Individual Ear Research Articles

Comparsion of Real EEG References with and Without Zero Potential According Resulting Topograthy Differencies

The problem to find an optimal EEG reference is the actual topic for discussion over 60 years. We have studied topographical differences in averaged EEG amplitudes of alpha domain recorded in 10–20 system during “eyes closed” test. These differences appeared due to the use of 13 reference schemes: top and bottom of the chin (Ch1, Ch2); nose (N); top and bottom of the neck (Nc1, Nc2); upper back (Bc); united electrodes at the base of the neck anteriorly and posteriorly (2Nc); united, ipsilateral, and individual ear electrodes (A12, Sym, A1, A2); vertex (Cz); and averaged reference (AR). Six experiments for each of the ten subjects were carried out with grounded and ungrounded states of three distant basic references Ch2, Bc, 2Nc. Pairwise comparisons of topographic consistency of 13 reference schemes were carried out on the proposed complex of three independent indicators with the evaluative criterion, followed by centroid-based clustering of the reference schemes and its discriminant verification. As a result, we have established: (1) that most coordinated topography is provided by the following reference electrodes —A12, Ch1, Ch2, Sym; (2) reference electrodes A1, Nc2, A2, Sh1, AR, Cz are characterized by individually varying topography, which may lead to contradictory conclusions obtained when they are used; (3) no significant reasons have been found for preferring the grounded (neutral) states of reference electrodes, that makes less important the search for or mathematical construct of an infinitely remote neutral reference electrode; (4) numerous distortions of EEG topography by reference electrode standardization technique (REST) raise serious doubts about its proclaimed advantages in EEG studies.

Binaural Interference and the Effects of Age and Hearing Loss.

The existence of binaural interference, defined here as poorer speech recognition with both ears than with the better ear alone, is well documented. Studies have suggested that its prevalence may be higher in the elderly population. However, no study to date has explored binaural interference in groups of younger and older adults in conditions that favor binaural processing (i.e., in spatially separated noise). Also, the effects of hearing loss have not been studied. To examine binaural interference through speech perception tests, in groups of younger adults with normal hearing, older adults with normal hearing for their age, and older adults with hearing loss. A cross-sectional study. Thirty-three participants with symmetric thresholds were recruited from the University of Iowa community. Participants were grouped as follows: younger with normal hearing (18-28 yr, n = 12), older with normal hearing for their age (73-87 yr, n = 9), and older with hearing loss (78-94 yr, n = 12). Prior noise exposure was ruled out. The Connected Speech Test (CST) and Hearing in Noise Test (HINT) were administered to all participants bilaterally, and to each ear separately. Test materials were presented in the sound field with speech at 0° azimuth and the noise at 180°. The Dichotic Digits Test (DDT) was administered to all participants through earphones. Hearing aids were not used during testing. Group results were compared with repeated measures and one-way analysis of variances, as appropriate. Within-subject analyses using pre-established critical differences for each test were also performed. The HINT revealed no effect of condition (individual ear versus bilateral presentation) using group analysis, although within-subject analysis showed that 27% of the participants had binaural interference (18% had binaural advantage). On the CST, there was significant binaural advantage across all groups with group data analysis, as well as for 12% of the participants at each of the two signal-to-babble ratios (SBRs) tested. One participant had binaural interference at each SBR. Finally, on the DDT, a significant right-ear advantage was found with group data, and for at least some participants. Regarding age effects, more participants in the pooled elderly groups had binaural interference (33.3%) than in the younger group (16.7%), on the HINT. The presence of hearing loss yielded overall lower scores, but none of the comparisons between bilateral and unilateral performance were affected by hearing loss. Results of within-subject analyses on the HINT agree with previous findings of binaural interference in ≥17% of listeners. Across all groups, a significant right-ear advantage was also seen on the DDT. HINT results support the notion that the prevalence of binaural interference is likely higher in the elderly population. Hearing loss, however, did not affect the differences between bilateral and better unilateral scores. The possibility of binaural interference should be considered when fitting hearing aids to listeners with symmetric hearing loss. Comparing bilateral to unilateral (unaided) performance on tests such as the HINT may provide the clinician with objective data to support subjective preference for one hearing aid as opposed to two.

