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.

Pregnancy, Estrogen Exposure, and the Development of Otosclerosis: A Case-Control Study of 1196 Women.

OBJECTIVE: This study sought to determine whether a history of pregnancy or bilateral oophorectomy is associated with subsequent otosclerosis development or disease severity. STUDY DESIGN: Population-based case-control study. SETTING: Olmsted County, Minnesota. METHODS: Women diagnosed with otosclerosis were matched to 3 women without otosclerosis based on age and historical depth of medical records. Associations of prior delivery and bilateral oophorectomy with subsequent development of otosclerosis and with pure-tone average (PTA) at the time of otosclerosis diagnosis were evaluated. RESULTS: We studied 1196 women: 299 cases of otosclerosis and 897 matched controls. The odds ratio for the association of ≥1 delivery with otosclerosis was 1.16 (95% confidence interval [CI] 0.85-1.60; P = .35). Odds ratios for the associations of 1, 2, 3, or ≥4 deliveries with otosclerosis were 1.22 (0.83-1.80), 1.09 (0.71-1.68), 1.28 (0.77-2.12), and 1.00 (0.54-1.84), respectively. The odds ratio for the association of prior bilateral oophorectomy with otosclerosis was 1.12 (0.58-2.18; P = .73). In cases with otosclerosis, PTA at diagnosis was not significantly higher for women with ≥1 delivery as compared with those without (median 45 dB hearing loss [HL] [interquartile range {IQR} 36-55] vs 43 [IQR 34-53]; P = 0.18) but was significantly higher for women with bilateral oophorectomy compared with those without (median 54 dB HL [IQR 44-61] vs 44 [IQR 34-53]; P = .03). CONCLUSION: These data do not support a relationship between endogenous estrogen exposure and development of otosclerosis. Women with otosclerosis who had a history of pregnancy did not have significantly worse hearing at the time of diagnosis, suggesting that pregnancy is not associated with disease severity.

GPER-1 and sex-hormone levels in patients with otosclerosis.

OBJECTIVE: Otosclerosis is a widespread disease but the etiopathogenesis is still not fully understood. Hormonal factors especially estrogens are accused in recent years. The study aimed to evaluate the levels of G-protein associated membrane estrogen receptor-1 (GPER-1) and sex-hormones in patients with otosclerosis. SUBJECT AND METHODS: The study included 60 people (30 otosclerosis patients, 30 control group). Serum sex-hormone (estradiol, progesterone, prolactin and total testosterone) and GPER-1 levels were measured in otosclerosis patients and compared with the normal population. For the otosclerosis group, air conduction and bone conduction thresholds and air-bone gaps were viewed from audiograms and the relationships between hearing and GPER-1 or sex-hormone levels were also investigated. RESULTS: Sex-hormone levels were not different between the groups. GPER-1 level was significantly lower in the otosclerosis group [3.1353 (0.76-8.21) ng/mL] than the control group [5.4773 (0.96-20.31) ng/mL] (p =0.017). Differential diagnosis with ROC analysis for the GPER-1 level was also significant (p=0.017). GPER-1 level was significantly lower for the females than the males in the otosclerosis group (p=0.043). Serum estradiol, progesterone, and prolactin levels were significantly higher (p=0.02, p =0.029 and p=0.019 respectively) and the GPER-1 level was significantly lower (p= 0.04) in the female patients compared to the female controls. There was no statistically significant relationship between GPER-1 or sex-hormone levels and hearing parameters. CONCLUSION: GPER-1 level was lower in the otosclerosis patients compared to healthy volunteers and also lower in females than males in the patient group. Female sex-hormone levels were higher and GPER-1 level was lower in the female patient group than the female control group. Neither GPER-1 nor sex-hormone levels were not predictive of hearing levels. These findings indicate that sex-hormones especially estrogen and GPER-1 might have a potential role in the etiopathogenesis of otosclerosis. This is the first study in the literature that investigates the GPER-1 values in otosclerosis.

Otosclerosis: From Genetics to Molecular Biology.

Over the past several years, with the evolution of genetic and molecular research, several etiologic factors have been implicated in the pathogenesis of otosclerosis. Overall, current evidence suggests that otosclerosis is a complex disease with a variety of potential pathways contributing to the development of abnormal bone remodeling in the otic capsule. These pathways involved in the pathogenesis of otosclerosis are influenced by both genetic and environmental factors.

