Normal Ear Research Articles

Predicting children’s real-ear-to-coupler differences based on tympanometric data

Objective Paediatric hearing-aid verification relies on measures of output obtained from the ear canal or in a coupler with the child’s real-ear-to-coupler difference (RECD). Measured RECD cannot always be completed in children, leading to fitting inaccuracies. Audiologists often have tympanometry data that characterises the child’s ear-canal acoustics. The goal of this study was to determine if tympanometry can be used to improve predictions of measured RECD. Design A retrospective analysis of RECD and admittance, tympanometric peak pressure, and equivalent ear-canal volume from 226 Hz tympanometry collected as part of a longitudinal study of children with hearing loss were modelled with Bayesian hierarchical regression. Study sample Two-hundred sixty-six children with mild-to-severe hearing loss contributed data. Results Age-based average RECD models were within 3 dB of measured RECD values in 54% of cases with normal middle ear status and 50.6% of cases with abnormal middle ear status. Immittance-predicted RECD were within 3 dB in 69.6% of cases with normal middle ear status and 74.4% of cases with abnormal middle ear status. Conclusion Immittance-predicted RECD was more accurate than age-based average RECD, particularly in children with abnormal middle ear status. The findings suggest that 226 Hz tympanometry could be used clinically to improve predictions of measured RECD when it cannot be measured.

Vestibular hydrops in patients with semicircular canal malformation

ObjectiveTo investigate the vestibular endolymphatic hydrops in patients with semicircular canal malformation. MethodsWe searched 7864 patients who underwent MR Imaging after contrast injection and found 21 patients with semicircular canal malformations. Another 9 non-malformed patients with unilateral hearing loss were randomly included. We asked patients about their medical history and measured the volume of total vestibular fluid space and endolymphatic space. The vestibular volume ratio = endolymphatic space/total fluid space × 100. ResultsHearing loss was observed in 18 of 30 malformed ears and in 7 of 12 non-malformed ears. Statistical analysis showed no association between semicircular canal malformation and hearing loss. In the semicircular canal malformation group, the average vestibular volume ratio (22.6%) in the ears with hearing loss was higher than that in the ears without hearing loss (11.4%). There was no statistically significant difference in the average vestibular %EL in ears with hearing loss between the malformed inner ear group (22.6%) and non-malformed group (28.2%) (P>0.05). ConclusionThere was no correlation between semicircular canal malformation and hearing loss. The mean vestibular hydrops volume ratio of the semicircular canal deformed ears with hearing loss was about 22.6%, which was not different from that of normal ears.

Research on congenital severe-to-profound sensorineural hearing loss associated with central lucency of the bony island of the lateral semicircular canal

Background Central lucency of the bony island of the lateral semicircular canal (LSCC) is commonly found in patients with congenital severe-to-profound sensorineural hearing loss (SNHL). Objective Exploring the significance of bony island lucency of LSCC in congenital severe-to-profound SNHL patients. Material and Methods Retrospective measurements of the inner ear structures were made on axial temporal bone CT scans from 182 (364 ears) congenital severe-to-profound SNHL patients and 50 (100 ears) tympanic membrane perforation (TMP) patients. Results The incidence of bony island lucency of LSCC was 46.7% in the congenital severe-to-profound SNHL group and 0% in the TMP group. There was a statistically significant difference in inner ear structures among congenital severe-to-profound SNHL patients with normal inner ear structure and bony island lucency of LSCC, congenital severe-to-profound SNHL patients with normal inner ear structure and no bony island lucency of LSCC, and TMP patients. The importance of the bony island lucency of LSCC was further confirmed through multiple linear regression analysis. Conclusions and Significance Bony island lucency may have significance in congenital severe-to-profound SNHL and may be a manifestation of largely overlooked SCC malformation or hypoplasia of the inner ear.

Wideband Acoustic Immittance in Children.

