Histologically proven cochlear otosclerosis with pure sensorineural hearing loss

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.

Targeted Resequencing of Otosclerosis Patients from Different Populations Replicates Results from a Previous Genome-Wide Association Study

Otosclerosis is one of the most common causes of hearing loss in young adults. It has a prevalence of 0.3-0.4% in the European population. Clinical symptoms usually occur between the second and fifth decade of life. Different studies have been performed to unravel the genetic architecture of the disease. Recently, a genome-wide association study (GWAS) identified 15 novel risk loci and replicated the regions of three previously reported candidate genes. In this study, seven candidate genes from the GWAS were resequenced using single molecule molecular inversion probes (smMIPs). smMIPs were used to capture the exonic regions and the 3' and 5' untranslated regions (UTR). Discovered variants were tested for association with the disease using single variant and gene-based association analysis. The single variant results showed that 13 significant variants were associated with otosclerosis. Associated variants were found in five of the seven genes studied here, including AHSG, LINC01482, MARK3, SUPT3H and RELN. Conversely, burden testing did not show a major role of rare variants in the disease. In conclusion, this study was able to replicate five out of seven candidate genes reported in the previous GWAS. This association is likely mainly driven by common variants.

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.

Bilateral Vestibulopathy Due to Severe Cochlear Otosclerosis: A Well-Known Condition Without Any Favorable Solution

Bilateral vestibulopathy is a rare condition. It is one of the most difficult balance problems to treat because nearly all patients experience long-term unsteadiness. In this report, a 39-year-old woman gradually developing chronic dizziness and instability due to bilateral vestibulopathy as a result of progressive severe cochlear otosclerosis was presented with review of the literature.

Connexin 26 Immunohistochemistry in Temporal Bones With Cochlear Otosclerosis

HYPOTHESIS

Connexin-26 (Cx26) expression is diminished in the spiral ligament of subjects with hearing loss and cochlear otosclerosis (CO).

BACKGROUND

Human temporal bone (HTB) studies have demonstrated that CO is associated with hyalinization of the spiral ligament. We hypothesize that hyalinization is associated with a loss of fibrocytes with a consequent decline in Cx26 expression. Cx26 and Connexin-30 (Cx30) encode gap junction proteins expressed in supporting cells of the organ of Corti, the spiral limbus, stria vascularis, and in fibrocytes of the spiral ligament. These gap junctions are critical for potassium recycling and maintenance of the endocochlear potential. Diminished expression of these proteins would likely be associated with hearing dysfunction.

METHODS

Histopathology and clinical characteristics of 45 HTB specimens with CO and spiral ligament hyalinization were reviewed. Those with sensorineural or mixed hearing loss but normal or near-normal hair cell counts were analyzed with light microscopy, and Cx26-immunoreactive (IR) signal was qualitatively assessed.

RESULTS

H&E staining demonstrated hyalinization in the spiral ligament and loss of type II and type III fibrocytes. Cx26-IR was diminished throughout the cochlea affected with CO compared with normal controls.

CONCLUSIONS

Cx26-IR reduction in the spiral ligament of subjects with CO likely plays a role in hearing loss.

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.

Non-Ototoxic Local Delivery of Bisphosphonate to the Mammalian Cochlea

HYPOTHESIS

Local delivery of bisphosphonates results in superior localization of these compounds for the treatment of cochlear otosclerosis, without ototoxicity.

BACKGROUND

Otosclerosis is a common disorder of abnormal bone remodeling within the human otic capsule. It is a frequent cause of conductive hearing loss from stapes fixation. Large lesions that penetrate the cochlear endosteum and injure the spiral ligament result in sensorineural hearing loss. Nitrogen-containing bisphosphonates (e.g., zoledronate) are potent inhibitors of bone remodeling with proven efficacy in the treatment of metabolic bone diseases, including otosclerosis. Local delivery to the cochlea may allow for improved drug targeting, higher local concentrations, and the avoidance of systemic complications. In this study, we use a fluorescently labeled bisphosphonate compound (6-FAM-ZOL) to determine drug localization and concentration within the otic capsule. Various methods for delivery are compared. Ototoxicity is evaluated by auditory brainstem responses and distortion product otoacoustic emissions.