Experiences from Auditory Brainstem Implantation (ABIs) in four paediatric patients.

INTRODUCTION: Indications for auditory brainstem implants (ABIs) have been widened from patients with neurofibromatosis type 2 (NF2) to paediatric patients with congenital cochlear malformations, cochlear nerve hypoplasia/aplasia, or cochlear ossification after meningitis. We present four ABI surgeries performed in children at Uppsala University Hospital in Sweden since 2009. METHODS: Three children were implanted with implants from Cochlear Ltd. (Lane Cove, Australia) and one child with an implant from MedEl GMBH (Innsbruck, Austria). A boy with Goldenhar syndrome was implanted with a Cochlear Nucleus ABI24M at age 2 years (patient 1). Another boy with CHARGE syndrome was implanted with a Cochlear Nucleus ABI541 at age 2.5 years (patient 2). Another boy with post-ossification meningitis was implanted with a Cochlear Nucleus ABI24M at age 4 years (patient 3). A girl with cochlear aplasia was implanted with a MedEl Synchrony ABI at age 3 years (patient 4). In patients 1, 2, and 3, the trans-labyrinthine approach was used, and in patient 4 the retro-sigmoid approach was used. RESULTS: Three of the four children benefited from their ABIs and use it full time. Two of the full time users had categories of auditory performance (CAP) score of 4 at their last follow up visit (6 and 2.5 years postoperative) which means they can discriminate consistently any combination of two of Ling's sounds. One child has not been fully evaluated yet, but is a full time user and had CAP 2 (responds to speech sounds) after 3 months of ABI use. No severe side or unpleasant stimulation effects have been observed so far. There was one case of immediate electrode migration and one case of implant device failure after 6.5 years. CONCLUSION: ABI should be considered as an option in the rehabilitation of children with similar diagnoses.

Towards quantitative diagnosis of ossicular fixation: Measurement of stapes fixations using magnetically driven ossicles in human temporal bones.

CONCLUSION: Information on the degree of stapes fixation can be found by measuring the ratio of stapes to umbo and stapes to incus velocity. OBJECTIVES: To evaluate a method of quantifying ossicular fixation in an ear with elevated tympanic membrane. METHOD: Measurements were made on four fresh-frozen human temporal bones. After elevating the tympanic membrane, a small magnet was attached to the manubrium and an electromagnetic excitation coil was used to vibrate the ossicles. The vibration response of the umbo, the tip of the incus long process, and the posterior crus of the stapes were measured before and after partially fixing the footplate with luting cement. RESULTS: The velocities at the different measurement points were unequally affected by the fixation. The difference in the velocity ratio between different points provides an indication of the degree of footplate fixation.

Labyrinthitis Ossificans: On the Mechanism of Perilabyrinthine Bone Remodeling.

INTRODUCTION: It has been suggested that remodeling of the otic capsule is highly suppressed by the action of anti-resorptive signals emanating from structures of the inner ear space. Labyrinthitis ossificans (LO) is a severe complication to bacterial meningitis and is characterized by destruction of inner ear structures by the formation of new bone. The aim of this study was to explore the impact of LO on bone remodeling of the otic capsule. MATERIAL AND METHODS: In 11 human temporal bones with extensive LO and 10 control specimens, the degree of bone remodeling was explored indirectly by estimating the viability of osteocytes in perilabyrinthine bone and the mastoid. RESULTS: The viability of osteocytes was significantly lower in the perilabyrinthine bone compared to the mastoid in both groups. However, the loss of perilabyrinthine osteocytes was the same in the 2 groups, and the presence of cartilage remnants appeared to be the same. CONCLUSION: This study indicates that the factors affecting bone remodeling of the otic capsule and the degeneration of osteocytes are not altered by wholesale destruction of inner ear soft tissue and its replacement by bone. Therefore, alternative mechanisms may be implicated in the suppression of capsular bone remodeling.

Expression of TNF-α, OPG, IL-1ß 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 1ß (IL-1ß) and osteoprotegerin (OPG) in otosclerotic bone remodeling and to assess the relation of TNF-α, OPG and IL-1ß 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-1ß 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-1ß and OPG was detected in 40, 46 and 18 virus-positive stapes, respectively. The transcript level of TNF-α and IL-1ß 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-1ß 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-1ß mRNA in the majority of otosclerotic tissues reflect the bone remodeling process occurring in the stapes.

