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OBJECTIVES: To compare contralateral to ipsilateral stimulation with percutaneous and transcutaneous bone conduction implants. BACKGROUND: Bone conduction implants (BCIs) effectively treat conductive and mixed hearing losses. In some cases, such as in single-sided deafness (SSD), the BCI is implanted contralateral to the remaining healthy ear in an attempt to restore some of the benefits provided by binaural hearing. While the benefit of contralateral stimulation have been shown in at least some patients, it is not clear what cues or mechanisms contribute to this function. Previous studies have investigated the motion of the ossicular chain, skull, and round window in response to bone vibration. Here, we extend those reports by reporting simultaneous measurements of cochlear promontory velocity and intracochlear pressures during bone conduction stimulation with two common BCI attachments, and directly compare ipsilateral to contralateral stimulation. METHODS: Fresh-frozen whole human heads were prepared bilaterally with mastoidectomies. Intracochlear pressure (P(IC)) in the scala vestibuli (P(SV)) and tympani (P(ST)) was measured with fiber optic pressure probes concurrently with cochlear promontory velocity (V(Prom)) via laser Doppler vibrometry during stimulation provided with a closed-field loudspeaker or a bone conduction implant (BCI). Stimuli were pure tones between 120 – 10240 Hz, and response magnitudes and phases for P(IC) and V(Prom) were measured for air and bone conducted sound presentation. RESULTS: Contralateral stimulation produced lower response magnitudes and longer delays than ipsilateral in all measures, particularly for high frequency stimulation. Contralateral response magnitudes were lower than ipsilateral response magnitudes by up to 10–15 dB above ~2 kHz for a skin-penetrating abutment, which increased to 25–30 dB and extended to lower frequencies when applied with a transcutaneous (skin drive) attachment. CONCLUSION: Transcranial attenuation and delay suggest that ipsilateral stimulation will be dominant for frequencies over ~1 kHz, and that complex phase interactions will occur during bilateral or bimodal stimulation. These effects indicate a mechanism by which bilateral users could gain some bilateral advantage.

Otitis media (OM), a very common disease in young children, can result in hearing loss. In order to potentially replicate previously reported associations between OM and PLG, exome and Sanger sequencing, RNA-sequencing of saliva and middle ear samples, 16S rRNA sequencing, molecular modeling, and statistical analyses including transmission disequilibrium tests (TDT) were performed in a multi-ethnic cohort of 718 families and simplex cases with OM. We identified four rare PLG variants c.112A > G (p.Lys38Glu), c.782G > A (p.Arg261His), c.1481C > T (p.Ala494Val) and c.2045 T > A (p.Ile682Asn), and one common variant c.1414G > A (p.Asp472Asn). However TDT analyses for these PLG variants did not demonstrate association with OM in 314 families. Additionally PLG expression is very low or absent in normal or diseased middle ear in mouse and human, and salivary expression and microbial α-diversity were non-significant in c.1414G > A (p.Asp472Asn) carriers. Based on molecular modeling, the novel rare variants particularly c.782G > A (p.Arg261His) and c.2045 T > A (p.Ile682Asn) were predicted to affect protein structure. Exploration of other potential disease mechanisms will help elucidate how PLG contributes to OM susceptibility in humans. Our results underline the importance of following up findings from genome-wide association through replication studies, preferably using multi-omic datasets.

Beginning in the late 20th century, implantable hearing aids were developed and used as an alternative for individuals who were unable to tolerate conventional hearing aids. Since that time, several devices have been developed, with four currently remaining on the international market (Med‐el Vibrant Soundbridge, Envoy Esteem, Ototronix MAXUM, and Cochlear Carina). This review will briefly examine the history of middle ear implant development, describe current available devices, evaluate the benefits and limits of the technology, and consider the future directions of research in the field of implantable hearing aids.