As wideband absorbance (WBA) gains popularity, it is essential to understand the impact of different middle ear pathologies on the absorbance patterns as a function of frequency in children with various middle ear pathologies. More recently, the use of wideband tympanometry has enabled clinicians to conduct WBA at ambient pressure (WBA amb ) as well as the pressurized mode (WBA TPP ). This article reviews evidence for the ability of WBA measurements to accurately characterize the normal middle ear function across a wide range of frequencies and to aid in differential diagnosis of common middle ear disorders in children. Absorbance results in cases of otitis media with effusion, negative middle ear pressure, Eustachian tube malfunction, middle ear tumors, and pressure equalization tubes will be compared to age-appropriate normative data. Where applicable, WBA amb as well as WBA TPP will be reviewed in these conditions. The main objectives of this article are to identify, assess, and interpret WBA amb and WBA TPP outcomes from various middle ear conditions in children between the ages of 3 and 12 years.

Application Effect of Modified Through and Through Suture in Anterior Chondrectomy of Auricular Pseudocyst.

To introduce a novel method of modified through and through suture with collagen sutures in conjunction with anterior chondrectomy of auricular pseudocyst and assess its therapeutic efficacy. The study comprised 87 patients with unilateral auricular pseudocyst, treated in our department from December 2019 to November 2021. Following anterior chondrectomy of the cyst, modified through and through suture was performed using collagen sutures. Evaluation of successful resolution of the problem, assessment of complications, recurrence, and ultimate ear cosmesis was undertaken with a minimum of 6 months follow-up. There were 83 males and 4 females, ages ranged from 26-78 years old, with a median age of 41 years. The right and left ears were affected in, 52 and 35 patients, respectively. Local skin color deepening was found in 15 patients within 3 months, which returned to normal within 5 months. During the follow-up, such complications as anaphylaxis, hematocele in the surgical cavity, incision infection, and deformity were not observed in any patients. All patients were cured with a single operation without relapse. The modified through and through suture with collagen sutures in conjunction with anterior chondrectomy of an auricular pseudocyst is characterized by a straightforward, single-stage operation, with no relapses, few complications, restoration of normal ear cosmesis, and high patient acceptance.

Eustachian Tube Function Test of Normal Ear in Patients with Unilateral Chronic Otitis Media

Purpose: The aim of this study is to observe the importance of normal ear Eustachian Tube Function Test (ETFT) for unilateral Chronic Otitis Media (COM) and essential date on ETFT through Williams test (Y-266 Hz).Methods: Williams test Y-226 Hz is a test that can evaluate the function of the Eustachian tube only by controlling the pressure, and we retrospectively analyzed 182 otitis media patients who underwent surgery in Pusan National University Hospital. Three results obtained through the Williams test (Y-226 Hz) were classified according to categories and descriptive analysis was performed.Results: In the 182 subjects, 89 did not show changes in static compliance (SC) or had result bias. 1~5 daPa change in 6 (3.3%), 6~10 daPa change 17 (9.3%), 11~15 daPa change 18 (9.9%), 16~20 daPa change 22 (12.1%), 21~25 daPa change 5 (2.7%), 26~30 daPa change 5 (2.7%), 31~40 daPa change 4 (2.2%), 41~50 daPa change 6 (3.3%), 51~100 daPa change changes in 6 (3.3%) and the remaining 4 (2.2%) showed a change greater than 100 daPa. The mean standard SC value of 93 subjects with change was -4.9 daPa, and the mean value measured at positive pressure +400 daPa was -27.4 daPa. Additionally, the mean value measured at negative pressure -400 daPa was +22.9 daPa.Conclusion: Even if the contralateral eardrum appeared normal in the subjects who underwent COM, there were more cases of problems with the Eustachian tube. Normal ear ETFT is necessary for unilateral COM patients, and the Williams test is suitable as a criterion-referenced assessment.

Current Advances in Gene Therapies of Genetic Auditory Neuropathy Spectrum Disorder.

