Audiometric Pattern Research Articles

Distinct audiometric patterns in congenital round window atresia: A comparative study with common congenital middle ear anomalies

ObjectiveLittle is known about the hearing characteristics in patients with congenital round window atresia (CRWA). This study aimed to investigate hearing characteristics in patients with CRWA by comparing them with two relatively common congenital middle ear anomalies: congenital stapedial fixation (CSF) and congenital ossicular discontinuity (COD). MethodsLiterature searches yielded five patients with surgically confirmed CRWA (seven ears), who were included in the CRWA group, along with one of our patients. Air and bone conduction thresholds; air-bone gap (ABG); and presence and depth of the Carhart notch were analyzed. These audiometric variables in the CRWA group were compared with those in the CSF (n = 15) and COD (n = 22) groups, comprising patients identified from our institution's medical database. ResultsAverage bone and air conduction thresholds in the CRWA group were 16.4 (standard deviation [SD]: 2.9; 95 % confidence interval [CI]: 14.6–18.3) and 44.6 (SD: 3.5; 95 % CI: 42.6–47.3) dB hearing level (HL). Bone conduction thresholds at high frequencies (≥2 kHz) were higher than those at low frequencies (<2 kHz), while air conduction thresholds at high frequencies were lower than those at low frequencies: ABGs at high frequencies were significantly smaller than those at low frequencies (2 kHz vs. 0.5 kHz, p = 0.027; 2 kHz vs. 1 kHz, p = 0.041; 4 kHz vs. 0.5 kHz, p = 0.042; 4 kHz vs. 1 kHz, p = 0.027). There were no between-group differences in incidence and depth of the Carhart notch. ConclusionCRWA could manifest as a distinct audiometric pattern with poorer bone conduction and better air conduction at ≥2 kHz, resulting in significantly smaller ABGs at higher frequencies than that at lower frequencies. Our findings indicated that this pattern differed from that of CSF and COD. The unique beer bottle-shaped audiogram associated with CRWA might facilitate its early diagnosis in patients with congenital conductive hearing loss.

Management of Petrous Bone Cholesteatoma: The Gruppo Otologico Experience.

The term petrous bone cholesteatoma (PBC) refers to lesions extending deep to the bony labyrinth via superior, inferior, and posterior cell tracts. PBC is a rare incidence accounting for only 4-9% of petrous bone lesions. Lesions of petrous bone represent a real surgical challenge due to its complex relationship with critical neurovascular structures. To demonstrate our 40-plus years' experience in the management of PBC, depict the clinical features of PBC according to Sanna's Classification, evaluate the postoperative follow-up of surgically treated PBC patients, and determine the recurrence rate. Retrospective medical record review. Medical records of 298 PBC cases operated from the year 1983 to 2024 were thoroughly evaluated. A total of 298 PBC cases were surgically treated at our center. The average age at presentation in this series was 47 years. Males are more affected than females with a male-to-female ratio of 2.2:1. The most common presenting symptoms were hearing loss (84%), tinnitus (48%), and facial nerve paralysis (45%). Mixed hearing loss (41%) was the commonest audiometric pattern of hearing loss followed by conductive hearing loss (26%) and profound sensorineural hearing loss (4%) and a total of 86 (29%) had anacusis at presentation. On preoperative facial nerve function examination, 133(45%) of patients had various degrees of paresis and complete paralysis whereas 55% had normal HB-I function. The commonest degree of paresis noted was HB-III (18%) followed by HB-VI (5%). A total of 150 (50%) patients had previous otologic surgery and two-thirds of these cases had two or more prior otologic surgeries. According to Sanna's PBC Classification system, we identified that the supralabyrinthine class (44%) is the commonest of all classes followed by massive (33%), infralabyrinthine-apical (9%), infralabyrinthine(8%), and apical (5%) classes in that order. However, only ten patients had congenital type of PBC. Extension to clivus, sphenoid, nasopharynx, intradural space, and occipital condyle was found in 8, 2, 1, and 2 cases respectively. The most commonly used surgical approaches at our center were TO, MTCA with rerouting of the facial nerve, and TLAB with external auditory canal (EAC) closure. Postoperative complications were minimal and the duration of follow-up ranged from one to 458 months with a mean duration of 65 months. Residual lesions were evident in 11 cases (3.7%), with the surgical cavity, middle and posterior fossa dura, and jugular bulb being the commonest sites. Petrous bone cholesteatoma represents diagnostically and surgically challenging lesions of temporal bone which are usually frustrating to the treating surgeon. A high index of clinical suspicion, thorough clinical evaluation examination, and preoperative radiologic evaluation make the diagnosis easier. Preoperative anatomic classification of the lesion enables the physician to choose the appropriate surgical approach. Sanna's classification is widely used to classify PBC in relation to the labyrinthine block. Radical disease removal should always come before hearing preservation. Cavity obliteration is the solution to the problems related to a large cavity. Finally, advancements in lateral skull base approaches create adequate surgical access for the complete removal of the lesion with excellent control of critical neurovascular structures.