Previous genetic studies on susceptibility to otitis media and airway infections have focused on immune pathways acting within the local mucosal epithelium, and outside of allergic rhinitis and asthma, limited studies exist on the overlaps at the gene, pathway or network level between the upper and lower airways. In this report, we compared [1] pathways identified from network analysis using genes derived from published genome-wide family-based and association studies for otitis media, sinusitis, and lung phenotypes, to [2] pathways identified using differentially expressed genes from RNA-sequence data from lower airway, sinus, and middle ear tissues, in particular cholesteatoma tissue compared to middle ear mucosa. For otitis media, a large number of genes (n = 1,806) were identified as differentially expressed between cholesteatoma and middle ear mucosa, which in turn led to the identification of 68 pathways that are enriched in cholesteatoma. Two differentially expressed genes CR1 and SAA1 overlap in middle ear, sinus, and lower airway samples and are potentially novel genes for otitis media susceptibility. In addition, 56 genes were differentially expressed in both tissues from the middle ear and either sinus or lower airways. Pathways that are common in upper and lower airway diseases, whether from published DNA studies or from our RNA-sequencing analyses, include chromatin organization/remodeling, endocytosis, immune system process, protein folding, and viral process. Taken together, our findings from genetic susceptibility and differential tissue expression studies support the hypothesis that the unified airway theory wherein the upper and lower respiratory tracts act as an integrated unit also applies to infectious and nonallergic airway epithelial disease. Our results may be used as reference for identification of genes or pathways that are relevant to upper and lower airways, whether common across sites, or unique to each disease.

HYPOTHESIS: Insertion of cochlear implant electrodes generates transient pressure spikes within the vestibular labyrinth equivalent to high intensity acoustic stimuli. BACKGROUND: Though cochlear implant (CI) surgery is regarded as having low-risk of impacting the vestibular system, several studies have documented changes in vestibular function after implantation. The mechanism of these changes is not understood. We have previously established that large, potentially-damaging pressure transients can be generated in the cochlea during electrode insertion, but whether pressure transients occur within the vestibular labyrinth has yet to be determined. Here, we quantify the exposure of the vestibular system to potentially-damaging pressure transients during CI surgery. METHODS: Five human cadaveric heads were prepared with an extended facial recess and implanted sequentially with eight different CI electrode styles via a round window approach. Fiber-optic sensors measured intralabyrinthine pressures in scala vestibuli (SV), scala tympani (ST), and the lateral semicircular canal (LSCC) during insertions. RESULTS: Electrode insertion produced a range of high-intensity pressure spikes simultaneously in the cochlea and LSCC with all electrodes tested. Pressure transients recorded were found to be significantly higher in the vestibular labyrinth than the cochlea and occurred at peak levels known to cause acoustic trauma. CONCLUSION: Insertion of CI electrodes can produce transients in intralabyrinthine fluid pressure levels equivalent to high-intensity, impulsive acoustic stimuli. Results from this investigation affirm the importance of atraumatic surgical techniques and suggest that in addition to the cochlea, the vestibular system is potentially exposed to damaging fluid pressure waves during cochlear implantation.

