Etiopathogenesis of otosclerosis

Dynamic Molecular Markers of Otosclerosis in the Human Cochlea

OBJECTIVE

To investigate the role and distribution of various molecular markers using immunohistochemistry and immunofluorescence to further elucidate and understand the pathogenesis of otosclerosis.

METHODS

Archival celloidin formalin-fixed 20-micron thick histologic sections from 7 patients diagnosed with otosclerosis were studied and compared to controls. Sections in the mid-modiolar region were immunoreacted with rabbit polyclonal antibodies against nidogen-1, β2-laminin, collagen-IX, BSP, and monoclonal antibodies against TGF β-1 and ubiquitin. Digital images were acquired using a high-resolution light and laser confocal microscope.

RESULTS

Nidogen-1, BSP, and collagen-IX were expressed in the otospongiotic regions, and to lesser extent, in the otosclerotic regions, the latter previously believed to be inactive. β2-laminin and ubiquitin were uniformly expressed in both otospongiotic and otosclerotic regions. There was a basal level of expression of all of these markers in the normal hearing and sensorineural hearing loss specimens utilized as control. TGF β -1, however, though present in the otosclerosis bones, was absent in the normal hearing and sensorineural hearing loss controls.

CONCLUSIONS

Our results propose that the activity and function of TGF-1 may play a key role in the development and pathogenesis of otosclerosis. Further studies utilizing a higher number of temporal bone specimens will be helpful for future analysis and to help decipher its role as a potential target in therapeutic interventions.

Mutation of foxl1 Results in Reduced Cartilage Markers in a Zebrafish Model of Otosclerosis

Bone diseases such as otosclerosis (conductive hearing loss) and osteoporosis (low bone mineral density) can result from the abnormal expression of genes that regulate cartilage and bone development. The forkhead box transcription factor FOXL1 has been identified as the causative gene in a family with autosomal dominant otosclerosis and has been reported as a candidate gene in GWAS meta-analyses for osteoporosis. This potentially indicates a novel role for foxl1 in chondrogenesis, osteogenesis, and bone remodelling. We created a foxl1 mutant zebrafish strain as a model for otosclerosis and osteoporosis and examined jaw bones that are homologous to the mammalian middle ear bones, and mineralization of the axial skeleton. We demonstrate that foxl1 regulates the expression of collagen genes such as collagen type 1 alpha 1a and collagen type 11 alpha 2, and results in a delay in jawbone mineralization, while the axial skeleton remains unchanged. foxl1 may also act with other forkhead genes such as foxc1a, as loss of foxl1 in a foxc1a mutant background increases the severity of jaw calcification phenotypes when compared to each mutant alone. Our zebrafish model demonstrates atypical cartilage formation and mineralization in the zebrafish craniofacial skeleton in foxl1 mutants and demonstrates that aberrant collagen expression may underlie the development of otosclerosis.

Is Menière's Disease a Contraindication to Stapedectomy?

OBJECTIVE

Review surgical outcomes of stapedectomy for otosclerosis in patients with Menierè's disease.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Patients with otosclerosis and Menière's disease undergoing stapedectomy between 2010 and 2017.

INTERVENTION

Stapedectomy.

MAIN OUTCOME MEASURES

Pre- and postoperative hearing and complications. Hearing was measured by air conduction (AC) and bone conduction (BC) pure-tone frequency, pure-tone averages (PTA), air-bone gap (ABG), and word recognition scores (WRS).

RESULTS

Among 1,499 patients with otosclerosis, the incidence of concomitant Menière's disease was 1.7%. Fifteen patients with otosclerosis and Menière's disease underwent stapedectomy, 12 primary and three revisions. Mean AC PTA was 43 dB preoperatively, and 25 dB postoperatively (p = 0.0007), while the ABG improved on average from 20 to 5 dB (p = 0.0001). There was no significant difference in BC PTA or WRS postoperatively. Two patients experienced fluctuation of hearing in the postoperative period, one of which resolved with a course of steroids. The mean follow-up time was 41 months.

