Postnatal expression and possible function of RANK and RANKL in the murine inner ear

Intracochlear Trauma and Local Ossification Patterns Differ Between Straight and Precurved Cochlear Implant Electrodes

HYPOTHESIS

Trauma to the osseous spiral lamina (OSL) or spiral ligament (SL) during cochlear implant (CI) insertion segregates with electrode type and induces localized intracochlear ossification and fibrosis.

BACKGROUND

The goal of atraumatic CI insertion is to preserve intracochlear structures, limit reactive intracochlear tissue formation, and preserve residual hearing. Previous qualitative studies hypothesized a localized effect of trauma on intracochlear tissue formation; however, quantitative studies failed to confirm this.

METHODS

Insertional trauma beyond the immediate insertion site was histologically assessed in 21 human temporal bones with a CI. Three-dimensional reconstructions were generated and virtually resectioned perpendicular to the cochlear spiral at high resolution. The cochlear volume occupied by ossification or fibrosis was determined at the midpoint of the trauma and compared with regions proximal and distal to this point.

RESULTS

Seven cases, all implanted with precurved electrodes, showed an OSL fracture beyond the immediate insertion site. Significantly more intracochlear ossification was observed at the midpoint of the OSL fracture, compared with the -26 to -18 degrees proximal and 28 to 56 degrees distal to the center. No such pattern was observed for fibrosis. In the 12 cases with a perforation of the SL (9 straight and 3 precurved electrodes), no localized pattern of ossification or fibrosis was observed around these perforations.

CONCLUSION

OSL fractures were observed exclusively with precurved electrodes in this study and may serve as a nidus for localized intracochlear ossification. Perforation of the SL, in contrast, predominantly occurred with straight electrodes and was not associated with localized ossification.

Genome-wide screen of otosclerosis in population biobanks: 27 loci and shared associations with skeletal structure

Otosclerosis is one of the most common causes of conductive hearing loss, affecting 0.3% of the population. It typically presents in adulthood and half of the patients have a positive family history. The pathophysiology of otosclerosis is poorly understood. A previous genome-wide association study (GWAS) identified a single association locus in an intronic region of RELN. Here, we report a meta-analysis of GWAS studies of otosclerosis in three population-based biobanks comprising 3504 cases and 861,198 controls. We identify 23 novel risk loci (p < 5 × 10^-8) and report an association in RELN and three previously reported candidate gene or linkage regions (TGFB1, MEPE, and OTSC7). We demonstrate developmental stage-dependent immunostaining patterns of MEPE and RUNX2 in mouse otic capsules. In most association loci, the nearest protein-coding genes are implicated in bone remodelling, mineralization or severe skeletal disorders. We highlight multiple genes involved in transforming growth factor beta signalling for follow-up studies.

Osteoporosis, bisphosphonate use, and risk of moderate or worse hearing loss in women

BACKGROUND

Osteoporosis and low bone density (LBD) may be associated with higher risk of hearing loss, but findings are inconsistent and longitudinal data are scarce. Bisphosphonates may influence risk, but the relation has not been studied in humans. We longitudinally investigated associations of osteoporosis and LBD, bisphosphonate use, vertebral fracture (VF), hip fracture (HF), and risk of self-reported moderate or worse hearing loss.

DESIGN

Longitudinal cohort study.

SETTING

The Nurses' Health Study (NHS) (1982-2016) and Nurses' Health Study II (NHS II) (1995-2017).

PARTICIPANTS

Participants included 60,821 NHS women, aged 36-61 years at baseline, and 83,078 NHS II women, aged 31-48 years at baseline (total n = 143,899).

MEASUREMENTS

Information on osteoporosis, LBD, bisphosphonate use, VF, HF, and hearing status was obtained from validated biennial questionnaires. In a subcohort (n = 3749), objective hearing thresholds were obtained by audiometry. Multivariable-adjusted Cox proportional hazards models were used to examine independent associations between osteoporosis (NHS), osteoporosis/LBD (NHS II), and risk of hearing loss.

RESULTS

The multivariable-adjusted relative risk (MVRR, 95% confidence interval) of moderate or worse hearing loss was higher among women with osteoporosis or LBD in both cohorts. In NHS, compared with women without osteoporosis, the MVRR was 1.14 (1.09, 1.19) among women with osteoporosis; in NHS II, the MVRR was 1.30 (1.21, 1.40) among women with osteoporosis/LBD. The magnitude of the elevated risk was similar among women who did and did not use bisphosphonates. VF was associated with higher risk (NHS: 1.31 [1.16, 1.49]; NHS II: 1.39 [1.13, 1.71]), but HF was not (NHS: 1.00 [0.86, 1.16];NHS II: 1.15 [0.75,1.74]). Among participants with audiometric measurements, compared with women without osteoporosis/LBD, the mean multivariable-adjusted hearing thresholds were higher (i.e., worse) among those with osteoporosis/LBD who used bisphosphonates.

CONCLUSION

Osteoporosis and LBD may be important contributors to aging-related hearing loss. Among women with osteoporosis, the risk of hearing loss was not influenced by bisphosphonate use.