Sudden Hearing Loss as an Initial Symptom of Vestibular Schwannoma

This study aims to determine the prevalence of vestibular schwannoma (VS) among patients presenting with sudden hearing loss (SHL) and to characterize the clinical features of individuals diagnosed with both VS and SHL. We conducted an observational retrospective review at a tertiary referral center, spanning a 30-year period, focusing on patients diagnosed with SHL where VS was confirmed as the underlying cause. We included patients meeting these criteria while excluding those lacking imaging or with a pre-existing diagnosis of VS. We evaluated the audiological characteristics at the time of diagnosis and assessed clinical outcomes following treatment. Among the 403 patients presenting with SHL during the study period, 9 (2.2%) were diagnosed with VS, aged between 25 and 72years. Although audiometric profiles varied, high-frequency hearing loss predominated, mostly categorized as mild to moderate. Six patients (66%) had Koos grade I-II schwannomas. Only 2 patients achieved complete hearing recovery post-treatment, while 4 showed no improvement. VS is a rare etiology of SHL, accounting for slightly over 2% of cases. Its symptomatology, severity, and audiometric patterns do not significantly differ from SHL caused by other factors. Tumor size does not correlate with hearing characteristics. Treatment modalities resemble those for other SHL cases, and hearing improvement does not obviate the necessity for follow-up magnetic resonance imaging (MRI) scans.

Sensitivity of Methods for Diagnosing Noise-Induced Hearing Loss in Cases of Exposures Including Intense Low-Frequency Noise.

Exposure to intense low-frequency sounds, for example inside tanks and armoured vehicles, can lead to noise-induced hearing loss (NIHL) with a variable audiometric pattern, including low- and mid-frequency hearing loss. It is not known how well existing methods for diagnosing NIHL apply in such cases. Here, the audiograms of 68 military personnel (mostly veterans) who had been exposed to intense low-frequency noise (together with other types of noise) and who had low-frequency hearing loss (defined as a pure-tone average loss at 0.25, 0.5 and 1 kHz ≥20 dB) were used to assess the sensitivity of three diagnostic methods: the method of Coles, Lutman and Buffin, denoted CLB, which depends on the identification of a notch or bulge in the audiogram near 4 kHz, and two methods specifically intended for diagnosing NIHL sustained during military service, the rM-NIHL method, which depends on the identification of a notch or bulge in the audiogram near 4 kHz and/or a hearing loss at high frequencies greater than expected from age alone, and the MLP(18) method based on a multi-layer perceptron. The proportion of individuals receiving a positive diagnosis for either or both ears, which provides an approximate measure of sensitivity, was 0.40 for the CLB method, 0.79 for the rM-NIHL method and 1.0 for the MLP(18) method. It is concluded that the MLP(18) method is suitable for diagnosing NIHL sustained during military service whether or not the exposure includes intense low-frequency sounds.

Occupational Lead Exposure Ototoxicity Evaluated With Distortion-Product Otoacoustic Emissions.

To evaluate the extent of hearing loss among pottery workers in Mexico exposed to lead. The authors conducted a cross-sectional study including 315 adult pottery workers. Auditory function was evaluated by air conduction pure-tone audiometry (pure-tone average) and distortion-product otoacoustic emission (DPOAE) levels (amplitude and signal-to-noise ratio). Lead exposure was assessed with a single blood sample test and classified as low, medium, and high according to blood lead tertiles. Logistic regression models were calculated for the association between blood lead levels, pure-tone average, and DPOAE records. Median (25th-75th) blood lead levels were 14 μg/dL (7.5-22.6 μg/dL). The audiometric pattern and DPOAE records were similar across blood lead levels groups in all frequencies, and no statistically significant differences were found. Adjusted logistic regression models showed no increase in the odds for hearing thresholds >25 dB (HL) and DPOAE absence associated with blood lead levels, and no dose-response pattern was observed ( p > 0.05). Given the results from this cross-sectional study, no association was found between blood lead levels and hearing loss assessed with DPOAE. Future longitudinal work should consider chronic lead exposure estimates among underrepresented populations, which can potentially inform safer work practices to minimize the risk of ototoxicity.

