Pathophysiology of otosclerosis

Exploring delivery systems for targeted nanotechnology-based gene therapy in the inner ear

Hearing loss places a significant burden on our aging population. However, there has only been limited progress in developing therapeutic techniques to effectively mediate this condition. This review will outline several of the most commonly utilized practices for the treatment of sensorineural hearing loss before exploring more novel techniques currently being investigated via both in vitro and in vivo research. This review will place particular emphasis on novel gene-delivery technologies. Primarily, it will focus on techniques used to deliver genes that have been shown to encourage the proliferation and differentiation of sensory cells within the inner ear and how these technologies may be translated into providing clinically useful results for patients.

Endoscopic-Assisted Cochlear Implantation in Far Advanced Otosclerosis

OBJECTIVES

To evaluate the effectiveness of cochlear implantation (CI) in case of far advanced otosclerosis and to evaluate the value of using intraoperative otoendoscopy to facilitate the identification of the round window membrane and the scala tympani without the need to remove the posterior canal wall or to perform a subtotal petrosectomy.

STUDY DESIGN

Retrospective case-series study.

SETTING

Tertiary academic CI center.

PATIENTS AND METHODS

This study was conducted on patients with far advanced otosclerosis who underwent endoscopic-assisted CI between January 2010 and June 2020 at the same CI center. The minimum follow-up period was 2 years after surgery.

RESULTS

Fourteen patients were included in the study. Ten patients had undergone a previous stapedotomy. Electrode insertion in the scala tympani was successfully accomplished in all cases included in the study. There was a statistically significant improvement in pure-tone average and speech discrimination scores in all cases of the study group (p < 0.0001). There were no statistically significant differences in postoperative pure-tone average or speech discrimination scores between cases with and without cochlear ossification or between cases with and without a previous stapedotomy (p > 0.05).

CONCLUSION

Endoscopic-assisted CI is an effective option for hearing restoration in patients with far advanced otosclerosis. Otoendoscopy can facilitate visualization and access to the scala tympani without the need to remove the posterior canal wall or to perform a subtotal petrosectomy.

Factors Associated With Hearing Outcomes After Stapedotomy in Taiwanese Patients With Clinical Otosclerosis

OBJECTIVE

To examine the clinical factors associated with the effectiveness of stapedotomy in improving hearing sensitivity in Taiwanese patients with otosclerosis.

METHODS

In this retrospective study, we reviewed the medical records of 31 patients (36 ears) with otosclerosis undergoing stapedotomy performed by a single surgeon. Preoperative and postoperative hearing results were analyzed to identify factors associated with hearing outcomes after stapedotomy in the Taiwanese population with clinical otosclerosis.

RESULTS

Compared with preoperative pure tone averages (PTAs), stapedotomy significantly improved postoperative air conduction (AC) thresholds (P < .0001), bone conduction (BC) thresholds (P = .025), and air-bone gaps (ABGs; P < .0001). Postoperative closure of ABGs less than 10 or 20 dB was achieved in 16 (44.4%) and 33 (91.7%) of 36 surgical ears. Improvement in postoperative AC thresholds and ABGs and the size of preoperative ABGs were significantly correlated (r = .650, P < .001 and r = .745, P < .001, respectively). Gender-stratified analysis indicated a stronger correlation between improvement in postoperative AC thresholds and preoperative ABGs in male patients than in female patients (r = .893, P < .001 and r = .476, P = .014, respectively), and in postoperative and preoperative ABGs (r = .933, P < .001 and r = .626, P < .001, respectively). With the more stringent criteria for surgical success, factors including age (≤50 years), type (conductive, BC ≤25 dB), and degree (PTA ≤55 dB) of preoperative hearing loss led to more favorable outcomes.

CONCLUSIONS

We reported evidence supporting a potential gender difference on hearing outcomes after stapedotomy in Taiwanese patients with otosclerosis. Age, type, and degree of preoperative hearing loss may affect the surgical success rate.

SMARCA4 mutation causes human otosclerosis and a similar phenotype in mice

BACKGROUND

Otosclerosis is a common cause of adult-onset progressive hearing loss, affecting 0.3%-0.4% of the population. It results from dysregulation of bone homeostasis in the otic capsule, most commonly leading to fixation of the stapes bone, impairing sound conduction through the middle ear. Otosclerosis has a well-known genetic predisposition including familial cases with apparent autosomal dominant mode of inheritance. While linkage analysis and genome-wide association studies suggested an association with several genomic loci and with genes encoding structural proteins involved in bone formation or metabolism, the molecular genetic pathophysiology of human otosclerosis is yet mostly unknown.

METHODS

Whole-exome sequencing, linkage analysis, generation of CRISPR mutant mice, hearing tests and micro-CT.

RESULTS

Through genetic studies of kindred with seven individuals affected by apparent autosomal dominant otosclerosis, we identified a disease-causing variant in SMARCA4, encoding a key component of the PBAF chromatin remodelling complex. We generated CRISPR-Cas9 transgenic mice carrying the human mutation in the mouse SMARCA4 orthologue. Mutant Smarca4+/E1548K mice exhibited marked hearing impairment demonstrated through acoustic startle response and auditory brainstem response tests. Isolated ossicles of the auditory bullae of mutant mice exhibited a highly irregular structure of the incus bone, and their in situ micro-CT studies demonstrated the anomalous structure of the incus bone, causing disruption in the ossicular chain.

CONCLUSION

We demonstrate that otosclerosis can be caused by a variant in SMARCA4, with a similar phenotype of hearing impairment and abnormal bone formation in the auditory bullae in transgenic mice carrying the human mutation in the mouse SMARCA4 orthologue.

Genetic variants and altered expression of SERPINF1 confer disease susceptibility in patients with otosclerosis

Otosclerosis (OTSC) is a focal and diffuse bone disorder of the human middle ear characterized by abnormal bone growth and deposition at the stapes' footplate. This hinders the transmission of acoustic waves to the inner ear leading to subsequent conductive hearing loss. The plausible convections for the disease are genetic and environmental factors with yet an unraveled root cause. Recently, exome sequencing of European individuals with OTSC revealed rare pathogenic variants in the Serpin Peptidase Inhibitor, Clade F (SERPINF1) gene. Here, we sought to investigate the causal variants of SERPINF1 in the Indian population. The gene and protein expression was also evaluated in otosclerotic stapes to ameliorate our understanding of the potential effect of this gene in OTSC. A total of 230 OTSC patients and 230 healthy controls were genotyped by single-strand conformational polymorphism and Sanger sequencing methods. By comparing the case controls, we identified five rare variants (c.72 C > T, c.151 G > A, c.242 C > G, c.823 A > T, and c.826 T > A) only in patients. Four variants c.390 T > C (p = 0.048), c.440-39 C > T (p = 0.007), c.643 + 9 G > A (p = 0.035), and c.643 + 82 T > C (p = 0.005) were found to be significantly associated with the disease. Down-regulation of SERPINF1 transcript level in otosclerotic stapes was quantified by qRT-PCR, ddPCR and further validated by in situ hybridization. Similarly, reduced protein expression was observed by immunohistochemistry and immunofluorescence in otosclerotic stapes that corroborate with immunoblotting of patients' plasma samples. Our findings identified that SERPINF1 variants are associated with the disease. Furthermore, reduced expression of SERPINF1 in otosclerotic stapes might contribute to OTSC pathophysiology.

