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Background: Since the discovery of the perilymphatic fistula (PLF), the diagnosis and treatment remain controversial. If successfully recognized, the PLF is surgically repairable with an obliteration of the fistula site. Successful treatment has a major impact on patient's quality of life with an improvement in their audiological and vestibular symptoms. Objective: To prospectively investigate patients' clinical and audiological evolution with PLF suspicion after middle ear exploration and obliteration of the round and oval window. Study Design: Prospective comparative study. Setting: Tertiary care center. Methods: Patients were divided into two groups: Group I consisted of patients where no PLF had been identified intraoperatively at the oval and/or at the round window, and Group II consisted of patients where a fistula had been visualized. Patient assessment was a combination of past medical history, the presence of any risk factors, cochlear and vestibular symptoms, a physical examination, temporal bone imaging, audiograms, and a videonystagmogram (VNG). Results: A total of 98 patients were divided into two groups: 62 in Group I and 36 in Group II. A statistically significant difference regarding gender was observed in Group II (83.3% of males vs. 16.7% of females, p = 0.008). A total of 14 cases (4 and 10 in Groups I and II, respectively) were operated for a recurrent PLF. Fat graft material was used in the majority of their previous surgery; however, no difference was found when comparing fat to other materials. In addition, no statistically significant difference was noted between Groups I and II concerning predisposing factors, imaging, VNG, symptom evolution, or a physical exam before the surgery and at 12 months post-operative. However, both groups showed statistically significant hearing and vestibular improvement. On the other hand, the air conduction (AC) and bone conduction (BC) at each frequency were not statistically different between the two groups before surgery but showed statistically significant improvement at 12 months post-operatively, especially for the BC at the frequencies 250 (p = 0.02), 500 (p = 0.0008), and 1000 Hz (p = 0.04). Conclusions: Whenever you suspect a perilymphatic fistula, do not hesitate to explore middle ear and do window obliterations using a tragal perichondrium material. Our data showed that cochlear and vestibular symptoms improved whether a fistula had been identified or not. [ABSTRACT FROM AUTHOR]

Congenital agenesis of the stapes and the oval window is rare. Congenital stapedial agenesis (CSA) may be recognized preoperatively in the presence of conductive hearing loss. The principal radiological imaging approach of the temporal bone, computed tomography (CT), can be used to diagnose CSA. Our 17-year-old male patient (case A) had long-term hearing loss which was getting worse. A temporal bone CT scan revealed the absence of the stapes and the oval window on both sides and an abnormal position of the facial nerve. No anomalies were detected in the external ear structures. Explorative right ear tympanotomy revealed an abnormal inferior course and dehiscence of the facial nerve. The oval window and stapedial structures were absent. Patients were evaluated for continued hearing aid use or bone-anchored hearing aid implantation. Similar CT imaging and clinical abnormalities were seen in his 16-year-old sister (case B). They did not have any other siblings and neither of their parents nor any of their relatives had hearing loss. This report presents the CT scans of the two siblings with mixed hearing loss (mainly conductive) and the perioperative image of the first case. A genetic study may help explain the etiopathogenesis since both cases had similar clinical and imaging findings.

Congenital agenesis of the stapes and the oval window is rare. Congenital stapedial agenesis (CSA) may be recognized preoperatively in the presence of conductive hearing loss. The principal radiological imaging approach of the temporal bone, computed tomography (CT), can be used to diagnose CSA. Our 17-year-old male patient (case A) had long-term hearing loss which was getting worse. A temporal bone CT scan revealed the absence of the stapes and the oval window on both sides and an abnormal position of the facial nerve. No anomalies were detected in the external ear structures. Explorative right ear tympanotomy revealed an abnormal inferior course and dehiscence of the facial nerve. The oval window and stapedial structures were absent. Patients were evaluated for continued hearing aid use or bone-anchored hearing aid implantation. Similar CT imaging and clinical abnormalities were seen in his 16-year-old sister (case B). They did not have any other siblings and neither of their parents nor any of their relatives had hearing loss. This report presents the CT scans of the two siblings with mixed hearing loss (mainly conductive) and the perioperative image of the first case. A genetic study may help explain the etiopathogenesis since both cases had similar clinical and imaging findings. [ABSTRACT FROM AUTHOR]