Auditory neuropathy spectrum disorder (ANSD) refers to a range of hearing impairments characterized by an impaired transmission of sound from the cochlea to the brain. This defect can be due to a lesion or defect in the inner hair cell (IHC), IHC ribbon synapse (e.g., pre-synaptic release of glutamate), postsynaptic terminals of the spiral ganglion neurons, or demyelination and axonal loss within the auditory nerve. To date, the only clinical treatment options for ANSD are hearing aids and cochlear implantation. However, despite the advances in hearing-aid and cochlear-implant technologies, the quality of perceived sound still cannot match that of the normal ear. Recent advanced genetic diagnostics and clinical audiology made it possible to identify the precise site of a lesion and to characterize the specific disease mechanisms of ANSD, thus bringing renewed hope to the treatment or prevention of auditory neurodegeneration. Moreover, genetic routes involving the replacement or corrective editing of mutant sequences or defected genes to repair damaged cells for the future restoration of hearing in deaf people are showing promise. In this review, we provide an update on recent discoveries in the molecular pathophysiology of genetic lesions, auditory synaptopathy and neuropathy, and gene-therapy research towards hearing restoration in rodent models and in clinical trials.

Effects of Age at Implantation on Outcomes of Cochlear Implantation in Children with Short Durations of Single-Sided Deafness.

Children with single-sided deafness (SSD) show reduced language and academic development and report hearing challenges. We aim to improve outcomes in children with SSD by providing bilateral hearing through cochlear implantation of the deaf ear with minimal delay. Prospective cohort study of 57 children with SSD provided with cochlear implant (CI) between May 13, 2013, and June 25, 2021. Tertiary children's hospital. Children with early onset (n = 40) or later onset of SSD (n = 17) received CIs at ages 2.47 ± 1.58 years (early onset group) and 11.67 ± 3.91 years (late onset group) (mean ± SD). Duration of unilateral deafness was limited (mean ± SD = 1.93 ± 1.56 yr). Cochlear implantation of the deaf ear. Evaluations of device use (data logging) and hearing (speech perception, effects of spatial release from masking on speech detection, localization of stationary and moving sound, self-reported hearing questionnaires). Results indicated that daily device use is variable (mean ± SD = 5.60 ± 2.97, range = 0.0-14.7 h/d) with particular challenges during extended COVID-19 lockdowns, including school closures (daily use reduced by mean 1.73 h). Speech perception with the CI alone improved (mean ± SD = 65.7 ± 26.4 RAU) but, in the late onset group, remained poorer than in the normal hearing ear. Measures of spatial release from masking also showed asymmetric hearing in the late onset group ( t13 = 5.14, p = 0.001). Localization of both stationary and moving sound was poor (mean ± SD error = 34.6° ± 16.7°) but slightly improved on the deaf side with CI use ( F1,36 = 3.95, p = 0.05). Decreased sound localization significantly correlated with poorer self-reported hearing. Benefits of CI in children with limited durations of SSD may be more restricted for older children/adolescents. Spatial hearing challenges remain. Efforts to increase CI acceptance and consistent use are needed.

Fabrication of 3D-Printed Implant for Two-Stage Ear Reconstruction Surgery and Its Clinical Application.

Ear reconstruction is one of the most difficult areas in the field of reconstructive surgery. Due to limitations of the current practice, a novel method of auricular reconstruction is needed. Major advancements in three-dimensional (3D) printing technique have rendered the process of ear reconstruction more favorable. Herein, we present our experience in designing and clinically using 3D implants in both 1st and 2nd stage ear reconstruction surgery. After obtaining 3D CT data from each patient, a 3D geometric ear model was created using mirroring and segmentation processes. The 3D-printed implant design resembles but does not exactly match the normal ear shape, and can be inserted in harmony with the currently used surgical technique. The 2nd stage implant was designed to minimize dead space and support the posterior ear helix. The 3D implants were finally fabricated with a 3D printing system and used in ear reconstruction surgery in our institute. The 3D implants were manufactured for application to the currently used two-stage technique while maintaining the shape of the patient's normal ear. The implants were successfully used for ear reconstruction surgery in microtia patients. A few months later, the 2nd stage implant was used in the 2nd stage operation. The authors were able to design, fabricate, and apply patient-specific 3D-printed ear implants for 1st and 2nd stage ear reconstruction surgeries. This design, combined with 3D bioprinting technique, may be a future alternative for ear reconstruction.