Effects of model definitions and parameter values in finite element modeling of human middle ear mechanics

BackgroundDespite continuing advances in finite element software, the realistic simulation of middle ear response under acoustic stimulation continues to be challenging. One reason for this is the wide range of possible choices that can be made during the definition of a model. Therefore, an explorative study of the relative influences of some of these choices is potentially very helpful. MethodThree finite element models of the human middle ear were constructed, based on high-resolution micro-computed tomography scans from three different human temporal bones. Interesting variations in modeling definitions and parameter values were selected and their influences on middle ear transmission were evaluated. The models were compared against different experimental validation criteria, both from the literature and from our own measurements. Simulation conditions were restricted to the frequency range 0.1–10 kHz. ResultsModeling the three geometries with the same modeling definitions and parameters produces stapes footplate response curves that exhibit similar shapes, but quantitative differences of 4 dB in the lower frequencies and up to 6 dB around the resonance peaks. The model properties with the largest influences on our model outcomes are the tympanic membrane (TM) damping and stiffness and the cochlear load. Model changes with a small to negligible influence include the isotropy or orthotropy of the TM, the geometry of the connection between the TM and the malleus, the microstructure of the incudostapedial joint, and the length of the tensor tympani tendon. ConclusionThe presented results provide insights into the importance of different features in middle ear finite element modeling. The application of three different individual middle ear geometries in a single study reduces the possibility that the conclusions are strongly affected by geometrical abnormalities. Some modeling variations that were hypothesized to be influential turned out to be of minor importance. Furthermore, it could be confirmed that different geometries, simulated using the same parameters and definitions, can produce significantly different responses.

Ear biometrics for patient identification in global health: a cross-sectional study to test the feasibility of a simplified algorithm.

BackgroundOne of the greatest public health challenges in low- and middle-income countries (LMICs) is identifying people over time and space. Recent years have seen an explosion of interest in developing electronic approaches to addressing this problem, with mobile technology at the forefront of these efforts. We investigate the possibility of biometrics as a simple, cost-efficient, and portable solution. Common biometrics approaches include fingerprinting, iris scanning and facial recognition, but all are less than ideal due to complexity, infringement on privacy, cost, or portability. Ear biometrics, however, proved to be a unique and viable solution.MethodsWe developed an identification algorithm then conducted a cross sectional study in which we photographed left and right ears from 25 consenting adults. We then conducted re-identification and statistical analyses to identify the accuracy and replicability of our approach.ResultsThrough principal component analysis, we found the curve of the ear helix to be the most reliable anatomical structure and the basis for re-identification. Although an individual ear allowed for high re-identification rate (88.3%), when both left and right ears were paired together, our rate of re-identification amidst the pool of potential matches was 100%.ConclusionsThe results of this study have implications on future efforts towards building a biometrics solution for patient identification in LMICs. We provide a conceptual platform for further investigation into the development of an ear biometrics identification mobile application.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-016-2287-9) contains supplementary material, which is available to authorized users.

Limited Irrigation for Sweet Corn Planted at Different Dates on Claypan Soil

Irrigation sources in the claypan soil areas of the eastern Great Plains are limited, but supplemental irrigation at certain growth stages may help lessen crop stress. The objective of this research was to determine the effect of critically timed, limited‐amount irrigation on yield and growth of sweet corn (Zea mays L.) planted at two dates with different levels of N fertilization. During the three years of this study, planting date influenced both the total number and total fresh weight of harvested sweet corn, but the effect of early and late plantings was not consistent. Early plantings resulted in up to 65% more harvested ears, nearly twice the total fresh weight yields, and increased number of ears/plant and individual ear weight, especially when plantings were delayed in one year because of inclement weather conditions. But early plantings also can result in lower production when rainfall is great and temperatures are cool. Although irrigation at the V12 and R1 growth stages was found to improve sweet corn yield by as much as 30% over no irrigation, especially when planted late, droughty conditions were not prevalent at the site used in this study and the benefit was sporadic with few differences between irrigation timings. On this site, N fertilization rates had little effect on sweet corn production. Growth of sweet corn was mainly affected by planting date, but dry matter produced during the season was not a consistent indicator of yield.

Behavioral Pure-Tone Threshold Shifts Caused by Tympanic Membrane Electrodes.