METHODS

6-FAM-ZOL was administered to guinea pigs via intraperitoneal injection, placement of alginate beads onto the round window membrane, or microfluidic pump infusion via a cochleostomy. Hearing was evaluated. Specimens were embedded into resin blocks, ground to a mid-modiolar section, and quantitatively imaged using fluorescence microscopy.

RESULTS

There was a dose-dependent increase in fluorescent signal after systemic 6-FAM-ZOL treatment. Local delivery via the round window membrane or a cochleostomy increased delivery efficiency. No significant ototoxicity was observed after either systemic or local 6-FAM-ZOL delivery.

CONCLUSION

These findings establish important preclinical parameters for the treatment of cochlear otosclerosis in humans.

Cochlear otosclerosis adjacent to round window and oval window: a histopathological temporal bone study

HYPOTHESIS

The purpose of this histopathological study is to examine temporal bones of patients with cochlear otosclerosis adjacent to the round window or adjacent to the oval window as compared with healthy controls.

BACKGROUND

It is unclear if the extent and site of otosclerosis affects the extent of damage to cochlear structures and hearing loss.

METHODS

Twelve temporal bones from 10 patients with cochlear otosclerosis adjacent to the round window, 11 temporal bones from 8 patients with cochlear otosclerosis adjacent to the oval window, and 12 bones of healthy age-matched controls were selected for study. We calculated the number of spiral ganglion cells, changes in cochlear structures, the extent and site of cochlear otosclerosis, and audiometric data.

RESULTS

The loss of spiral ganglion cells and the absence of outer hair cells in patients with cochlear otosclerosis adjacent to the round window were significantly higher than those in patients with cochlear otosclerosis adjacent to the oval window and healthy controls. The area of the spiral ligament in patients with cochlear otosclerosis adjacent to the oval window was significantly smaller than that in healthy controls. However, no significant difference was found in the spiral ligament of patients with cochlear otosclerosis adjacent to the round window and healthy controls. There was no significant difference between patients with cochlear otosclerosis and age-matched controls in audiometric data.

CONCLUSION

Cochlear otosclerosis adjacent to the round window caused significantly more damage to spiral ganglion cells and outer hair cells than cochlear otosclerosis adjacent to the oval window without loss of spiral ligament.

The etiology of otosclerosis: a combination of genes and environment

Otosclerosis is a common form of hearing loss characterized by abnormal bone remodeling in the otic capsule. It is a complex genetic disease, caused by a combination of genetic and environmental factors. During the past decade, several attempts have been made to identify factors for otosclerosis. This review provides an overview of the current understanding of the etiology of otosclerosis and describes the genetic and environmental factors that have been implicated in the disease. Environmental factors include fluoride and viral factors, particularly measles. Genetic association studies for otosclerosis have reported several associations of genetic variants that influence the risk of disease, mainly involving bone remodeling pathways, although their individual risk contributions are small. Rare monogenic forms of otosclerosis also exist, which are caused by a mutation in a single gene leading to a clear familial segregation of the disease. Linkage analysis of large otosclerosis families has led to the identification of seven loci, and recently evidence was found that T cell receptor beta is a gene responsible for familial otosclerosis, suggesting an underlying immunological pathway. However, this might also represent an autoimmune process, a hypothesis that is supported by other data as well. In conclusion, a variety of pathways have been identified to be involved in the development of otosclerosis, showing that distinct mechanisms involving both genetic and environmental risk factors can influence and contribute to a similar disease outcome.

Genetics of otosclerosis

OBJECTIVES

Otosclerosis is a major cause of acquired hearing loss in adult life affecting exclusively the human temporal bone. Until recently, the etiopathogenesis of otosclerosis was still a matter of debate. Genetic research, however, has evolved enormously the last years and unveiled important clues regarding the cause of otosclerosis. The objective of this article is to review the genetics of otosclerosis with special attention for the links to the bone homeostasis of the otic capsule.