Brazilian Society of Otology task force - Otosclerosis: evaluation and treatment

OBJECTIVES

To review and provide evidence-based recommendations for the diagnosis and treatment of otosclerosis.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on otosclerosis were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: 1) Diagnosis - audiologic and radiologic; 2) Treatment - hearing AIDS, pharmacological therapy, stapes surgery, and implantable devices - bone-anchored devices, active middle ear implants, and Cochlear Implants (CI).

CONCLUSIONS

The pathophysiology of otosclerosis has not yet been fully elucidated, but environmental factors and unidentified genes are likely to play a significant role in it. Women with otosclerosis are not at increased risk of worsening clinical condition due to the use of contraceptives or during pregnancy. Drug treatment has shown little benefit. If the patient does not want to undergo stapedotomy, the use of hearing aids is well indicated. Implantable systems should be indicated only in rare cases, and the CI should be indicated in cases of profound deafness.

Effect of closing material on hearing rehabilitation in stapedectomy and stapedotomy: A finite element analysis

Stapedotomy or stapedectomy operations are often performed to treat otosclerosis. During the operation, the space created by bone removal is usually filled with a closing material such as fat or fascia. In this study, the effect of the Young's modulus of the closing material on the hearing level was investigated through the 3D finite element model of a human head including auditory periphery. The Young's moduli of the closing material used to implement stapedotomy and stapedectomy conditions in the model were varied from 1 kPa to 24 MPa. The results showed that the hearing level improved when the closing material was more compliant after stapedotomy. Therefore, when the stapedotomy was performed using fat whose Young's modulus is lowest among the potential closing materials, the hearing level recovered the best among all simulated cases. On the other hand, in stapedectomy, the Young's modulus did not have the linear relationship between the hearing level and the compliance of the closing material. Hence, the Young's modulus causing the best hearing rehabilitation in stapedectomy was found not at the end of the investigated range of Young's modulus but somewhere in the middle of the given range.

Improved Bone Conduction Hearing After Middle Ear Surgery: Investigation of the Improvement Mechanism

OBJECTIVES

When performing middle ear operations, such as ossiculoplasty or stapes surgery, patients and surgeons expect an improvement in air conduction (AC) hearing, but generally not in bone conduction (BC). However, BC improvement has often been observed after surgery, and the present study investigated this phenomenon.

METHODS

We reviewed the preoperative and postoperative surgical outcomes of 583 patients who underwent middle ear surgery. BC improvement was defined as a BC threshold decrease of >15 dB at two or more frequencies. Subjects in group A underwent staged ossiculoplasty after canal wall up mastoidectomy (CWUM), group B underwent staged ossiculoplasty after canal wall down mastoidectomy (CWDM), group C underwent ossiculoplasty only (thus, they had no prior history of CWUM or CWDM), and group D received stapes surgery. We created a hypothetical circuit model to explain this phenomenon.

RESULTS

BC improvement was detected in 12.8% of group A, 9.1% of group B, and 8.5% of group C. The improvement was more pronounced in group D (27.0%). A larger gain in AC hearing was weakly correlated with greater BC improvement (Pearson's r=0.395 in group A, P<0.001; r=0.375 in group B, P<0.001; r=0.296 in group C, P<0.001; r=0.422 in group D, P=0.009). Notably, patients with otosclerosis even experienced postoperative BC improvements as large as 10.0 dB, from a mean value of 30.3 dB (standard error [SE], 3.2) preoperatively to 20.3 dB (SE, 3.2) postoperatively, at 1,000 Hz, as well as an improvement of 9.2 dB at 2,000 Hz, from 37.8 dB (SE, 2.6) to 28.6 dB (SE, 3.1).

CONCLUSION

BC improvement may be explained by a hypothetical circuit model applying the third window theory. Surgeons should keep in mind the possibility of BC improvement when making a management plan.

Cellular voids in the pathogenesis of otosclerosis

BACKGROUND

Otosclerosis is a common ear disease that causes fixation of the stapes and conductive hearing impairment. However, the pathogenesis of otosclerosis is still unknown. Otosclerosis could be associated with the unique bony environment found in the otic capsule. Normal bone remodelling is almost completely absent around the inner ear after birth allowing degenerative changes and dead osteocytes to accumulate. High levels of inner ear anti resorptive osteoprotegerin (OPG) is most likely responsible for this capsular configuration. Studies have demonstrated how osteocyte lifespan variation creates occasional clusters of dead osteocytes, so-called cellular voids, at otosclerotic predilection sites in the human otic capsule. These cellular voids have been suggested as possible starting points of otosclerosis.

AIM

To describe the cellular viability in otosclerotic lesions and compare it to that of cellular voids.

MATERIALS AND METHODS

The study was based on unbiased stereological quantifications in undecalcified human temporal bones with otosclerosis.

RESULTS

Osteocyte viability was found to vary within the otosclerotic lesions. Furthermore, the results presented here illustrate that inactive otosclerotic lesions consist of mainly dead interstitial bone, much like cellular voids.

CONCLUSIONS AND SIGNIFICANCE

Focal degeneration in the otic capsule may play an important role in the pathogenesis of otosclerosis.

Radiological parameters and audiometric findings in otosclerosis: is there any relationship?

OBJECTIVE

The role of high-resolution computed tomography scans in otosclerosis remains uncertain. There is a debate over the relationship between radiological and audiometric findings among patients.

METHOD

Pre-operative audiometry and high-resolution computed tomography findings from 40 ears with surgically confirmed otosclerosis were compared. High-resolution computed tomography scan data regarding the characteristics of the disease foci, the endosteal extension and the occurrence of internal auditory canal diverticula were obtained. The influence of each radiological variable on the simple pure tone average, the high-frequency pure tone average and the bone-conduction pure tone average were investigated.

RESULTS

Cases with endosteal extension (p = 0.047) and a higher number of affected sites within the otic capsule had a worse bone-conduction pure tone average, although it was only significant for the latter (p = 0.006). Those without concomitant retrofenestral disease (p = 0.019) had better simple pure tone average.

CONCLUSION

The number of sites of involvement and concomitant retrofenestral disease seem to significantly impact audiometric findings in otosclerosis.

Comprehensive vestibular evaluation in patients with Otosclerosis: a case control study

Aim

Otosclerosis is one of the common otologic diseases. The mechanism and the probable site of vestibular involvement are not yet fully understood. The present study aimed to perform a comprehensive vestibular evaluation in patients with otosclerosis, compared to the cases without otosclerosis.

Materials and methods

patients underwent a comprehensive cochleovestibular evaluation, including audiometry, ocular and cervical vestibular evoked myogenic potential (o-VEMP and c-VEMP), video head impulse (vHIT) and caloric tests. The results were compared with those obtained from the non-otosclerosis control group.

