Third window lesions of the inner ear: A pictorial review.

PURPOSE: Radiographic review of pathologies that associate with third window syndrome. METHODS: Case series and literature review. RESULTS: Eight unique third window conditions are described and illustrated, including superior, lateral, and posterior semicircular canal dehiscence; carotid-cochlear, facial-cochlear, and internal auditory canal-cochlear dehiscence, labyrinthine erosion from endolymphatic sac tumor, and enlarged vestibular aqueduct. CONCLUSION: The present study highlights the characteristic imaging features and symptoms to differentiate third window pathologies for expedient diagnosis and management planning.

Use of topical fluorescein in the diagnosis and localization of perilymphatic fistula.

OBJECTIVE: The purpose of this video presentation is to demonstrate the effect of intraoperative dilute topical fluorescein in perilympatic fistula diagnosis and localization. MATERIALS AND METHODS: Explorative tympanotomy was performed for the diagnosis, localization and repair of the fistula in the patient who had a pre-diagnosis of perilymphatic fistula. Topical fluorescein was applied intraoperatively to localize the defect. RESULT: A clear change of color was distinguished from yellow to green leading to diagnosis of the perilymphatic fistula and also showed the origin of the fistula. CONCLUSION: Topical application of dilute fluorescein is a convenient and effective tool in the diagnosis and localization of perilymphatic fistula.

Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects.

Duane retraction syndrome (DRS) is a congenital eye-movement disorder defined by limited outward gaze and retraction of the eye on attempted inward gaze. Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness. Using genotype-phenotype correlations in humans and Mafb-knockout mice, we propose a threshold model for variable loss of MAFB function. Postmortem studies of DRS have reported abducens nerve hypoplasia and aberrant innervation of the lateral rectus muscle by the oculomotor nerve. Our studies in mice now confirm this human DRS pathology. Moreover, we demonstrate that selectively disrupting abducens nerve development is sufficient to cause secondary innervation of the lateral rectus muscle by aberrant oculomotor nerve branches, which form at developmental decision regions close to target extraocular muscles. Thus, we present evidence that the primary cause of DRS is failure of the abducens nerve to fully innervate the lateral rectus muscle in early development.

Inner ear drug delivery using liposomes.

Dysfunction of inner ear can result in from several disease procedures and introduce a possibility for therapeutic intervention. The existence of a blood-cochlear obstacle and round window membrane restricts direct access into the inner ear and following inner ear drug, gene, protein and cell delivery. Several strategies have designed to increase drug delivery to the inner ear. One of main particles for inner ear drug delivery is liposome. Here we reviewed the application of liposomes in inner ear drug delivery.

[Tumors of the inner ear and adjacent structures]. / Tumoren des Innenohrs und angrenzender Strukturen.

Tumors of the inner ear and adjacent structures often present with hearing loss, tinnitus and vertigo due to compression of the traversing cranial nerves. More than 90% of the tumors of the inner ear with or without expansion into the cerebellopontine angle are histologically diagnosed as vestibular schwannomas. Less common tumorous lesions include ectopic meningiomas located in the petrous bone, glomus tympanicum paragangliomas or endolymphatic sac tumors (ELST) originating in the vestibular recess. Most tumors are sporadic, but hereditary disorders have to be considered. Bilateral vestibular schwannomas are indicative of neurofibromatosis type 2 and ELST in conjunction with other abdominal tumors indicates von Hippel-Lindau disease. The neuropathological diagnostics and grading guides the subsequent therapy of these mostly benign lesions.

Intralabyrinthine schwannomas : Surgical management and hearing rehabilitation with cochlear implants.

Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss and vertigo. In an own case series of 12 patients, 6 tumors showed an intracochlear, 3 an intravestibular, 1 a transmodiolar including the cerebellopontine angle (CPA), 1a transotic including the CPA, and 1 a multilocular location. The tumors were removed surgically in 9 patients, whereas 3 patients decided for a "wait-and-test-and-scan" strategy. Of the surgical patients, 3 underwent labyrinthectomy and cochlear implant (CI) surgery in a single-stage procedure; 1 patient had extended cochleostomy with CI surgery; 3 underwent partial or subtotal cochleoectomy, with partial cochlear reconstruction and CI surgery (n = 1) or implantation of electrode dummies for possible later CI after repeated MRI follow-up (n = 2); and in 2 patients, the tumors of the internal auditory canal and cerebellopontine angle exhibiting transmodiolar or transmacular growth were removed by combined translabyrinthine-transotic resection. For the intracochlear tumors, vestibular function could mostly be preserved after surgery. In all cases with CI surgery, hearing rehabilitation was successful, although speech discrimination was limited for the case with subtotal cochleoectomy. Surgical removal of intracochlear schwannomas via partial or subtotal cochleoectomy is, in principle, possible with preservation of vestibular function. In the authors' opinion, radiotherapy of ILS is only indicated in isolated cases. Cochlear implantation during or after tumor resection (i. e., as synchronous or staged surgeries) is an option for hearing rehabilitation in cartain cases and represents a therapeutic approach in contrast to a "wait-and-test-and-scan" strategy.

[Endoscopic ear surgery - complement to microscopic ear surgery]. / Endoskopische Ohrchirurgie ­ eine Weiterentwicklung der modernen Ohrchirurgie.

Wullstein, the founder of modern microscopic ear surgery, already used an oto-endoscope intraoperatively. However, it is only after the recent development of modern video-endoscopy with high definition, 4­k, and 3­dimensional imaging that endoscopically guided surgery of the middle ear is gaining some importance. Key ventilation routes like the isthmus tympani and the epitympanic diaphragma can be visualized far better by using an endoscope rather than a microscope. Going through the external meatus surgery of middle ear pathologies is possible without external incision. This type of primary endoscopic ear surgery has to be distinguished from secondary endoscopic ear surgery, where standard microscopic ear surgery is supplemented by endoscopic surgery. Having to hold the endoscope in one hand, surgery has to be performed single-handed, which is awkward. In case of extensive bone removal or excessive bleeding the view through the endoscope lense is obscured, the endoscope therefore cannot fully substitute the use of the microscope. It is however an interesting adjunct to microscopic ear surgery.

Noddy, a mouse harboring a missense mutation in protocadherin-15, reveals the impact of disrupting a critical interaction site between tip-link cadherins in inner ear hair cells.

In hair cells of the inner ear, sound or head movement increases tension in fine filaments termed tip links, which in turn convey force to mechanosensitive ion channels to open them. Tip links are formed by a tetramer of two cadherin proteins: protocadherin 15 (PCDH15) and cadherin 23 (CDH23), which have 11 and 27 extracellular cadherin (EC) repeats, respectively. Mutations in either protein cause inner ear disorders in mice and humans. We showed recently that these two cadherins bind tip-to-tip in a "handshake" mode that involves the EC1 and EC2 repeats of both proteins. However, a paucity of appropriate animal models has slowed our understanding both of the interaction and of how mutations of residues within the predicted interface compromise tip link integrity. Here, we present noddy, a new mouse model for hereditary deafness. Identified in a forward genetic screen, noddy homozygotes lack inner ear function. Mapping and sequencing showed that noddy mutant mice harbor an isoleucine-to-asparagine (I108N) mutation in the EC1 repeat of PCDH15. Residue I108 interacts with CDH23 EC2 in the handshake and its mutation impairs the interaction in vitro. The noddy mutation allowed us to determine the consequences of blocking the handshake in vivo: tip link formation and bundle morphology are disrupted, and mechanotransduction channels fail to remain open at rest. These results offer new insights into the interaction between PCDH15 and CDH23 and help explain the etiology of human deafness linked to mutations in the tip-link interface.

Imaging for cochlear implantation: structuring a clinically relevant report.

Cochlear implantation is a proven treatment for bilateral severe to profound hearing loss. Imaging has an important role in deciding candidacy, providing realistic preoperative counselling, and predicting postoperative outcomes. Imaging also provides information about the potential difficulties a surgeon may encounter during the implantation. High-resolution computed tomography and high-resolution magnetic resonance imaging complement each other in assessing different aspects of the temporal bone and the auditory pathway in such patients. This review provides a structured format for reading pre-cochlear implant imaging studies with special focus on the surgeon's expectations in order to prepare a clinically relevant report. A constant communication between the imaging specialist and the cochlear implant surgeon improves image interpretation and ensures a successful implantation.