DATA SOURCES

A detailed literature study was performed focusing on the recent genetic findings in otosclerosis and the special bone turnover of the otic capsule. A PubMed search and own research data were used to bring the relevant information for this review together.

CONCLUSION

Unlike all other bones in the human skeleton, the otic capsule undergoes very little remodeling after development, possibly due to local inner ear factors. Otosclerosis is a process of pathologic increased bone turnover in the otic capsule, which in most cases leads to stapes fixation, resulting in a conductive hearing loss. Although environmental factors such as estrogens, fluoride, and viral infection have been implicated, it is clear that genetic factors play a significant role in the manifestation of otosclerosis. From a genetic viewpoint, otosclerosis is considered to be a complex disease with rare autosomal dominant forms caused by a single gene. Already, 7 monogenic loci have been published, but none of the genes involved have been identified. For the complex form of otosclerosis, caused by an interaction between genetic and environmental factors, the first susceptibility genes were identified by case-control association studies. All 3 replicated genes, TGFB1, BMP2, and BMP4, are a part of the transforming growth factor-beta1 pathway. Data from both genetic association studies and gene expression analysis of otosclerotic bone showed that the TGF-beta1 pathway is most likely an important factor in the pathogenesis of otosclerosis.

Otosclerosis 1: the aetiopathogenesis of otosclerosis

Otosclerosis is a bone dystrophy localised to the inner ear and the stapes footplate. Otosclerosis is a frequent cause of deafness in adults. The patient with otosclerosis typically presents with a history of slowly progressive conductive or mixed hearing loss that is usually bilateral and often asymmetric, usually between the ages of 15 and 45 years. The disease is characterised by alternating phases of bone resorption and formation. The majority of studies on families with otosclerosis suggest an autosomal dominant mode of inheritance with incomplete penetrance.

Clinical and genetic analysis of two Tunisian otosclerosis families

Otosclerosis is caused by an abnormal bone homeostasis of the otic capsule resulting in a conductive hearing loss when the free motion of the stapes is compromised. An additional sensorineural hearing loss arises in some patients, most likely due to otosclerotic foci that invade the cochlear endosteum. Otosclerosis is a very common hearing impairment among Caucasians with a prevalence of about 0.3-0.4% among white adults. In the majority of cases, otosclerosis can be considered as a complex disease, caused by both genetic as environmental factors, but autosomal dominant forms of otosclerosis exist. However, families large enough for genetic analysis are very rare and often show reduced penetrance. To date five loci have been reported, but none of the genes have been cloned yet. In this study, we analyzed two new autosomal dominant otosclerosis families from Tunisia, and genotyped them with microsatellite markers for the known loci, the collagen genes COL1A1 and COL1A2, and NOG gene. In the family LK, linkage to all known loci was excluded. However, the family LS shows suggestive linkage to the OTSC3 region on chromosome 6p21.3-p22.3. This result points out that, besides the five reported loci, there must be at least one additional locus for autosomal dominant otosclerosis.

Effect of cochlear reserve on postoperative outcome in otosclerosis

Patients with elevated bone conduction (BC) thresholds are not considered a good candidate for otosclerosis surgery. Sometimes, it might be difficult to decide to operate these patients considering relatively poor cochlear function. However, viewpoints may vary among otologists. This study was undertaken to compare hearing outcome following otosclerosis surgery in patients who had bone conduction (BC) thresholds >or= 30 dB, and to investigate whether BC thresholds >30 dB has a negative impact on hearing outcome. Medical records of 111 patients who had undergone otosclerosis surgery were reviewed. Of 111 patients, 83 had undergone stapedotomy, and 28 stapedectomy. The patients were grouped based on preoperative four-tone BC threshold. Eighty-seven patients had average BC threshold <or= 30 dB, and were assigned to good-cochlear reserve group. The remaining 24 patients had average BC > 30 dB, and constituted poor-cochlear reserve group. Pre- and postoperative air conduction (AC) and BC thresholds, air-bone (AB) gap, vocal audiometry results and amount of deterioration in BC were determined. Mean postoperative AB gap was almost the same in both groups (14 and 15 dB) (P > 0.05). Percentage of AB gap = 10 dB favored good-cochlear reserve group (41 vs 29%)(P > 0.05). Analysis of mean hearing gain was slightly in favor of good-cochlear reserve group (19 vs 15 dB) (P > 0.05). Better BC thresholds were obtained postoperatively in good-cochlear reserve group (P < 0.001). Deterioration > 10 dB in BC was observed in 5.7 and 12.5% of the patients with good- and poor-cochlear reserve, respectively (P > 0.05). Based on the results of this small sample-size study, even though BC threshold of 30 dB was not considered a negative factor for hearing gain, otosclerosis surgery might have detrimental effects on postoperative BC thresholds in patients who had BC thresholds >30 dB.