Purpose: Overhanging facial nerve (FN) may be challenging in imaging diagnosis. The purpose of the study is to investigate the imaging clues for overhanging FN near the oval window on ultra-high-resolution computed tomography (U-HRCT) images. Methods: Between October 2020 and August 2021, images of 325 ears (276 patients) were included in the analysis obtained by an experimental U-HRCT scanner. On standard reformatted images, the morphology of FN was evaluated and its position was quantitatively measured using the following indices: protrusion ratio (PR), protruding angle (A), position of FN (P-FN), distance between FN and stapes (D-S), and distance between FN and anterior and posterior crura of stapes (D-AC and D-PC). According to the FN morphology in imaging, images were divided into overhanging FN group and non-overhanging FN group. Binary univariate logistic regression analysis was used to identify the imaging indices independently associated with overhanging FN. Results: Overhanging FN was found in 66 ears (20.3%), which manifested as downwards protrusion of either local segment (61 ears, 61/66) or the entire course near the oval window (5 ears, 5/66). D-AC [odds ratio: 0.063, 95% CI 0.012–0.334, P = 0.001) and D-PC (odds ratio: 0.008, 95% CI 0.001–0.050, P = 0.000) were identified as independent predictors of FN overhang (area under the curve: 0.828 and 0.865, respectively). Conclusion: Abnormal morphology of the lower margin of FN, D-AC and D-PC on U-HRCT images provide valuable diagnostic clues for FN overhang. [ABSTRACT FROM AUTHOR]

BACKGROUND: The aim of the study was to measure the distance of the tympanic nerve to the oval window and round window niche in adult cadavers for evaluating its usability as an anatomical landmark during middle ear-related surgeries, including stapedotomy and cochleostomy, and for preventing its iatrogenic damage during surgical practices such as otosclerosis surgery and cochlear implantation. METHODS: The middle ears of 10 adult cadavers aged 74.70 ± 14.56 years were bilaterally dissected with the help of an endoscope and microscope to measure the distance of tympanic nerve to round window niche and oval window. RESULTS: Tympanic nerve was found as 1.60 ± 0.86 mm (range, 0-3.11 mm) and 1.55 ± 0.38 mm (range, 1.04-2.20 mm) away from round window niche and oval window, respectively. In relation to the quantitative values of these 2 distances, neither right-left nor male-female significant differences were determined (P > .05). Tympanic nerve was observed in all temporal bones. In terms of the shape and twigs of tympanic nerve, extreme variations among cadaveric temporal bones were determined. Tympanic nerve-round window niche distance between 0-1 mm was defined as type 1 (20%), between 1 and 2 mm as type 2 (45%), between 2 and 3 mm as type 3 (30%), and between 3 and 4 mm as type 4 (5%). CONCLUSION: Tympanic nerve may be vulnerable at round window niche- or oval window-related surgeries (e.g., cochleostomy). [ABSTRACT FROM AUTHOR]

Introduction: In all otologic surgeries, the facial nerve can be considered the most important structure that must be protected. The surgical damage risk of the facial nerve will be increased in the presence of facial canal dehiscence (FCD). Aim: In this study, we aimed to evaluate FCD and its associated situations in patients with chronic otitis media undergoing mastoidectomy. Materials and methods: 850 patients who performed ear surgery were reviewed. Patients who did not perform mastoidectomy were excluded. In patients, the ratios, locatation of FCD, and association of facial canal dehiscence with cholesteatoma were researched. Association between FCD and closed-cavity tympanomastoidectomy, open-cavity tympanomastoidectomy, and radical mastoidectomy procedures, and also an association between FCD and primary or revision surgery were evaluated. Results: Facial canal dehiscence was found in 8.4% of patients. The relationship between dehiscence and cholesteatoma was found significant (P<0.001). In the comparison of radical mastoidectomy and closed-cavity tympanomastoidectomy, dehiscence was higher in the radical mastoidectomy group (P<0.03). In revision cases, dehiscence was seen more frequently (P<0.003). FCD incidence was higher in adult patients than in pediatric patients (P<0.001). 20 of 468 patients who were operated on for cholesteatoma had congenital cholesteatoma. Conclusion: Facial canal dehiscence can be seen especially in cases with cholesteatoma and when performing radical mastoidectomy and revision surgeries. Therefore, a detailed evaluation of the status of facial nerve and determination of situations in which occurrence of FCD is more likely both preoperatively and intraoperatively will minimalize potential complications. [ABSTRACT FROM AUTHOR]