Fallopian canal dehiscence at pediatric cholesteatoma surgery.

The objectives of the study were to investigate the characteristics of ears with dehiscence of the fallopian canal at the time of cholesteatoma surgery and the relationship between dehiscence and age, and to consider the reasons why the fallopian canal tends to be preserved in pediatric patients. This study included 37 ears with cholesteatoma in pediatric patients (mean age 9.2 years, age range 4-14 years) and 273 ears with cholesteatoma in non-pediatric patients (mean age 45 years, age range 15-84 years). Patients were treated between January 2006 and April 2012. All patients had undergone prior tympanoplasty under general anesthesia at our institution. Facial canal dehiscence was evaluated by inspection and through palpation by blunt picking after the pathological tissues had been removed. The size of fallopian canal dehiscence was not investigated in this study. The frequency of dehiscence of the fallopian canal according to the type of cholesteatoma and coexisting pathological conditions, including destruction of the stapes, presence of a labyrinthine fistula, and dural exposure, were compared between the pediatric and non-pediatric groups. The frequency of dehiscence in cases with destruction of the stapes was also compared between the pediatric and non-pediatric groups. Dehiscence of the fallopian canal occurred in 6 of 37 ears (16.8 %) in the pediatric group and 91 of 273 ears (33.3 %) in the non-pediatric group (p < 0.05). In congenital cholesteatoma, the frequency of dehiscence was lower in the pediatric group than in the non-pediatric group (p < 0.05). However, in other types of cholesteatoma there was no statistically difference between the two types of cholesteatoma. The frequency of the destruction of the stapes was higher in the pediatric group than in the non-pediatric group (43.2 vs. 16.5 %, p < 0.001). In patients with severe destruction of the stapes, the fallopian canal was preserved more frequently in the pediatric group than in the non-pediatric group (p < 0.05). The frequency of dehiscence of the fallopian canal at the time of cholesteatoma surgery was lower in the ears of pediatric patients than in the ears of non-pediatric patients. This is probably due to the difference in types of cholesteatoma between the two groups and other unknown mechanisms.

[The hearing function in the patients presenting with the intralabyrinthine distribution of giant cholesteatoma].

The objective of the present study was to evaluate the state of the hearing function in the patients presenting with the intralabyrinthine distribution of giant cholesteatoma before and after the surgical treatment based on the results of examination by the subjective and objective methods. The possibility of preservation of the hearing function after the surgical intervention has been demonstrated.

A Rare Case of Angiofibroma Presenting as an Endolymphatic Sac Tumor.

A 30-year-old man presented with minute-long episodes of vertigo and severe autophony. CVEMP showed a decreased threshold when testing the left side, potentially indicating SSCD. A subsequent MRI demonstrated a multi-lobulated, cystic mass in the temporal bone and the radiological diagnosis at that time was ELST. Tumor excision was performed, and microscopic examination of the excised material revealed fibrovascular tissue without signs of papillary or cystic projections. The conclusion of the histological assessment rendered a diagnosis of angiofibroma. We were unable to find a previous report of ENA originating around the endolymphatic sac. Laryngoscope, 134:1897-1900, 2024.

A mouse model of autoimmune inner ear disease without endolymphatic hydrops.

Autoimmune inner ear disease (AIED) is an organ-specific disease characterized by irreversible, prolonged, and progressive hearing and equilibrium dysfunctions. The primary symptoms of AIED include asymmetric sensorineural hearing loss accompanied by vertigo, aural fullness, and tinnitus. AIED is divided into primary and secondary types. Research has been conducted using animal models of rheumatoid arthritis (RA), a cause of secondary AIED. However, current models are insufficient to accurately analyze vestibular function, and the mechanism underlying the onset of AIED has not yet been fully elucidated. Elucidation of the mechanism of AIED onset is urgently needed to develop effective treatments. In the present study, we analyzed the pathogenesis of vertigo in autoimmune diseases using a mouse model of type II collagen-induced RA. Auditory brain stem response analysis demonstrated that the RA mouse models exhibited hearing loss, which is the primary symptom of AIED. In addition, our vestibulo-oculomotor reflex analysis, which is an excellent vestibular function test, accurately captured vertigo symptoms in the RA mouse models. Moreover, our results revealed that the cause of hearing loss and vestibular dysfunction was not endolymphatic hydrops, but rather structural destruction of the organ of Corti and the lateral semicircular canal ampulla due to an autoimmune reaction against type II collagen. Overall, we were able to establish a mouse model of AIED without endolymphatic hydrops. Our findings will help elucidate the mechanisms of hearing loss and vertigo associated with AIED and facilitate the development of new therapeutic methods.