Comparison of Hearing Thresholds among Patients on Treatment for Drug-Resistant Versus Drug-Susceptible Pulmonary Tuberculosis in A SubSaharan African Healthcare Setting

Background: Pulmonary tuberculosis is a debilitating infectious disease that affects all age groups and sadly, a leading cause of death in developing countries particularly in sub-Saharan Africa. One major challenge facing the global efforts against tuberculosis is drug-resistance, which necessitates the use of aminoglycoside-based second line drugs that are known to have ototoxic potentials. Hearing impairment can be a source of social distress, professional disability and in some cases, litigation. This research compared the pure tone audiometric patterns of patients on treatment for drug-resistant versus drug-susceptible pulmonary tuberculosis. The incidence of hearing loss between the groups was assessed. Patients and Method: The research was a prospective comparative study of all eligible newly diagnosed pulmonary tuberculosis patients admitted into the Pulmonology unit of Federal Medical Centre, Owerri, Nigeria. Pre-treatment (baseline) and monthly pure tone audiometry was done for each patient before and during treatment respectively. The patients were followed up and assessed for three months. Data collected was analyzed with Statistical Package for Social Sciences (SPSS) version 20.0 software for Windows. Statistical significance was set at p&lt; 0.05. Results: A total of 76 patients (38 in each group) completed the study. The M:F ratio was 1.53:1 and 1.24:1 for the drug resistant and drug susceptible groups respectively while the mean duration of presenting symptoms were 11.7 ± 7.8 and 7.4 ± 5.1 weeks for the groups respectively. The prevalence of baseline hearing impairment was 73.7% among both groups while by the third month it was 89.5% among the dug-resistant group and 78.9% among the drug-susceptible group implying a cumulative incidence of hearing loss of 15.8% and 5.3% respectively over three months. This difference was statistically significant. Conclusion: The incidence of hearing impairment among patients on treatment for drug-resistant pulmonary tuberculosis was approximately three-fold higher than their drug susceptible counterparts after three months of treatment; this was statistically significant.

Audiometric Profile of Patients on Treatment for Drug-Resistant Pulmonary Tuberculosis in Owerri, South-East Nigeria.

Background: Tuberculosis is an existential medical challenge in certain parts of the world necessitating global efforts. Perhaps more challenging is the treatment of drug-resistant forms of the disease as this requires use of second line drugs, predominantly potentially ototoxic aminoglycosides. The hearing impairment so caused, besides constituting social disability, can impair compliance and have far-reaching consequences. This study aimed at assessing the hearing patterns of patients on treatment for drug-resistant pulmonary tuberculosis to determine if, and to what extent their treatment affected their hearing status. Patients and method: The study was an 18-month prospective analysis of consecutive newly diagnosed drug-resistant pulmonary tuberculosis patients in a tertiary hospital in Owerri, Nigeria. Baseline audiometry was conducted on the patients with subsequent monthly audiometry for 3 months during treatment. A control group drawn from normal population and matched for age and sex with the study group was recruited and audiometry performed on the participants in similar pattern. The audiometric patterns of both groups were analyzed and compared using Statistical Package for Social Sciences (SPSS) version 20.0 software for Windows. Statistical significance was set at p&lt; 0.05. Results: Thirty-eight (38) patients treated for drug-resistant pulmonary tuberculosis completed the study alongside thirty-eight (38) control subjects with M:F ratio was 1.53:1. The baseline prevalence of hearing impairment of any sort was 73.7% and 68.4% among the test and control groups respectively, whereas after three months it was 89.5% and 68.4% respectively. The cumulative incidence of hearing loss over three months was 15.8% and 0% respectively. This difference was statistically significant. Conclusion: Treatment of drug-resistant tuberculosis with second line drugs can lead to significant hearing impairment within the first three months of treatment.