Results

A total of 61 individuals were included in the study who were divided into two groups of the case (50.82%) and control (49.18%). The results showed that there was a significant difference in the mean vHIT gain between the case and control groups (P < 0.05). However, the mean gain was still within the normal range. Besides, the patients with otosclerosis had significant bilateral or unilateral weaknesses according to caloric test results. Moreover, their o-VEMP and c-VEMP results were significantly abnormal as well (P < 0.05).

Conclusion

Based on the results of the present study, the vestibular system even in asymptomatic cases, is affected by otosclerosis. Furthermore, it seems that the otolithic system has a higher chance of involvement, compared to the semicircular canals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-022-03147-5.

The Effects of Middle-ear Stiffness on the Auditory Brainstem Neural Encoding of Phase

The middle-ear system relies on a balance of mass and stiffness characteristics for transmitting sound from the external environment to the cochlea and auditory neural pathway. Phase is one aspect of sound that, when transmitted and encoded by both ears, contributes to binaural cue sensitivity and spatial hearing. The study aims were (i) to investigate the effects of middle-ear stiffness on the auditory brainstem neural encoding of phase in human adults with normal pure-tone thresholds and (ii) to investigate the relationships between middle-ear stiffness-induced changes in wideband acoustic immittance and neural encoding of phase. The auditory brainstem neural encoding of phase was measured using the auditory steady-state response (ASSR) with and without middle-ear stiffness elicited via contralateral activation of the middle-ear muscle reflex (MEMR). Middle-ear stiffness was quantified using a wideband acoustic immittance assay of acoustic absorbance. Statistical analyses demonstrated decreased ASSR phase lag and decreased acoustic absorbance with contralateral activation of the MEMR, consistent with increased middle-ear stiffness changing the auditory brainstem neural encoding of phase. There were no statistically significant correlations between stiffness-induced changes in wideband acoustic absorbance and ASSR phase. The findings of this study may have important implications for understanding binaural cue sensitivity and horizontal plane sound localization in audiologic and otologic clinical populations that demonstrate changes in middle-ear stiffness, including cochlear implant recipients who use combined electric and binaural acoustic hearing and otosclerosis patients.

Do CT values change over time and correlate with hearing in the non-surgical ears of otosclerosis patients?

BACKGROUND

High-resolution computed tomography (HRCT) is often used to diagnose otosclerosis.

AIMS/OBJECTIVES

To investigate whether CT values change over time and correlate with hearing in the non-surgical ears of otosclerosis patients.

MATERIALS AND METHODS

32 patients with bilateral otosclerosis who had undergone unilateral stapedectomy were enrolled in the study. HRCT examination and pure tone audiometry were performed before and after the surgery. CT values of different regions of interest (ROIs) were measured manually and the data were collected for analysis.

RESULTS

The CT value of anterior to the inner auditory meatus (AIAM) decreased by 88.5 HU (p < .05), and the changes in CT values in other ROIs showed no statistical difference. Regarding hearing, the value of air bone gap (ABG) increased by 3.6 dB (p = .020), and the average hearing deterioration rate of ABG was 3.1 dB/year. The CT value of the mid-point of the stapes footplate (MPSF) showed a certain correlation with the change of ABG (p < .05).

CONCLUSIONS AND SIGNIFICANCE

The CT value of AIAM may change over time. The overall hearing of non-surgical ears in otosclerosis patients shows a deteriorating trend. Moreover, the changes in the CT value of MPSF may be related to the hearing, which needs further research.

Role of HRCT Temporal Bone in Predicting Surgical Difficulties Encountered in Fenestral Otosclerosis Surgery

To study spectrum of high resolution computed tomography (HRCT) imaging findings in otosclerosis, to predict approximate length of prosthesis required from pre-operative HRCT measurements and to correlate between oval window niche (OWN) height preoperatively and difficulty in introducing foot plate perforator during surgery. A cross sectional study was conducted on 23 patients with a clinical diagnosis of otosclerosis from September 2018 to July 2020. Sensitivity of HRCT in detecting otosclerosis, correlation between pre-operative incudo-stapedial length (ISL) and intra operative prosthesis length, and correlation between OWN height and difficulty in introducing perforator were sought. The mean age of 23 patients studied was 39.9 years with a female preponderance of 56.5%. 17 out of 19 patients with foci of otosclerosis during surgery had HRCT findings of otosclerosis providing a sensitivity of 89.5%. Mean OWN height obtained was 1.29 mm preoperatively and a cut off value of 1.325 mm found using receiver operating characteristic curve method classifying OWN height as narrow or normal. Mean ISL measured pre operatively was 4.25 mm and mean length of prosthesis used was 4.56 mm with significant positive correlation using intraclass correlation coefficient method with correlation coefficient = 0.879. HRCT is an invaluable modality aiding the surgeon to detect otosclerotic foci with high sensitivity, identify thick obliterative otosclerotic foci requiring additional drilling, to predict the length of prosthesis used and to predict difficulties in approaching footplate when OWN height is below 1.325 mm.

Prognostic factors influencing postoperative air-bone gap in stapes surgery

Objective

Otosclerosis is an osteodystrophic disease of the otic capsule, determining conductive or mixed hearing loss, which can be successfully treated with stapedotomy. The aim of the present multicentric retrospective study was to identify prognostic factors related to better auditory outcomes in stapes surgery.

Methods

581 patients affected by otosclerosis were submitted to stapedotomy under local anaesthesia in two different hospitals. Both Teflon and titanium prostheses were adopted.

Results

A statistically significant decrease of postoperative air-conduction thresholds and air-bone gap (ABG) values was seen, whereas the mean bone-conduction threshold did not differ from the preoperative condition. Among the various parameters investigated, the prosthetic material, duration of surgery and intraoperative detection of unexpected anatomical anomalies of the middle ear were found to be related to lower postoperative ABG values.

Conclusions

All the previously mentioned parameters played a significant role in determining the postoperative auditory outcomes and can therefore be considered prognostic factors for the success of the stapedotomy.

Genetic Association of rs1021188 and DNA Methylation Signatures of TNFSF11 in the Risk of Conductive Hearing Loss

Otosclerosis (OTSC) is a complex bone disorder of the otic capsule, which causes conductive hearing impairment in human adults. The dysregulation of the signaling axis mediated by the receptor activator of nuclear factor-kappa-B (RANK), RANK ligand (RANKL), and osteoprotegerin has been widely attributed to the context of metabolic bone disorders. While genetic associations and epigenetic alterations in the TNFSF11 gene (RANKL) have been well-linked to metabolic bone diseases of the skeleton, particularly osteoporosis, they have never been addressed in OTSC. This study aimed to assess whether the genetic association of rs1021188 polymorphism in the upstream of TNFSF11 and the DNA methylation changes in its promoter CpG-region reveal the susceptibility of OTSC. Peripheral blood DNA samples were collected from unrelated Tunisian-North African subjects for genotyping (109 cases and 120 controls) and for DNA methylation analysis (40 cases and 40 controls). The gender-stratified analysis showed that the TNFSF11 rs1021188 C/T was associated with OTSC in men (p = 0.023), but not in women (p = 0.458). Individuals with CC genotype were more susceptible to OTSC, suggesting an increased risk to disease development. Using publicly available data, the rs1021188 was within a cluster grouping the subpopulations with African ethnicity. Moreover, 26 loci in the TNFSF11 gene were in linkage disequilibrium with rs1021188, revealing relative similarities between different populations. Significant differences in both DNA methylation and unmethylation status were detected with 4.53- and 4.83-fold decreases in the global DNA methylation levels in female and male OTSC groups, respectively. These changes could contribute to an increased risk of OTSC development. Bioinformatic analyses indicated that each of the rs1021188 variations and the DNA methylation changes in the promoter CpG-sites within TNFSF11 may play an important role in its transcription regulation. To our knowledge, this is the first study that investigates an independent effect of the rs1021188 polymorphism and DNA hypomethylation of TNFSF11 promoter in OTSC. Genetic and epigenetic changes in the regulatory regions of TNFSF11 could offer new molecular insights into the understanding of the complexity of OTSC.

