Objective: To investigate the clinical features of patients with congenital atresia of the oval window (CAOW). Methods: A retrospective analysis was conducted on 7 cases (8 ears) of surgically confirmed CAOW treated at our department from July 2018 to July 2024. Among the cases, 1 patient had bilateral CAOW, and 4 patients had unilateral CAOW combined with other types of ossicular chain malformations in the contralateral ear. We collected and analyzed the clinical data, audiological features, and temporal bone HRCT results of all patients. Results: The 7 patients were diagnosed at ages ranging from 8 to 19 years, with a mean age of (13.2±6.9) years. None of the patients exhibited significant auricular deformities. All presented with conductive hearing loss or mixed hearing loss predominantly of the conductive type, with an intact tympanic membrane. The diagnosis of CAOW was confirmed via endoscopic tympanotomy, revealing a concave oval window area on the medial wall of the tympanic cavity, sealed by a bony plate. All 8 ears exhibited additional ossicular chain deformities. Stapes absence was present in all 8 ears. Partial absence of the incus long process was observed in 3 ears, while, abnormal bony connections between the incus long process and the promontory were seen in 4 ears, 1 ear had a short malleolar handle, 1 ear had a smaller than normal malleus volume. In addition, facial nerve deformities were found in 6 ears, with 4 ears showing bifurcation of the facial nerve and 2 ears showing facial nerve obscuration of the oval window. Pure-tone audiometry revealed that 62.5% (5/8 ears) of patients had air conduction (AC) thresholds≥60 dB preoperatively, with a mean pure-tone average (PTA) of (69.0±11.8) dB HL and a mean air-bone gap (ABG) of (52.0±7.0) dB. The mean AC threshold and ABG were higher in the low-frequency (125-1 000 Hz) range compared to the high-frequency (2 000-8 000 Hz) range (both P<0.05). Preoperative HRCT showed abnormalities in all patients, with 7 ears being diagnosable as CAOW. Although the remaining 1 ear could not be diagnosed as CAOW, stapes and incus long process absence were detected. Conclusion: CAOW is rare in clinical, as the patients with non-progressive conductive hearing loss (AC≥60 dB, ABG≥50 dB) since childhood, intact tympanic membrane without malformations of auricle and external auditory canal, and thick bony plate covered the oval window of the HRCT imaging, CAOW should be highly suspected, which could be confirmed by the exploratory tympanotomy.

Objective: To summarize the clinical features and postoperative efficacy of patients with oval window atresia accompanied by facial nerve aberration. Methods: The clinical data of patients with congenital middle ear malformation with facial nerve aberration admitted to our hospital from January 2015 to March 2023 were retrospectively analyzed. There were 97 cases (133 ears) in total. Among them, 39 patients (44 ears) had complete follow-up data, including 27 male patients and 12 females, aged 7-48 years old, with an average age of 17.8 years old. Of these, 14 cases (16 ears) were patients combined with facial nerve aberration, and 25 cases (28 ears) were without facial nerve aberration. The results of imaging examination, pure-tone audiometry, selection of surgical strategy, intraoperative findings and postoperative hearing improvement were summarized and analyzed. The malformations of malleus, incus, stapes, oval window and facial nerve were recorded. Prism 9 software was used to statistically analyze the mean bone conductance and air-bone gap of patients before and after surgery. Results: All the 14 patients (16 ears) with middle ear malformation accompanied by facial nerve aberration and oval window atresia showed poor hearing and no facial palsy since childhood. High resolution CT (HRCT) examination of temporal bone, pure tone audiometry and Gelle test were performed before surgery. The malformations of malleus, incus, stapes, oval window and facial nerve were recorded. Preoperative high-resolution CT (HRCT) examination of temporal bone found 12 ears with 4 or more deformities, accounting for 75.00%, in the group of patients with facial nerve malformation. The preoperative average bone conductive threshold was (15.3±10.4) dB and the average air-bone gap was (46.3±10.6) dB in pure-tone audiometry (0.5, 1, 2, 4kHz). According to the different degrees of facial nerve and ossicle malformation, we performed three different hearing reconstruction strategies for the 14 patients (16 ears) with facial nerve aberration and oval window atresia, including 7 ears of incus bypass artificial stape implantation, 7 ears of Malleostapedotomy (MS) and 2 ears of Malleus-cochlear-prothesis (MCP). After 3 months to 18 months of follow-up, all patients showed no facial paralysis. The postoperative mean bone conductive threshold was (15.7±7.9) dB and air-bone gap was (19.8±8.5) dB. There were significant differences in mean air-bone gap before and after operation (t=7.766, P<0.05), and there was no significant difference between the mean bone conductive threshold before and after surgery (t=0.225, P=0.824). There was no significant difference of mean reduction of air-bone gap between patients with and without facial nerve aberration (t=1.412, P=0.165). There was no significant difference between the three hearing reconstruction strategies. There was no significant displacement of the Piston examined by U-HRCT. Conclusion: For patients of middle ear malformation whose facial nerve cover the oval window partially, incus bypass artificial stape implantation or Malleostapedotomy (MS) can be selected according to the specific condition of auditory ossis malformation, and for patients whose facial nerve completely covers the oval window area, Malleus-cochlear-prothesis (MCP) can be selected. Three types of stapes surgery are safe and reliable for patients with oval window atresia accompanied by facial nerve aberration. There was no significant difference in efficacy between them. Preoperative HRCT assessment of middle ear malformation is effective. There is no significant difference of surgical effect with or without facial nerve aberration. The U-HRCT can be used to evaluate the middle ear malformation before surgery and the Piston implantation status after surgery. Due to the risks of surgery, those who do not want to undergo surgery can choose artificial hearing AIDS, such as hearing aid, vibrating soundbridge, bone bridge or bone-anchored hearing aid.