CONCLUSIONS

In patients with otosclerosis and Menière's disease, stapedectomy provides excellent hearing outcomes in a majority of patients. As is characteristic of Menière's disease, some patients will continue to experience fluctuating hearing postoperatively, which may progress to severe sensorineural hearing loss. Menière's disease may not be an absolute contraindication to stapes 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.

Ethanol infiltration into the stapedio-vestibular joint reduces low-frequency vibration of the ossicular chain and round window membrane in the guinea pig

BACKGROUND

The synovial stapedio-vestibular joint (SVJ), which serves as a bridge between the stape and oval window, can be found in guinea pigs and most human adults. Unlike the fibrous SVJs in other animals, the contribution of the synovial SVJ to middle ear sound transmission remains unknown.

AIMS/OBJECTIVES

In this study, we investigate whether sclerosis of the synovial SVJ contributes to frequency-dependent vibration of the ossicular chain and round window membrane (RWM).

MATERIALS AND METHODS

A model of SVJ sclerosis model was established in the guinea pig using 75% ethanol. A laser Doppler vibrometer was then used to measure vibrations of the RWM and the long process of the incus (LPI) under pure tone sound stimulations of 0.25-16 kHz. The influence of SVJ sclerosis was analysed by comparing structural vibration displacement between the normal and sclerosis groups.

RESULTS

Both LPI and RWM vibrations significantly decreased at low frequencies after infiltration of ethanol, which caused SVJ sclerosis.

CONCLUSIONS

SVJ sclerosis reduces low-frequency vibration of the ossicular chain and RWM in the guinea pig, which indicates that the synovial SVJ is vital to low-frequency sound transmission in the middle ear.

SIGNIFICANCE

Providing useful data for further research regarding middle ear biomechanics.

Inner ear ossification and mineralization kinetics in human embryonic development - microtomographic and histomorphological study

Little is known about middle and inner ear development during the second and third parts of human fetal life. Using ultra-high resolution Microcomputed Tomography coupled with bone histology, we performed the first quantitative middle and inner ear ossification/mineralization evaluation of fetuses between 17 and 39 weeks of gestational age. We show distinct ossification paces between ossicles, with a belated development of the stapes. A complete cochlear bony covering is observed within the time-frame of the onset of hearing, whereas distinct time courses of ossification for semicircular canal envelopes are observed in relation to the start of vestibular functions. The study evidences a spatio-temporal relationship between middle and inner ear structure development and the onset of hearing and balance, critical senses for the fetal adaptation to birth.

Stapedotomy and its effect on hearing - our experience with 54 cases

INTRODUCTION

This study reviews the cases of stapedotomy and evaluates its effectiveness at improving hearing loss in patients with otosclerosis.

MATERIALS AND METHODS

Retrospective review of patients' records who had clinical and audiometric diagnosis of otosclerosis from January to December 2012.

RESULTS

A total of 54 stapedotomy surgeries (52 unilateral and 1 bilateral surgeries) were received. Average post-operative ABG for 0.5, 1, 2 and 4 KHz showed that 61.1% had complete closure of ABG ( ABG < 10 dB) compared with 1.6% preoperatively and 85.2% had closure of ABG to within 20dB compared with 4.7% preoperatively (t - 13.89, p = 0.000). More than 94% had hearing improvement and 81.5% had ABG closure greater than 10 dB postoperatively (mean gain 23.38 ± 12.37, t = 13.89, p = 0.000). A total of 13% complications were recorded with TM perforation (5.6%) being the commonest complication.

CONCLUSION

Stapedotomy is an effective surgical procedure for the treatment of otosclerosis which leads to improvement in patients' quality of life. A favorable hearing outcome can be obtained by the combination of experienced hands with minimal surgical trauma and appropriate surgical technique.