To determine whether tympanic membrane (TM) electrodes induce behavioral pure-tone threshold shifts. Pure-tone thresholds (250 to 8000 Hz) were measured twice in test (n = 18) and control (n = 10) groups. TM electrodes were placed between first and second threshold measurements in the test group, whereas the control group did not receive electrodes. Pure-tone threshold shifts were compared between groups. The effect of TM electrode contact location on threshold shifts was evaluated in the test group. TM electrodes significantly increased average low-frequency thresholds, 7.5 dB at 250 Hz and 4.2 dB at 500 Hz, and shifts were as large as 25 dB in individual ears. Also, threshold shifts did not appear to vary at any frequency with TM electrode contact location. Low-frequency threshold shifts occur when using TM electrodes and insert earphones. These findings are relevant to interpreting electrocochleographic responses to low-frequency stimuli.

Audiologic Outcomes in Ehlers-Danlos Syndrome.

The focus of this study was to evaluate the prevalence, type, and severity of hearing impairment in patients with Ehlers-Danlos Syndrome (EDS) and to compare these characteristics with patient demographics and other otologic factors. Retrospective analysis of the AudGen Database. Tertiary academic referral center. Pediatric patients in AudGenDB with a diagnosis EDS. Appropriate audiologic, otologic, and demographic data were recorded. One hundred forty one patients met inclusion criteria. Data for each patient were selected based on their first encounter by age with available audiometric data or their first encounter with a type of hearing loss documented. The patients were then stratified by type and severity of hearing loss, and available otologic issues were documented. One hundred nine patients had normal hearing. Thirty two patients had hearing loss, with 19 bilateral, and 13 unilateral. Of the 51 individual ears, 25 had conductive, 23 had sensorineural, and 3 had mixed hearing loss. Audiometric configuration was primarily flat in nature. The hearing loss severity was significantly correlated with age, but not influenced by the type of loss. Hearing loss is prevalent in patients with EDS. The hearing loss is equally of conductive and sensorineural origin, with a predisposition to be bilateral. Further evaluation of the underlying pathology of hearing loss in these patients is warranted to aid otolaryngologists and audiologists in diagnosis and management.

Optimal choice of a reference electrode for EEG recording

We have studied topographical differences in averaged EEG amplitudes in alpha domain recorded in 10–20 system during “eyes closed” test. These differences appeared due to the use of 13 reference schemes: top and bottom of the chin (P1, P2); nose (N); top and bottom of the back of the neck (Sh1, Sh2); upper back (C); united electrodes at the base of the neck anteriorly and posteriorly (2Sh); united, ipsilateral, and individual ear electrodes (A12, Sym, A1, A2); vertex (Cz); and averaged reference (AR). Six experiments for each of the ten subjects were carried out with grounded and ungrounded states of three distant basic references P2, C, and 2Sh. Pairwise comparisons of topographic consistency of 13 reference schemes were carried out on the proposed complex of three independent indicators with evaluative criterion, followed by centroid-based clustering of the reference schemes and its discriminant verification. As a result, we have established (1) that most coordinated topography is provided by the following reference electrodes—A12, P1, P2, Sym; (2) reference electrodes A1, Sh2, A2, Sh1, AR, Cz are characterized by individually varying topography, which may lead to contradictory conclusions obtained when they are used; (3) no significant reasons have been found for preferring a grounded (neutral) states of reference electrodes, that makes the search for or mathematical construct of an infinitely remote neutral reference electrode less important.

Unilateral cochlear implantation in children with a potentially useable contralateral ear

Increasingly, children are considered for a unilateral CI, even if the contralateral ear falls outside current audiological guidelines, especially if they are not considered to be reaching their educational potential. The primary aim was to investigate the benefit of unilateral CI in children currently outside UK [National Institute for Health and Care Excellence Technology Appraisal Guidance. 2009. Cochlear implants for children and adults with severe to profound deafness. NICE technology appraisal guidance [TAG166]. Available January 29, 2016 from http://www.nice.org.uk/ta166] audiological guidelines in the contralateral ear. The secondary aim was to measure compliance. A retrospective case review with standard demographic data was performed. Forty-seven children were identified as having received a unilateral CI with the contralateral ear falling outside of current UK audiological criteria. These children were allocated to two groups; with hearing between 50 and 70 dB, and 70 and 90 dB at 2 and 4 kHz in the contralateral ear, respectively. Categories of auditory performance (CAP) were assessed. Pre- and post-operative CAP scores demonstrated a statistically significant improvement in auditory perception. We would suggest that assessing candidacy in individual ears and subsequent unilateral CI, has given these children a benefit they may not otherwise have acquired if they only had bilateral hearing aid.