Morphometric studies of 3D micro CT-scanned images can provide insights into the evolution of the brain and sensory structures but such data are still scarce for the most diverse mammalian order of rodents. From reviewed and new data, we tested for convergence to extreme aridity and high elevation in the sensory and brain morphology of rodents, from morphometric data from micro-CT X-ray scans of 174 crania of 16 species of three distantly related African murid (soft-furred mice, Praomyini, laminate-toothed rats, Otomyini, and gerbils, Gerbillinae) clades and one North American cricetid (deer mice and white-footed mice, Peromyscus) clade. Recent studies demonstrated convergent evolution acting on the oval window area of the cochlea (enlarged in extremely arid-adapted species of Otomyini and Gerbillinae) and on endocranial volume (reduced in high elevation taxa of Otomyini and Peromyscus). However, contrary to our predictions, we did not find evidence of convergence in brain structure to aridity, or in the olfactory/respiratory system (turbinate bones) to high elevation. Brain structure differed, particularly in the petrosal lobules of the cerebellum and the olfactory bulbs, between Otomyini and Gerbillinae, with extreme arid-adapted species in each clade being highly divergent (not convergent) from other species in the same clade. We observed greater "packing" of the maxillary turbinate bones, which have important respiratory functions, in Peromyscus mice from high and low elevations compared to the high-elevation African Praomyini, but more complex patterns within Peromyscus, probably related to trade-offs in respiratory physiology and heat exchange in the nasal epithelium associated with high-elevation adaptation.

ObjectiveThe assessment of bone conduction thresholds in patients with conductive hearing loss is not a full measure of the function of the inner ear due to the weakening of the influence of middle ear components on bone conduction. This relationship has been called the 'Carhart effect'.MethodsThe retrospective analysis covered 977 patients diagnosed and treated for middle ear diseases from 2010 to 2020. The Carhart effect was considered to be an increase in the bone conduction threshold by a minimum of 10dB relative to adjacent frequencies. The study was performed with the aim of assessing the presence of the Carhart effect in the course of middle ear diseases in pretreatment analysis.ResultsThe Carhart effect was observed in 532 cases, most often in patients with chronic otitis media and otosclerosis. It was least often observed in patients with otitis media with effusion. In otitis media with effusion, the Carhart effect was more often noted for the frequency of 4000Hz, in otosclerosis for the frequency of 2000Hz. In patients with chronic otitis media, this effect for the frequency of 4000Hz was correlated with the location of inflammatory changes in the attic area. The presence of inflammatory lesions in the oval window area was associated with the presence of the Carhart effect for the frequency of 2000Hz.Conclusions1. The frequency of the Carhart effect observed in diseases of the middle ear does not depend on the disease entity but on the type and location of abnormalities in the middle ear. 2. The Carhart effect observed for the frequency of 4000Hz coexists with the localization of lesions in the range of the malleus and incus, and for the frequency of 2000Hz, it is partially associated with abnormalities in the range of stapes and oval window.