The effect of female hormone in otosclerosis. A comparative study and speculation about their effect on the ossicular chain based on the clinical results

Purpose

This study aimed at identifying gender differences in the hearing thresholds in a sample of patients with otosclerosis before and after surgery to understand the impact of female hormones on auditory thresholds.

Methods

This retrospective study analyzed 184 patients (123 women and 61 men) affected by otosclerosis. All the patients were affected by conductive hearing loss and treated by stapedoplasty. Auditory thresholds at the baseline (T0) and one month after surgery (T30) were collected. Air and bone thresholds and Air Bone Gap (ABG) were compared between females and males using one-way ANOVA.

Results

Statistically significant differences were observed comparing the air threshold at T0 vs T30 both in women and men (p < 0.0001). No statistically significant differences were observed in the bone conduction thresholds before and after surgery. The comparison between females and males showed statistically significant differences both at T0 (p < 0.01) and T30 (p < 0.05) for air conduction thresholds and ABG at 4000 Hz.

Conclusion

Although stapedoplasty reduced the difference between females and males in the air conduction thresholds and ABG, women showed better recovery of their middle ear function with better auditory thresholds and ABG. The female hormones might positively impact the ligaments of the incudostapedial joint improving chain flexibility. This benefit might explain the statistically significant difference observed in women at 4000 Hz before and after surgery.

Stapedotomy using skeeter drill and self-retaining ear canal retractor: a single surgeon's 1000-plus surgical procedure experience

Objective

This study aimed to evaluate the long-term hearing outcomes in stapedotomy surgery using skeeter oto-drill and to assess safety in difficult situations.

Method

A retrospective study was conducted with 944 patients who underwent 1007 stapedotomy procedures over 16 years, performed by a single surgeon using a trans-canal approach and a self-retaining ear canal retractor. Hearing thresholds were calculated over four frequencies. Air–bone conduction hearing thresholds were obtained at 1, 5 and 10 years post-operatively and compared to the pre-operative records.

Results

Out of 1007 operated ears with one year follow up, 98.61 per cent of cases showed a negligible air–bone gap of equal to or less than 5 dB, 1.19 per cent of cases showed an air–bone gap equal to or more than 5 dB but less than 10 dB, and only 0.2 per cent of cases showed an air–bone gap of more than 10 dB.

Conclusion

In this study, using skeeter drill with a 0.6 mm diamond burr to make the fenestra was constant in all the cases and one of the safest techniques, showing persistent long-term hearing results.

Measuring the density of the fissula antefenestram and the section of the basal turn of the cochlea: are they useful in the radiological diagnosis of otosclerosis?

Introduction

The role of objective parameters in terms of improvement of the accuracy of high-resolution computed tomography (HRCT) of the temporal bone in the diagnosis of otosclerosis remains unclear.

Objectives

To investigate the relationship between the density of the fissula antefenestram (FAF) and of the width of the transversal section of the basal turn of the cochlea (BTC), and the diagnosis of otosclerosis.

Methods

This is a retrospective study in which preoperative HRCT data from ears of patients submitted to stapedotomy due to otosclerosis (case group) were evaluated. For the control group, normal hearing ears having undergone HRCT for other purposes were included. Case and control HRCT images were objectively assessed by an experienced blinded radiologist. During this evaluation, measurements of the relative radiological density of the FAF and of the transversal section of the BTC were obtained. The results were compared between the groups. Also, a receiver operating characteristic curve was created and the area under the curve (AUC) was calculated for each variable. Significance level was set at .05.

Results

40 ears were included in each group. Case ears presented reduced values for the relative radiological density on the FAF (p-value<0.0001). Moreover, ears with otosclerosis (p-value: 0.022) presented lower transversal section of the BTC. The AUC for these variables reached 0.929 and 0.646, respectively.

Conclusions

Otosclerotic ears present reduced radiological density on the FAF and narrower BTC. The relative density of the FAF also shows a great diagnostic power in the context of this disease.

Stability of computed tomography densitometry in patients with otosclerosis:a two-year follow-up

Objectives

To quantify the progression of otosclerosis in the unoperated ear between two stapedotomy procedures for patients with bilateral otosclerosis which can help to determine whether a HRCT scan should be re-performed before the second surgery for patients who already received HRCT imaging before the initial surgery.

Methods

35 patients who underwent bilateral stapedotomy were included. Two rounds of HRCT examination and audiometry were performed at the time of the first surgery and second surgery on the ear that was not operated on during the initial surgery. The relationship between the changes in HRCT densitometry and audiometry over time was analyzed.

Results

The second round of HRCT did not add significant information about the changes to the otosclerosis lesions in either the imaging diagnosis or the HRCT density values except for small changes in the HRCT densitometry readings at the area anterior to the inner auditory (P = 0.01). While the changes in HRCT manifestation are small, changes near the fissula ante fenestram (FAF) were still positively correlated with the air bone gap (ABG) of patients (p = 0.031, r = 0.388).

Conclusions

The progression of lesions in otosclerosis is slow resulting in small and insignificant changes to the HRCT features. Therefore, a repeat HRCT evaluations prior to surgery is not necessary for patients who have had a previous HRCT evaluation within 2 years of the operation. The small changes in HRCT manifestation near the FAF were still correlated with negative effects on the ABG which could cause worsened hearing thresholds over this timeframe.

Genetics of otosclerosis: finally catching up with other complex traits?

Otosclerosis is a relatively common cause of hearing impairment, characterized by abnormal bone remodeling of the middle and inner ear. In about 50-60% of the patients, the disease is present in a familial form. In most of these families, otosclerosis seems to be caused by a small number of genetic factors (oligogenic) while only in a small number of families the disease seems to be truly monogenic. In the remaining patients a complex genetic form of otosclerosis is present. Several studies have aimed to identify the genetic factors underlying otosclerosis, which has led to the identification of eight published loci for monogenic otosclerosis, as well as several genes and one chromosomal region (11q13.1) with a clear association with otosclerosis. Implementation of next-generation sequencing (NGS) in otosclerosis research has led to the identification of pathogenic variants in MEPE, ACAN and SERPINF1, although the pathogenic role of the latter is under debate. In addition, a recent GWAS can be considered a breakthrough for otosclerosis as it identified several strong associations with otosclerosis and suggested new potential candidate genes. These recent findings are important for unraveling the genetic architecture of otosclerosis. More future studies will help to understand the complete pathogenesis of the disease.