Objective: To compare the efficacy and safety characteristics of different materials used for oval window sealing during stapedotomy. Methods: A systematic review was conducted according to the PRISMA guidelines. Published international English literature from January 1, 2000 to December 2021 was screened, checking for studies that compared different materials utilization in patients undergoing stapedotomy surgery for otosclerosis or congenital stapes fixation. Data related to the efficacy and safety of each material were extracted. The primary outcome measure was the air–bone gap (ABG) closure after surgical intervention. Results: Six studies were included in the metanalysis. Because of the heterogeneity of the treatments adopted, we assessed the use of the fat compared to all other treatments, and the use of the gelfoam compared to all other treatments. In the former analysis (fat vs others) we did not identify differences in ABG closure between the groups (p = 0.74), with a low heterogeneity of the results (I2 = 28.36%; Hedge's g = 0.04, 95% CI − 0.19 0.27); similarly, we did not identify differences between the use of gelfoam and other treatments (p = 0.97), with a low heterogeneity of the results (I2 = 28.91%; Hedge's g = 0.00, 95% CI − 0.20 0.21). Conclusions: Numerous options are available for oval window sealing during stapedotomy, with acceptable safety and effectiveness profiles. Based on the current data, no definitive recommendation can be made regarding the choice of one material over another, and the convenience of sealing over no sealing at all. [ABSTRACT FROM AUTHOR]

Purpose: To investigate how the anatomical configuration of the oval window region (OWR) influences the management of the chorda tympani (ChT) and the curetting of adjacent bony structures, in a setting of patients undergoing endoscopic stapes surgery (EStS); to assess the incidence of early and late post-operative dysgeusia and to identify anatomical and surgical factors influencing taste function after EStS. Methods: Surgical video recordings of 48 patients undergoing EStS for otosclerosis between January 2019 and July 2020 were retrospectively revised, to classify the anatomical variability of selected middle ear structures and the management strategies for the ChT. Clinical records of included patients were reviewed for subjective early and late post-operative taste impairment using a 5-point Likert-scale. Results: The most common configuration of the OWR was type III. The extension of the bony curettage resulted inversely proportional to the exposure of the OWR. The long-term rate of preserved post-operative taste function was 85%. Displacement of the ChT was necessary in 43/48 cases (90%), mostly medially (36/48, 75%). Conclusion: Bone curetting during EStS does not correlate with post-operative taste impairment. Despite 100% ChT preservation rate, dysgeusia may occur in a minority of patients, with no apparent relationship to anatomical variability or intraoperative management of the ChT. The use of CO2 laser could have a role in increasing the risk of post-operative dysgeusia after EStS. [ABSTRACT FROM AUTHOR]

The origin of the stapes footplate has been controversial for decades, especially regarding involvement of the otic capsule in the development of the footplate. We report two cases of stapes malformation in which the stapes footplate was absent, while the oval window was formed but was covered with mucosal membrane. Both the patients visited our department for long-standing hearing loss, which was due to congenital ossicular anomalies of rare variation, as suggested by intraoperative findings. Through two operated cases, we have also discussed the origin and the mechanisms in the development of the stapes and the oval window. The findings suggest that the formation of the oval window is independent from the development of the stapes footplate. Further reports and accumulation of cases with ossicular malformation are required to develop an appropriate classification of congenital ossicular anomalies based on both developmental mechanisms and analyses of the surgical outcomes.