Experimental in vitro infection of rat osteoblasts with measles virus stimulates osteogenic differentiation.

In this work we characterized the infection of a primary culture of rat osteoblastic lineage cells (OBCs) with measles virus (MeV) and the effect of infection on cell differentiation and maturation. Infection of OBCs with MeV led to high titers of infectivity released early after infection. Also, analysis of mRNAs corresponding to osteogenic differentiation markers like alkaline phosphatase (ALP), bone sialo-protein (BSP) and bone morphogenetic proteins (BMPs) 1-4-5-7 in OBCs revealed higher values (2-75-fold of increment) for infected cells in comparison with uninfected controls. Differentiation of OBCs in osteogenic medium prior to infection influenced the level of stimulation induced by MeV. Furthermore, treatment of OBCs with Ly294002, a PI3K/AKT inhibitor, increased viral titers, whereas treatment with 10µM or 100µM ATPγS diminished MeV multiplication. In addition, increments of osteogenic differentiation markers induced by MeV infection were not modified either by treatment with Ly294002 or ATPγS. These data provide the first evidence demonstrating that MeV can infect osteoblasts in vitro leading to osteoblastic differentiation, a key feature in bone pathogenic processes like otosclerosis.

Differences in otosclerotic and normal human stapedial osteoblast properties are normalized by alendronate in vitro.

OBJECTIVE: Identify and compare phenotypic properties of osteoblasts from patients with otosclerosis (OSO), normal bones (HOB), and normal stapes (NSO) to determine a possible cause for OSO hypermineralization and assess any effects of the bisphosphonate, alendronate. STUDY DESIGN: OSO (n = 11), NSO (n = 4), and HOB (n = 13) cultures were assayed for proliferation, adhesion, mineralization, and gene expression with and without 10(-10)M-10(-8)M alendronate. SETTING: Academic hospital. METHODS: Cultures were matched for age, sex, and passage number. Cell attachment and proliferation + alendronate were determined by Coulter counting cells and assaying tritiated thymidine uptake, respectively. At 7, 14, and 21 days of culture + alendronate, calcium content and gene expression by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were determined. RESULTS: OSO had significantly more cells adhere but less proliferation than NSO or HOB. Calcification was significantly increased in OSO compared to HOB and NSO. NSO and HOB had similar cell adhesion and proliferation rates. A dose-dependent effect of alendronate on OSO adhesion, proliferation, and mineralization was found, resulting in levels equal to NSO and HOB. All cultures expressed osteoblast-specific genes such as RUNX2, alkaline phosphatase, type I collagen, and osteocalcin. However, osteopontin was dramatically reduced, 9.4-fold at 14 days, in OSO compared to NSO. Receptor activator of nuclear factor κB ligand/osteoprotegerin (RANKL/OPG), important in bone resorption, was elevated in OSO with decreased levels of OPG levels. Alendronate had little effect on gene expression in HOB but in OSO increased osteopontin levels and decreased RANKL/OPG. CONCLUSIONS: OSO cultures displayed properties of hypermineralization due to decreased osteopontin (OPN) and also had increased RANKL/OPG, which were normalized by alendronate.

In search of correlation between hand preference and laterality of hearing impairment in patients with otosclerosis.

The aim of this study was to investigate a possible correlation between handedness and laterality of hearing impairment due to otosclerosis. All patients operated for otosclerosis between August 2008 and February 2014 were queried about their handedness. The study group consisted of 218 right-handed and 21 left-handed (8.9%) patients [139 female (58.2%) and 100 male] with an age range of 18-75 years (mean 46.1 years). One-hundred and fifty-seven patients had a bilateral otosclerosis (BO) and 82 (34.3%) had a unilateral otosclerosis (UO). There were 11 left-handed male and 10 left-handed female (11% vs. 7.2 %, p = 0.305). In patients with UO, the left ear (LE) was affected in 6/11 (58.3%) left handed ones, and the right ear (RE) in 41/71 (57.7%) right handed ones (p = 0.842). In patients with BO, the LE was more affected in the left-handed ones, and the RE in the right-handed ones (7/10, 70% and 87/147, 59.2 %, respectively, p = 0.5). Overall, 13/21 (61.9%) left-handed patients presented with only/mostly left-sided otosclerosis, while 128/218 (58.7%) right-handed patients presented with only/mostly right-sided otosclerosis (p = 0.584). Clinical relevance of presented findings is unclear yet nevertheless current study may contribute one more element in the multifactorial process of otosclerosis-related hearing loss.