Effects of Negative Middle Ear Pressure on Wideband Acoustic Immittance in Normal-Hearing Adults.

Wideband acoustic immittance (WAI) measurements are capable of quantifying middle ear performance over a wide range of frequencies relevant to human hearing. Static pressure in the middle ear cavity affects sound transmission to the cochlea, but few datasets exist to quantify the relationship between middle ear transmission and the static pressure. In this study, WAI measurements of normal ears are analyzed in both negative middle ear pressure (NMEP) and ambient middle ear pressure (AMEP) conditions, with a focus on the effects of NMEP in individual ears. Eight subjects with normal middle ear function were trained to induce consistent NMEPs, quantified by the tympanic peak pressure (TPP) and WAI. The effects of NMEP on the wideband power absorbance level are analyzed for individual ears. Complex (magnitude and phase) WAI quantities at the tympanic membrane (TM) are studied by removing the delay due to the residual ear canal (REC) volume between the probe tip and the TM. WAI results are then analyzed using a simplified classical model of the middle ear. For the 8 ears presented here, NMEP has the largest and most significant effect across ears from 0.8 to 1.9 kHz, resulting in reduced power absorbance by the middle ear and cochlea. On average, NMEP causes a decrease in the power absorbance level for low- to mid-frequencies, and a small increase above about 4 kHz. The effects of NMEP on WAI quantities, including the absorbance level and TM impedance, vary considerably across ears. The complex WAI at the TM and fitted model parameters show that NMEP causes a decrease in the aggregate compliance at the TM. Estimated REC delays show little to no dependence on NMEP. In agreement with previous results, these data show that the power absorbance level is most sensitive to NMEP around 1 kHz. The REC effect is removed from WAI measurements, allowing for direct estimation of complex WAI at the TM. These estimates show NMEP effects consistent with an increased stiffness in the middle ear, which could originate from the TM, tensor tympani, annular ligament, or other middle ear structures. Model results quantify this nonlinear, stiffness-related change in a systematic way, that is not dependent on averaging WAI results in frequency bands. Given the variability of pressure effects, likely related to intersubject variability at AMEP, TPP is not a strong predictor of change in WAI at the TM. More data and modeling will be needed to better quantify the relationship between NMEP, WAI, and middle ear transmission.

Stability of Audiometric Thresholds for Children with Hearing Aids Applying the American Academy of Audiology Pediatric Amplification Guideline: Implications for Safety.

Children who wear hearing aids may be at risk for further damage to their hearing from overamplification. Previous research on amplification-induced hearing loss has included children using linear amplification or simulations of predicted threshold shifts based on nonlinear amplification formulae. A relationship between threshold shifts and the use of nonlinear hearing aids in children has not been empirically verified. The purpose of the study was to compare predicted threshold shifts from amplification to longitudinal behavioral thresholds in a large group of children who wear hearing aids to determine the likelihood of amplification-induced hearing loss. An accelerated longitudinal design was used to collect behavioral threshold and amplification data prospectively. Two-hundred and thirteen children with mild-to-profound hearing loss who wore hearing aids were included in the analysis. Behavioral audiometric thresholds, hearing aid outputs, and hearing aid use data were collected for each participant across four study visits. Individual ear- and frequency-specific safety limits were derived based on the Modified Power Law to determine the level at which increased amplification could result in permanent threshold shifts. Behavioral thresholds were used to estimate which children would be above the safety limit at 500, 1000, 2000, and 4000 Hz using thresholds in dB HL and then in dB SPL in the ear canal. Changes in thresholds across visits were compared for children who were above and below the safety limits. Behavioral thresholds decreased across study visits for all children, regardless of whether their amplification was above the safety limits. The magnitude of threshold change across time corresponded with changes in ear canal acoustics as measured by the real-ear-to-coupler difference. Predictions of threshold changes due to amplification for children with hearing loss did not correspond with observed changes in threshold over across 2-4 yr of monitoring amplification. Use of dB HL thresholds and predictions of hearing aid output to set the safety limit resulted in a larger number of children being classified as above the safety limit than when safety limits were based on dB SPL thresholds and measured hearing aid output. Children above the safety limit for the dB SPL criteria tended to be fit above prescriptive targets. Additional research should seek to explain how the Modified Power Law predictions of threshold shift overestimated risk for children who wear hearing aids.

Individual Differences in Behavioural Decision Weights Related to Irregularities in Cochlear Mechanics.