Cochlear implantation outcomes in advanced otosclerosis

INTRODUCTION

Several studies support the use of cochlear implants (CI) in far-advanced otosclerosis (FAO).

MATERIAL AND METHODS

We compared our results of CI in patients with FAO and unknown origin hearing loss (UOHL) and our incidence of facial electrical stimulation and difficult insertion of the electrode bundle up to 3 to 5 years from surgery.

RESULTS

We found 17 patients with CI in FAO and UOHL. FAO patients achieved better results on the pure tone average (PTA) and recognition of monosyllables by GEE test (p=0.022; p=0.006), and particularly at 1 year on the PTA (p=0.002), at 6 months and a year in monosyllables (p=0.002; p=0.001), and at 6 months in disyllables (p=0.004). There were no differences toward complications.

CONCLUSION

In our experience, placement of CI in FAO has proven successful, with results comparable to other similar cohorts, and with low complications.

Expression of TNF-α, OPG, IL-1β and the presence of the measles virus RNA in the stapes of the patients with otosclerosis

Persistent measles virus infections play a crucial role in the pathomechanism of otosclerosis. The study was undertaken to investigate the role of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and osteoprotegerin (OPG) in otosclerotic bone remodeling and to assess the relation of TNF-α, OPG and IL-1β expression levels in otosclerotic stape footplates to the occurrence of measles virus infection. 61 patients with otosclerosis were treated surgically. Thirty-one stapes obtained from cadavers of people, who had died from a sudden cause were used as a control group. The presence of measles virus RNA and the expression levels of TNF-α, IL-1β and OPG in otosclerotic foci were assessed using one-step RT-PCR. The presence of measles virus RNA was noted in 80.3 % of otosclerotic stapes (49 out of 61) and 9.7 % of normal tissues (3 out of 31). Transcript of TNF-α, IL-1β and OPG was detected in 40, 46 and 18 virus-positive stapes, respectively. The transcript level of TNF-α and IL-1β was significantly higher in otosclerotic tissues comparing to normal tissue. The OPG expression level was significantly lower in otosclerotic tissues comparing to controls. The presence of measles virus RNA in the stapes may indicate its role in the pathogenesis of otosclerosis. The presence of TNF-α and IL-1β mRNA in the virus-positive stapes could be the result of viral antigen stimulation and may be a marker of inflammation the otosclerotic focus. The lack of OPG mRNA and the presence of TNF-α and IL-1β mRNA in the majority of otosclerotic tissues reflect the bone remodeling process occurring in the stapes.

Association of COL1A1 polymorphism in Turkish patients with otosclerosis

OBJECTIVE

To evaluate the role of COL1A1 gene polymorphism in the etiology of otosclerosis.

MATERIAL AND METHODS

Peripheric blood samples are obtained from 28 patients diagnosed with otosclerosis and 50 control subjects. DNA's of all samples are isolated and amplified by using the PCR technique. The products are restricted by appropriate enzymes and the allele distributions were compared.

RESULTS

SS (homozygous normal), Ss (heterozygous mutant) and ss (homozygous mutant) alleles of the otosclerotic and control subjects were significantly different from each other.

CONCLUSION

Otosclerosis is a disease with progressive hearing loss. There are viral, hormonal, immunologic and genetic hypothesis of etiology. In this study, we concluded that the polymorphism seen in the COL1A1 gene resulting in production of excessive type 1 collagen, could play a role in the pathogenesis of otosclerosis.

[Treatment results of otosclerosis regarding different types of prosthesis]

Surgery is the most effective method of improving hearing in patients with otosclerosis. The level of improvement depends on the stage of the disease and the chosen surgical method.

THE AIM OF THIS STUDY

is to present hearing results in patients treated surgically by means of different types of prostheses and methods of vestibule sealing.