Nontuberculous mycobacteria otomastoiditis with facial palsy.

Nontuberculous mycobacteria otomastoiditis with facial palsy.

Evaluation of the Effect of Nasal Septal Deviation on the Middle Ear with Wideband Acoustic Immitancemetry

Objectives: This study aimed to objectively reveal the effects of nasal septal deviation (NSD) and its subgroups on normal middle ear physiology by wideband acoustic immitancemetry (WAI), (it is also known as Wideband Tympanometry). Methods: Eighty-five participants with normal hearing were included in the study. Types of NSD finalized with the paranasal CT. The group without NSD was taken as the control group. Wideband absorbance and resonance frequency values were measured at ambient pressure and in the frequency range of 0.25–8.0 kHz. Results: Normal WAI results were obtained in 20 (31%) participants in the NSD group, compared to 13 (72%) in the Control group. The peak pressure values, resonance frequencies, and absorbance at ambient pressure were significantly different between the NSD and the control groups. Conclusion: WAI may be used as an objective method to evaluate middle ear involvement in patients with NSD problems.

Electrically Evoked Auditory Brainstem Responses in Children Fitted with Hearing Aids Prior to Cochlear Implantation.

This study investigates the effect of hearing aid use on the peripheral auditory pathways in children with sensorineural hearing loss prior to cochlear implantation, as revealed by the electrically evoked auditory brainstem response (EABR). Forty children with hearing aids were recruited. Half of them had normal inner ear structures and the other half had inner ear malformations (IEMs). The EABR was evoked by electrically stimulating the round window niche (RWN) and round window membrane (RWM) during the cochlear implantation operation. The onset age of hearing aid use was significantly correlated with the peak latencies, but not amplitudes, of the wave III (eIII) and wave V (eV). Higher EABR thresholds were found for RWN stimulation than for RWM stimulation and in the children with IEMs than in those without IEMs. Our study provides neurophysiological evidence that earlier use of hearing aids may ameliorate physiological functions of the peripheral auditory pathway in children with and without IEMs. The EABR evoked by the electrical stimulation at RWM is more sensitive compared with that at RWN for evaluating functions of the auditory conduction pathway.

Application of finite element model of middle ear in the study of the middle ear biomechanics in normal and diseased states

Aim: The aim of this study was to create a three-dimensional model of the middle ear by finite element (FE) analysis, using measurements performed on human and cadaveric high-resolution computed tomography (HRCT) temporal bone, and to study the biomechanics in diseased conditions. Materials and Methods: This observational, cross-sectional study was conducted in Acharya Vinoba Bhave Rural Hospital, Sawangi, Meghe, Maharashtra, in the Department of Otorhinolaryngology. The first step of FE modeling approach comprised computer-aided geometric model incorporating the static dimensions from human and cadaveric temporal bones and dynamic dimensions from prepublished data. HRCT Scans of both sets of temporal bones were performed with 0.5 mm cuts, and measurements of the ossicles, middle ear, and tympanic membrane were taken. The cadaveric temporal bones were drilled, the ossicles dissected out and measured using HRCT as well as vernier calipers. This was followed by construction of the working FE model and application of this FE model for studying middle ear biomechanics in normal and diseased states. Results: The mean measurements of ossicles were calculated, and the movement of tympanic membrane was maximum at the site of umbo and stapes footplate, whereas minimum movement was within the ossicles. Larger peak-to-peak displacement was seen at 1000 Hz to 3000 Hz frequency. Our results suggest that FE model can prove beneficial in the study of middle ear biomechanics. Conclusion: The changes in the tympanic membrane movement in diseased state have been compared to normal ear and can be applied to reconstructed ears. FE analysis can be used to study the effect of material properties of various graft materials used in tympanomastoidectomy.

