Membranous Labyrinth Research Articles

3D-real IR MRI detects serendipity of inner ear in enlarged vestibular aqueduct syndrome

Background: Although, the diagnostic criteria for enlarged vestibular aqueduct syndrome (EVAS) were determined by years. On the shoulders of predecessors, we still detected some new discoveries about EVAS by using 3D-real IR MRI.Aims/objectives: To analyze the signal intensity of membranous and osseous labyrinths of vestibular aqueduct (VA) and endolymphatic sac (ES) in EVAS using three-dimensional real inversion recovery (3D-Real-IR) magnetic resonance imaging (MRI) after intratympanic injection of gadolinium.Material and methods: The study is a prospective trial, diagnosed EVAS patients (n = 10) and none- patients (n = 10) were included. 3D-real-IR MRIs were performed to assess the endolymphatic hydrops (EH) and differentiated the endolymphatic and perilymphatic signal intensities of VA and ES.Results: Compared to control group, EVAS group had VA osseous labyrinths middle diameter >1.5 mm different from membranous labyrinths. The cochlear EH was correlated with Mondini malformation and irrelation with the level of hearing loss (HL).Conclusions and significance: Interspace of osseous labyrinths of VA and ES are much larger than their membranous labyrinths, which is not consistance with previous research. And cochlear Mondini malformation may cause endolymphatic fluid malabsorption, inducing cochlear EH. Osteal ampliative of VA and ES and cochlear EH, which are morphogenetic anomalies, may not the direct cause of HL in EVAS.

Three-dimensional study of vestibular anatomy as it relates to the stapes footplate and its clinical implications: an augmented reality development.

The anatomy of the membranous labyrinth within the vestibule has direct implications for surgical intervention. The anatomy of the otoliths has been studied, but there is limited information regarding their supporting connective tissue structures such as the membrana limitans in humans. One guinea pig and 17 cadaveric human temporal bones were scanned using micro computed tomography, after staining with 2 per cent osmium tetroxide and preservation with Karnovsky's solution, with a resolution from 1 µm to 55 µm. The data were analysed using VGStudio Max software, rendered in three-dimensions and published in augmented reality. In 50 per cent of ears, the membrana limitans attached directly to the postero-superior part of the stapes footplate. If attachments were present in one ear, they were present bilaterally in 100 per cent of cases. Micro computed tomography imaging allowed three-dimensional assessment of the inner ear. Such assessments are important as they influence the surgical intervention and the evolution of future innovations.

Etiology-Specific Mineralization Patterns in Patients with Labyrinthitis Ossificans.

Our aim was to identify whether specific patterns of ossification in labyrinthitis ossificans are associated with the known risk factors. Labyrinthitis ossificans has been described as sequela of prior temporal bone trauma, prior infection, and other disorders including sickle cell disease. Specific patterns of mineralization in the membranous labyrinth associated with these risk factors has not been previously described. This was a retrospective study evaluating temporal bone CT scans at our institution from November 2005 to May 2018 in patients with labyrinthitis ossificans. Membranous labyrinthine structures evaluated for ossification included the following: basal, middle, and apical cochlear turns; lateral, posterior, and superior semicircular canals; and the vestibule for both ears in all patients. These structures were assigned a severity score, 0-4, based on degree of mineralization. Clinical records were reviewed for potential labyrinthitis ossificans risk factors. Basic descriptive statistics and a mixed model were used to correlate the degree and patterns of ossification with clinical history. Forty-four patients (58 ears) with labyrinthitis ossificans were identified and evaluated. The most common risk factors were chronic otomastoiditis (n = 18), temporal bone surgery (n = 9), temporal bone trauma (n = 6), sickle cell disease (n = 5), and meningitis (n = 4). For all etiologies, the semicircular canals were most severely affected, and the vestibule was the least. In patients with prior temporal bone surgery, significantly greater mineralization was seen in the basal turn of the cochlea (P = .027), the vestibule (P = .001), and semicircular canals (P < .001-.008). No significant pattern was identified in patients with meningitis, sickle cell disease, or trauma. Significant patterns of mineralization in labyrinthitis ossificans were observed in patients with prior temporal bone surgery. For all etiologies, the semicircular canals were most severely affected. No significant mineralization pattern was observed in patients with chronic otomastoiditis, meningitis, sickle cell disease, or prior temporal bone trauma.

Evaluation of 3D Printed Temporal Bone Models in Preparation for Middle Cranial Fossa Surgery.