MATERIAL AND METHODS

230 cases (160 men, 70 women) between the age of 21 and 64 (median 36 years) treated for the first time in the Department of Otolaryngology of Medical University in Gdańsk underwent epidemiologic and clinical analysis. The researches took into account the level of hearing improvement based on the reduced air-bone reserve for frequencies 0.5, 1.0, 2.0 i 4.0 kHz in groups with where prostheses type 1 and 2 were used.

RESULTS

230 stapedotomies were performed. In 110 patients prosthesis type 1 was used (PTFE) and in 120 type 2 (piston PTFE with platinum tape). Each vestibule was sealed with homogenic fat tissue or fibrin sponge. After 6 weeks from the operation the air-bone reserve was reduced by 5 to 30 dB, the reserve existed after one year from the operation in some patients. 35% of the patients presented with vertigo after the operation and 5% with tinnitus.

CONCLUSIONS

Stapedotomy is a method of hearing improvement in patients with otosclerosis. Best results are achieved when prosthesis type 2 is used and homogenic fat tissue serves to seal the vestibule. Broad opening of the vestibule may be the cause for vertigo and lack of hearing improvement occurrence.

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.

Castleman's disease accompanied by pleural effusion

Castleman's disease is a rare disorder of the lymphoid tissue. We report the case of a female patient with bilateral otosclerosis, no respiratory symptoms, and pleural effusion discovered as an incidental finding on a chest X-ray. Computed tomography of the chest revealed a mediastinal mass. The biopsy findings demonstrated that it was a plasmacytic variant of Castleman's disease. The patient underwent mediastinal mass resection. This resulted in near-total resolution of the effusion, which remained as a small loculation within the left pleural space.

Association of bone morphogenetic proteins with otosclerosis

We studied the role of polymorphisms in 13 candidate genes on the risk of otosclerosis in two large independent case-control sets. We found significant association in both populations with BMP2 and BMP4, implicating these two genes in the pathogenesis of this disease.

INTRODUCTION

Otosclerosis is a progressive disorder of the human temporal bone that leads to conductive hearing loss and in some cases sensorineural or mixed hearing loss. In a few families, it segregates as a monogenic disease with reduced penetrance, but in most patients, otosclerosis is more appropriately considered a complex disorder influenced by genetic and environmental factors.

MATERIALS AND METHODS

To identify major genetic factors in otosclerosis, we used a candidate gene approach to study two large independent case-control sets of Belgian-Dutch and French origin. Tag single nucleotide polymorphisms (SNPs) in 13 candidate susceptibility genes were studied in a stepwise strategy.

RESULTS

Two SNPs were identified that showed the same significant effect in both populations. The first SNP, rs3178250, is located in the 3' untranslated region of BMP2. Individuals homozygote for the C allele are protected against otosclerosis (combined populations: p = 2.2 x 10(-4); OR = 2.027; 95% CI = 1.380-2.979). The second SNP, rs17563, is an amino acid changing (p.Ala152Val) SNP located in BMP4. The G allele, coding for the amino acid alanine, confers susceptibility in both populations (combined populations: p = 0.002; OR = 1.209; 95% CI: 1.070-1.370).

CONCLUSIONS

These results indicate that polymorphisms in the BMP2 and BMP4 genes, both members of the TGF-beta superfamily, contribute to the susceptibility to otosclerosis and further strengthen the results from the recently reported association of TGFB1 with this disease.

Otosclerosis: mid-term results of cochlear implantation

INTRODUCTION

Constant histological changes in otosclerosis lead to progressive hearing loss which may end up in a profound hearing loss and then be treated by means of cochlear implants. These progressive changes could be followed by changes in cochlear implants fitting and speech discrimination results over the years.

OBJECTIVES

The aim of the study is to correlate the progressive histological changes to the cochlear implant clinical outcomes (fitting and speech discrimination results). Also main complications (facial nerve stimulation and difficulties at insertion) and new complications will be discussed.

DESIGN

A 5-year prospective case-control study was performed in order to compare cochlear implant results in otosclerosis patients to those in a matched-pair control group.