Objectives: Obliteration of the round window (RW) in cases of otosclerosis presents a significant clinical challenge due to its association with more severe hearing loss and a poorer prognosis for functional recovery after stapes surgery. The objective is to assess and characterize the occurrence of RW involvement in otosclerosis cases and to identify patterns of disease progression that may indicate a potential for RW obliteration., Methods: We selected archival temporal bones from donors with otosclerosis. We evaluated the degree of RW obliteration using a semi-quantitative scale and the location of the foci within the temporal bone, and whether the foci were continuous or isolated., Results: Most of the foci were located anteriorly to the oval window (89.2%), while RW area involvement was seen in 26.9% of the ears. In cases with fenestral foci, 68.1% directly involved and/or fixed the footplate. Among donors with bilateral otosclerosis, foci affected both ears in a similar pattern in 64.2%. Among donors with RW involvement, ones with continuous, large lesions that extended from the oval window associated with complete RW obliteration, while ones with smaller degrees of obliteration had solitary foci scattered within the otic capsule., Conclusion: Our results demonstrate a high rate of RW involvement in cases of otosclerosis. Ears with continuous lesions extending from the oval window region to the RW area were more likely to present with complete RW obliteration. These results provide insights that could lead to better prognostic assessment of patients with otosclerosis in the future., Level of Evidence: N/A Laryngoscope, 2024., (© 2024 The Author(s). The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: The study aimed to examine morphometric properties of the round window (RW) and oval window (OW) and to show their relation with the tympanic nerve (the Jacobson's nerve, JN) in human fetuses from the otologic surgeon's perspective. Methods: Thirty temporal bones of 15 fetal cadavers (8 males, 7 females) aged with 24.40 ± 3.71 weeks were included in the study. The height, width and surface area of the RW and OW and also distance from the JN to the OW and RW were measured. Results: The height, width and surface area of the RW in this work were measured as 1.48 ± 0.25 mm, 1.57 ± 0.37 mm, and 2.05 ± 0.69 mm2, respectively. The RW was detected as round-shaped (8 cases, 26.7%), oval-shaped (15 cases, 50%), and dome-shaped (7 cases, 23.3%). The height, width and surface area of the OW were measured as 1.42 ± 0.26 mm, 2.90 ± 0.44 mm, and 3.63 ± 0.74 mm2, respectively. The OW was observed as oval-shaped (15 cases, 50%), kidney-shaped (10 cases, 33.3%), D-shaped (4 cases, 13.3%), and trapezoid-shaped (1 case, 3.3%). The JN was found 1.21 ± 0.60 and 1.18 ± 0.54 mm away from the RW and OW, respectively. Conclusion: This study containing morphological data about the shapes, diameters and area of the RW and OW may be useful to predict surgical difficulty, and to select implants of suitable size preoperatively for the windows. Knowing the relationship between the JN and the windows can be helpful to avoid iatrogenic injuries of the nerve. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the study is to study the details of dimensions and shape of oval window in different age groups, sides and genders and their clinical implications. The oval window is a key structure while performing surgeries in relation to stapes. An intricate knowledge of the shape and size of the oval window is important for the reconstruction and fitting of cartilage compatible with the native shape of the oval window. Methods: Sixty normal wet cadaveric temporal bones of known age; gender and side were micro-dissected. The maximum height and width of the oval window was measured. The shape of the oval window was noticed. Results: The mean value for maximum height and width of the oval window was 1.31 ± 0.28 mm and 2.67 ± 0.42 mm, respectively. The height and width of the oval window ranged between 1 mm and 1.5 mm and 2 mm and 3 mm in majority of the cases. he oval window was found to be oval shaped in 53.3% cases, other shapes such as kidney, D shape, rectangular or trapezoidal were also observed. Conclusions: The refined morphometric information of the oval window will help in preoperative assessment and surgical planning of various oval window-related surgical procedures. The knowledge may also help in designing and selecting proper cartilage shoe for the best outcome. Narrow oval window may cause procedural complications and surgeon discomfort in various stapes surgeries. [ABSTRACT FROM AUTHOR]

The origin of the stapes footplate has been controversial for decades, especially regarding involvement of the otic capsule in the development of the footplate. We report two cases of stapes malformation in which the stapes footplate was absent, while the oval window was formed but was covered with mucosal membrane. Both the patients visited our department for long-standing hearing loss, which was due to congenital ossicular anomalies of rare variation, as suggested by intraoperative findings. Through two operated cases, we have also discussed the origin and the mechanisms in the development of the stapes and the oval window. The findings suggest that the formation of the oval window is independent from the development of the stapes footplate. Further reports and accumulation of cases with ossicular malformation are required to develop an appropriate classification of congenital ossicular anomalies based on both developmental mechanisms and analyses of the surgical outcomes. [ABSTRACT FROM AUTHOR]

Background: Simple or non-syndromic types of oval window (OW) or round window (RW) atresia are relatively rare in clinical. Few studies have assessed bone conduction (BC) hearing in OW or RW atresia patients, with some reporting that BC hearing lies within the normal range, whereas others observing impaired BC hearing. Aims/Objectives: This study explored the effect of blocking the OW and RW during BC in cat models. Material and Methods: Twenty-four cats were randomly divided into three immobilization groups (OW blockage, RW blockage, and OW + RW blockage) and control group. Each immobilization group also had the initial control state before blockage. Medical adhesive and ear mould glue were used to immobilise the stapes footplate and RW, respectively. Comparisons were made of the auditory brainstem response (ABR) thresholds before and after immobilization for the three immobilization groups during three different stimuli [air conduction (AC) click, BC click, and BC pure tones]. Results: The AC click thresholds increased after immobilisation in three experimental groups compared to the control group (p <.05). The AC click thresholds increased compared to their initial control state after all three immobilization groups (p <.05). With an increase in frequency from 2 to 8 kHz, there was a general decrease in the difference between pre- and post-immobilization BC hearing thresholds in all three immobilization groups. The BC click threshold and BC tone thresholds at 2–4 kHz in both OW blockage and OW + RW blockage groups exceeded those in RW blockage group (p <.05). Conclusions and Significance: The use of medical adhesive and ear mould glue for the blockages of OW and RW, respectively in cats was feasible. The effect of blocking the OW and RW in BC hearing was larger at low frequencies than high frequencies between 2 and 8 kHz. OW blockage had a greater effect than RW blockage on BC hearing at 2–4 kHz range. [ABSTRACT FROM AUTHOR]