Monogenic nonsyndromic otosclerosis: audiological and linkage analysis in a large Greek pedigree

OBJECTIVE

The aim of our study was to characterize the hearing impairment in a large multigenerational Greek family with autosomal dominant nonsyndromic otosclerosis and to perform genetic linkage analysis to known otosclerosis loci and collagen genes. In addition, we looked for mutations in the NOG gene to rule out congenital stapes ankylosis syndrome.

METHODS

Audiological analysis of the affected persons was based on multiple linear regression (MLR) analysis and construction of age-related typical audiograms (ARTA). Genotyping of microsatellite DNA polymorphisms for known otosclerosis (OTSC) loci or collagen genes and linkage analysis using the MLINK computer program were performed. The coding region of the NOG gene was screened for mutations by direct DNA sequencing.

RESULTS

The hearing loss in this family appears in childhood as conductive, but soon becomes mixed. Because the additional sensorineural component is progressive, this finally has lead to a pure sensorineural hearing loss in some family members, as the conductive component is masked. Audiological analysis showed an age-independent conductive component and a progressive frequency-specific sensorineural component. Linkage analysis excluded linkage to the four known otosclerosis loci (OTSC1, OTSC2, OTSC3, and OTSC5), as well as to the COL1A1 and COL1A2 genes. Mutation analysis of the coding region of the NOG gene did not reveal any disease causing mutation.

CONCLUSIONS

This study represents the first description of a detailed audiological analysis in a large pedigree segregating otosclerosis as a monogenic autosomal dominant trait. Exclusion of the four known otosclerosis loci in this family shows that monogenic otosclerosis is a genetically heterogeneous disease involving at least five different genes. A mutation in the NOG gene is not the underlying molecular mechanism of the early onset otosclerosis segregating in this family.

Spiral ligament and stria vascularis changes in cochlear otosclerosis: effect on hearing level

OBJECTIVE

To investigate the effect of changes within the spiral ligament and stria vascularis on hearing in cochlear otosclerosis, we examined spiral ligament hyalinization, stria vascularis atrophy, and sensory hearing loss in cochlear otosclerosis and described changes in ion transport molecule expression.

STUDY DESIGN

Retrospective.

SETTING

Tertiary referral center.

PATIENTS

Thirty-two cochleae from 24 temporal bone donors with histologic evidence of cochlear otosclerosis, including spiral ligament hyalinization.

INTERVENTION

Audiography.

MAIN OUTCOME MEASURES

Measurements of spiral ligament width, stria vascularis, and bone-conduction thresholds were compared by the amount of hyalinization. Expression of the ion transport molecules Na,K-ATPase, connexin 26, and carbonic anhydrase II were assessed by immunohistochemical techniques.

RESULTS

Hyalinization most often involved the posterior basal turn (88%) and the posterior middle turn (27%). Spiral ligament hyalinization correlated significantly with stria vascularis atrophy in the posterior middle turn of the cochlea (rho = -0.63, p < 0.01). There was a trend toward a significant association in the posterior basal turn (rho = -0.31, p < 0.08). Bone-conduction thresholds at 2,000 and 4,000 Hz were significantly associated with the amount of stria vascularis atrophy (rho = -0.44, -0.40, p < 0.05). In addition, we observed decreased immunostaining for both carbonic anhydrase II with Type I fibrocytes and Na,K-ATPase with stria vascularis and Type II and Type IV fibrocytes of the spiral ligament in cochlear otosclerosis sections compared with normal cochlea. Na,K-ATPase staining within the stria vascularis was further decreased in the presence of spiral ligament hyalinization. No significant differences were seen with connexin 26 immunostaining. However, immunostaining results were somewhat inconsistent.