We studied the mass growth trajectories of middle ear ossicles and tympanic membrane and oval window area in 19 specimens of postnatal ages 30–180 days of the gray short-tailed opossum Monodelphis domestica. We weighed the skull mass and the mass of the three middle ear ossicles with appropriate balances. Using a binocular microscope provided with a grid, we measured the length of malleus and incus, as well as the longest axis and the one perpendicular to it on both the tympanic membrane and the stapes footplate. The size variation was studied with least squares regression analyses between various measurements. The incus and stapes change little in mass after 40 days of postnatal life, while the malleus does, reaching maximum mass at around 100 PND (postnatal days). This modularity in growth trajectory is in contrast with the shared evolutionary origin of malleus and incus from branchial arch 1. The maturation of the middle – and as indicated by previous work, that of the inner ear – is coupled with the improvement of hearing sensitivity at low and high frequencies after the initial onset of hearing at 29 PND.

Objective:Some inner ear malformations may cause recurrent meningitis, which may be fatal. The etiology is usually a stapes footplate fistula which enables microorganisms to pass into the inner ear containing cerebrospinal fluid (CSF), causing repeated attacks of meningitis. Radiological signs of the fistula are not obvious and are not reported in detail in the literature. The aim of the study is to investigate the radiological features of stapes footplate fistula in inner ear malformations.Methods:Radiological findings were analyzed for seventeen patients with inner ear malformations (IEMs) operated on because of recurrent meningitis. Using this information, images of 1,010 patients with IEMs were retrospectively reviewed to investigate the radiological findings of stapes footplate fistula and their relationship to IEMs. They were classified according to the Sennaroglu classification system, and according to different stages of stapes footplate fistula.Results:In the case of a stapes footplate cyst, computerized tomography shows an opacity at the oval window. On magnetic resonance imaging, a fluid filled cystic structure continuous with and having similar signal characteristics to the CSF in the inner ear is a pathognomonic finding of a stapes footplate cyst. It is most commonly found in common cavity anomaly (18.2%); the second most frequent finding is incomplete partition type I (15%). And it can even be seen in cases of cochlear aplasia where only the vestibule is present.Conclusion:If the history reveals recurrent meningitis, particular attention should be given to the oval window area, where an opacity, cyst or a leaking lesion should be looked for on the imaging. It is the responsibility of the otolaryngologist to notice these findings, and to operate on the patient to prevent further attacks of meningitis.

Management of stapes footplate fistula in inner ear malformations

The learning curve in endoscopic stapes surgery, is flat and long. There is limited space during training for advanced and salvage procedures, which could be necessary in unexpected intraoperative scenarios. The aim of the present study is to develop an ex-vivo animal model for training in salvage and advanced procedures in endoscopic stapes surgery METHODS: After defining the difficult intraoperative scenarios requiring a salvage procedure during stapes surgery, we used the ovine model to create those intraoperative situations. After assessing the suitability of the model for that purpose, it was validated by subjective feedback rating (scale from 1 to 10) and by comparing the relevant anatomical structures for stapes surgery with the human. Finally, an optimal sequence of surgical steps was defined. 8 Fresh frozen lamb heads (16 ears) were studied. The selected intraoperative scenarios were: floating footplate, footplate fracture, luxation of the incus or necrosis of the long process, overhanging facial nerve, obliterative otosclerosis. The simulation resulted feasible and close to real. The mean overall rating for surgical scenarios ranged from 7.5 to 8.8 for residents and was consistent with the rating of senior surgeons, ranging from 7.67 and 9.0. Anatomical measures of the oval window area resulted similar between the ovine and the human. The ex-vivo ovine model is a suitable model for training in salvage and advanced procedures in exclusively endoscopic stapes surgery. The model can be used both for the training and maintenance of the acquired advanced skills in endoscopic stapes surgery.