Audiometric and Otologic Findings in Children and Young Adults with Neurofibromatosis Type 1 and Plexiform Neurofibromas.

To characterize otologic and audiologic manifestations in our NF1 cohort and explore the relationship between otologic and audiologic findings in a subset of patients with ear-related plexiform neurofibromas (PNs). Audiologic and otologic clinical evaluations were conducted on 102 patients with NF1 in a natural history study (5-45 years; M=14.4 years; Mdn=14). Testing included pure tone and speech audiometry, middle ear function, neurodiagnostic auditory brainstem response (ABR), auditory processing, and MRIs of the head and neck region. Patients referred to this study had an overall higher incidence and burden of PNs than the overall NF1 population. The majority of subjects in this cohort had normal hearing sensitivity (81%) and normal middle ear function (78%). Nineteen participants had hearing loss that ranged in degree from mild to profound, with the majority in the mild range. Hearing loss was twice as likely to be conductive than sensorineural. In patients with ear-related PNs (n=12), hearing loss was predominantly conductive (60%). Seventy-five percent of ears with PNs had atypical tympanometric tracings that could not be characterized by the classic categories. In all 20 patients with a PN in the temporal bone, the ear canal was affected, and the PNs often extended to the surrounding soft tissue regions. People with NF1-related PNs in the temporal bone and adjacent skull base should have audiometric and otologic monitoring. Addressing hearing concerns should be part of routine clinical evaluations in patients with NF1. Magnetic resonance imaging (MRI) should be performed in patients with NF1 who have hearing loss. 3 Laryngoscope, 133:2770-2778, 2023.

Conductive Hearing Loss Estimated From Wideband Acoustic Immittance Measurements in Ears With Otitis Media With Effusion.

Previous work has shown that wideband acoustic immittance (WAI) is sensitive to the volume of effusion present in ears with otitis media with effusion (OME). Prior work also demonstrates that the volume of the effusion appears to drive, or at least play a significant role in, how much conductive hearing loss (CHL) a child has due to a given episode of OME. Given this association, the goal of this work was to determine how well CHL could be estimated directly from WAI in ears with OME. Sixty-three ears from a previously published study on OME (ages 9 months to 11 years, 2 months) were grouped based on effusion volume (full, partial, or clear) determined during tympanostomy tube placement surgery and compared with age-matched normal control ears. Audiometric thresholds were obtained for a subset of the 34 ears distributed across the four groups. An electrical-analog model of ear-canal acoustics and middle-ear mechanics was fit to the measured WAI from individual ears. Initial estimates of CHL were derived from either (1) average absorbance or (2) the model component thought to represent damping in the ossicular chain. The analog model produced good fits for all effusion-volume groups. The two initial CHL estimates were both well correlated (87% and 81%) with the pure-tone average hearing thresholds used to define the CHL. However, in roughly a third of the ears (11/34), the estimate based on damping was too large by nearly a factor of two. This observation motivated improved CHL estimates. Our CHL estimation method can estimate behavioral audiometric thresholds (CHL) within a margin of error that is small enough to be clinically meaningful. The importance of this finding is increased by the challenges associated with behavioral audiometric testing in pediatric populations, where OME is the most common. In addition, the discovery of two clusters in the damping-related CHL estimate suggests the possible existence of two distinctly different types of ears: pressure detectors and power detectors.

Reliability of Endolymphatic Hydrops Qualitative Assessment in Magnetic Resonance Imaging

The study aimed to compare the consistency of MRI interpretation of endolymphatic hydrops qualitative assessment of inner ear structures performed by independent observers. MRI with a delayed post-contrast 3D-FLAIR sequence was performed to visualize EH in patients suspected of having or diagnosed with MD. The scans were analyzed independently by three observers. In total, 220 ears were evaluated and, of these, 75 had definite MD, five probable MD, 67 with other Menieriform symptoms, and 73 were asymptomatic. Significant differences in cochlear endolymphatic hydrops (CoEH) grading between all observers were observed. On the Barath scale of vestibular endolymphatic hydrops (VEH), differences were found between the radiologists and otorhinolaryngologist in grading. No differences were noted in VEH on the Bernaerts scale and increased perilymphatic enhancement. Our study showed that evaluation of vestibular endolymphatic hydrops is repeatable between observers and easy to learn. It proved that Bernaerts' modification increased the sensitivity of EH diagnosis. Both parameters, CoEH and VEH, may serve as a differentiation method of EH from normal ears. The distinction between normal and hydropic ears is much easier to perform than EH grading. Therefore, it may be used to diagnose MD rather than EH staging.