Cochlear implantation among patients with otosclerosis: a systematic review of clinical characteristics and outcomes

PURPOSE

There have been considerable advancements in cochlear implants in different clinical scenarios; however, their use in patients with otosclerosis remains challenging. This review aimed to investigate the surgical and clinical outcomes of cochlear implantation in patients with otosclerosis.

METHODS

An electronic literature search was performed using four main databases through February 2021 to identify original studies of cochlear implantation in patients with otosclerosis for inclusion in this systematic review. The study protocol was registered with the Prospectively Registered Systematic Reviews and Meta-analyses (reference number: CRD42021234753).

RESULTS

A total of 23 studies including 3162 patients were enrolled. Of these patients, only 392 had otosclerosis and underwent cochlear implantation. The duration of deafness was reported in only eight studies, extending up to 50 years. Far-advanced otosclerosis was observed in 153 patients. A total of 56 patients used hearing aids. Stapedectomy and stapedotomy were performed in 118 and 63 patients, respectively. In three studies, the temporary success of stapedectomy and stapedotomy was 6 (43%) and 5 (71%) patients, respectively. Computed tomography was used as a preoperative assessment tool in most studies (n = 14, 60.9%). Incomplete implant insertion occurred in 17 patients, while facial nerve stimulation occurred in 36 patients after implantation.

CONCLUSION

Cochlear implantation is a relatively safe modality that can provide promising audiological outcomes in patients with otosclerosis. However, several factors, including cochlear ossification, duration of deafness, and previous operations, can affect its outcomes. Further studies with a larger sample population are recommended.

Neuroimaging of Dizziness and Vertigo

Dizziness and vertigo are common symptoms in the primary care and emergency settings, resulting in a significant decrease in quality of life and a high cost burden to the US health care system. The etiology of these symptoms is difficult to elucidate owing to a wide range of diseases with overlapping manifestations. The broad differential diagnosis based on whether the disease process is central or peripheral is showcased. Each differential will be categorized into neoplastic, infectious or inflammatory, structural, traumatic, and iatrogenic causes. Computed tomography scans, MRI, and vascular imaging are frequently complimentary in providing diagnoses and guidance in management.

The use of explainable artificial intelligence to explore types of fenestral otosclerosis misdiagnosed when using temporal bone high-resolution computed tomography

Background

The purpose of this study was to explore the common characteristics of fenestral otosclerosis (OS) which are misdiagnosed, and develop a deep learning model for the diagnosis of fenestral OS based on temporal bone high-resolution computed tomography scans.

Methods

We conducted a study to explicitly analyze the clinical performance of otolaryngologists in diagnosing fenestral OS and developed an explainable deep learning model using 134,574 temporal bone high-resolution computed tomography (HRCT) slices collected from 1,294 patients for the automatic diagnosis of fenestral OS. We prospectively created an external test set with 31,774 CT slices from 144 patients, which contained 86 fenestral OS ears and 202 normal ears and used it to evaluate the performance of our otosclerosis-Logical Neural Network (LNN) model to assess its potential clinical utility. In addition, we compared the diagnostic acumen of seven otolaryngologists with the otosclerosis-LNN approach in the clinical test set, which was mixed with 78 fenestral OS and 62 normal ears. Finally, to evaluate the assisting value of the model, the seven participants were again invited to classify all cases in the clinical test set after referring to the diagnostic results of the model, to which they were blinded.

Results

The diagnostic performance of otologists was not satisfactory, and those CT samples which were misdiagnosed had similar characteristics. Based on this finding, we defined three subtypes of fenestral OS lesions that are suitable for clinical diagnosis guidance: “focal”, “transitional”, and “typical” fenestral OS. The most encouraging result is that the model achieved an area under the curve (AUC) of 99.5% (per-ear-sensitivity of 96.4%, per-ear-specificity of 98.9%) on the prospective unknown external test. Furthermore, we used this model to assist otologists and observed a consistent and significant improvement in diagnostic performance, especially for the newly defined focal and transitional fenestral OS, which led to the initial high misdiagnosis rate.

Conclusions

Our findings of the fine-grained classification of fenestral OS could have implications for future diagnosis and prevention programs. In addition, our deep OS localization network is an effective approach providing assistance to otologists to deal with the significant challenge of the misdiagnosis of fenestral OS.

A new phenomenon of cochlear otosclerosis: an acquired or congenital disease? - A clinical report of cochlear otosclerosis

BACKGROUND

No cochlear otosclerosis in infants with congenital bilateral SNHL has been reported.

AIMS/OBJECTIVES

We report an infant male with bilateral cochlear otosclerosis, suggesting that cochlear otosclerosis may be a congenital disease and to further analyze the etiology of and genetic expression in congenital bilateral cochlear otosclerosis. We also describe the clinical characteristics and experience of patients with bilateral cochlear otosclerosis treated with cochlear implants (CIs).

MATERIALS AND METHODS

Seven patients, including an infant, who were diagnosed with cochlear otosclerosis underwent CI surgery. Their medical records, audiological and radiological results, surgical procedures, and CI outcomes were collected and reviewed.

RESULTS

The median age at hearing loss was 38 years, ranging from 0 to 47 years. The child had bilateral hearing loss at birth and received a CI at 1 year of age. He also had growth retardation and was diagnosed with 3q+/3p- syndrome. All patients (8 ears) had better postoperative auditory performance than that preoperatively.

CONCLUSIONS AND SIGNIFICANCE

Although cochlear otosclerosis often starts at middle age and progresses slowly, it may be a congenital disease that is related to chromosome abnormality. This disease presents with SNHL or MHL, and treatment with a CI is beneficial.

Morphological comparison of internal auditory canal diverticula in the presence and absence of otospongiosis on computed tomography and their impact on patterns of hearing loss

PURPOSE

The association of internal auditory canal (IAC) fundal diverticula with otospongiosis (OS) and their clinical significance remain unclear. We explored whether isolated IAC diverticula were morphologically different from those with additional CT features of OS, and whether IAC diverticula morphology influenced patterns of hearing loss.

METHODS

Consecutive temporal bone CT studies with (n = 978) and without (n = 306) features of OS were retrospectively assessed. Two independent observers evaluated the presence of IAC diverticula morphological features (depth, neck:depth ratio, definition of contour and angulation of shape), and these were correlated with the presence of fenestral and pericochlear OS. Audiometric profiles were analysed for the isolated IAC diverticula and those with fenestral OS alone. Continuous data was compared using Wilcoxon rank sum tests and categorical data with chi-squared and Fisher's exact tests.