CONCLUSION

These data suggest that spiral ligament structure and function are essential for stria vascularis survival. In addition, dampened expression of ion transport molecules within the spiral ligament and stria vascularis may disrupt potassium ion recycling, resulting in loss of endocochlear potential and sensory hearing loss.

Klippel-Trenaunay-Weber syndrome with labyrinthine bony overgrowth and mixed hearing loss, a case report

Klippel-Trenaunay syndrome (KTS) is a congenital disorder characterized by a triad of (1) capillary malformations, (2) venous malformations, and (3) soft tissue or bony hypertrophy. There exists one report of a patient with KTS and an associated sensorineural hearing loss. We describe an adolescent girl with KTS and AV fistulas who was found to have a bony overgrowth extending from the cochlea into the middle ear cavity and an ipsilateral mixed hearing loss. In both of these patients, there were obvious KTS deformities involving the face. We suggest conducting hearing screening in patients with KTS and obvious head involvement.

Questioning the Relationship between Cochlear Otosclerosis and Sensorineural Hearing Loss: A Quantitative Evaluation of Cochlear Structures in Cases of Otosclerosis and Review of the Literature

BACKGROUND

The literature provides conflicting information regarding the prevalence and cause of sensorineural hearing loss (HL) in individuals with otosclerosis.

OBJECTIVE

The purpose of this study was to further evaluate the association between involvement of the cochlear endosteal layer with otosclerosis and sensorineural HL.

STUDY DESIGN

Retrospective case review.

METHODS

Temporal bones and audiograms from five individuals with otosclerosis were evaluated. The cochlear elements were quantified. The location and extent of the cochlear element loss was correlated with the location and extent of endosteal involvement with otosclerosis.

RESULTS

A reduction in the population of cochlear elements was observed in most individuals; however, the reduction was not proportional to the extent of endosteal involvement with otosclerosis. The cochlear elements remained normal adjacent to some areas of endosteal involvement with otosclerosis. One individual with extensive cochlear otosclerosis had normal hearing and predominantly normal cochlear elements.

CONCLUSION

This study demonstrates a variable amount of degeneration of the cochlear elements in individuals with otosclerotic involvement of the endosteum. The reduction in the population of cochlear elements was not related to the extent and location of endosteal involvement with otosclerosis. These findings suggest that factors that limit the effect of otosclerotic endosteal involvement on the cochlear elements or processes that effect the cochlear elements directly and are independent of bone involvement may be present.

Sensorineural hearing loss and otosclerosis: a clinical and radiologic survey of 437 cases

The aim of this study was to determine if a relationship exists between bone level thresholds and the extension of otosclerotic foci within the otic capsule. The study consisted of a retrospective case review in a university hospital. We included patients who underwent surgery for otosclerosis in our department and who had a CT scan prior to surgery. We analyzed the data charts and CT scans of 437 cases (386 patients). On CT scan, we distinguished patients with fenestral otosclerosis and/or with a pericochlear focus. A pericochlear focus could be extended (Group 2) or not (Group 1) to the cochlear endosteum. Data for Groups 1 and 2 were compared with those for the control group of all patients for whom CT scan showed no cochlear focus (Group 3). Of the 437 CT scans, 399 were positive (91.3%). An anterior focus was reported in 305 cases (69.8%), a footplate thickening in 21 cases (4.8%) and both anomalies were encountered in 60 cases (13.7%). A pericochlear focus was reported in 53 examinations. This focus was extended to the endosteum in 14 cases (26.4% of the pericochlear foci). In Group 1, preoperative air conduction (AC) thresholds were significantly lower than in the control group (p < 0.05). The air--bone gap was also significantly larger in Group 1 (p < 0.05). Bone conduction (BC) thresholds were lower in Group 1 than in the control group but the difference was not significant. In Group 2, preoperative AC thresholds were significantly lower than in the control group (p < 0.05). BC thresholds were also lower in Group 2 than in the control group and the difference was significant (p < 0.05). As a result of this study, we assume that there may be a relationship between bone level thresholds and the radiological extension of otosclerosis within the otic capsule.

