To characterise auditory involvement secondary to excessive craniotubular bone growth in individuals with sclerosteosis in South Africa.

This cross-sectional study assessed the auditory profile of 10 participants with sclerosteosis. An auditory test battery was used and results for each ear were recorded using descriptive and comparative analyses.

All participants presented with bilateral, mixed hearing losses. Of the 20 ears, hearing loss was moderate in 5 per cent (n = 1), severe in 55 per cent (n = 11) and profound in 40 per cent (n = 8). Air–bone gaps were smaller in older participants, although the difference was not statistically significant (p > 0.05). Computed tomography scans indicated pervasive abnormalities of the external auditory canal, tympanic membrane, middle-ear space, ossicles, oval window, round window and internal auditory canal. Narrowed internal auditory canals corresponded to poor speech discrimination, indicative of retrocochlear pathology and absent auditory brainstem response waves.

Progressive abnormal bone formation in sclerosteosis involves the middle ear, the round and oval windows of the cochlea, and the internal auditory canal. The condition compromises conductive, sensory and neural auditory pathways, which results in moderate to profound, mixed hearing loss.