RESULTS

Ninety-five isolated IAC diverticula were demonstrated in 54/978 patients (5.5%) without CT evidence of OS (31M, 23F, mean age 46), and 119 IAC diverticula were demonstrated in 71/306 patients (23%) with CT evidence of OS (23M, 48F, mean age 55). Reduced neck:depth ratio, ill definition and angulation were all significantly associated with the presence of pericochlear OS (p < 0.001), whilst only ill definition was associated with the presence of fenestral OS alone (p < 0.05). No morphological feature was associated with conductive hearing loss in isolated diverticula or with sensorineural hearing loss in diverticula with fenestral OS alone.

CONCLUSION

IAC diverticula associated with pericochlear OS demonstrate different morphological features from isolated IAC diverticula. There are no clear audiometric implications of these morphological features.

Utility of deep learning for the diagnosis of otosclerosis on temporal bone CT

OBJECTIVE

Diagnosis of otosclerosis on temporal bone CT images is often difficult because the imaging findings are frequently subtle. Our aim was to assess the utility of deep learning analysis in diagnosing otosclerosis on temporal bone CT images.

METHODS

A total of 198 temporal bone CT images were divided into the training set (n = 140) and the test set (n = 58). The final diagnosis (otosclerosis-positive or otosclerosis-negative) was determined by an experienced senior radiologist who carefully reviewed all 198 temporal bone CT images while correlating with clinical and intraoperative findings. In deep learning analysis, a rectangular target region that includes the area of the fissula ante fenestram was extracted and fed into the deep learning training sessions to create a diagnostic model. Transfer learning was used with the deep learning model architectures of AlexNet, VGGNet, GoogLeNet, and ResNet. The test data set was subsequently analyzed using these models and by another radiologist with 3 years of experience in neuroradiology following completion of a neuroradiology fellowship. The performance of the radiologist and the deep learning models was determined using the senior radiologist's diagnosis as the gold standard.

RESULTS

The diagnostic accuracies were 0.89, 0.72, 0.81, 0.86, and 0.86 for the subspecialty trained radiologist, AlexNet, VGGNet, GoogLeNet, and ResNet, respectively. The performances of VGGNet, GoogLeNet, and ResNet were not significantly different compared to the radiologist. In addition, GoogLeNet and ResNet demonstrated non-inferiority compared to the radiologist.

CONCLUSIONS

Deep learning technique may be a useful supportive tool in diagnosing otosclerosis on temporal bone CT.

KEY POINTS

• Deep learning can be a helpful tool for the diagnosis of otosclerosis on temporal bone CT. • Deep learning analyses with GoogLeNet and ResNet demonstrate non-inferiority when compared to the subspecialty trained radiologist. • Deep learning may be particularly useful in medical institutions without experienced radiologists.

Otosclerosis in an Urban Population

OBJECTIVE

To investigate the evolving prevalence of otosclerosis in a large urban population.

METHODS

A retrospective review of patients in a large, urban, public health system was conducted from January 2010 to August 2019 to identify subjects with otosclerosis. Diagnostic testing included audiometry and computed tomography scans. Sex, age at diagnosis, treatment received, race, ethnicity, and country of birth were analyzed for each subject and compared with all eligible patients in the reference population.

RESULTS

A total of 134 patients from a reference population of 672,839 were diagnosed with otosclerosis and analyzed. The otosclerosis patients were predominantly Hispanic (73%), of which the majority were foreign born (87%). The average age at onset was 46 years and 59% were women. The overall prevalence of otosclerosis was 20 of 100,000 patients. The crude prevalence of otosclerosis by ethnicity was 43 of 100,000 for Hispanics, 12.6 of 100,000 for Caucasians, and 3 of 100,000 for African Americans. Within the Hispanic population, the prevalence of otosclerosis was 60 of 100,000 for foreign-born individuals and 16 of 100,000 for those born in the USA (odds ratio [OR] = 3.69, [95% confidence interval [CI], 2.02-6.76], p < 0.0001). Prevalence was not significantly different among Caucasians and US-born Hispanics.

CONCLUSION

Otosclerosis in the studied population was most common among Hispanic patients, though it was strongly influenced by country of birth. The "imported" otosclerosis cases are best explained by environmental influence rather than ethnic susceptibility. This discrepancy is likely due to variance in measles immunization rates among North and Central American countries before 1990.

Rapid imaging of tympanic membrane vibrations in humans

Functional imaging of the human ear is an extremely challenging task because of its minute anatomic structures and nanometer-scale motion in response to sound. Here, we demonstrate noninvasive in vivo functional imaging of the human tympanic membrane under various acoustic excitations, and identify unique vibration patterns that vary between human subjects. By combining spectrally encoded imaging with phase-sensitive spectral-domain interferometry, our system attains high-resolution functional imaging of the two-dimensional membrane surface, within a fraction of a second, through a handheld imaging probe. The detailed physiological data acquired by the system would allow measuring a wide range of clinically relevant parameters for patient diagnosis, and provide a powerful new tool for studying middle and inner ear physiology.

Imaging Studies in Otosclerosis: An Up-to-date Comprehensive Review

Introduction  Otosclerosis is a primary osteodystrophy of the otic capsule, frequently responsible for acquired hearing loss in adults. Although the diagnostic value of imaging investigations in otosclerosis is debatable, they might still be employed with different goals within the context of the disease.

Objectives  The present paper aims to review the most recent literature on the use of imaging studies in otosclerosis for the most varied purposes, from routine application and differential diagnosis to prognostic prediction and investigation of surgical failure.

Data Synthesis  The diagnosis of otosclerosis is usually clinical, but computed tomography (CT) is paramount in particular cases for the differential diagnosis. The routine use, however, is not supported by strong evidence. Even so, there is growing evidence of the role of this method in surgical planning and prediction of postoperative prognosis. In specific scenarios, for example when superior semicircular canal dehiscence (SSCD) syndrome is suspected or in surgical failure, CT is crucial indeed. Magnetic resonance imaging (MRI), however, has limited – although important – indications in the management of individuals with otosclerosis, especially in the evaluation of postoperative complications and in the follow-up of medical treatment in active ostosclerosis.

Conclusion  Imaging studies have a broad range of well-established indications in otosclerosis. Besides, although the routine use of CT remains controversial, the most recent papers have shed light into new potential benefits of imaging prior to surgery.

Otosclerosis and Measles: Do Measles Have a Role in Otosclerosis? A Review Article

Otosclerosis is a common cause of conductive hearing loss which is an autoimmune inflammatory disorder related to abnormal bone remodeling of the human otic capsule that has complex etiopathogenesis attributed to genetics, autoimmunity, viral infection, inflammation, hormonal factor, environmental factor, and disturbed bone metabolism. It has a prevalence of 0.3%-0.4% in Caucasians, which makes up 5-9% of all hearing loss and 18-22% of all conductive hearing loss. This review article aims to study the postulated role of sustained measles virus infection in the etiopathogenesis of otosclerosis, among others. A PubMed search of the related topic identified 97,990 articles. After we applied the inclusion and exclusion criteria, it was determined that 52 articles were relevant, which included 38 observational studies, 13 review articles, and a systematic review. Among them, 33 observational studies, 13 review articles and a systematic review spotted a positive association between persistent measles virus infection and otosclerosis. On the contrary, five observational studies reported no evidence of the association. The majority of the current literature supported the presence of the measles virus component in the otosclerotic stapes samples and its role in the etiopathogenesis of otosclerosis. Measles virus infection may have the amplitude to initiate a pathological process, which in the presence of other factors like autoimmunity and genes plays a significant role in causing otosclerosis. However, other studies have failed to show the presence of the measles virus component in otosclerotic stapes. So, more studies are needed to probe the role of persistent measles virus infection in the etiopathogenesis of otosclerosis.