Patient-specific 3D printed models are useful presurgical planning tools because they accurately represent the anatomy and drilling characteristics of the middle cranial fossa (MCF) approach to the internal auditory canal (IAC). The MCF approach to the IAC can be challenging due to variability of the bony architecture along the floor of the middle fossa. Patient-specific 3D printed models may enhance surgeon knowledge of a given patient's anatomy when preparing for MCF surgery. Six temporal bone models were printed from photoacrylic resin based on CT data obtained from cadaveric specimens using a desktop stereolithography 3D printer. Critical structures to avoid injuring, the facial nerve and membranous labyrinth, were modeled as hollow cavities and filled with indicator paint. Two neurotologists each drilled three 3D printed models and the corresponding cadaveric specimens, and then completed a 41-item visual analog scale questionnaire (score range of each item: 0-10) to assess the model's accuracy, utility, and potential as a training tool. Drilling the model was favorably rated (median score 9.2; range 7.3-9.6) for its ability to provide surgeons with an accurate mental image of the corresponding cadaveric anatomy. Overall similarity of feel of drilling the model in comparison to human bone was moderate (median 7.6; range 6.6-9.0). Surgeons would use this model to prepare for future cases (median 9.4; range 5.1-9.9) and felt it had excellent utility for training purposes (median 9.3; range 8.4-9.9). Patient-specific 3D printed models provide an anatomically accurate and favorable tool for preparing for MCF surgery.

3D finite element model of posterior membranous labyrinth from in vivo MRI of human temporal bone, including sensory zones

3D finite element model of posterior membranous labyrinth from in vivo MRI of human temporal bone, including sensory zones

Gene therapy for hereditary hearing loss by SLC26A4 mutations in mice reveals distinct functional roles of pendrin in normal hearing.

Rationale: Mutations of SLC26A4 that abrogate pendrin, expressed in endolymphatic sac, cochlea and vestibule, are known to cause autosomal recessive sensorineural hearing loss with enlargement of the membranous labyrinth. This is the first study to demonstrate the feasibility of gene therapy for pendrin-related hearing loss.Methods: We used a recombinant viral vector to transfect Slc26a4 cDNA into embryonic day 12.5 otocysts of pendrin-deficient knock-out (Slc26a4∆/∆) and pendrin-deficient knock-in (Slc26a4tm1Dontuh/tm1Dontuh) mice.Results: Local gene-delivery resulted in spatially and temporally limited pendrin expression, prevented enlargement, failed to restore vestibular function, but succeeded in the restoration of hearing. Restored hearing phenotypes included normal hearing as well as sudden, fluctuating, and progressive hearing loss.Conclusion: Our study illustrates the feasibility of gene therapy for pendrin-related hearing loss, suggests differences in the requirement of pendrin between the cochlea and the vestibular labyrinth, and documents that insufficient pendrin expression during late embryonal and early postnatal development of the inner ear can cause sudden, fluctuating and progressive hearing loss without obligatory enlargement of the membranous labyrinth.

Tympanogenic labyrinthine ossificans as rare sequelae of cholesteatoma

Labyrinthine ossificans (LO) is the formation of pathological new bone within the membranous labyrinth of the inner ear. Most commonly, it is caused by meningitis, via communication of labyrinth with subarachnoid via the cochlear aqueduct and internal auditory canal. We highlight a case of cholesteatoma with a rare complication of tympanogenic LO that results in unilateral profound mixed hearing loss with concomitant severe vertigo.

Comparative ultrastructure of cells and cuticle in the anterior chamber and papillate region of Porcellioscaber (Crustacea, Isopoda) hindgut.

Isopod hindgut consists of two anatomical and functional parts, the anterior chamber, and the papillate region. This study provides a detailed ultrastructural comparison of epithelial cells in the anterior chamber and the papillate region with focus on cuticle ultrastructure, apical and basal plasma membrane labyrinths, and cell junctions. Na+/K+-ATPase activity in the hindgut epithelial cells was demonstrated by cytochemical localisation. The main difference in cuticle ultrastructure is in the thickness of epicuticle which is almost as thick as the procuticle in the papillate region and only about one sixth of the thickness of procuticle in the anterior chamber. The apical plasma membrane in both hindgut regions forms an apical plasma membrane labyrinth of cytoplasmic strands and extracellular spaces. In the papillate region the membranous infoldings are deeper and the extracellular spaces are wider. The basal plasma membrane is extensively infolded and associated with numerous mitochondria in the papillate region, while it forms relatively scarce basal infoldings in the anterior chamber. The junctional complex in both hindgut regions consists of adherens and septate junctions. Septate junctions are more extensive in the papillate region. Na+/K+-ATPase was located mostly in the apical plasma membranes in both hindgut regions. The ultrastructural features of hindgut cuticle are discussed in comparison to exoskeletal cuticle and to cuticles of other arthropod transporting epithelia from the perspective of their mechanical properties and permeability. The morphology of apical and basal plasma membranes and localisation of Na+/K+-ATPase are compared with other arthropod-transporting epithelia according to different functions of the anterior chamber and the papillate region.

