Bilateral cochlear implantation or bimodal listening in the paediatric population : retrospective analysis of decisive criteria

Introduction: In children with bilateral severe to profound hearing loss, bilateral hearing can be achieved by either bimodal stimulation (CIHA) or bilateral cochlear implantation (BICI). The aim of this study was to analyse the audiologic test protocol that is currently applied to make decisions regarding the bilateral hearing modality in the paediatric population. Methods: Pre- and postoperative audiologic test results of 21 CIHA, 19 sequential BICI and 12 simultaneous BICI children were examined retrospectively. Results: Deciding between either simultaneous BICI or unilateral implantation was mainly based on the infant's preoperative Auditory Brainstem Response thresholds. Evolution from CIHA to sequential BICI was mainly based on the audiometric test results in the contralateral (hearing aid) ear after unilateral cochlear implantation. Preoperative audiometric thresholds in the hearing aid ear were significantly better in CIHA versus sequential BICI children (p < 0.001 and p = 0.001 in unaided and aided condition, respectively). Decisive values obtained in the hearing aid ear in favour of BICI were: An average hearing threshold measured at 0.5, 1, 2 and 4 kHz of at least 93 dB HL without, and at least 52 dB HL with hearing aid together with a 40% aided speech recognition score and a 70% aided score on the phoneme discrimination subtest of the Auditory Speech Sounds Evaluation test battery. Conclusions: Although pure tone audiometry offers no information about bimodal benefit, it remains the most obvious audiometric evaluation in the decision process on the mode of bilateral stimulation in the paediatric population. A theoretical test protocol for adequate evaluation of bimodal benefit in the paediatric population is proposed

Hearing with a cochlear implant: from bionic to bimodal listening

Introduction: Currently, cochlear implantation (CI) is the standard procedure for bilateral severe hearing loss in both children and adults. However, a considerable number of hearing-impaired patients, who are candidates for CI, have residual hearing in the low-frequency range. In addition to the refinement of the surgical techniques by the application of the principles of soft surgery, the design of particular, atraumatic electrodes, which are thinner, shorter and more flexible, has contributed to electroacoustic stimulation (EAS). The use of these atraumatic electrodes has resulted in preservation of residual hearing in up to 90% of cases. Electroacoustic hearing is associated with potential advantages over pure electric hearing: better speech understanding in noise, and superior music appreciation and sound quality. In addition, patients with EAS have awareness of sound, even when not wearing their CI. Methods: In the Ghent University Hospital, 6 severely hearing-impaired adult patients with sufficient low-frequency hearing were implanted with atraumatic electrodes. In 5/6 recipients, a Cochlear® Hybrid-L24 implant was used, whereas 1/6 received a Cochlear® CI422 implant. Results: Low-frequency acoustic hearing has been preserved in 5/6 patients. Three out of 6 patients use electroacoustic amplification postoperatively; 2/7 are stimulated electrically for the mid- and high-frequency range and have residual low-frequency hearing without need of amplification; and 1/6 patients is exclusively stimulated electrically for the whole frequency range because of deterioration of preoperative low-frequency hearing thresholds. Conclusion: In candidates for CI, application of soft surgery principles and the use of atraumatic electrodes should be raised to a standard because of the medical advantages, irrespective of the presence of residual hearing. In case of residual hearing, additional benefit is obtained in terms of better speech understanding in noise and a higher level of listening comfort

Longitudinal analysis of the audiological phenotype in osteogenesis imperfecta : a follow-up study

Objective. This prospective study involved a longitudinal analysis of the progression of hearing thresholds in patients with osteogenesis imperfecta. Methods. Audiometric results from 36 osteogenesis imperfecta patients (age range, 6-79 years) were compared between two test times with an average interval of 4 years. Audiometric evaluation included acoustic admittance measurements, acoustic stapedial reflex measurements, pure tone audiometry and otoacoustic emissions testing. Results. Air conduction pure tone average, corrected for sex and age, and bone conduction pure tone average increased significantly in the study population (p < 0.05 and p < 0.001, respectively). In 14.3 per cent of the evaluated ears, an alteration in type and/or severity of hearing loss was observed. Conclusion. After an average time interval of four years, significant changes in hearing status occurred in a population of osteogenesis imperfecta patients. These findings highlight the importance of regular audiological follow up in osteogenesis imperfecta patients, including audiometry, and measurements of acoustic admittance, acoustic stapedial reflexes and otoacoustic emissions

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

Evaluation of the olivocochlear efferent reflex strength in the susceptibility to temporary hearing deterioration after music exposure in young adults

The objective of the current study was to evaluate the predictive role of the olivocochlear efferent reflex strength in temporary hearing deterioration in young adults exposed to music. This was based on the fact that a noise-protective role of the medial olivocochlear (MOC) system was observed in animals and that efferent suppression (ES) measured using contralateral acoustic stimulation (CAS) of otoacoustic emissions (OAEs) is capable of exploring the MOC system. Knowing an individual's susceptibility to cochlear damage after noise exposure would enhance preventive strategies for noise-induced hearing loss. The hearing status of 28 young adults was evaluated using pure-tone audiometry, transient evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs) before and after listening to music using an MP3 player during 1 h at an individually determined loud listening level. CAS of TEOAEs was measured before music exposure to determine the amount of ES. Regression analysis showed a distinctive positive correlation between temporary hearing deterioration and the preferred gain setting of the MP3 player. However, no clear relationship between temporary hearing deterioration and the amount of ES was found. In conclusion, clinical measurement of ES, using CAS of TEOAEs, is not correlated with the amount of temporary hearing deterioration after 1 h music exposure in young adults. However, it is possible that the temporary hearing deterioration in the current study was insufficient to activate the MOC system. More research regarding ES might provide more insight in the olivocochlear efferent pathways and their role in auditory functioning

A role for B cells to transmit hepatitis C virus infection

Hepatitis C virus (HCV) is highly variable and transmits through infected blood to establish a chronic liver infection in the majority of patients. Our knowledge on the infectivity of clinical HCV strains is hampered by the lack of in vitro cell culture systems that support efficient viral replication. We and others have reported that HCV can associate with and infect immune cells and may thereby evade host immune surveillance and elimination. To evaluate whether B cells play a role in HCV transmission, we assessed the ability of B cells and sera from recent (<2 years) or chronic (≥ 2 years) HCV patients to infect humanized liver chimeric mice. HCV was transmitted by B cells from chronic infected patients whereas the sera were non-infectious. In contrast, B cells from recently infected patients failed to transmit HCV to the mice, whereas all serum samples were infectious. We observed an association between circulating anti-glycoprotein E1E2 antibodies and B cell HCV transmission. Taken together, our studies provide evidence for HCV transmission by B cells, findings that have clinical implications for prophylactic and therapeutic antibody-based vaccine design