Changes in the Audiometric Patterns in Presbycusis with Ongoing Medical Upgradation

Changes in the Audiometric Patterns in Presbycusis with Ongoing Medical Upgradation

Sudden sensorineural hearing loss: Recovery rates according to audiometric patterns

PurposeThe aim of this study was to evaluate the different audiometric patterns in sudden sensorineural hearing loss (SSNHL), assess recovery rates based on the initial pattern and also, analyse the impact on speech discrimination scores (SDS). MethodsA retrospective, descriptive, study was completed for patients with SSNHL from January 2010 until June 2020. Outcome measures included audiometric patterns, recovery rates, improvements over time for hearing loss as well as for SDS at 14 days and 3 months follow-up. The Kruskal–Wallis test and Mann–Whitney U test were used to compare differences between the different groups. Post-hoc testing involved the Wilcoxon signed-rank test. A P<0.05 was considered statistically significant. ResultsWe included 211 patients, 64.3% showed downward-sloping or flat audiometric curves. Overall, 40% of the patients had recovered 50% or more of their hearing by day 14. We observed that hearing did improve over time, and this was more common for the upward-sloping cases, with 65% recovering to at least 50% of the maximum possible recovery by 3 months follow-up. Thirty percent had concomitant vertigo and/or dizziness; these patients had worse initial speech PTAs (pure tone average) (P≤0.0001) and inferior recovery rates (P=0.0007) as compared to patients without vertigo and/or dizziness. ConclusionSSNHL is still a controversial topic. Variability was observed with regards to audiometric curves, recovery rates and SDS recovery. We provide a table with recovery rates based on audiometric patterns that may help guide clinicians when explaining this condition to their patients.

Sudden sensorineural hearing loss: Recovery rates according to audiometric patterns

The aim of this study was to evaluate the different audiometric patterns in sudden sensorineural hearing loss (SSNHL), assess recovery rates based on the initial pattern and also, analyse the impact on speech discrimination scores (SDS).

Multiple Audiometric Analysis in the Screening of Vestibular Schwannoma.

IntroductionAsymmetric sensorineural hearing loss is the main early symptom of retrocochlear lesions, hence its importance in screening for vestibular schwannomas. Currently, there is no consensus regarding its definition. The objective was to identify the audiometric pattern that would serve as a predictor for vestibular schwannoma in patients with asymmetric hearing loss.Materials and methodsA cross-sectional study was conducted that included patients with asymmetric hearing loss attending a secondary care center and a tertiary care center. Clinical, audiometric and imaging (MRI with gadolinium) variables were collected. Asymmetric hearing loss was defined as a difference of 15 dB in one or more frequencies between both ears. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of different audiometric patterns were analyzed.ResultsA total of 107 patients were studied and divided into two groups: group 1 without vestibular schwannoma (n=98); and group 2 with vestibular schwannoma (n=9). No significant difference in demographic characteristics or audiometric patterns was found in patients with and without vestibular schwannoma. The audiometric pattern with the best sensitivity as a screening test was a difference >20 dB in the 4,000 Hz frequency, with a sensitivity of 77.78%, specificity of 30.61%, PPV of 8.33%, NPV of 93.75% and accuracy of 34.50%.ConclusionThe audiometric pattern with the best results was a difference >20 dB in the 4,000 Hz frequency range; however, patients with asymmetric hearing loss could not be differentiated from patients with retrocochlear lesions based only on audiometry. Asymmetrical hearing loss must be studied with MRI.

Audiological Features in 63 Patients With Cochlear Nerve Deficiency.