Assessment of inflammatory markers in otosclerosis patients

INTRODUCTION

Otosclerosis is an idiopathic disease characterized by new bone formation in foci of the human otic capsule. It is more common in Caucasian populations; affecting females twice as often as males. Its etiopathogenesis has not yet been fully elucidated.

OBJECTIVE

The aim of this study was to investigate the relationship between otosclerosis and white blood cell and thrombocyte counts, mean platelet volume, neutrophil lymphocyte ratio, and the platelet lymphocyte ratio.

METHODS

This retrospective case-control study was conducted in the outpatient clinic Mustafa Kemal University, in the department of otolaryngology, between 2015 and 2018. A total of 30 patients with an established diagnosis of otosclerosis were compared to a control group of 30 healthy subjects, matched for age, gender and body mass index. The white blood cell, thrombocyte, mean platelet volume, neutrophil lymphocyte ratio and platelet lymphocyte ratio values were calculated for all participants.

RESULTS

There was no statistically significant difference between the groups with respect to age, gender, or body mass index, or for the mean neutrophil lymphocyte ratio, platelet lymphocyte ratio, white blood cell, or thrombocyte values (p>0.05). A statistically significant difference was determined between the groups for the mean platelet volume values. The mean platelet volume values were lower in the otosclerotic patients (p=0.047).

CONCLUSION

These results show that neutrophil lymphocyte ratio, platelet lymphocyte ratio, white blood cell and thrombocytes should not be used to predict otosclerosis, but suggest that mean platelet volume may be a negative predictive marker.

In Situ Characterization of Micro-Vibration in Natural Latex Membrane Resembling Tympanic Membrane Functionally Using Optical Doppler Tomography

Non-invasive characterization of micro-vibrations in the tympanic membrane (TM) excited by external sound waves is considered as a promising and essential diagnosis in modern otolaryngology. To verify the possibility of measuring and discriminating the vibrating pattern of TM, here we describe a micro-vibration measurement method of latex membrane resembling the TM. The measurements are obtained with an externally generated audio stimuli of 2.0, 2.2, 2.8, 3.1 and 3.2 kHz, and their respective vibrations based tomographic, volumetric and quantitative evaluations were acquired using optical Doppler tomography (ODT). The micro oscillations and structural changes which occurred due to diverse frequencies are measured with sufficient accuracy using a highly sensitive ODT system implied phase subtraction method. The obtained results demonstrated the capability of measuring and analyzing the complex varying micro-vibration of the membrane according to implied sound frequency.

Contributions of Contemporary Human Temporal Bone Histopathology to Clinical Otology

Contemporary techniques have greatly enhanced the contributions of human temporal bone (HTB) histopathology to our understanding of the mechanisms of human otologic disease and disease treatment. Herein, we review some of the most salient contributions of this research to disease management. The field of HTB histopathology is challenged by limited resources as applies to trained investigators, infrastructure, and well-equipped laboratories. This research provides insights into clinical otology that cannot be obtained by any other means. Measures should be taken to preserve and extend the contributions of HTB research.

Otosclerosis: anatomical distribution of otosclerotic loci analyzed by high-resolution computed tomography

PURPOSE

To clarify the anatomical distribution of otosclerotic loci in otosclerosis.

METHODS

Ninety-five patients with surgically confirmed uni- or bilateral otosclerosis were enrolled into the study. Hypodense areas observed in the otic capsule by high-resolution computed tomography (HRCT) were defined as otosclerotic loci. The location and number of lesions were examined, and the probability of lesion overlap and correlation with age/hearing parameters (air and bone conduction threshold, air-bone gaps) were tested.

RESULTS

Otosclerotic loci were confirmed by HRCT in 77 out of 115 operated ears. The three commonly affected sites were the anterior part of the oval window (ant-OW), anterior part of the internal auditory canal (ant-IAC), and pericochlear area (PCochA), with lesions detected in 96.1%, 46.8%, and 26.0% of ears, respectively. Only the ant-OW area was affected in 48.1% of the ears; the ant-IAC in 3.9%; and PCochA in none with significant differences (p < 0.01). The ant-OW lesions preferentially overlapped with ant-IAC (44.6%) than PCochA lesions (27.0%) (p < 0.05). Among double sites diseases, triple sites diseases occurred more commonly in the ant-OW + PCochA group (80%) than ant-OW + ant-IAC group (48.5%) (p < 0.05). There was no correlation between a number of lesions and age/hearing parameters.

CONCLUSIONS

Based on the probability of lesion overlap, otosclerotic lesions may initiate at ant-OW followed by ant-IAC and later PCochA. Although the number of lesions showed no immediate correlation with hearing level or age, anatomical stage of the disease estimated by the location and the number of otosclerotic loci could be useful in predicting the future hearing status.

Ear and Temporal Bone: Cartilaginous and Osseous Pathologies

Although the majority of conditions involving the ear and temporal bone are inflammatory or epithelial based, cartilage and osseous entities will also be encountered. The pathologic examination of these underlying cartilaginous and osseous structures and their histologic findings and associated differential diagnoses will be discussed. Correlation with clinical and imaging findings are also critical for accurate determination of the pathologic entity.

Evidence of distinct RELN and TGFB1 genetic associations in familial and non-familial otosclerosis in a British population

Otosclerosis is a common form of hearing loss which typically presents in young adults. The disease has a familial, monogenic form and a non-familial form with a more complex aetiology. A previous genome wide association study identified evidence that variants within RELN are associated with the condition. Other genes in which an association has been reported include BMP2, COL1A1, FGF2, PPP2R5B and TGFB1. However, follow up studies have often failed to replicate initial positive results. The aim of this study was to establish if an association exists between eight single nucleotide polymorphisms (SNPs) in these six previously implicated genes and otosclerosis in a British case–control cohort (n = 748). Evidence of an association between rs1800472 in TGFB1 and otosclerosis was found (p = 0.034), this association was strongest amongst non-familial cases (p = 0.011). No evidence of an association was detected with variants in COL1A1, FGF2, BMP2, and PPP2R5B. No association between variation in RELN and otosclerosis was observed in the whole cohort. However, a significant association (p = 0.0057) was detected between one RELN SNP (rs39399) and otosclerosis in familial patients. Additionally, we identify expression of one RELN transcript in 51 of 81 human stapes tested, clarifying previous conflicting data as to whether RELN is expressed in the affected tissue. Our findings strengthen the association of TGFB1 (rs1800472) with otosclerosis and support a relationship between RELN and familial otosclerosis only, which may explain previous variable replications.