An unexpected finding of previous psychophysical studies is that listeners show highly replicable, individualistic patterns of decision weights on frequencies affecting their performance in spectral discrimination tasks--what has been referred to as individual listening styles. We, like many other researchers, have attributed these listening styles to peculiarities in how listeners attend to sounds, but we now believe they partially reflect irregularities in cochlear micromechanics modifying what listeners hear. The most striking evidence for cochlear irregularities is the presence of low-level spontaneous otoacoustic emissions (SOAEs) measured in the ear canal and the systematic variation in stimulus frequency otoacoustic emissions (SFOAEs), both of which result from back-propagation of waves in the cochlea. SOAEs and SFOAEs vary greatly across individual ears and have been shown to affect behavioural thresholds, behavioural frequency selectivity and judged loudness for tones. The present paper reports pilot data providing evidence that SOAEs and SFOAEs are also predictive of the relative decision weight listeners give to a pair of tones in a level discrimination task. In one condition the frequency of one tone was selected to be near that of an SOAE and the frequency of the other was selected to be in a frequency region for which there was no detectable SOAE. In a second condition the frequency of one tone was selected to correspond to an SFOAE maximum, the frequency of the other tone, an SFOAE minimum. In both conditions a statistically significant correlation was found between the average relative decision weight on the two tones and the difference in OAE levels.

Anthropometric Measurements of External Ear

AIM: To analyse the anthropometric measurements of external ear among Tamilnadu population. OBJECTIVE: This study aims to determine the mean values of different morphometric measurements from right and left ears of individuals of age group between 17-25 years using a vernier calliper. BACKGROUND: Anthropometry refers to the measurement of living human body dimensions for the purpose of understanding human physical variation as it plays an important role in plastic surgery, prosthetics, and so on for data collection.In human, ear is the defining feature of face and its structure shows the signs of age and sex. REASON: This study is to create awareness for the knowledge of people in determining the relationship of external ear measurements to the variations of the mean values among individuals..

Efficacy of cervical and ocular vestibular-evoked myogenic potentials in evaluation of benign paroxysmal positional vertigo of posterior semicircular canal.

Benign paroxysmal positional vertigo (BPPV) constitutes a major proportion of the population with peripheral vestibulopathies. Although the freely floating otoconia within the semicircular canals is responsible for the symptoms of BPPV, the source of the otoconia debris is mainly believed to be the otolith organs. Therefore, the pathology in either or both the otolith organs appears a logical proposition. Cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP), being the tests for functional integrity of the otolith organs, appear promising for investigating otolith involvement in BPPV. While recent evidences are suggestive of equivocal findings for cVEMP, there are only a few studies on oVEMP. Additionally, both these potentials have never been explored in the same set of individuals with BPPV. Therefore, the present study aimed to evaluate the functional integrity of the otolith organs through cVEMP and oVEMP in individuals with posterior canal BPPV. Thirty-one individuals with unilateral posterior canal BPPV and 31 age- and gender-matched healthy controls underwent 500Hz tone-burst-evoked cVEMP and oVEMP. The results demonstrated no significant group difference on any of the cVEMP parameters (p>0.05). A similar trend was noticed for the latency-related parameters of oVEMP. However, the peak-to-peak amplitude was significantly smaller in the affected ears of individuals with BPPV than their unaffected ears and the ears of healthy controls (p<0.05). The BPPV group showed significantly higher inter-aural amplitude difference ratio than the healthy controls (p<0.05). Further, the sensitivity and specificity of oVEMP were also found to be far superior to those of cVEMP. Thus, the outcome of the present study revealed involvement of utricle rather than saccule in posterior canal BPPV, and therefore, oVEMP appears to be better suited to clinical investigation than cVEMP in individuals with posterior canal BPPV.

