The Clinical Manifestation and Temporal Bone Computed Tomography Findings of Non-Traumatic Hearing Loss With Air-Bone Gap and Intact Tympanic Membrane

Abstract

Background and Objectives This study aimed to investigate the causes, clinical manifestations, temporal bone CT findings, and audiologic results of outpatients with non-traumatic hearing loss with air-bone gaps and intact tympanic membranes.Subjects and Method The medical records from 2014 to 2022 of 66 patients (77 ears) with normal tympanic membranes but who had the air-bone gap of more than 20 dB over two consecutive frequencies were reviewed.Results The mean age of the patients was 46.8±17.0 years old. The mean air-bone gap was 24.8±10.3 dB. Of the 77 ears (66 patients) studied, 10 ears were surgically diagnosed with otosclerosis (6 ears), ossicular discontinuity (2 ears), superior semicircular canal dehiscence (1 ear), and unknown etiology (1 ear). Additionally, 29 more ears (28 patients) were clinically diagnosed with silent otitis media (7 ears), otosclerosis (5 ears), thickened tympanic membrane (5 eras), E-tube dysfunction (4 ears), ossicular anomaly (4 ears), semicircular canal dysplasia (2 ears), and endolymphatic hydrops (2 ears). Temporal bone CT images showed normal findings in 33 ears (54.1%) and abnormal findings in 28 ears (45.9%). Patients with abnormal CT findings had a poorer speech discrimination score than those with normal findings (<i>p</i><0.05). The airbone gap was significantly decreased postoperatively from 30.5±12.7 dB to 6.4±4.0 dB, with a tendency to decrease greater at a low frequency than at a high frequency.Conclusion Among patients with air-bone gap and intact tympanic membrane, otosclerosis was the most commonly confirmed diagnosis through surgery, while silent otitis media was the most frequently observed diagnosis based on clinical evaluations.