Introduction: Although operating microscope is used worldwide for stapes surgery, the use of endoscopes would provide much benefit such as good panoramic view of middle ear and easy accessibility of the oval window area, stapes, and facial nerve. Objective: We aimed to analyze our experiences of endoscopic transcanal stapedotomy performed at a tertiary care teaching hospital of Eastern India. Materials and Methods: This prospective study was done at the Department of Otorhinolaryngology between March 2017 and April 2019. The patients were diagnosed as having otosclerosis with fulfilling the selection criteria. All underwent endoscopic transcanal stapedotomy. Results: Out of 52 patients those underwent endoscopic transcanal stapedotomy, there were 28 females and 24 males. The mean age was 32.40 years. The mean operation time was 35.43 min. The mean preoperative air–bone gap (ABG) was 34.84 dB, whereas the mean postoperative ABG was 9.81 dB. Tympanomeatal flap tear was seen in one case. One case showed chorda tympani injury and two patients presented with vertigo after surgery. No other complications were seen after endoscopic stapedotomy. Conclusion: The important advantages of endoscopic stapedotomy are good-quality visualization with identification of vital parts of the middle ear cleft, minimal handling to the chorda tympani nerve with almost no curettage of the scutum. The development of endoscopic ear surgery techniques promises the change the way we approach for stapes surgery. The wide field view of endoscope helps the surgeon to visualize better the middle ear recess, especially oval window niche and stapes.

Morphological variation within the southern African hypodigm of Paranthropus has been the focus of major interest since the earliest discoveries in the "Cradle of Humankind." Given the relevance of the bony labyrinth for investigating fossil primate paleobiodiversity, this article aims to provide additional evidence for assessing the degree of regional variation within Paranthropus through the comparative analysis of the inner ear of DNH 22. As comparative material, 18 southern African hominin specimens from Sterkfontein, Swartkrans, and Makapansgat (plus published data from Kromdraai B), attributed to Australopithecus, early Homo or Paranthropus, as well as 10 extant human and 10 extant common chimpanzee specimens are investigated. A landmark-based geometric morphometric method is applied for quantitatively assessing labyrinthine morphology. Additionally, cochlear parameters and oval window area are measured. In terms of semicircular canal and cochlear shape, DNH 22 most resembles the Paranthropus specimen SKW 18 from Swartkrans. Both specimens differ from the other Paranthropus specimens investigated in this study by an anteroposteriorly large posterior semicircular canal and a cochlea with loose turns in the apical portion. Conversely, the oval window area in DNH 22 closely fits the range observed in Paranthropus from Swartkrans and Kromdraai B. The inner ear of the DNH 22 specimen represents a unique opportunity to provide further insight into the early hominin labyrinthine variation pattern. In particular, the description of DNH 22 raises critical questions on the diversity of the vestibular system and evolutionary pattern of the auditory apparatus in Paranthropus.

The surgical treatment of otosclerosis can be challenging in case of anatomical abnormalities or variations of the oval window niche (OWN) area, as in very narrow OWN or in an overhanging facial nerve. The aim of the present study was to explore the role of endoscopic stapes surgery in cases with difficult OWN anatomy. Patients undergoing endoscopic stapes surgery from 2008 to 2017, which fulfilled the CT scan criteria for a "difficult" anatomical condition, according to the measurements and cut-off values defined in the literature, were retrospectively selected. The intraoperative endoscopic view of the anatomical details and surgical difficulties were analysed through the review of the operative videos. Finally, a statistical analysis of the relationship between endoscopic visualization of anatomical details and radiological measurements was carried out. Eighteen out of 205 patients (8.7%) were included in the study. The 94.4% of patients obtained an optimal endoscopic exposure and visualization of all the anatomical details considered in the study, during each step of stapes surgery. The OWN measurements (width, depth and facial-promontory angle) did not affect significantly the endoscopic surgical exposure of the footplate or any of the other anatomical details. The anatomic features of the oval window area which reduce the visualization in microscopic surgery, did not affect the surgical exposure in endoscopic stapes surgery. Patients having a difficult anatomy of the OWN can be treated safely with the endoscopic approach. In the case of a predicted "difficult anatomy", the endoscopic approach can be considered a viable option.

IntroductionOtitis media, mastoiditis or the pressure effect of tumorous lesions such as cholesteatoma can be the cause of facial canal dehiscence and facial nerve paralysis. The most common segment involved in dehiscence is the tympanic segment and the second most common is the lateral aspect of the facial canal in the oval window area. ObjectiveTo determine the prevalence of the facial canal dehiscence and the relationship between the angle at the second genu of the facial nerve and facial canal dehiscence. MethodsWe evaluated the surgical findings in 113 patients who underwent surgery for cholesteatoma. Facial canal dehiscence was detected in 62 of the 113 patients. Patients were divided into two groups: Group 1, with dehiscence of the facial canal and Group 2, without dehiscence of the facial canal. ResultsThe mean angles at the second genu of the facial nerve in Groups 1 and 2 were 117.8°±9.63° and 114°±9.9°, respectively. There was a statistically significant difference between the mean angles at the second genu for the two groups (p=0.04). ConclusionIn patients with dehiscence of the facial canal, the angle at the second genu was found to be wider than those without dehiscence.