The stapes is held in the oval window by the stapedial annular ligament (SAL), which restricts total peak-to-peak displacement of the stapes. Previous studies have suggested that for moderate (< 130 dB SPL) sound levels intracochlear pressure (PIC), measured at the base of the cochlea far from the basilar membrane, increases directly proportionally with stapes displacement (DStap), thus a current model of impulse noise exposure (the Auditory Hazard Assessment Algorithm for Humans, or AHAAH) predicts that peak PIC will vary linearly with DStap up to some saturation point. However, no direct tests of DStap, or of the relationship with PIC during such motion, have been performed during acoustic stimulation of the human ear. In order to examine the relationship between DStap and PIC to very high level sounds, measurements of DStap and PIC were made in cadaveric human temporal bones. Specimens were prepared by mastoidectomy and extended facial recess to expose the ossicular chain. Measurements of PIC were made in scala vestibuli (PSV) and scala tympani (PST), along with the SPL in the external auditory canal (PEAC), concurrently with laser Doppler vibrometry (LDV) measurements of stapes velocity (VStap). Stimuli were moderate (~100 dB SPL) to very high level (up to ~170 dB SPL), low frequency tones (20–2560 Hz). Both DStap and PSV increased proportionally with sound pressure level in the ear canal up to approximately ~150 dB SPL, above which both DStap and PSV showed a distinct deviation from proportionality with PEAC. Both DStap and PSV approached saturation: DStap at a value exceeding 150 μm, which is substantially higher than has been reported for small mammals, while PSV showed substantial frequency dependence in the saturation point. The relationship between PSV and DStap remained constant, and cochlear input impedance did not vary across the levels tested, consistent with prior measurements at lower sound levels. These results suggest that PSV sound pressure holds constant relationship with DStap, described by the cochlear input impedance, at these, but perhaps not higher, stimulation levels. Additionally, these results indicate that the AHAAH model, which was developed using results from small animals, underestimates the sound pressure levels in the cochlea in response to high level sound stimulation, and must be revised.

A genetic basis for otitis media is established, however, the role of rare variants in disease etiology is largely unknown. Previously a duplication variant within A2ML1 was identified as a significant risk factor for otitis media in an indigenous Filipino population and in US children. In this report exome and Sanger sequencing was performed using DNA samples from the indigenous Filipino population, Filipino cochlear implantees, US probands, Finnish, and Pakistani families with otitis media. Sixteen novel, damaging A2ML1 variants identified in otitis media patients were rare or low-frequency in population-matched controls. In the indigenous population, both gingivitis and A2ML1 variants including the known duplication variant and the novel splice variant c.4061 + 1 G>C were independently associated with otitis media. Sequencing of salivary RNA samples from indigenous Filipinos demonstrated lower A2ML1 expression according to the carriage of A2ML1 variants. Sequencing of additional salivary RNA samples from US patients with otitis media revealed differentially expressed genes that are highly correlated with A2ML1 expression levels. In particular, RND3 is upregulated in both A2ML1 variant carriers and high-A2ML1 expressors. These findings support a role for A2ML1 in keratinocyte differentiation within the middle ear as part of otitis media pathology and the potential application of ROCK inhibition in otitis media.

Hypothesis: A cochlear implant electrode within the cochlea contributes to the air-bone gap (ABG) component of postoperative changes in residual hearing after electrode insertion. Background: Preservation of residual hearing after cochlear implantation has gained importance as simultaneous electric-acoustic stimulation allows for improved speech outcomes. Postoperative loss of residual hearing has previously been attributed to sensorineural changes; however, presence of increased postoperative ABG remains unexplained and could result in part from altered cochlear mechanics. Here, we sought to investigate changes to these mechanics via intracochlear pressure measurements before and after electrode implantation to quantify the contribution to postoperative ABG. Methods: Human cadaveric heads were implanted with titanium fixtures for bone conduction transducers. Velocities of stapes capitulum and cochlear promontory between the two windows were measured using single-axis laser Doppler vibrometry and fiber-optic sensors measured intracochlear pressures in scala vestibuli and tympani for air- and bone-conducted stimuli before and after cochlear implant electrode insertion through the round window. Results: Intracochlear pressures revealed only slightly reduced responses to air-conducted stimuli consistent with previous literature. No significant changes were noted to bone-conducted stimuli after implantation. Velocities of the stapes capitulum and the cochlear promontory to both stimuli were stable after electrode placement. Conclusion: Presence of a cochlear implant electrode causes alterations in intracochlear sound pressure levels to air, but not bone, conducted stimuli and helps to explain changes in residual hearing noted clinically. These results suggest the possibility of a cochlear conductive component to postoperative changes in hearing sensitivity.