Cochlear otosclerosis 30 years after stapedectomy confirmed by CT, MRI

A 64-year-old Japanese male patient, status post-stapedectomy, presented with progressive, bilateral SNHL of 30 years' duration. CT showed extensive demineralization of the otic capsule, suggestive of otospongiotic change in both ears. There were no hyperostotic lesions found, which would have been suggestive of otosclerotic change. MRI showed a morphologically intact membranous labyrinth in both ears, with no obstruction of the cochlear lumen. It was concluded that the patient has progressive otospongiotic change of the otic capsule, but no otosclerotic change.

Etidronate for the Neurotologic Symptoms of Otosclerosis: Preliminary Study

The efficacy of etidronate, a Bisphosphonate, was assessed as a treatment for the inner ear symptoms of otosclerosis in a retrospective case review of 896 patients diagnosed with otosclerosis, with primary complaints of dizziness, hearing loss, tinnitus or Meniere's syndrome. The diagnosis of otosclerosis was based on small-pixel computed tomography of the temporal bones. Of the 896 patients placed on an etidronate protocol, 545 were followed for more than six months and were analyzed. The symptomatic response to etidronate, as well as audiologic and computerized rotary chair results were used in the assessment. Patients who were previously on sodium fluoride were separately analyzed. In this preliminary study etidronate appeared to be an effective treatment for the neurotologic symptoms of otosclerosis. Prospective blinded efficacy studies of the bisphosphonates in the treatment of otosclerosis should be undertaken.

Stapedectomy in profound cochlear loss

Stapedectomy can be used in certain patients with profound sensorineural hearing loss and stapes fixation to improve hearing to a level at which a hearing aid may be effective. This study reviews the outcomes of 11 patients with profound cochlear loss secondary to otosclerosis who underwent stapes surgery performed by the senior author (M.E.G.) over a 25-year period. Postoperative hearing aid usage was effective in 9 of 11 patients. Preoperatively, these patients derived no benefits from hearing aids. Stapedectomy may be of immense value in patients with the proper history and profound cochlear loss.

Otosclerosis: the University of Minnesota temporal bone collection

A study of 1452 human temporal bones revealed a previously unpublished material of 144 bones with otosclerosis. After exclusion of infants and individuals of races other than white, the incidence of otosclerosis was 12.75%. Of the bones with otosclerosis, 56.1% belonged to men and 43.9% to women. The incidence of clinical and histologic otosclerosis was practically the same for men (44.7% to 55.3%) as for women (47% to 53%). However, the incidence of bilateral otosclerosis was higher in women (88.9%) than in men (65.2%). Bilateral otosclerosis was present in 75.6%, whereas it was unilateral in 24.4%. Sixty-six (66) ears (45.8%) had clinical otosclerosis, whereas 78 (54.2%) had histologic otosclerosis--frequently unifocal lesions. The most common site was anterior to the oval window (117 ears, 81.25%), followed by round window niche (52 ears, 36.11%), apical and medial cochlear wall (31 ears, 21.52%), and anterior wall of the internal auditory canal (27 ears, 18.75%). The activity of lesions was directly related to their size. Smaller lesions were predominantly inactive, whereas medium and larger lesions were predominantly active. There was a positive correlation when the size of the lesions, activity, and degree of cochlear endosteal involvement were compared with bone conduction thresholds (37 cases). Correlations between size and activity, and between activity and associated sensorineural hearing loss did not necessarily follow the sequence of an initial active stage (spongiotic) to a final inactive one (sclerotic). Comparison of cases of otosclerosis with equivalent age groups of the normal population yielded worse bone conduction thresholds for the otosclerosis cases only in the age group 60 to 69 years and older. Comparison of average bone conduction thresholds between bones with one site of endosteal involvement (28.26 dB HL) revealed no significant differences. Bones with two or more sites of endosteal involvement had significant differences. Bones with two or more sites of endosteal involvement had significantly worse bone conduction thresholds (62 dB HL). The overall results are not suggestive of an association of sensorineural hearing loss with otosclerosis without stapedial fixation.