We aimed to investigate the clinical features of cochlear nerve deficiency (CND), and in particular, the long-term course of hearing disability and audiogram shapes. Retrospective observational nonrandomized group study. Academic medical center. The subjects were 63 children with congenital hearing loss who visited our hospital between 2009 and 2019 and underwent MRI, based on which they were diagnosed with CND. There were 61 cases of unilateral CND and two cases of bilateral CND. Imaging tests by MRI and CT and audiometric assessments by pure-tone audiometry and distortion product otoacoustic emission were performed. Among the cases of CND diagnosed by assessing the cochlear nerve on MRI, approximately 20% of the bony cochlear nerve canals that could be assessed on CT were normal. Of the 61 cases diagnosed with unilateral CND, 55 cases had cochlear nerve aplasia (90.2%), and six had cochlear nerve hypoplasia (9.8%), with a mean hearing ability of 92.2 and 94.6 dB HL, respectively. Thus, the majority of cases had severe-to-profound hearing loss. The overall audiometric patterns were 78.7% flat, 9.8% cookie-bite, and 9.8% high-frequency. Six of 61 cases (9.8%) had a distortion product otoacoustic emission (DPOAE) response based on the affected side, and none of the cases lost the response during follow-up. Herein, we report the largest study on CND and performed CND image and audiometric assessments. Accurately in diagnosing CND requires not only CT but also MRI assessment. Hearing loss is often severe to profound; however, various audiometric patterns have been observed. CND includes a small number of cases that respond to DPOAE, indicating that some CND cases are clinically diagnosed with auditory neuropathy spectrum disorder (ANSD). A sustained DPOAE response might help in differentiating CND from other ANSDs. Children with congenital deafness who have passed the newborn hearing screening by DPOAE should be examined by MRI to rule out CND.

Audiometric profiles and patterns of benefit: a data-driven analysis of subjective hearing difficulties and handicaps

Objective Hearing rehabilitation attempts to compensate for auditory dysfunction, reduce hearing difficulties and minimise participation restrictions that can lead to social isolation. However, there is no systematic approach to assess the quality of the intervention at an individual level that might help to evaluate the need of further hearing rehabilitation in the hearing care clinic. Design A data-driven analysis on subjective data reflecting hearing disabilities and handicap was chosen to explore “benefit patterns” as a result of rehabilitation in different audiometric groups. The method was based on (1) dimensionality reduction; (2) stratification; (3) archetypal analysis; (4) clustering; (5) item importance estimation. Study sample 572 hearing-aid users completed questionnaires of hearing difficulties (speech, spatial and qualities hearing scale; SSQ) and hearing handicap (HHQ). Results The data-driven approach revealed four benefit profiles that were different for each audiometric group. The groups with low degree of high-frequency hearing loss (HLHF) showed a priority for rehabilitating hearing handicaps, whereas the groups with HLHF > 50 dB HL showed a priority for improvements in speech understanding. Conclusions The patterns of benefit and the stratification approach might guide the clinical intervention strategy and improve the efficacy and quality of service in the hearing care clinic.

Type 2 diabetes mellitus and hearing impairment as seen in a tertiary hospital in Port Harcourt

&lt;p class="abstract"&gt;&lt;strong&gt;Background: &lt;/strong&gt;Diabetes mellitus prevalence has been on the increase especially the type 2. This study therefore is to determine the pattern, type and severity of hearing impairment and correlating it with the duration, presence of peripheral neuropathy, glycaemic control of the type 2 diabetes mellitus seen in university of Port Harcourt teaching hospital (UPTH).&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods: &lt;/strong&gt;It is a descriptive cross sectional study of adult diabetic patients seen at the endocrinology clinic of University of Port Harcourt teaching hospital. Consecutive patients with confirmed diagnosis of diabetes mellitus that gave their informed consent were recruited. A semi structured questionnaire aimed at obtaining the biodata, duration of diabetes and level of control, presence of neuropathy was administered to these patients. They had otoscopy done in addition to audiometric evaluation using pure tone audiometry.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results: &lt;/strong&gt;The study involved 108 subjects with confirmed diagnosis of type 2 diabetes mellitus. Males; 42 and females; 66. Age ranged from 20 -81years. Hearing impairment was present in 68.52% of the subjects. Audiometric pattern showed 54.6% with SNHL while 31.5% had normal hearing. Majority of the subjects had mild degree hearing loss (50%). Bilateral SNHL was the commonly seen type of hearing loss in 55.93%.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;There is a high prevalence of hearing loss in patients with type 2 diabetes mellitus. The commonest type of hearing loss in these subjects was bilateral mild sensorineural hearing loss. There is therefore a need to incorporate regular audiologic assessment in the management protocol of the adult diabetic patients.&lt;/p&gt;&lt;p class="abstract"&gt; &lt;/p&gt;

Audiometric Pattern in Moderate and Severe Tympanic Membrane Retraction.