Gene transfer in inner ear cells: a challenging race.

Recent advances in human genomics led to the identification of numerous defective genes causing deafness, which represent novel putative therapeutic targets. Future gene-based treatment of deafness resulting from genetic or acquired sensorineural hearing loss may include strategies ranging from gene therapy to antisense delivery. For successful development of gene therapies, a minimal requirement involves the engineering of appropriate gene carrier systems. Transfer of exogenous genetic material into the mammalian inner ear using viral or non-viral vectors has been characterized over the last decade. The nature of inner ear cells targeted, as well as the transgene expression level and duration, are highly dependent on the vector type, the route of administration and the strength of the promoter driving expression. This review summarizes and discusses recent advances in inner ear gene-transfer technologies aimed at examining gene function or identifying new treatment for inner ear disorders.

Sequence of vestibular deficits in patients with noise-induced hearing loss.

This study utilized audiometry, and cervical vestibular-evoked myogenic potential (cVEMP), ocular VEMP (oVEMP) and caloric tests to investigate the sequence of vestibular deficits in patients with noise-induced hearing loss (NIHL). Thirty patients with NIHL underwent an inner ear test battery. Another 30 normal controls with age- and sex-matched were included for comparison. The abnormal percentages of the audiometry, and cVEMP, oVEMP and caloric tests were 100, 70, 57 and 33 % in NIHL patients, which showed significant differences from 13, 13, 7 and 3 % in normal controls, respectively. A significantly decreasing trend among the four tests, with the sequence of damage from the cochlea, followed by the saccule, utricle, and semicircular canals was noted in NIHL patients, but not in normal controls. In conclusion, the decreasing order of abnormal percentages in the function of the cochlea, saccule, utricle and semicircular canals after chronic noise exposure further supports that the pars inferior (cochlea and saccule) is more vulnerable to noise exposure than the pars superior (utricle and semicircular canals).

Endolymphatic sac tumors: experience of three cases.

OBJECTIVES: To describe the clinical features, radiological findings, treatment and outcomes of three cases of endolymphatic sac tumors (ELST). METHODS: Retrospective analysis of three cases of ELST. RESULTS: The first patient had a large ELST invading the labyrinth after a long history of vertigo. He was recurrence-free 1 year after retrolabyrinthine surgical removal. In the second case, an acute peripheral facial nerve paralysis associated with ipsilateral sensorineural hearing loss led to the diagnosis. A translabyrinthine approach was used to remove the tumor, which recurred three times over 10 years. The third patient was a young woman suffering from von Hippel-Lindau (VHL) disease and referred for a sudden sensorineural hearing loss due to an intralabyrinthine hemorrhage secondary to a 2 mm-large endolymphatic sac-confined ELST. Her hearing was totally lost after the deafness recurred 1 month after this first episode. MRI demonstrated a small bilateral ELST. The patient refused surgery on the deaf side. CONCLUSION: ELST are difficult to diagnose due to the wide variety of their presentations. Patients with ELST should be screened for VHL disease. Dural invasion and tumor hypervascularization increase the risk of local recurrences after surgery. Early surgical resection may lead to complete tumor removal and inner ear preservation.

Prevalence of labyrinthine ossification in CT and MR imaging of patients with acute deafness to severe sensorineural hearing loss.