Cerebral Corpora amylacea are dense membranous labyrinths containing structurally preserved cell organelles

Corpora amylacea are cell-derived structures that appear physiologically in the aged human brain. While their histological identification is straightforward, their ultrastructural composition and microenvironment at the nanoscale have remained unclear so far, as has their relevance to aging and certain disease states that involve the sequestration of toxic cellular metabolites. Here, we apply correlative serial block-face scanning electron microscopy and transmission electron tomography to gain three-dimensional insight into the ultrastructure and surrounding microenvironment of cerebral Corpora amylacea in the human brainstem and hippocampal region. We find that cerebral Corpora amylacea are composed of dense labyrinth-like sheets of lipid membranes, contain vesicles as well as morphologically preserved mitochondria, and are in close proximity to blood vessels and the glymphatic system, primarily within the cytoplasm of perivascular glial cells. Our results clarify the nature of cerebral Corpora amylacea and provide first hints on how they may arise and develop in the aging brain.

Significance of Endolymphatic Hydrops Herniation Into the Semicircular Canals Detected on MRI.

The objective of this study was to investigate the relationship between endolymphatic hydrops (EH) and hearing level or vestibular symptoms by focusing on EH herniation into the semicircular canal (SCC). Retrospective study. University hospital. The study included 1,548 ears of 775 patients who underwent magnetic resonance imaging (MRI) examination in our university hospital to investigate possible EH. MRI was performed 4 hours after intravenous injection of a standard dose of gadodiamide hydrate and/or 24 hours after intratympanic injection of gadopentetate dimeglumine diluted eightfold. The hearing threshold and vestibular symptoms were compared between ears with unilateral and bilateral EH herniation into the SCC and between ears having vestibular EH adjacent to the stapes footplate with or without EH herniation. Forty-four ears (19 men and 25 women, mean age 53.6 yr) showed EH herniation into the SCC. The average hearing thresholds at 500 to 4000 Hz and presence of vestibular EH adjacent to the stapes footplate were significantly higher in ears with unilateral herniation than in those with bilateral herniation. The average hearing thresholds at 500 and 1000 Hz were significantly higher in the group of ears having adjacency with herniation than in those without herniation. Vestibular symptoms did not differ significantly between groups. Unilateral herniation occurs with EH progression. Bilateral herniation may occur regardless of EH progression and might be influenced by other factors that alter the membranous labyrinth.

Morphology of the Petrosal in Late Miocene Baleen Whales of Northwestern Ciscaucasia

Morphological features of the membranous labyrinth in extinct and extant baleen whales and their ancestors are discussed. The tomography of the membranous labyrinth of two species of Late Miocene baleen whales from Adygea has shown that Kurdalagonus, Zygiocetus, and Cetotherium have a comparable number of cochlear turns with representatives of herpetocetins, i.e., about three turns. Representatives of the genus Kurdalagonus differ from Zygiocetus in the structure of semicircular canals, the longer crus commune (much shorter in Zygiocetus), and in the size of the ampulla of the lateral semicircular canal. In addition, representatives of the genus Kurdalagonus differ from Zygiocetus and Cetotherium in the structure of the round window, which is much wider and has a more rounded shape.

