Prevalence and Spectrum of Congenital Osseous Inner Ear Malformations on High-Resolution CT in Children with Bilateral Profound Sensorineural Hearing Loss Undergoing Pre-Cochlear-Implantation Imaging: A Single-Centre Cross-Sectional Study from Libya

Cochlear implantation (CI) is the treatment of choice for children with bilateral severe-to-profound sensorineural hearing loss (SNHL). Pre-operative imaging is essential to identify inner ear malformations (IEMs) that influence candidacy, side selection, and surgical approach. In many resource-limited settings, high-resolution computed tomography (HRCT) of the temporal bone is the only available modality, and data from Libya are scarce. This study was conducted to determine the prevalence and spectrum of congenital osseous IEMs on HRCT in Libyan children with bilateral profound SNHL evaluated for CI, and to describe the imaging features relevant to surgical planning. A retrospective cross-sectional study of archived pre-CI HRCT temporal bone examinations (64-row MDCT, 0.67 mm slices with multiplanar and double-oblique reformations) of 110 consecutive children (55 boys, 55 girls; aged 1–6 years) imaged at the Department of Diagnostic Radiology, Misratah Medical Centre, between July 2016 and December 2019. The child was the primary unit of analysis; ear-level (n = 220) 95% confidence intervals (CIs) were adjusted for clustering. Malformations were categorised according to the Sennaroglu classification and supplementary structure-based criteria for the vestibule, vestibular aqueduct, semicircular canals (SCCs), cochlear nerve canal (CNC), and internal auditory canal (IAC). An osseous IEM was present in 25 of 110 children (22.7%; 95% CI 15.9–31.4%), corresponding to 50 of 220 temporal bones (22.7%; cluster-adjusted 95% CI 15.9–31.4%), and was bilateral in every affected child. Prevalence was 30.9% in girls and 14.5% in boys (p = 0.069). The most frequent anomalies were SCC anomalies (24 ears, 10.9%), enlarged vestibular aqueduct (20 ears, 9.1%), IAC anomalies (20 ears, 9.1%), CNC stenosis (19 ears, 8.6%), and dilated vestibule (8 ears, 3.6%). Cochlear malformations occurred in 14 ears (6.4%): incomplete partition type II in 4, incomplete partition type I in 4, incomplete partition type III in 2, common cavity in 2, and Michel deformity in 2. A remnant petrosquamous sinus accompanied gross malformations in 3 ears. Acquired abnormalities included otitis media (9 ears) and labyrinthitis ossificans (3 ears). Approximately one in five Libyan CI candidates (22.7% of children) harbours an osseous IEM, always bilateral, and several of these malformations directly affect candidacy or surgical approach. HRCT provides excellent delineation of the bony labyrinth, CNC and IAC but cannot assess the cochlear nerve; a dual-modality protocol (HRCT plus high-resolution MRI) is recommended for optimal pre-implantation work-up.