MATERIALS AND METHODS

Fifteen otosclerosis patients were followed throughout the study. Preoperatively temporal bone high-resolution computed tomography, electrically evoked auditory brainstem responses and speech discrimination tests were performed in order to select the patients to be implanted.

RESULTS

Not only difficulties with electrode guide insertion were reported, but also difficulties with fitting over the years, due to increasing difficulties to spread the electrical stimuli, which provokes increasing thresholds, maximum comfort levels and charges needed to stimulate hearing cells in basal and medial turn electrodes (p < 0.05), which required deactivating some basal and medial turn electrodes in order to improve cochlear implant effectiveness. The results demonstrated no statistical differences in speech discrimination in otosclerosis patients compared to the control group (p > 0.05). Several complications were reported: facial nerve stimulation (7.14%) and sudden episodes of tinnitus and headaches (14.28%).

CONCLUSIONS

Although progressive histological changes in otosclerosis lead to increasing thresholds, maximum comfort levels and charges needed to stimulate hearing cells, speech discrimination results support the cochlear implantation in otosclerosis.

A review on the genetics of otosclerosis

BACKGROUND

The aetiology of otosclerosis is not fully understood despite intensive research. It is, however, certain that a genetic component plays a significant role in the manifestation of otosclerosis, although the precise mode of inheritance is still uncertain.

OBJECTIVE OF REVIEW

To provide an up-to-date review for the genetics of otosclerosis. The mode of inheritance, chromosomal and linkage studies are presented. In addition, the possible genetic relationship between otosclerosis and osteogenesis imperfecta, and the association between otosclerosis and specific human leucocyte antigen types are described.

TYPE OF REVIEW

Systematic analysis of the literature was focused on any information related to the genetics of otosclerosis.

SEARCH STRATEGY

A MEDLINE search (1960-2007) was undertaken to perform a comprehensive review. Articles were also identified through searches of the files of authors.

RESULTS

The majority of epidemiological studies on families with otosclerosis suggest an autosomal dominant mode of inheritance with reduced penetrance of approximately 40%. Genetic linkage studies have demonstrated the presence of six loci (OTSC1, OTSC2, OTSC3, OTSC4, OTSC5 and OTSC7) located on chromosomes 15q, 7q, 6p, 16q, 3q and 6q respectively. Although these loci have been mapped, no causative genes have been identified, and we have little idea of the molecular process involved in this disease. While clinical similarities and some unreplicated genetic association studies suggest an aetiological relationship between otosclerosis and osteogenesis imperfecta-type I, there is no definite evidence of a common pathological process between the two diseases.

CONCLUSIONS

Otosclerosis may be considered as a complex disease with relatively common monogenic forms. Knowledge of these genes could lead to substantial improvements in our ability to diagnose and possibly even prevent or treat this type of hearing deterioration.

The coding polymorphism T263I in TGF-β1 is associated with otosclerosis in two independent populations

Otosclerosis is a progressive hearing loss characterized by an abnormal bone homeostasis of the otic capsule that leads to stapes fixation. Although its etiology remains unknown, otosclerosis can be considered a complex disease. Transforming growth factor-beta 1 (TGF-beta1) was chosen for a case-control association study, because of several non-genetic indications of involvement in otosclerosis. Single nucleotide polymorphism (SNP) analysis in a large Belgian-Dutch sample set gave significant results (P = 0.0044) for an amino acid changing SNP, T263I. Analysis of an independent French population replicated this association with SNP T263I (P = 0.00019). The results remained significant after multiple testing correction in both populations. Haplotype analysis and the results of an independent effect test using the weighted haplotype (WHAP) computer program in both populations were both compatible with SNP T263I being the only causal variant. The variant I263 is under-represented in otosclerosis patients and hence protective against the disease. Combining the data of both case-control groups for SNP T263I with a Mantel-Haenszel estimate of common odds ratios gave a very significant result (P = 9.2 x 10(-6)). Functional analysis of SNP T263I with a luciferase reporter assay showed that the protective variant I263 of TGF-beta1 is more active than the WT variant T263 (P = 1.6 x 10(-6)). On the basis of very low P-values, replication in an independent population and a functional effect of the protective variant, we conclude that TGF-beta1 influences the susceptibility for otosclerosis, and that the I263 variant is protective against the disease.