Enhanced contrast in X‐ray microtomographic images of the membranous labyrinth using different X‐ray sources and scanning modes

The vestibular system, located in the inner ear, plays a crucial role in balance and gaze stabilisation by sensing head movements. The interconnected tubes with membranous walls of the vestibular system are located in the skull bone (the 'membranous labyrinth'). Unfortunately, these membranes are very hard to visualise using three-dimensional (3D) X-ray imaging techniques. This difficulty arises due to the embedment of the membranes in the dense skull bone, the thinness of the membranes, and the small difference in X-ray absorption between the membranes and the surrounding fluid. In this study, we compared the visualisation of very small specimens (lizard heads with vestibular systems smaller than 3 mm) by X-ray computed micro-tomography (μCT) based on synchrotron radiation and conventional sources. A visualisation protocol using conventional X-ray μCT would be very useful thanks to the ease of access and lower cost. Careful optimisation of the acquisition parameters enables detection of the membranes by using μCT scanners based on conventional microfocus sources, but in some cases a low contrast-to-noise ratio (CNR) prevents fast and reliable segmentation of the membranes. Synchrotron radiation μCT proved to be preferable for the visualisation of the small samples with very thin membranes, because of their high demands for spatial and contrast resolution. The best contrast was obtained by using synchrotron radiation μCT working in phase-contrast mode, leading to up to twice as high CNRs than the best conventional μCT results. The CNR of the synchrotron radiation μCT scans was sufficiently high enough to enable the construction of a 3D model by the means of semi-automatic segmentation of the membranous labyrinth. Membrane thickness was found to range between 2.7 and 36.3 μm. Hence, the minimal membrane thickness was found to be much smaller than described previously in the literature (between 10 and 50 μm).

Peripheral Vestibular System Histopathologic Changes following Head Injury without Temporal Bone Fracture.

Vestibular symptoms such as dizziness and vertigo are common after head injury and may be due to trauma to the peripheral vestibular system. The pathophysiology of peripheral vestibular symptoms following head injury without temporal bone (TB) fracture, however, is not well understood. Herein, we investigate the histopathology of the peripheral vestibular system of patients who sustained head injury without a TB fracture. Otopathology study. Otopathology laboratory. TB of subjects with a history of head injury without TB fractures were included and evaluated by light microscopy. Specimens were assessed for qualitative and quantitative characteristics, such as number of Scarpa's ganglion cells in the superior and inferior vestibular nerves, vestibular hair cell and/or dendrite degeneration in vestibular end organs, presence of vestibular hydrops, and obstruction of the endolymphatic duct. Five cases (n = 5 TBs) had evidence of vestibular pathology. There was a decrease of 48.6% (range, 40%-59%) in the mean count of Scarpa's ganglion cells as compared with that of normative historical age-matched controls. Moderate to severe degeneration of the vestibular membranous labyrinth was identified in the posterior, superior, and lateral canals in several cases (50%, n = 4 TBs). The maculae utriculi and sacculi showed mild to severe degeneration in 2 cases. Additional findings include vestibular hydrops (25%, n = 2 TBs) and blockage of the endolymphatic duct (n = 1 TB). Otopathologic analysis of patients with a history of head injury without TB fracture demonstrated peripheral vestibular otopathology. Future studies are necessary to determine if otopathology findings are directly attributable to head injury.

Endolymphatic hydrops severity in magnetic resonance imaging evidences disparate vestibular test results

ObjectivesIt has been suggested that in Ménière’s disease (MD) a dissociated result in the caloric test (abnormal result) and video head-impulse test (normal result) probably indicates that hydrops affects the membranous labyrinth in the horizontal semicircular canal (HSC). The hypothesis in this study is that based on endolymphatic hydrops’ cochleocentric progression, hydrops should also be more severe in the vestibule of these patients than in those for whom both tests are normal. Methods22 consecutive patients with unilateral definite MD were included and classified as NN if both tests were normal or AN if the caloric test was abnormal. MRI evaluation of endolymphatic hydrops was carried out with a T2-FLAIR sequence performed 4h after intravenous gadolinium administration. The laterality and degree of vestibular endolymphatic hydrops and the presence or absence of cochlear endolymphatic hydrops were recorded. Demographic data, audiometric and vestibular evoked myogenic potentials were collected, and video head-impulse and caloric tests were performed. ResultsPatients in both groups (NN and AN) were similar in terms of demographic data and hearing loss. The interaural asymmetry ratio was significantly higher for ocular and cervical VEMP in patients in the AN group. There was a significantly higher degree of hydrops in the vestibule of the affected ear of AN patients (χ2; p=0.028). ConclusionSignificant canal paresis in the caloric test is associated with more severe endolymphatic hydrops in the vestibule as detected with gadolinium-enhanced MRI and with a more severe vestibular deficit.Level of evidence: 2a

A morphometric study of the structures bordering the infra-cochlear corridor – Relevant for endoscopic/microscopic ear surgery