Prevalence of Internal Auditory Canal Diverticulum and Its Association with Hearing Loss and Otosclerosis

BACKGROUND AND PURPOSE

Focal low-attenuation outpouching or diverticulum at the anterolateral internal auditory canal is an uncommon finding on CT of the temporal bone. This finding has been described as cavitary otosclerosis in small case reports and histology series. The purpose of this study was to establish the prevalence of internal auditory canal diverticulum and its association with classic imaging findings of otosclerosis and/or hearing loss.

MATERIALS AND METHODS

Temporal bone CT scans of 807 patients, obtained between January 2013 and January 2016, were retrospectively reviewed to identify internal auditory canal diverticula and/or classic imaging findings of otosclerosis. Clinical evaluations for hearing loss were reviewed for patients with internal auditory canal diverticula and/or otosclerosis.

RESULTS

Internal auditory canal diverticula were found in 43 patients (5%); classic otosclerosis, in 39 patients (5%); and both findings, in 7 patients (1%). Most temporal bones with only findings of internal auditory canal diverticula (91%) demonstrated hearing loss, with 63% of this group demonstrating sensorineural hearing loss. The hearing loss classification distribution was significantly different (P < .01) from that in the classic otosclerosis group and in the group with both diverticula and otosclerosis.

CONCLUSIONS

Internal auditory canal diverticula are not uncommon on CT examinations of the temporal bone and most commonly occur without classic imaging findings of otosclerosis. These lesions are associated with sensorineural hearing loss, and referral for hearing evaluation may be appropriate when present.

Absence of Measles Virus Detection from Stapes of Patients with Otosclerosis

Objective To determine molecularly the presence of measles virus genetic material in the stapes of patients with otosclerosis. Study Design A cross-sectional study. Setting A tertiary referral hospital. Subjects and Methods Genetic material was extracted from the stapes of patients with otosclerosis (n = 93) during the period from March 2011 to April 2012. The presence of viral measles sequences was evaluated by the real-time reverse transcriptase polymerase chain reaction (RT-PCR). The expression of the CD46 gene was determined. Results Ninety-three patients were included in the study. No sample was positive for any of 3 measles virus genes (H, N, and F). Measles virus RNA was not detected in any sample by real-time RT-PCR. CD46 levels were positive in 3.3% (n = 3) and negative in 96.7% (n = 90). Conclusion This study does not support the theory of measles virus as the cause of otosclerosis. It is necessary to do more research about other causal theories to clarify its etiology and prevention.

Long-term Incidence and Degree of Sensorineural Hearing Loss in Otosclerosis

OBJECTIVES

1) To evaluate the long-term incidence and degree of the sensorineural component of hearing loss (SNHL) in patients with otosclerosis after accounting for expected age-related hearing loss. 2) To identify variables that might predict development of sensorineural hearing loss due to otosclerosis.

STUDY DESIGN

Retrospective audiometric database and chart review.

SETTING

Tertiary referral center.

PATIENTS

Consecutive patients with otosclerosis observed between 1994 and 2004, with ≥10 years follow-up, excluding patients with postoperative hearing loss or surgery before the initial audiogram.

INTERVENTION

Bone conduction (BC) thresholds at 0.5, 1, 2, and 4 kHz and Word Recognition.

MAIN OUTCOME MEASURE

BC threshold change (BCTC) over ≥10 years minus estimated age-related threshold change (ARTC) specific to age and sex for each patient (based on ISO 7029 reference population).

RESULTS

Three-hundred fifty-seven ears (290 patients) met study criteria, including 217 ears that had undergone stapedectomy during the study period. Mean follow-up was 14.0 years. The average BCTC after subtracting estimated ARTC was 4.6, 2.6, 3, and 2.7 dB for 0.5, 1, 2, and 4 kHz frequencies, respectively. However, 34% of ears (122 ears) had clinically significant progression of SNHL during the study period (>10 dB BCTC beyond expected ARTC at ≥2 frequencies). Multivariate analysis demonstrated that the probability of developing clinically significant SNHL was higher for women (odds ratio 1.86, p = 0.018) and lower for operated patients (odds ratio 0.46, p = 0.002).

CONCLUSION

The average long-term sensorineural hearing loss due to otosclerosis was statistically significantly more than for age alone at each frequency, but these average values (from 2.6 to 4.6 dB for tested frequencies) were clinically insignificant. Approximately one-third of patients with otosclerosis demonstrated a clinically significant progression of the sensorineural component of hearing loss, with the average BCTC above expected age-related changes ranging from 10.2 to 14.6 dB for tested frequencies among this subgroup.

Intracochlear Drug Delivery Through the Oval Window in Fresh Cadaveric Human Temporal Bones

HYPOTHESIS

Drug delivered to the oval window can diffuse to the apex of the human cochlea.

BACKGROUND

We have previously demonstrated that zoledronate, a nitrogen-containing bisphosphonate, can arrest the sensorineural hearing loss in cochlear otosclerosis. We have also shown that, in animals, delivery of bisphosphonate into the cochlea can dramatically increase delivery efficiency. Intracochlear drug delivery has the potential to increase local concentration of drug while decreasing the risk of systemic toxicity. In the present study, a fluorescently labeled bisphosphonate compound (6-FAM-ZOL) was introduced into the human cochlea through the oval window and its distribution within the temporal bone was quantified.

METHODS

In three fresh human temporal bones, we introduced 6-FAM-ZOL via the oval window. We compared these specimens to control specimens treated with artificial perilymph alone. Specimens were then processed, embedded into methyl methacrylate, and ground to the mid-modiolar axis. We quantified the fluorescence in confocal images.

RESULTS

We found 6-FAM-ZOL to be distributed up to the apical cochlear turn. In specimens treated with 6-FAM-ZOL, we identified a strong baso-apical gradient of fluorescent signal along the lateral cochlear wall and the modiolus both in the scala vestibuli and in the scala tympani.

CONCLUSION

Bisphosphonate introduced via the oval window in the human cochlea can be delivered up to the apical cochlear turn. Interscalar communication is likely to play an important role in determining patterns of drug delivery in the inner ear.

Oxidative stress in otosclerosis

OBJECTIVES

Otosclerosis is a disease involving abnormal bone turnover in the human otic capsule that results in hearing loss. Several hypotheses have been suggested for the etiopathogenesis of otosclerosis; however, its etiology remains unclear.

METHODS

This study evaluated the correlation between otosclerosis and levels of paraoxonase-1 (PON1), arylesterase, total antioxidant status, total oxidant status (TOS), oxidative stress index (OSI), total sulfhydryl (-SH) groups, lipid hydroperoxide, and ceruloplasmin in the serum of otosclerosis patients and healthy subjects with respect to oxidative stress.

RESULTS

In our study, TOS and OSI levels were higher in the otosclerosis patients than in the controls. The PON1 levels showed that oxidative stress was severe, and as a result, antioxidants were consumed and depleted.

DISCUSSION

When an imbalance between oxygen free radical production and antioxidative defense mechanisms occurs, reactive oxygen species levels may increase, which in turn may damage cells and tissues through the peroxidation of phospholipid membrane structures. The body initially responds with increased antioxidant production, but if the oxidative stress is severe, decreased antioxidant levels may result. This study reports expression levels of oxidative stress species in otosclerosis patients.