Benefit of contralateral hearing aid in adult cochlear implant bearers

ObjectivesThe present study assessed the interest of a contralateral hearing aid (HA) in adult cochlear implant (CI) bearers. Material and methodsThe study recruited 10 French-speaking adult HA bearers with postlingual bilateral hearing loss, fitted for at least 2 years with a unilateral CI after loss of benefit from HA in one ear but continuing to use their contralateral HA: 4 male, 6 female; mean age, 58 years. All had regularly used bilateral HAs prior to CI. Audiometric assessment comprised: (1) individual ear hearing assessment on pure-tone audiometry and speech discrimination; and (2) free-field testing without aid, with CI only, with HA only and with CI plus HA, on pure-tone audiometry and speech discrimination with quiet background and on speech discrimination in noise. ResultsSpeech discrimination was significantly improved in the bimodal condition (CI plus HA) as compared to CI alone, on all tests. In quiet, discrimination for disyllabic words was>50% in 7 cases with HA alone, in 2 cases with CI alone and in 1 case in with HA+CI. Under 0dB signal-to-noise ratio, discrimination was>50% in 1 case with HA alone, in 3 cases with CI alone and in 6 cases with HA+CI. ConclusionThe present results showed benefit in auditory perception in quiet and in noise with bimodal stimulation. When there is residual hearing in the non-implanted ear, a HA should be fitted; and in progressive bilateral hearing loss, CI should be suggested when HA benefit decreases in one ear.

Porcine methionine sulfoxide reductase B3: molecular cloning, tissue-specific expression profiles, and polymorphisms associated with ear size in Sus scrofa.

BackgroundIn Sus scrofa, methionine sulfoxide reductase B3 (MSRB3) is a crucial candidate gene for ear size, and an important conformational trait of pig breeds. However, challenges in MSRB3 cDNA amplification have prevented further identification of MSRB3 allelic variants influencing pig ear size.ResultsWe cloned a full-length cDNA sequence of porcine MSRB3 by rapid-amplification of cDNA ends. The 3,765-bp gene contained a 5’-untranslated region (UTR) (190 bp), a coding region (552 bp), and a 3’-UTR (3,016 bp) and shared 84 %, 84 %, 87 %, 86 %, and 70 % sequence identities with human, orangutan, mouse, chicken, and zebrafish, respectively. The gene encoded a 183-amino acid protein, which shared 88 %, 91 %, 89 %, 86 %, and 67 % identities with human, orangutan, mouse, chicken, and zebrafish, respectively. Tissue expression analysis using qRT-PCR revealed that MSRB3 was expressed in the heart, liver, lung, kidney, spleen, ear, muscle, fat, lymph, skeletal, and hypothalamic tissues. Three single nucleotide polymorphisms (SNPs) were identified in MSRB3: c.-735C > T in the 5’ flanking region, c.2571 T > C in the 3’-UTR, and a synonymous mutation of c.484 T > C in the coding region. The SNPs c.-735C > T and c.2571 T > C were significantly associated with ear size in a Large White × Minzhu F2 population other than in Beijing Black pigs. Subsequently, at SNP c.-735C > T, the mRNA of MSRB3 was significantly higher expressed in ears of individuals with the TT genotype (Minzhu) than those with CC (Large White).ConclusionsThe porcine MSRB3 owned a 3,765-bp full-length cDNA sequence and was detected to express in ear tissue. Two SNPs of this gene were shown to be significantly associated with ear size in a Large White × Minzhu intercross population instead of Beijing Black pig population. What’s more, the individuals with higher mRNA expression of MSRB3 have larger ear sizes. These results provide useful information for further functional analyses of MSRB3 influencing ear size in pigs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40104-015-0060-x) contains supplementary material, which is available to authorized users.

Gentamicin alters Akt-expression and its activation in the guinea pig cochlea

Gentamicin treatment induces hair cell death or survival in the inner ear. Besides the well-known toxic effects, the phosphatidylinositol-3 kinase/Akt (PI3K/Akt) pathway was found to be involved in cell protection. After gentamicin application, the spatiotemporal expression patterns of Akt and its activated form (p-Akt) were determined in male guinea pigs. A single dose of 0.1mL gentamicin (4mg/ear/animal) was intratympanically injected. The auditory brainstem responses (ABRs) were recorded prior to application and 1, 2 and 7days afterward. At these three time points the cochleae (n=10 in each case) were removed, transferred to fixative and embedded in paraffin. Seven ears were used as untreated controls. Gentamicin, Akt and p-Akt were identified immunohistochemically in various regions of the cochlea and their staining intensities were quantified on sections using digital image analysis. The application of gentamicin resulted in hearing loss with a concomitant up-regulation of Akt-expression in the organ of Corti and spiral ganglion cells and an additional activation in spiral ganglion cells. At the level of individual ears, clear intracellular correlations were found between Akt- and p-Akt-expression in the stria vascularis and interdental cells and, to a minor extent, in the spiral ligament and the organ of Corti. Furthermore, statistical evidence for the connection between gentamicin up-take and hearing loss was detected. The increase in Akt- and p-Akt-expression in the organ of Corti and spiral ganglion cells indicates a selected response of the cochlea against gentamicin toxicity.