Non-secretor status due tohomozygosity for the commonFUT2 variant c. 461G> A(p. Trp154*) is associated witheither risk for autoimmune diseases or protection against viral diarrhea and HIV. We determined the role of FUT2 in otitis media susceptibility by obtaining DNA samples from 609 multi-ethnic families and simplex case subjectswith otitis media. Exome and Sanger sequencing, linkage analysis, and Fisher exact and transmission disequilibrium tests (TDT) were performed. The common FUT2 c. 604C> T (p. Arg202*) variant co-segregates with otitismedia in a Filipino pedigree (LOD = 4.0). Additionally, a rare variant, c. 412C> T (p. Arg138Cys), is associated with recurrent/ chronic otitismedia in European-American children (p = 1.2310(-5)) and US trios (TDT p = 0.01). The c. 461G> A (p. Trp154*) variant was also overtransmitted in US trios (TDT p = 0.01) and was associated with shifts inmiddle ear microbiota composition (PERMANOVA p 20 were combined, FUT2 variantswere over-transmitted in trios (TDTp = 0.001). Fut2 is transiently upregulated inmouse middle ear after inoculation withnon-typeable Haemophilus influenzae. Four FUT2 variants-namely p. Ala104Val, p. Arg138Cys, p. Trp154*, and p. Arg202*-reduced A antigen in mutant-transfected COS-7 cells, while the nonsense variants also reduced FUT2 protein levels. Common and rare FUT2 variants confer susceptibility to otitis media, likely by modifying the middle ear microbiome through regulation of A antigen levels in epithelial cells. Our familiesdemonstratemarked intra-familial genetic heterogeneity, suggesting thatmultiple combinations of common and rare variants plus environmental factors influence the individual otitis media phenotype as a complex trait.

HYPOTHESIS: Simulated otitis media with effusion reduces intracochlear pressures comparable to umbo velocity. BACKGROUND: Otitis media with effusion is a common cause of temporary hearing loss, particularly in children, that can produce conductive deficits of 30–40 dB. Previous studies have measured the effects of simulated effusion on ossicular mechanics; however, no studies have measured cochlear stimulation directly during effusion. Here, we compare pressures in the scala vestibuli and tympani to umbo velocity, before and after induction of simulated effusion in cadaveric human specimens. METHODS: Eight cadaveric, hemi-cephalic human heads were prepared with complete mastoidectomies. Intracochlear pressures were measured with fiber optic pressure probes, and umbo velocity measured via laser Doppler vibrometry (LDV). Stimuli were pure tones (0.1 – 14 kHz) presented in the ear canal via a custom speculum modified to accept speaker and microphone tubing, and sealed with a glass cover slip. Effusion was simulated by filling the mastoid cavity and middle ear space with water. RESULTS: Acoustic stimulation with middle ear effusion resulted in decreased umbo velocity up to ~26 dB, whereas differential pressure at the base of the cochlea, the driving force to the basilar membrane, decreased by only ~16 db. CONCLUSION: Simulating effusion leads to a frequency-dependent reduction in intracochlear sound pressure levels consistent with audiological presentation and prior reports. Results reveal that intracochlear pressure measurements (P(SV) & P(ST)) decrease less than expected, and less than the decrease observed in the differential pressure (P(Diff)). The observed decrease in umbo velocity is greater than in the differential intracochlear pressures, suggesting that umbo velocity overestimates the induced conductive hearing loss. These results suggest that an alternate sound conduction pathway transmits sound to the inner ear during effusion.