To evaluate the audiometric pattern in moderate/severe retractions of the tympanic membrane and correlate it with the severity of the otoscopy findings. Cross-sectional study. Tertiary hospital. Consecutive patients with moderate or severe tympanic membrane retraction in at least one ear (451 ears) between August 2000 and January 2019, and no surgical history or effusion (mean [standard deviation] age, 32.8 [20.2] yr; 54% female and 42.4% children). Pure-tone audiometry. Air conduction (AC) and bone conduction thresholds, and air-bone gap (ABG) measured at the four-frequency pure-tone average. The median in decibel hearing level (dB HL) (minimum-maximum) of the AC, BC, and ABG were 25 dB HL (0-120 dB HL), 10 dB HL (0-75 dB HL), and 12.5 dB HL (0-55 dB HL), respectively. Seventy-two percent of the ears had an ABG ≤ 20 dB HL. For severity of the retraction of pars flaccida (PF), the AC, bone conduction, and ABG were similar across groups, with a weak correlation. For the pars tensa (PT), there was a global difference in the medians of AC and ABG in terms of the degree of severity, with a moderate correlation. Retraction in PF and PT at the same time was observed in 6 4% of the ears. ABG median was lower in ears with PF retraction (6.25 dB HL) than PT retraction, isolated (15 dB HL) or not (13.75 dB HL; p < 0.05). The ABG pure-tone average median was higher when PT was involved. We found a significant correlation between the retraction severity and worsening of AC and ABG thresholds, only for PT.

Acute onset of tinnitus in patients with sudden deafness.

Objective:We made hypotheses that tinnitus will appear more likely in patients with sudden deafness with superior hearing in unaffected ear or with more severe acute hearing loss.Methods:A retrospective cohort study was performed. Five hundred forty-one patients were identified with idiopathic sudden sensorineural hearing loss (ISSHL) from January 1995 to August 2006. The exclusion criteria for this study were as follows: bilateral sudden hearing loss and Meniere disease, previous tinnitus or bilateral tinnitus at initial evaluation, and onset of hearing loss less than 7 days. The cohort enrolled 454 patients. The enrolled patients were classified into two groups: patient with acute onset tinnitus in the affected ear and patients without tinnitus at initial visit. Main outcome measures were patient age, the presence or absence of vertigo and tinnitus, audiometric patterns, the severity of hearing loss, and hearing in the unaffected ear.Results:Better contralateral hearing (n = 220 versus n = 72, P < 0.001) and younger age (48 versus 55 years, P < 0.001) were independently associated with the acute onset of tinnitus in patients with ISSHL. The degree of asymmetry between the ears did not differ significantly between patients with and without tinnitus. The sex, presence of vertigo, shape of audiogram, and severity of hearing loss were not correlated with tinnitus occurrence.Conclusions:Tinnitus triggered by ISSHL was more frequent in patients with better contralateral hearing and of a younger age, irrespective of the severity of hearing loss on the affected side or the asymmetry between the ears.

Age-Related Hearing Loss Is Dominated by Damage to Inner Ear Sensory Cells, Not the Cellular Battery That Powers Them.

Age-related hearing loss arises from irreversible damage in the inner ear, where sound is transduced into electrical signals. Prior human studies suggested that sensory-cell loss is rarely the cause; correspondingly, animal work has implicated the stria vascularis, the cellular "battery" driving the amplification of sound by hair cell "motors." Here, quantitative microscopic analysis of hair cells, auditory nerve fibers, and strial tissues in 120 human inner ears obtained at autopsy, most of whom had recent audiograms in their medical records, shows that the degree of hearing loss is well predicted from the amount of hair cell loss and that inclusion of strial damage does not improve the prediction. Although many aging ears showed significant strial degeneration throughout the cochlea, our statistical models suggest that, by the time strial tissues are lost, hair cell death is so extensive that the loss of battery is no longer important to pure-tone thresholds and that audiogram slope is not diagnostic for strial degeneration. These data comprise the first quantitative survey of hair cell death in normal-aging human cochleas, and reveal unexpectedly severe hair cell loss in low-frequency cochlear regions, and dramatically greater loss in high-frequency regions than seen in any aging animal model. Comparison of normal-aging ears to an age-matched group with acoustic-overexposure history suggests that a lifetime of acoustic overexposure is to blame.SIGNIFICANCE STATEMENT This report upends dogma about the causes of age-related hearing loss. Our analysis of over 120 autopsy specimens shows that inner-ear sensory cell loss can largely explain the audiometric patterns in aging, with minimal contribution from the stria vascularis, the "battery" that powers the inner ear, previously viewed as the major locus of age-related hearing dysfunction. Predicting inner ear damage from the audiogram is critical, now that clinical trials of therapeutics designed to regrow hair cells are underway. Our data also show that hair cell degeneration in aging humans is dramatically worse than that in aging animals, suggesting that the high-frequency hearing losses that define human presbycusis reflect avoidable contributions of chronic ear abuse to which aging animals are not exposed.

