (31.6%) in the profound USNHL group accompanied malformations, which was significantly higher than 23.8% (15 of 78) in the nonprofound (mild to severe) USNHL group (p = 0.036). Of 115 patients who were regularly followed up for more than 6 months, 7 (6.1%) had hearing decrement (including 3 cases of bilateral decrement). Of 85 patients in the normal TBCT group, 4 (4.7%) revealed hearing decrement, and considering there were only 27 patients with nonprofound USNHL in this group, the rate of decrement was as much as 14.8% (4 of 27). Of 24 patients in the unilateral malformation group, 1 patient (4.2%) showed worsening of hearing, and 2 of 6 (33.3%) patients showed worsening of hearing in the bilateral malformation group. Conclusion: Based on the results, we propose all children with USNHL should have a TBCT scan because management, including genetic counseling and prognostic predictions of these cases, may be significantly influenced by the CT outcome. Moreover, the non-negligible rate of progressive nature of ipsilateral and contralateral SNHL in normal-looking TBCT group and in groups with inner ear malformations mandates longitudinal audiologic assessments for both ears.