Association between bone mineral density and hearing loss in osteogenesis imperfecta

Objectives: The main phenotypic characteristic of osteogenesis imperfecta (OI) is bone fragility. In addition, progressive hearing loss develops in about half of the patients apparently independently from the underlying OI genotype. The hearing loss is often associated with abnormal bony changes involving the middle ear ossicles, the stapes footplate and the temporal bone surrounding the otic capsule. We aimed to investigate whether the hearing loss in OI may be related to the overall aberrant bone quality. Methods: Associations between hearing characteristics and bone mineral density were investigated in 56 adults with OI. Following audiological evaluation they were classified as presenting normal hearing (NL H), conductive/mixed hearing loss (C/M HL) or sensorineural hearing loss (SNHL). Areal bone mineral density (aBMD) was measured using lumbar spine (LS) and whole body (WB) dual X-ray absorptiometry (DXA). By means of peripheral computed tomography (pQCT) volumetric BMD (vBMD) was calculated at distal and proximal radius, providing separate results for trabecular and cortical bone. Results: Z-scores demonstrated LS aBMD, WB aBMD and trabecular vBMD to be reduced in OI adults in comparison with the healthy population. Furthermore, patients with C/M HL had lower trabecular BMD compared to those with NL H or SNHL at both whole-group and between-relatives comparisons. Conclusions: It is hypothesized that the OI patients with the lowest trabecular BMD might be more susceptible to accumulating microfractures, which interfere with the bone remodeling inhibition pathways in the temporal bone and, therefore, contribute to stapes footplate fixation and a conductive hearing loss component