Echoes from the past: New insights into the early hominin cochlea from a phylo-morphometric approach

Changes in lifestyles and body weight affected mammal life-history evolution but little is known about how they shaped species’ sensory systems. Since auditory sensitivity impacts communication tasks and environmental acoustic awareness, it may have represented a deciding factor during mammal evolution, including apes. Here, we statistically measure the influence of phylogeny and allometry on the variation of five cochlear morphological features associated with hearing capacities across 22 living and 5 fossil catarrhine species. We find high phylogenetic signals for absolute and relative cochlear length only. Comparisons between fossil cochleae and reconstructed ape ancestral morphotypes show that Australopithecus absolute and relative cochlear lengths are explicable by phylogeny and concordant with the hypothetized ((Pan,Homo),Gorilla) and (Pan,Homo) most recent common ancestors. Conversely, deviations of the Paranthropus oval window area from these most recent common ancestors are not explicable by phylogeny and body weight alone, but suggest instead rapid evolutionary changes (directional selection) of its hearing organ. Premodern (Homo erectus) and modern human cochleae set apart from living non-human catarrhines and australopiths. They show cochlear relative lengths and oval window areas larger than expected for their body mass, two features corresponding to increased low-frequency sensitivity more recent than 2 million years ago. The uniqueness of the “hypertrophied” cochlea in the genus Homo (as opposed to the australopiths) and the significantly high phylogenetic signal of this organ among apes indicate its usefulness to identify homologies and monophyletic groups in the hominid fossil record.

Oval window atresia: A novel surgical approach and pathognomonic radiological finding

The objective of this study was to evaluate the histopathological incidence of facial canal dehiscence in otosclerosis cases compared with non-otosclerotic controls. 133 temporal bones from 84 otosclerosis (35 unilateral otosclerosis, 49 bilateral otosclerosis) cases were compared to 102 age-matched normal temporal bones from 70 subjects (38 unilateral normal cases, 32 bilateral normal cases). Temporal bones were serially sectioned in the horizontal plane at a thickness of 20μm, and were stained with hematoxylin and eosin. We evaluated the location and the invasion of otosclerosis to the facial canal and incidence of facial canal dehiscence under light microscopy. Facial canal was subdivided into four portions: (1) the geniculate ganglion, (2) the tensor tympani muscle, (3) the oval window, and (4) mastoid. The incidence of facial canal dehiscence in otosclerosis [66 temporal bones (49.6%)] was significantly lower than normal controls [67 control temporal bones (65.7%)] in the oval window area (P=0.019). Temporal bones with otosclerotic invasion to the thin bone of the canal were significantly less likely to have dehiscence [10 temporal bones (31.3%)] compared to the otosclerotic bones without invasion [56 temporal bones (55.5%)] (P=0.025). There was no significant difference in the incidence of facial canal dehiscence between temporal bones with and without otosclerosis in the entire segment of facial nerve. Our findings in this study suggest that otosclerotic lesions have the potential to close dehiscence of the facial canal in the oval window area.

Facial canal dehiscence in the initial operation for chronic otitis media without cholesteatoma

Abstract The marsupial middle ear performs an anatomical impedance matching for acoustic energy travelling in air to reach the cochlea. The size of the middle ear sets constraints for the frequencies transmitted. For generalized placental mammals, it has been shown that the limit for high‐frequency hearing can be predicted on the basis of middle ear ossicle mass, provided that the ears fulfil requirements of isometry. We studied the interspecific size variation of the middle ear in 23 marsupial species, with the following measurable parameters: skull mass, condylobasal length, ossicular masses for malleus, incus and stapes, tympanic membrane area, oval window area, and lever arm lengths for malleus and incus. Our results show that the middle ear size grows with negative allometry in relation to body size and that the internal proportions of the marsupial middle ear are largely isometric. This resembles the situation in placental mammals and allows us to use their isometric middle ear model to predict the high‐frequency hearing limit for marsupials. We found that the isometry model predicts the high‐frequency hearing limit for different marsupials well, indicating that marsupials can be used as auditory models for general therian mammalian hearing. At very high frequencies, other factors, such as the inner ear, seem to constrain mammalian hearing.

Labyrinthine fistulae as a complication of chronic suppurative otitis media

High-resolution CT and cochlear densitometry in otosclerosis