CVEMP, oVEMP and Caloric Test Results in Individuals with Meniere’s Disease

Objective : The present study aimed to characterize cVEMP, oVEMP and caloric test findings in individuals with Meniere’s disease. Methods : 29 participants with Meniere’s disease and 29 participants with normal hearing were enrolled for the study. Out of 29 participants in the experimental group, 25 of them had unilateral Meniere’s disease and 4 of them had bilateral Meniere’s disease (Total 33 ears diagnosed with Meniere’s and 25 ears with non-Meniere’s disease). All the participants underwent routine audiological, cVEMP, oVEMP and Caloric testing. Results : Out of 33 ears with Meniere’s disease, 29 ears had absent responses on cVEMP, 23 ears showed absent oVEMP responses, 27 ears had hypo-activity, five ears showed hyper activity and one ear showed normal response to caloric stimulation. In the contralateral ear (25 ears with non-Meniere’s disease) both cVEMP and oVEMP were absent in 5 of the ears, cVEMP was absent and oVEMP was present in 13 ears, cVEMP was present and oVEMP was absent in 1 ear, whereas both cVEMP and oVEMP were present in 6 ears in individuals with Meniere’s disease. However, the caloric responses were present normally in the contralateral ear in individuals with Meniere’s disease. Conclusions : The combination of cVEMP, oVEMP and caloric test provides valuable information regarding localization of hydrops in individuals with Meniere’s disease.

The discrete scar in prominent ear correction: a digital 3-dimensional analysis to determine the ideal incision for otoplasty.

Various postauricular incision sites can be used for prominent ear correction depending on technique and surgeon preference. No study has previously looked at the most aesthetic (least visible) location for the postauricular scar. We investigated the visibility of various scar locations on the posterior ear from a third person perspective through a "Visibility Arc"-a formal assessment of the range of degrees where a particular scar is visible. The objective was to determine the least visible incision-that is, the scar with the shortest visibility arc. Normal ears were marked with 3 different color markers to simulate postoperative scar position, namely, (1) black in auriculocephalic sulcus, (2) blue in the sulcus of the antihelical fold/groove, and (3) green between black and blue. Starting laterally from the right ear toward the left ear, each head was photographed across 180 degrees posteriorly, at 10-degree intervals to determine which colored line (corresponding to a particular scar location) was visible over what "visibility arc." Forty individual ears were analyzed. Scars located in the sulcus of the antihelical fold had the shortest average visible arc, which was a 70-degree arc. The auriculocephalic sulcus had the largest visibility arc, and was most obvious of all of the scar locations-a 100-degree arc. The scar location in between these 2 locations had an 80-degree arc. The least visible scar for pinnaplasty rests in the groove of the antihelix posteriorly, with scars slightly medial to this almost as discrete. The most visible scars when viewed from behind will be those in the "traditional" location of the auriculocephalic sulcus.

Dexamethasone prevents hearing loss by restoring glucocorticoid receptor expression in the guinea pig cochlea.

Dexamethasone is widely used in the treatment of various inner ear diseases. However, knowledge about its direct impact on glucocorticoid receptor (GR) expression is still limited. Prospective animal study in male guinea pigs. A therapeutic concentration of dexamethasone (8 mg/mL) or a physiological concentration of NaCl (0.9% solution) were intratympanically injected into the ears of guinea pigs (n = 10 in each case) 14 hours prior to 90 dB noise exposure (1 hour). Eighteen ears were exposed to noise only. Seven untreated ears were used as controls. Auditory brainstem responses were recorded prior to noise exposure or treatment and 2 hours thereafter. The cochleae were removed from the bullae, transferred to fixative, and embedded in paraffin. GR expression was identified immunohistochemically in the cochlea. Local staining intensities were quantified for seven regions by a computer. Dexamethasone application significantly lowered noise-induced hearing loss. Statistically significant alterations in the average GR expression levels were identified exclusively in the spiral ligament. Comparing GR expression at the level of individual ear, numerous highly significant local associations were identified in the other six cochlear regions. The intratympanic application of dexamethasone is suitable for supporting cochlear homeostasis under stress conditions. The lateral wall, mainly responsible for potassium recycling, seems to be the main target in glucocorticoid therapy.