Clinical audiometric patterns of hearing loss following blast-related injury in U.S. military personnel

Objective: To identify clinical audiometric patterns of hearing loss following blast-related injury (BRI) in US military personnel. Design: Retrospective cohort study. Study sample: A total of 1186 male Navy and Marine Corps service members with normal hearing thresholds on pre-injury audiograms who had post-injury audiograms in the Blast-Related Auditory Injury Database. Results: Low- and high-frequency pure-tone averages (PTAs) were significantly higher in those with BRI than non-blast-related injury (NBRI) for both ears (p < 0.001 for all comparisons). Overall, 172 (15%) service members met criteria for post-injury hearing loss and were categorised into PTA or single-frequency hearing loss subgroups. PTA hearing loss was more common in the BRI group (50% vs. 33%, p < 0.036), whereas single-frequency hearing loss was more common in the NBRI group. Most hearing loss was mild to moderate in degree, and three distinct audiometric patterns emerged (i.e. flat, sloping and rising). A flat pattern was the most prevalent configuration among those with PTA hearing loss, especially bilateral loss. Single-frequency hearing loss was mostly unilateral and high frequency. Conclusions: In this study, BRI produced hearing loss across test frequencies, generating more clinically actionable post-injury audiograms than NBRI. We found that post-injury audiometric patterns of hearing loss among military personnel may vary.

A Novel Method for Classifying Hearing Impairment in Epidemiological Studies of Aging: The Wisconsin Age-Related Hearing Impairment Classification Scale.

Purpose Longitudinal population-based cohort data were used to develop a standardized classification system for age-related hearing impairment using thresholds for frequencies (0.5-8 kHz) typically measured in cohort studies. Method Audiometric testing data collected in the Epidemiology of Hearing Loss Study from participants (n = 1,369) with four visits (1993-1995, 1998-2000, 2003-2005, and 2009-2010) were included (10,952 audiograms). Cluster analyses (Wald's method) were used to identify audiometric patterns. Maximum allowable threshold values were defined for each cluster to create an ordered scale. Progression was defined as a two-step change. Results An eight-step scale was developed to capture audiogram shape and severity of hearing impairment. Of the 1,094 participants classified as having normal hearing based on a pure-tone average, only 25% (n = 277) were classified as Level 1 (all thresholds ≤ 20 dB HL) on the new scale, whereas 17% (n = 182) were Levels 4-6. During the 16-year follow-up, 64.9% of those at Level 1 progressed. There was little regression using this scale. Conclusions This is the first scale developed from population-based longitudinal cohort data to capture audiogram shape across time. This simple, standardized scale is easy to apply, reduces misclassification of normal hearing, and may be a useful method for identifying risk factors for early, preclinical, age-related changes in hearing.

Assessing fractional hair cell survival in archival human temporal bones.

Histopathological analysis of hair cell survival in human temporal bone sections has historically been binarized such that each hair cell row is rated as either present or absent, thereby greatly underestimating the amount of hair cell loss. Here, we describe and validate a technique to reliably assess fractional hair cell survival in archival sections stained with hematoxylin and eosin (H&E) using high-resolution light microscopy and optical sectioning. Technique validation. Hair cell counts in archival temporal bone slide sets were performed by several observers using either differential interference contrast (DIC) or confocal microscopy of the endogenous eosin fluorescence in hair cells. As a further cross-check, additional decelloidinized sections were immunostained with hair cell markers myosin VI and VIIa. Cuticular plates and stereocilia bundles are routinely resolvable in DIC imaging of archival H&E-stained human material using standard research-grade microscopes, allowing highly accurate counts of fractional hair cell survival that are reproducible across observer and can be verified by confocal microscopy. Reanalysis of cases from the classic temporal bone literature on presbycusis suggests that, contrary to prior reports, differences in audiometric patterns may be well explained by the patterns of hair cell loss. NA Laryngoscope, 130:487-495, 2020.