Correlation of otosclerotic foci and degenerative changes in the organ of Corti and spiral ganglion

Statistical analyses of histopathologic findings in the cochlea and spiral ganglion of 37 temporal bones with otosclerosis, 12 controls of similar age, and seven controls with normal hearing were performed. In temporal bones with otosclerosis there was significant atrophy of the spiral ligament and stria vascularis in regions with endosteal involvement by otosclerosis, compared with regions without endosteal involvement (P less than .0001). There was more generalized atrophy of the stria vascularis in cochleae with two or more sites of endosteal involvement by otosclerosis than in cochleae with only one site of endosteal involvement (P less than .02), cochleae in temporal bones with otosclerosis but without endosteal involvement (P less than .05), or cochleae of controls of similar age (P less than .007). In addition, there was more atrophy of the spiral ligament in cochleae with two or more sites of endosteal involvement than in cochleae of similar age from the control group (P less than .03). In temporal bones with otosclerosis, there was no significant difference in counts of outer hair cells and density of spiral ganglion cells between regions demonstrating endosteal involvement by otosclerosis and regions without such involvement. However, total outer hair cell counts were lower in cochleae with two or more sites of endosteal involvement of otosclerosis than in cochleae with one site of endosteal involvement (P less than .04), cochleae in temporal bones with otosclerosis but without endosteal involvement (P less than .02), or cochleae from individuals of similar age but without otosclerosis (P = .05). Comparison of the mean bone conduction threshold, as measured in life, in temporal bones with otosclerosis compared with the air conduction threshold in aged-matched controls, demonstrated that only cochleae with two or more sites of endosteal involvement had a mild but statistically significant (P = .05) decrease in hearing. There was no evidence to support the concept that otosclerotic foci without stapedial fixation frequently cause significant degeneration of the cochlea or elevation of bone conduction thresholds.

Thirty years of stapes surgery

The modern stapedectomy with prosthesis insertion and living oval window seal, like the modern cataract extraction with lens replacement, is now performed, very much the same, throughout the world. I have reviewed the evolution of stapes surgery during these last thirty years and tried to gain some agreement for several important facts about otosclerosis and several basic principals of stapes surgery. While a well-performed stapedectomy can eliminate the conductive component, the sensorineural hearing loss continues and, in about one-third, will progress till the patient, after age 65, must return to a hearing aid. A piston prosthesis gives the best hearing results: 0.6 mm diameter, when half the footplate is removed and a living oval window seal interposed, and 0.6 mm diameter when a small opening is made in the footplate obliterated by otosclerosis. I prefer a teflon prosthesis to stainless steel because it can be altered by the surgeon at operation, and vein as an oval window seal. I have presented a rare group of patients who develop facial palsy 5-1/2 days after uncomplicated stapedectomy, of whom all recover quickly and completely. I am confident that progress will continue to be made in the understanding of otosclerosis, and the performance of stapes surgery, but in these last thirty years we have made a good beginning.

Otosclerosis and sensorineural hearing loss: a histopathologic study

The precise role and mechanism whereby otosclerosis is associated with sensorineural hearing loss remains unclear. Previous histopathologic reports are inconsistent with regard to the location of the otosclerotic focus, invasion of the otic capsule, and the number of remaining peripheral sensorineural elements. From the combined temporal bone collections of the University of Chicago and the Mayo Clinic, we identified a group of 125 ears from 80 patients, all with confirmed otosclerosis. Six of these ears were associated clinically with sensorineural hearing loss without stapes fixation. The histopathology of the otosclerotic focus was reviewed in terms of its location and depth of invasion. The cochlea and spiral ganglion were reconstructed, and the state of the organ of Corti and the presence or absence of peripheral cochlear nerve fibers were noted. Correlations with ganglion cell counts were made. The present study showed that the pattern of degeneration of peripheral sensory and neural elements in the cases presented is very similar to that found in cases of age-related processes such as presbycusis.