CHD7 deficiency in "Looper", a new mouse model of CHARGE syndrome, results in ossicle malformation, otosclerosis and hearing impairment.

CHARGE syndrome is a rare human disorder caused by mutations in the gene encoding chromodomain helicase DNA binding protein 7 (CHD7). Characteristics of CHARGE are varied and include developmental ear and hearing anomalies. Here we report a novel mouse model of CHD7 dysfunction, termed Looper. The Looper strain harbours a nonsense mutation (c.5690C>A, p.S1897X) within the Chd7 gene. Looper mice exhibit many of the clinical features of the human syndrome, consistent with previously reported CHARGE models, including growth retardation, facial asymmetry, vestibular defects, eye anomalies, hyperactivity, ossicle malformation, hearing loss and vestibular dysfunction. Looper mice display an otosclerosis-like fusion of the stapes footplate to the cochlear oval window and blepharoconjunctivitis but not coloboma. Looper mice are hyperactive and have vestibular dysfunction but do not display motor impairment.

[Stapedoplasty in a HIV-infected patient].

This paper reports an observation illustrating the possibility of the successful surgical treatment of otosclerosis in a HIV-infected patient presenting with acquired immunodeficiency syndrome (AIDS) and positive response in the test for hepatitis C. The authors used the results of multispiral computed tomography (MSCT) of the temporal bones as a basis for the prediction of the outcome of the surgical intervention taking into consideration specific primary manifestations of HIV infection as well as immunological and virlogical responses to anti-retroviral therapy.

On the biology of the bony otic capsule and the pathogenesis of otosclerosis.

In human otosclerosis, focal pathological bone remodeling occurs in significant amounts inside the normally anti-resorptive perilabyrinthine domain of the bony otic capsule. Otosclerosis causes hearing loss in 0.2-0.5% of the population by ankylosis of the footplate. The disease cannot be predicted, avoided or medically reversed as the pathogenesis remains unknown. Previously genetic research has failed to identify a specific otosclerosis-gene and earlier theories of virus infections, autoimmunity or association to generalized bone diseases have been unable to explain why otosclerosis only occurs in the bony otic capsule while the rest of the skeleton remains completely normal. Studies from the otopathological laboratory (RH) have revealed how the bone turnover rates increase centrifugally from a sub-normal 0.1% adjacent to the inner ear space towards a normal 10% per year at the capsular periphery. This graded restriction of bone remodeling is most likely caused by the anti-resorptive action of the cytokine osteoprotegerin (OPG), which is expressed in high levels (1000 x normal bone levels) by inner ear structures to inhibit perilabyrinthine osteoclast formation and function. OPG knockout mice develop excessive, irregular bone remodeling, stapes fixation and progressive hearing loss. The lacuno-canalicular porosity is the candidate anatomical routes for the transmission of OPG-derived signals to the surrounding bone. This extracellular signaling pathway depends crucially on the viability of individual osteocytes. When bone remodeling is low, the average age of the bone matrix and osteocytes increases. We detected a high fetal density of labyrinthine osteocytes, which may secure a life-long anatomical route for inner ear OPG despite accumulation of non-viable osteocytes. Moreover, 3-D reconstructions and vector-based stereology revealed a co-existence between non-viable osteocytes and otosclerosis. We suggest that bone remodeling may commence when the effect of anti-resorptive OPG fails locally within regions of non-viable osteocytes. A sustained OPG signal from surrounding osteocyte survivors might distort the process and account for the otosclerotic morphology.

[Otosclerosis- <> or the loss of the natural variant of inertness (<> of the labyrinth capsule)].

The author suggests an original hypothesis of otosclerosis based on the analyses of the literature publications for many years and his personal clinical observations. The normal labyrinth capsule is considered to be bradytrophic, i.e. inert and showing an extremely low level of metabolic processes. The disturbance of bradytrophicity under the action of individual factors and/or especially their combination make it involved in the maintenance of calcium homeostasis in the body. The validity of this conjecture is confirmed by the results of histological investigations, viz. the appearance of diquide or xplasma-like, bone in the labyrinth of the patients suffering otosclerosis. Such bone resorption is known to occur in other parts of the bony skeletontoo and should be regarded as a normal physiological process contributing to the replenishment of blood calcium deficiency.The subsequent reorganization (remodeling) of any part of the bony skeleton is physiologically neutral. In the labyrinth capsule,with its small size and delicate structure, such reorganization induces the otosclerotic process responsible for dysfunction of the membranaceous labyrinth. The surgical treatment of the patients presenting with otosclerosis should be supplemented by conservative treatment intended to slow down the otosclerotic reorganization and to restore bradytrophicity of the labyrinth capsule.