Hypothesis Cochlear implants (CIs) designed for hearing preservation will not alter mechanical properties of the middle and inner ears as measured by intracochlear pressure (P(IC)) and stapes velocity (Vstap). Background CIs designed to provide combined electroacoustic stimulation are now available. To maintain functional acoustic hearing, it is important to know if a CI electrode can alter middle or inner ear mechanics because any alteration could contribute to elevated low-frequency thresholds in electroacoustic stimulation patients. Methods Seven human cadaveric temporal bones were prepared, and pure-tone stimuli from 120 Hz to 10 kHz were presented at a range of intensities up to 110 dB sound pressure level. P(IC) in the scala vestibuli (P(SV)) and tympani (PST) were measured with fiber-optic pressure sensors concurrently with VStap using laser Doppler vibrometry. Five CI electrodes from two different manufacturers with varying dimensions were inserted via a round window approach at six different depths (16-25 mm). Results The responses of P(IC) and VStap to acoustic stimulation were assessed as a function of stimulus frequency, normalized to sound pressure level in the external auditory canal, at baseline and electrode-inserted conditions. Responses measured with electrodes inserted were generally within approximately 5 dB of baseline, indicating little effect of CI electrode insertion on P(IC) and VStap. Overall, mean differences across conditions were small for all responses, and no substantial differences were consistently visible across electrode types. Conclusion Results suggest that the influence of a CI electrode on middle and inner ear mechanics is minimal despite variation in electrode lengths and configurations.

HYPOTHESIS Intracochlear sound pressures (PIC) and velocity measurements of the stapes, round window, and promontory (VStap/RW/Prom) will show frequency-dependent attenuation using magnet-based transcutaneous bone conduction implants (TCBCIs) in comparison with direct-connect skin-penetrating implants (DCBCIs). BACKGROUND TCBCIs have recently been introduced as alternatives to DCBCIs. Clinical studies have demonstrated elevated high-frequency thresholds for TCBCIs as compared with DCBCIs; however, little data exist examining the direct effect of skin thickness on the cochlear input signal using TCBCIs. METHODS Using seven cadaveric heads, PIC was measured in the scala vestibuli and tympani with fiber-optic pressure sensors concurrently with VStap/RW/Prom via laser Doppler vibrometry. Ipsilateral titanium implant fixtures were placed and connected to either a DCBCI or a TCBCI. Soft tissue flaps with varying thicknesses (no flap and 3, 6, and 9 mm) were placed successively between the magnetic plate and sound processor magnet. A bone conduction transducer coupled to custom software provided pure-tone stimuli between 120 and 10,240 Hz. RESULTS Stimulation via the DCBCI produced the largest response magnitudes. The TCBCI showed similar PSV/ST and VStap/RW/Prom with no intervening flap and a frequency-dependent nonlinear reduction of magnitude with increasing flap thickness. Phase shows a comparable dependence on transmission delay as the acoustic baseline, and the slope steepens at higher frequencies as flap thickness increases, suggesting a longer group delay. CONCLUSION Proper soft tissue management is critical to optimize the cochlear input signal. The skin thickness-related effects on cochlear response magnitudes should be taken into account when selecting patients for a TCBCI.

Coeliac disease is caused by T cell sensitisation of the intestine to cereal prolamins, which results in a range of mucosal abnormalities that may lead to malabsorption.1 The population prevalence in western countries is ∼1 in 200.2–4 Evidence for an inherited predisposition to coeliac disease comes from studies of first degree relatives of patients and studies of twins.5,6 A strong association is seen between coeliac disease and the HLA-DQ (α1*05, β1*02) heterodimer (DQ2) which is present in approximately 95% of patients,7–9 compared with 20-30% of healthy subjects.10,11 The difference in concordance rates between monozygotic twins and HLA identical sibs (80-100% v 25%) implicates non-HLA genes in the genetic predisposition to coeliac disease.11 The overall relative risk in sibs is at least 20 and is therefore four-fold higher than that attributable to HLA alone under model of inheritance.7 Genome linkage searches carried out on Irish,12 Italian,13, and UK14 coeliac disease families have identified a number of potential sites for the location of non-HLA linked genes. The putative candidate loci detected in the three studies are, however, largely inconsistent and the findings have not been replicated in other populations.15–19 Here we report the results of a genome screen of 24 multiplex families with coeliac disease and discuss the findings of this study in relation to previously published analyses. Twenty-four families with two or more members affected with coeliac disease were recruited for this study (fig 1). Nine of these families (Nos 1, 3, 4, 6, 30, 32, 39, 43, and 44) have been used in a previous study of candidate regions.16 All the families were of northern European ancestry. Twelve of the families were recruited from the UK, nine from Sweden, two from Switzerland, …

