An Auditory profile of sclerosteosis

Abstract

Sclerosteosis is a rare genetic bone dysplasia disorder characterised by generalised craniotubular bone modelling. Alongside many clinical appearances marked in sclerosteosis, the auditory system is considerably compromised on several levels during the disease progression. Extensive otolaryngological research on the history of sclerosteosis, the clinical presentation of sclerosteosis, radiographic studies and the gene causing the condition had been documented. No studies had been found describing the audiological profiles, auditory functioning and abnormalities for subjects with sclerosteosis. Thus the object of this study aimed to describe the auditory profile of subjects with sclerosteosis. A cross-sectional descriptive research design and quantitative research approach was followed to investigate the auditory characteristics of subjects with sclerosteosis. Subjects were selected from a database of patients with confirmed diagnoses of sclerosteosis. Ten subjects responded and provided written informed consent. Test procedures included otoscopy, tympanometry, acoustic reflexes, diagnostic pure-tone airand bone-conduction audiometry, speech audiometry, distortion product otoacoustic emissions (DPOAE), auditory brainstem responses (ABR) and computed tomographic (CT) scans. The subjects were assessed with a comprehensive audiological test-battery within a single test session lasting approximately two hours. A CT scan was conducted on a separate occasion shortly after the audiological data were obtained. Normal type A tympanograms were obtained in 50% (n=10/20) of ears. All subjects presented with mixed hearing losses varying from moderate (5%; n=1), severe (55%; n=11) and profound (40%; n=8) degrees across ears. Hearing loss configurations ranged from rising (15%), sloping (35%) and air-conduction thresholds peaking at 2000 Hz (50%). Air bone gaps (ABG) were larger in older subjects, although not statistically significant (p>.05). The CT scans indicated anatomical abnormalities of the external auditory canal, tympanic membrane, middle ear space, ossicles, oval window, round window and the internal auditory canal. The progressive abnormal bone formation in sclerosteosis involved the middle ear, the round and oval windows of the cochlea and internal auditory canal. The progressive abnormal bony overgrowth, which is the hallmark of sclerosteosis, led to functional impairment at various levels in the auditory system. The current findings provided a comprehensive auditory profile for sclerosteosis. Results might be utilised alongside future research findings to direct criteria and audiological indications for surgical and audiological intervention.