Case report: Meniere's disease and otosclerosis—Different outcomes of the same disease?

The etiologies of Meniere's disease and otosclerosis are largely unknown. An association between these two diseases has been proposed on both a clinical and histopathologic basis but the causal relationship is controversial. In this paper we report two families in which both otosclerosis and Meniere's disease are inherited as independent phenotypes suggesting that the two diseases represent different outcomes of the same mutation. Thus the Meniere's disease occasionally seen in otosclerotic patients might not be caused by otosclerosis, but rather by a molecular defect leading to endolymphatic hydrops and/or clinical otosclerosis.

Surgical treatment of otosclerosis in medical residency training

The number of patients with stapes otosclerosis compared to the number of otorhinolaryngologists has declined over the past several years. As a result a controversy has arisen in the literature, whether or not stapes surgery should be included in residency programs.

AIM

the objective of the present study is to evaluate the results and complications of estapedotomies performed by residents between January, 1997 and January, 2000, and consequently study the feasibility of including estapedotomies in residency programs. STUD DESIGN: retrospective review of prospectively collected audiometric data.

MATERIALS AND METHODS

fifty charts of patients that were submitted to a total of 51 primary stapedotomies were reviewed mainly for complications and audiological results.

RESULTS

there was closure of the air-bone gap within 10 dB HL in 70.5% of ears and closure to within 20 dB HL in 86.3% of ears. There was one ear with total hearing loss (2%).

CONCLUSION

From the results and complications seen in the present study, and analyzing papers from the literature, it is possible to conclude that stapedotomy is a procedure that can be included in residency programs, if there are surgical cases for the residents.

Computed tomography in the diagnosis of otosclerosis

OBJECTIVES

To identify the main tomographic findings of otosclerosis and to evaluate the usefulness of high-resolution computed tomography as a diagnostic method for this osteodystrophy.

STUDY DESIGN AND SETTING

A prospective and multicenter study consisting of computed tomography (CT) of the temporal bone was conducted on 54 patients with a clinical and surgical diagnosis of otosclerosis. Twenty-two patients were included in the control group.

RESULTS

The CT scan was positive in 87% of the patients. The tomographic findings were mainly bilateral and fenestral foci were more prevalent.

CONCLUSIONS

CT showed a high rate of positivity, mainly for fenestral lesions. Foci anterior to the oval window were the most prevalent in this population.

SIGNIFICANCE

CT is useful as a diagnostic method and therapeutic indicator of otosclerosis.

EBM RATING

B-3b.

Three-dimensional regular arrangement of the annular ligament of the rat stapediovestibular joint

The stapes footplate articulates with the vestibular window through the annular ligament. This articulation is known as the stapediovestibular joint (SVJ). We investigated the ultrastructure of adult rat SVJ and report here on the characteristic ultrastructure of the corresponding annular ligament. Transmission electron microscopy showed that this annular ligament comprises thick ligament fibers consisting of a peripheral mantle of microfibrils and an electron-lucent central amorphous substance that is regularly arranged in a linear fashion, forming laminated structures parallel to the horizontal plane of the SVJ. Scanning electron microscopy revealed that transverse microfibrils cross the thick ligament fibers, showing a lattice-like structure. The annular ligament was vividly stained with elastica van Gieson's stain and the Verhoeff's iron hematoxylin method. Staining of the electron-lucent central amorphous substance of the thick ligament fibers by the tannate-metal salt method revealed an intense electron density. These results indicate that the annular ligament of the SVJ is mainly composed of mature elastic fibers.