Objectives: To assess the importance of 2 variables, transducer tip diameter and resection of the round window (RW) niche, affecting the optimization of the mechanical stimulation of the RW membrane with an active middle ear implant (AMEI). Materials and Methods: Ten temporal bones were prepared with combined atticotomy and facial recess approach to expose the RW. An AMEI stimulated the RW with 2 ball tip diameters (0.5 and 1.0 mm) before and after the resection of the bony rim of the RW niche. The RW drive performance, assessed by stapes velocities using laser Doppler velocimetry, was analyzed in 3 frequency ranges: low (0.25–1 kHz), medium (1–3 kHz) and high (3–8 kHz). Results: Driving the RW produced mean peak stapes velocities (HEV) of 0.305 and 0.255 mm/s/V at 3.03 kHz, respectively, for the 1- and 0.5-mm tips, with the RW niche intact. Niche drilling increased the HEV to 0.73 and 0.832 mm/s/V for the 1- and 0.5-mm tips, respectively. The tip diameter produced no difference in output at low and medium frequencies; however, the 0.5-mm tip was 5 and 6 dB better than the 1-mm tip at high frequencies before and after niche drilling, respectively. Drilling the niche significantly improved the output by 4 dB at high frequencies for the 1-mm tip, and by 6 and 10 dB in the medium- and high-frequency ranges for the 0.5-mm tip. Conclusion: The AMEI was able to successfully drive the RW membrane in cadaveric temporal bones using a classical facial recess approach. Stimulation of the RW membrane with an AMEI without drilling the niche is sufficient for successful hearing outputs. However, the resection of the bony rim of the RW niche significantly improved the RW stimulation at medium and higher frequencies. Drilling the niche enhances the exposure of the RW membrane and facilitates positioning the implant tip.

Summary The goals of this study were to collect normative data on asymptomatic, ambulatory, community-dwelling adults on a standard diagnostic test of vestibular function in balance and to determine if their responses differ significantly from younger adults. Subjects were divided into four age groups, 18-44 years (young), 45-69 years (middle-aged), 70-79 (old), and 80-89 (elderly). Subjects were seen in the neurotologic diagnostic laboratory at a tertiary care facility. Their dynamic balance was tested under a variety of sensory conditions using the EquiTest (NeuroCom), a standard diagnostic test. The data from one subtest, the Sensory Organization Test (SOT) were evaluated. These data showed significant age-associated declines in overall score and changes in movement strategy. These results suggest that those parts of the vestibular system involved with balance have age-related declines through the end of the life span, even in asymptomatic people, and that these changes do not level off but continue into the ninth decade. Therefore, when elderly people are evaluated for balance disorders age-appropriate norms should be used. These results also suggest that declines in motor performance on laboratory tests are not directly related to reduced independence in essential activities of daily living in elderly people.

With advances in imaging, intracanalicular acoustic neuromas are identified readily in patients including, oftentimes, those with serviceable hearing. Fourteen patients were operated on in an attempt to preserve hearing. Hearing was retained in 10 (71%) of the 14. Serviceable hearing was present in 7 (50%), borderline serviceable hearing in 2 (14%), and nonserviceable hearing in 1 (7%). The problems, advantages, and disadvantages of the differing approaches are discussed.

The potential usefulness of impedance studies is reviewed and a case of osteogenesis imperfecta, having bilateral ossicular discontinuity and intact acoustic reflexes, is presented. This seeming paradox was explainable on the basis of surgically confirmed, bilateral disruption of the stapes crura, central to the stapedial tendon insertion.