Application of surgical endoscope, used alone or in combination with the surgical microscope, for the operative management of ear and temporal bone conditions may allow improved access and clearance of disease. Preservation of normal structures may also be improved.As the use of this tool is increasing, the need for better understanding of the anatomy of the ear is becoming evident. This is particularly so for endoscopic surgery aiming at removal of lesions involving the infra-cochlear corridor and/or petrous apex.Human temporal bone-derived labyrinth casts (molds), originally made for endolymphatic duct and sac analysis which genuinely represent the membranous labyrinth and its adjacent soft tissues, were morphometrically analyzed in terms of the anatomic relations between structures in and around the infra-cochlear corridor. The distance between the petrous carotid artery (PCA) and the basal turn of the cochlea, the distance between PCA and infra-cochlear vein (ICV)/cochlear aqueduct (CA), and the distance between the lower surface of basal cochlear turn and the point where the carotid artery and jugular vein (JV) meet close to the jugular foramen, were measured to be around 1.3 mm, 6 mm and 8 mm respectively, thus constituting an approximate 6 × 8 mm2 infra-cochlear corridor. This analysis and further study with larger samples might be helpful for operation via this corridor led to the petrous apex where cholesterol granuloma, cholesteatoma and other lesions are not uncommon.

Recent and Frequent Vertigo Attacks Produce Negative Findings on Furosemide-Loading Vestibular Evoked Myogenic Potential Testing in Meniere's Disease.

Objective: The peak-to-peak amplitude of the p13-n23 wave in cervical vestibular evoked myogenic potential can increase after furosemide administration in patients with Meniere's disease [furosemide-loading VEMP (FVEMP) testing]. The examination is used to test for the presence of endolymphatic hydrops; we investigated factors that may influence the results.Methods: Forty-two subjects (23 males and 19 females, aged 24–70 years) with unilateral definite Meniere's disease who underwent FVEMP testing were retrospectively studied. Possible factors associated with the results of FVEMP testing were studied using logistic regression analysis.Results: Ages, sex, affected side, stage, disease duration, and mean hearing level of pure tone audiometry did not influence the results of FVEMP testing in the univariate analysis (p > 0.05). Number of days since the last vertigo attack [odds ratio (OR): 1.07, p = 0.031] and frequency of vertigo attacks per month (OR: 0.42, p = 0.003) were significantly associated with the results of testing. Multivariate analysis showed that both days since the last vertigo attack < 7 (OR: 0.13, p = 0.04) and frequency of vertigo attacks per month ≥ 2 (OR: 0.06, p = 0.004) were risk factors for negative results on FVEMP testing.Conclusion: This study found that recent and frequent vertigo attacks produced negative findings on FVEMP testing in Meniere's disease. This apparently irrational finding can be explained by the consequences of membranous labyrinth rupture during vertigo attacks, where the altered saccular resonance due to EH cannot be recovered by furosemide administration because of the dissolving dehydration effect that occurs through communication between the endolymphatic and perilymphatic spaces. In addition, the impairment of sensory cells that is caused by endolymph and perilymph mixing upon rupture does not improve upon furosemide administration. FVEMP testing results may provide us with pathophysiological information regarding the membranous labyrinth.

Visualization of the Membranous Labyrinth and Nerve Fiber Pathways in Human and Animal Inner Ears Using MicroCT Imaging

Design and implantation of bionic implants for restoring impaired hair cell function relies on accurate knowledge about the microanatomy and nerve fiber pathways of the human inner ear and its variation. Non-destructive isotropic imaging of soft tissues of the inner ear with lab-based microscopic X-ray computed tomography (microCT) offers high resolution but requires contrast enhancement using compounds with high X-ray attenuation. We evaluated different contrast enhancement techniques in mice, cat, and human temporal bones to differentially visualize the membranous labyrinth, sensory epithelia, and their innervating nerves together with the facial nerve and middle ear. Lugol’s iodine potassium iodine (I2KI) gave high soft tissue contrast in ossified specimens but failed to provide unambiguous identification of smaller nerve fiber bundles inside small bony canals. Fixation or post-fixation with osmium tetroxide followed by decalcification in EDTA provided superior contrast for nerve fibers and membranous structures. We processed 50 human temporal bones and acquired microCT scans with 15 μm voxel size. Subsequently we segmented sensorineural structures and the endolymphatic compartment for 3D representations to serve for morphometric variation analysis. We tested higher resolution image acquisition down to 3.0 μm voxel size in human and 0.5 μm in mice, which provided a unique level of detail and enabled us to visualize single neurons and hair cells in the mouse inner ear, which could offer an alternative quantitative analysis of cell numbers in smaller animals. Bigger ossified human temporal bones comprising the middle ear and mastoid bone can be contrasted with I2KI and imaged in toto at 25 μm voxel size. These data are suitable for surgical planning for electrode prototype placements. A preliminary assessment of geometric changes through tissue processing resulted in 1.6% volume increase caused during decalcification by EDTA and 0.5% volume increase caused by partial dehydration to 70% ethanol, which proved to be the best mounting medium for microCT image acquisition.