Stickler syndrome type I and Stapes ankylosis

OBJECTIVE

To report a successful stapedectomy for stapedial fixation in a patient with Stickler syndrome type I (COL2A1).

SETTING

University Hospital Department for Otology, Pathology, Ophthalmology and Clinical Genetics.

STUDY DESIGN

A clinical and genetic evaluation of a mother and daughter focusing mainly on the otological, ophthalmological, histological and genetical aspects.

INTERVENTION

A stapedectomy was performed successfully.

RESULTS

Hearing impairment improved after stapedectomy. Postoperatively a shift in high-frequency threshold wa seen related to the stapedectomy. A new mutation in COL2A1 gene was dectected.

CONCLUSION

Stapedial fixation can be the cause of hearing impairment in Stickler syndrome type I (COL2A1). The hearing impairment can be improved by stapes surgery.

Measles Virus Prevalence in Otosclerotic Stapes Footplate Samples

HYPOTHESIS

The cause of otosclerosis is still unknown. Persistent measles virus infection of the otic capsule is supposed to be one of the etiologic factors in otosclerosis. Chronic viral antigen expression on the surface of infected cells can induce a secondary autoimmune reaction against the otic capsule.

BACKGROUND

In the past 15 years, some reports proposed the possible etiologic role of measles virus in otosclerosis. The presence of measles virus was shown in otosclerotic patients by reverse-transcriptase polymerase chain reaction amplification of the viral RNA, detecting the viral proteins by immunohistochemistry and detecting antimeasles immunoglobulin G in the perilymph samples. Many concerns were elicited by these results.

METHODS

Nucleic acid was extracted from pulverized, frozen stapes footplate samples of otosclerotic patients. Measles virus RNA was amplified by reverse-transcriptase polymerase chain reaction: reverse transcription and the first round polymerase chain reaction amplification was performed by heat stable recombinant Thermus thermophilus polymerase, whereas in the nested round, polymerase chain reaction Taq-polymerase was used. Measles virus nucleoprotein RNA-specific oligonucleotide primers were used in these reactions. An Edmonston-type measles virus served as a positive control and cortical bone fragments or stapes superstructures served as negative controls.

RESULTS

Among 34 otosclerotic patients, 20 stapes footplate samples contained measles virus RNA. Measles virus RNA was not detected in other bone specimens of the patients.

CONCLUSION

The etiologic role of measles virus in the pathogenesis of otosclerosis should be considered. The 14 negative samples may be genetically determined otosclerotic cases.

Tomografia computadorizada no diagnóstico da otosclerose fenestral

OBJETIVO: Identificar os principais achados tomográficos da otosclerose fenestral e avaliar a utilidade da tomografia computadorizada de alta resolução (TCAR), como método diagnóstico dessa osteodistrofia. FORMA DE ESTUDO: Estudo prospectivo multicêntrico com tomografia computadorizada (TC) de ossos temporais. MATERIAL E MÉTODO: 54 pacientes com diagnóstico clínico e cirúrgico de otosclerose. Foi realizada uma análise tomográfica, em que foi avaliada a sensibilidade da TC no diagnóstico radiológico da otosclerose fenestral, sendo verificados os principais sítios de lesões dessa doença, como também a sua bilateralidade e simetria. Foram incluídos neste estudo 22 pacientes submetidos à TC de ossos temporais para investigação de outras afecções otológicas, que constituíram o grupo controle. RESULTADOS: A TC foi positiva em 87% dos pacientes (77% das orelhas). Os achados tomográficos foram bilaterais na maioria dos casos (78,7%), e o foco fenestral mais prevalente foi o foco anterior à janela oval (FAJO). CONCLUSÕES: A TC apresentou um alto índice de positividade e o FAJO foi o foco mais prevalente nessa população, podendo ser considerado um achado tomográfico altamente sugestivo de otosclerose.