Does drilling affect the hearing of contralateral normal ear after mastoid surgery?

<p><strong>Background:</strong> Chronic otitis media (COM) is a recurrent infection of the middle ear and/or mastoid air cells affecting 2-3% of global population. Mastoidectomy is the mainstay of the treatment of COM. Bone drilling during mastoidectomy procedure exposes both the ears to acoustic trauma leading to sensorineural hearing loss. The present study was conducted to assess the possible deleterious effect of drilling on hearing of contralateral normal ear by monitoring pre-operative and post-operative pure tone audibility (PTA) and otoacoustic emissions (OAE). Aims and objectives were to evaluate the effect of drill- generated noise on hearing in non-operated ear during mastoidectomy in terms of hearing loss, its nature and duration and recovery of hearing loss.</p><p><strong>Methods:</strong> An observational study was carried out in ENT department at SMS medical college and hospital, Jaipur. Total 40 patients were studied. Pre-operative and post-operative PTA and OAE were studied and compared. Mean drilling time during mastoid surgery was also studied.</p><p><strong>Results:</strong> Out of 40 subjects, maximum patients were 11-20 years of age group (37.5%) with female preponderance (57.5%). All had undergone mastiodectomy. Only 6 (15%) subjects had transient sensorineural hearing loss of contralateral normal ear as determined by comparing pre-operative and post-operative PTA and OAE. The mean recovery time was 2-3 days. The study had shown significant effect of drill generated noise on hearing of contralateral healthy ear following mastoidectomy.</p><p><strong>Conclusions</strong>: Drill-generated noise can’t be lowered to a great extent therefore drilling time should be minimized during mastoid surgeries.</p>

Auricular cartilage regeneration using different types of mesenchymal stem cells in rabbits

BackgroundCartilaginous disorders comprise a wide range of diseases that affect normal joint movement, ear and nose shape; and they have great social and economic impact. Mesenchymal stem cells (MSCs) provide a promising regeneration alternative for treatment of degenerative cartilaginous disorders. This study aimed to compare therapeutic potential of different types of laser activated MSCs to promote auricular cartilage regeneration. Twelve adult rabbit allocated equally in four groups, all animals received a surgical mid auricular cartilage defect in one ear; Group I (Positive control) injected sub-perichondrially with phosphate-buffered saline (PBS), Group II (ADMSC-transplanted group) injected adipose-derived MSCs (ADMSCs), Group III (BMMSCs-transplanted group) received bone marrow-derived MSCs (BMMSCs), and Group IV (EMSC-transplanted group) received ear MSCs (EMSCs) in the defected ear. The auricular defect was analyzed morphologically, histopathologically and immunohistochemically after 4 weeks. In addition, a quantitative real-time polymerase chain reaction was used to examine expression of the collagen type II (Col II) and aggrecan as cartilage growth factors.ResultsThe auricles of all treatments appeared completely healed with smooth surfaces and similar tissue color. Histopathologically, defective areas of control positive group, ADMSCs and EMSCs treated groups experienced a small area of immature cartilage. While BMMSCs treated group exhibited typical features of new cartilage formation with mature chondrocytes inside their lacunae and dense extracellular matrix (ECM). In addition, BMMSC treated group showed a positive reaction to Masson’s trichrome and orcein stains. In contrary, control positive, ADMSC and EMSC groups revealed faint staining with Masson’s trichrome and Orcein. Immunohistochemically, there was an intense positive S100 expression in BMMSCs (with a significant increase of area percentage + 21.89 (P < 0.05), a moderate reaction in EMSCs (with an area percentage + 17.97, and a mild reaction in the control group and ADMSCs (area percentages + 8.02 and + 11.37, respectively). The expression of relative col II and aggrecan was substantially highest in BMMSCs (± 0.91 and ± 0.89, respectively). While, Control positive, ADMSCs and EMSCs groups recorded (± 0.41: ± 0.21, ± 0.6: ± 0.44, ± 0.61: ± 0.63) respectively.ConclusionBMMSCs showed the highest chondrogenic potential compared to ADMSCs and EMSCs and should be considered the first choice in treatment of cartilaginous degenerative disorders.