De novo variants in GREB1L are associated with non-syndromic inner ear malformations and deafness.

Congenital inner ear malformations affecting both the osseous and membranous labyrinth can have a devastating impact on hearing and language development. With the exception of an enlarged vestibular aqueduct, non-syndromic inner ear malformations are rare, and their underlying molecular biology has thus far remained understudied. To identify molecular factors that might be important in the developing inner ear, we adopted a family-based trio exome sequencing approach in young unrelated subjects with severe inner ear malformations. We identified two previously unreported de novo loss-of-function variants in GREB1L [c.4368G>T;p.(Glu1410fs) and c.982C>T;p.(Arg328*)] in two affected subjects with absent cochleae and eighth cranial nerve malformations. The cochlear aplasia in these affected subjects suggests that a developmental arrest or problem at a very early stage of inner ear development exists, e.g., during the otic pit formation. Craniofacial Greb1l RNA expression peaks in mice during this time frame (E8.5). It also peaks in the developing inner ear during E13-E16, after which it decreases in adulthood. The crucial function of Greb1l in craniofacial development is also evidenced in knockout mice, which develop severe craniofacial abnormalities. In addition, we show that Greb1l-/- zebrafish exhibit a loss of abnormal sensory epithelia innervation. An important role for Greb1l in sensory epithelia innervation development is supported by the eighth cranial nerve deficiencies seen in both affected subjects. In conclusion, we demonstrate that GREB1L is a key player in early inner ear and eighth cranial nerve development. Abnormalities in cochleovestibular anatomy can provide challenges for cochlear implantation. Combining a molecular diagnosis with imaging techniques might aid the development of individually tailored therapeutic interventions in the future.

Dorsoventral differences in cAMP levels and correlated changes in the subcellular distribution of the PKA catalytic domain, provide further evidence that PKA signaling coordinates dorsoventral patterning of the otocyst.

Dorsoventral (DV) patterning of the otocyst gives rise to formation of the morphologically and functionally complex membranous labyrinth composed of unique dorsal and ventral sensory organs. DV patterning results from extracellular signaling by secreted growth factors, which presumably form reciprocal concentration gradients across the DV axis of the otocyst. Previous work suggested a model in which two important growth factors, bone morphogenetic protein (BMP) and SHH, undergo crosstalk through an intersecting pathway to coordinate DV patterning. cAMP-dependent protein kinase A (PKA) lies at the heart of this pathway. Here, we provide further evidence that PKA signaling coordinates DV patterning, showing that both BMPs and SHH regulate cAMP levels, with BMPs increasing levels in the dorsal otocyst and SHH decreasing levels in the ventral otocyst. This, in turn, results in regional changes in the subcellular distribution of the catalytic domain of PKA, as well as DV regulation of PKA activity, increasing it dorsally and decreasing it ventrally. These new results fill an important gap in our previous understanding of how ligand signaling acts intracellularly during otocyst DV patterning and early morphogenesis, thereby initiating the series of events leading to formation of the inner ear sensory organs that function in balance and hearing.

The Role of Autoimmunity in the Pathogenesis of Sudden Sensorineural Hearing Loss.

Sudden sensorineural hearing loss (SSHL) is a clinically common acute symptom in otolaryngology. Although the incidence of SSHL has increased around the world in recent years, the etiology of the disease is still unclear. It has been reported that infections, ototoxic drugs, membrane labyrinth rupture, carcinomas, circulatory system diseases, autoimmune diseases, brain lesions, mental diseases, congenital or inherited diseases, and so on, are all risk factors for SSHL. Here, we discuss the autoimmune mechanisms behind SSHL, which might be induced by type II–IV allergic reactions. We also introduce the main immunosuppressive medications that have been used to treat SSHL, which will help us to identify potential targets for immune therapy.