Abstract Effective and safe treatment of auditory and vestibular diseases has become increasingly dependent on inner ear drug delivery systems. This review highlights recent advances in inner ear drug delivery research and technologies. The focus is on strategies to overcome delivery barriers and to improve drug residence and targeting, with special attention to in vivo animal and human studies. The research in gene and stem cell delivery to the inner ear is briefly reviewed. Newly developed research tools to address experimental challenges and safety issues are discussed. Local drug delivery to the inner ear with non-invasive or minimally invasive approaches still remains challenging. Nanocarrier-based systems with sustained and targeted delivery properties may be promising for future clinical applications. Precisely controlled intratympanic and intracochlear administration with minimized trauma to the delicate inner ear represents the future perspective in inner ear drug research and development. Trans-oval window delivery may be promising as it allows direct delivery of drugs to the vestibule for vestibular disorders while avoiding the undesired effects due to drug distribution to the cochlea. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract Drug delivery to the inner ear by nanomedicine strategies has emerged as an effective therapeutic approach for the management of inner ear diseases including hearing and balance disorders. It is well accepted that substance enters the perilymph from the middle ear through the round window membrane (RWM), but the passage through the oval window (OW) has long been neglected. Up to now, researchers still know little about the pathway via which nanoparticles (NPs) enter the inner ear or how they reach the inner ear following local applications. Herein, we engineered fluorescence traceable chitosan (CS) NPs, investigated the NP distribution within cochlear and vestibular organs, and assessed the availability of RWM and OW pathways to NP transport. Intriguingly, there were high levels of CS NPs in vestibular hair cells, dark cells and supporting cells, but negligible ones in cochlear hair cells and epithelial cells after intratympanic administration. However, the NPs were visualized in two cell models, L929 and HEI-OC1 cell lines, and in the hair cells of cochlear explants after co-incubation in vitro. These combined studies implied that CS NPs might enter the vestibule directly through the OW and then preferentially accumulated in the cells of vestibular organs. Thus, in vivo studies were carried out and clearly revealed that CS NPs entered the inner ear through both the RWM and OW, but the latter played a governing role in delivering NPs to the vestibule with vivid fluorescence signals in the thin bone of the stapes footplate. Overall, these findings firstly suggested that the OW, as a royal gate, afforded a convenient access to facilitate CS NPs transport into inner ear, casting a new light on future clinical applications of NPs in the effective treatment of vestibular disorders by minimizing the risk of hearing loss associated with cochlear hair cell pathology. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract Local drug delivery to the ear has gained wide clinical acceptance, with the choice of drug and application protocol in humans largely empirically-derived. Here, we review the pharmacokinetics underlying local therapy of the ear using the drugs commonly used in clinical practice as examples. Based on molecular properties and perilymph measurements interpreted through computer simulations we now better understand the principles underlying entry and distribution of these and other drugs in the ear. From our analysis, we have determined that dexamethasone-phosphate, a pro-drug widely-used clinically, has molecular and pharmacokinetic properties that make it ill-suited for use as a local therapy for hearing disorders. This polar form of dexamethasone, used as a more soluble agent in intravenous preparations, passes less readily through lipid membranes, such as those of the epithelia restricting entry at the round window membrane and stapes. Once within the inner ear, dexamethasone-phosphate is cleaved to the active form, dexamethasone, which is less polar, passes more readily through lipid membranes of the blood-perilymph barrier and is rapidly eliminated from perilymph without distributing to apical cochlear regions. Dexamethasone-phosphate therefore provides only a brief exposure of the basal regions of the cochlea to active drug. Other steroids, such as triamcinolone-acetonide, exhibit pharmacokinetic properties more appropriate to the ear and merit more detailed consideration. Highlights • Quantitative pharmacokinetic studies of the inner ear allow drug therapies to be compared. • Molecular properties determine how readily drugs pass through membranous boundaries of the ear. • The properties of dexamethasone-phosphate make it unsuitable as a therapy for hearing disorders. [ABSTRACT FROM AUTHOR]