Three-dimensional quantification of fibrosis and ossification after cochlear implantation via virtual re-sectioning: Potential implications for residual hearing

Hearing preservation may be achieved initially in the majority of patients after cochlear implantation, however, a significant proportion of these patients experience delayed hearing loss months or years later. A prior histological report in a case of delayed hearing loss suggested a potential cochlear mechanical origin of this hearing loss due to tissue fibrosis, and older case series highlight the frequent findings of post-implantation fibrosis and neoosteogenesis though without a focus on the impact on residual hearing.Here we present the largest series (N = 20) of 3-dimensionally reconstructed cochleae based on digitally scanned histologic sections from patients who were implanted during their lifetime. All patients were implanted with multichannel electrodes via a cochleostomy or an extended round window insertion. A quantified analysis of intracochlear tissue formation was carried out via virtual re-sectioning orthogonal to the cochlear spiral.Intracochlear tissue formation was present in every case. On average 33% (SD 14%) of the total cochlear volume was occupied by new tissue formation, consisting of 26% (SD 12%) fibrous and 7% (SD 6%) bony tissue. The round window was completely covered by fibro-osseous tissue in 85% of cases and was associated with an obstruction of the cochlear aqueduct in 100%. The basal part of the basilar membrane was at least partially abutted by the electrode or new tissue formation in every case, while the apical region, corresponding with a characteristic frequency of < 500 Hz, appeared normal in 89%.This quantitative analysis shows that after cochlear implantation via extended round window or cochleostomy, intracochlear fibrosis and neoossification are present in all cases at anatomical locations that could impact normal inner ear mechanics.

Interspecies transfer of RAMOSA1 orthologs and promoter cis sequences impacts maize inflorescence architecture.

Grass inflorescences support floral structures that each bear a single grain, where variation in branch architecture directly impacts yield. The maize (Zea mays) RAMOSA1 (ZmRA1) transcription factor acts as a key regulator of inflorescence development by imposing branch meristem determinacy. Here, we show RA1 transcripts accumulate in boundary domains adjacent to spikelet meristems in sorghum (Sorghum bicolor, Sb) and green millet (Setaria viridis, Sv) inflorescences similar as in the developing maize tassel and ear. To evaluate the functional conservation of syntenic RA1 orthologs and promoter cis sequences in maize, sorghum, and setaria, we utilized interspecies gene transfer and assayed genetic complementation in a common inbred background by quantifying recovery of normal branching in highly ramified ra1-R mutants. A ZmRA1 transgene that includes endogenous upstream and downstream flanking sequences recovered normal tassel and ear branching in ra1-R. Interspecies expression of two transgene variants of the SbRA1 locus, modeled as the entire endogenous tandem duplication or just the nonframeshifted downstream copy, complemented ra1-R branching defects and induced unusual fasciation and branch patterns. The SvRA1 locus lacks conserved, upstream noncoding cis sequences found in maize and sorghum; interspecies expression of a SvRA1 transgene did not or only partially recovered normal inflorescence forms. Driving expression of the SvRA1 coding region by the ZmRA1 upstream region, however, recovered normal inflorescence morphology in ra1-R. These data leveraging interspecies gene transfer suggest that cis-encoded temporal regulation of RA1 expression is a key factor in modulating branch meristem determinacy that ultimately impacts grass inflorescence architecture.