[Postoperative vertigo caused by too long stapes prosthesis--radiological diagnostics]. / Pooperacyjne zawroty glowy zwiazane z nadmierna dlugoscia protezki strzemiaczka--diagnostyka radiologiczna.

The aim of the study was to describe the value of High Resolution Computed Tomography (HRCT) with MPR and VR reconstruction of the temporal bone in patients with persistent vertigo after stapedotomy. High Resolution Computed Tomography with MPR and VR reconstruction of the temporal bone in the axial and coronal planes with 0.625 - mm slice thickness were performed in 2 patients with persistent vertigo after stapedotomy. Persistent vertigo were observed in 2 patients suffered from otosclerosis several months after stapedotomy. High Resolution Computed Tomography with MPR and VR reconstruction of the temporal bone showed in both cases too long stapes prosthesis. On the base of HRCT results restapedotomy and length reduction of stapes prosthesis were done. The vertigo was resolved in all the cases with revision surgery. HRCT with MPR and VR reconstruction can diagnosed the possible cause of persistent vertigo in patients after stapedotomy.

[Skull base defects in the middle and posterior cranial fossa with unchanged mucous lining middle ear spaces]. / Ubytki kosci podstawy srodkowego i tylnego dolu czaszki przy niezmienionej wysciólce ucha srodkowego.

BACKGROUND: Skull bone defects in the region of middle ear are usually observed in the cases of chronic otitis media. Such loses can also be congenital, posttraumatic, iatrogenic or due to hyperplasia. They can potentially lead to development of otogenic intracranial complications. AIM: We present the patients who were not observed during otosurgery to have any pathological changes to the mucous of the middle ear and were diagnosed as having bone defects in the middle and/or posterior cranial fossa. We discuss also methods of reconstruction during otosurgery. MATERIAL AND METHODS: The prospective analysis involves the patients operated on middle ear in the Department of Otolaryngology at the Jagiellonian University of Krakow in the years 2007-2011. 495 first-time otosurgeries were performed in this period of time. RESULTS: Skull bone defects were diagnosed in 46 patients who had undergone surgery and 25% of these patients had no changes to the middle ear mucous. This points to congenital etiology of the defects. In this group the most common cause for otosurgery was chronic otitis media (10 patients). In 1 patient, bone defect occurred along with otosclerosis. In patients with congenital skull bone defects otogenic intracranial complications were described in 4 cases. CONCLUSIONS: Nearly 80% of skull bone defects remain asymptomatic; they are revealed incidentally during the surgery of the middle ear. The above observations emphasize the significant role of preoperative imaging diagnostics. The methods of bone defects reconstruction using the fascia, strengthened with the pedicle muscle flap where larger defects occurred, as well as with either bone lamella or cartilage in particular cases, proved successful.

Otopathology in Osteogenesis Imperfecta.

BACKGROUND: Osteogenesis Imperfecta (OI) is a genetic disorder of connective tissue matrix. OI is caused by mutations that affect type I collagen. The hearing loss in OI is characterized by onset in early adulthood and can be conductive, sensorineural, or mixed. OBJECTIVES: To describe the temporal bone histopathology in 9 individuals with OI. MATERIALS AND METHODS: Four adult, 1 pediatric, and 4 infant specimens were identified. Temporal bones were removed at autopsy and studied using light microscopy. RESULTS: All adults and 1 pediatric specimen showed otosclerotic lesions. The findings included examples of clinical, histologic, and cochlear otosclerosis. The temporal bones of infants showed delayed ossification of the endochondral layer of bone and of the ossicles. There were no infant specimens with otosclerotic lesions. CONCLUSION: Hearing loss in OI may be the result of clinical or cochlear otosclerosis. Fracture or atrophy of the ossicles may also be present in OI. A third unidentified mechanism of hearing loss may lead to cochlear degeneration. The described findings of otosclerotic lesions have implications for the observed heterogeneity of hearing loss patterns and for the surgical management of hearing loss in OI.