OBJECTIVE: To evaluate the prevalence of labyrinthine ossification, and especially cochlear ossification, in a cohort of patients with unilateral sudden deafness or severe sensorineural hearing loss. DESIGN: Retrospective data collection. STUDY SAMPLE: Sixty-four consecutive patients with unilateral sudden deafness or severe sensorineural hearing loss and either high-resolution CT (HRCT) of the temporal bone (isotropic spatial resolution ≤ 0.8 mm; n = 18) or high resolution CISS MRI (isotropic spatial resolution ≤ 1 mm; n = 55) were included. Nine patients underwent both imaging modalities. A standardized reading regarding labyrinthine ossifications was performed by an experienced head and neck radiologist blinded to clinical symptoms. RESULTS: Radiologic signs of cochlear ossification were present in 14 patients (12 CT and 2 MRI). Eight patients showed unilateral and six patients bilateral signs of cochlear ossification. In all except one of the unilateral cases, the deafened ear was affected. CONCLUSIONS: Signs of cochlear ossification were found in an unexpectedly high rate (14/64, 22%) of patients with acute deafness. The data suggest HRCT of the temporal bone to be more sensitive to detect labyrinthine ossification than MRI. HRCT of the temporal bone should therefore be considered in patients with impaired recovery of acute deafness to exclude cochlear ossification; if present, and, in cases of early signs, the patient should be evaluated further to facilitate early cochlear implantation before progression impedes electrode insertion, reflecting latest developments considering cochlea implants for single-sided deafness to be effective.

The role of the stria vascularis in neglected otologic disease.

The stria vascularis (SV) has been shown to play a critical role in the pathogenesis of many diseases associated with sensorineural hearing loss (SNHL), including age-related hearing loss (ARHL), noise-induced hearing loss (NIHL), hereditary hearing loss (HHL), and drug-induced hearing loss (DIHL), among others. There are a number of other disorders of hearing loss that may be relatively neglected due to being underrecognized, poorly understood, lacking robust diagnostic criteria or effective treatments. A few examples of these diseases include autoimmune inner ear disease (AIED) and/or autoinflammatory inner ear disease (AID), Meniere's disease (MD), sudden sensorineural hearing loss (SSNHL), and cytomegalovirus (CMV)-related hearing loss (CRHL). Although these diseases may often differ in etiology, there have been recent studies that support the involvement of the SV in the pathogenesis of many of these disorders. We strive to highlight a few prominent examples of these frequently neglected otologic diseases and illustrate the relevance of understanding SV composition, structure and function with regards to these disease processes. In this study, we review the physiology of the SV, lay out the importance of these neglected otologic diseases, highlight the current literature regarding the role of the SV in these disorders, and discuss the current strategies, both approved and investigational, for management of these disorders.

Apoptosis of the fibrocytes type 1 in the spiral ligament and blood labyrinth barrier disturbance cause hearing impairment in murine cerebral malaria.

BACKGROUND: Experimental murine malaria has been shown to result in significant hearing impairment. Microscopic evaluation of the temporal bones of these animals has revealed regular morphology of the cochlea duct. Furthermore, the known vascular pathologic changes being associated with malaria could not be found. Immunohistochemistry for ICAM1 showed a strong marking in the stria vascularis, indicating a disturbance of the endocochlear potential. The aim of this study was to evaluate the role of apoptosis and the disturbance of the blood labyrinth barrier in the murine malaria associated hearing impairment. METHODS: The temporal bones of seven mice with cerebral malaria-four with hearing impairment, three without hearing impairment-were evaluated with immunohistochemistry for cleaved caspase 3 to detect apoptosis and connexin 26, a gap junction protein being a cornerstone in the endocochlear potassium recirculation. Furthermore five animals with cerebral malaria were treated with Evans blue prior to sacrification to detect disturbances of the blood labyrinth barrier. RESULTS: Cleaved caspase 3 could clearly be detected by immunohistochemistry in the fibrocytes of the spiral ligament, more intensively in animals with hearing impairment, less intensively in those without. Apoptosis signal was equally distributed in the spiral ligament as was the connexin 26 gap junction protein. The Evans blue testing revealed a strong signal in the malaria animals and no signal in the healthy control animals. CONCLUSION: Malfunction of the fibrocytes type 1 in the spiral ligament and disruption of the blood labyrinth barrier, resulting in a breakdown of the endocochlear potential, are major causes for hearing impairment in murine cerebral malaria.