The round window niche veil (RWNV) is a potential anatomic barrier at the round window niche due to thickened middle ear mucosa or fibrosis that either partially or completely covers the niche and may prevent intratympanic medication efficacy. This study aimed to characterize the in vivo capability of photon-counting-detector (PCD) CT to visualize the RWNV. 80 PCD-CT temporal bones were included in the study between April and June 2025. Two experienced neuroradiologists independently reviewed each scan and assigned each with one of the following scores: 1: partial veil seen with or without fluid, 2: complete veil seen with or without fluid, 3: no round window niche veil, and 4: not seen, complete round window niche opacification. PCD-CT visualized either partial or complete RWNV in 43.8% of ears. Further, the RWNV was not visualized in 48.8% of ears when the round window was clear. In 7.5% of ears, complete opacification of the round window niche was noted without visualization of a RWNV. The presence or absence of RWNV visualization demonstrated high inter-rater reliability with unweighted kappa of 0.81 (0.69, 0.92). PCD-CT may visualize the round window niche veil in vivo and may be helpful in determining if the round window niche is patent.

Noise-induced hearing loss (NIHL) constitutes a growing global health burden, yet effective pharmacological interventions remain elusive. Current therapeutic development is severely constrained by two critical bottlenecks: the lack of rationally identified molecular targets and the absence of dosage forms tailored to the physiological barriers of the inner ear. Addressing these limitations, we propose an integrated precision therapy strategy. First, to overcome the unpredictability of drug selection, we employed a transcriptome-guided network pharmacology approach, which rationally identified GBR-12935 - a dopamine transporter (DAT) inhibitor - as a potent candidate capable of reversing the pathological gene signature of noise injury. However, as a central nervous system (CNS)-active agent, the clinical translation of GBR-12935 is hindered by its rapid clearance from the middle ear and the risk of off-target CNS effects due to the ear's anatomical proximity to the brain. To resolve this delivery dilemma, we engineered an injectable, in situ forming hydrogel specifically designed for sustained intratympanic administration. This biomaterial platform effectively prolongs drug residence time in the round window niche while minimizing systemic leakage, thereby maximizing local cochlear bioavailability and mitigating potential neurotoxicity. In a mouse model of severe acoustic trauma (110 dB SPL), the hydrogel-mediated delivery significantly outperformed free drug administration. Quantitative immunofluorescence revealed that this localized intervention not only prevented the loss of cochlear ribbon synapses but, crucially, inhibited the pathological enlargement and aggregation of surviving ribbons, maintaining their morphological stability against excitotoxic edema. This structural preservation translated into robust functional recovery, evidenced by attenuated Auditory Brainstem Response (ABR) threshold shifts (15 dB rescue at 24 kHz, P < 0.01 vs. noise). Collectively, our study establishes a closed-loop paradigm combining computational prediction with rational biomaterial design, providing a potent and safe non-steroidal auditory protection strategy for addressing cochlear synaptopathy.

Round Window Niche Stenosis After Stapes Surgery.

To determine the prevalence of anatomic obstructions, including pseudomembranes and tissue plugs, in the round window niche among human temporal bone specimens. To identify patient factors associated with these obstructions. Effective drug delivery to the inner ear is critical for intratympanic and emerging intracochlear therapies for sensorineural hearing loss (SNHL). Both rely on access to the round window membrane (RWM), which may be obstructed by pseudomembranes or tissue plugs that impair therapeutic efficacy. This is the largest survey to date of RWM obstructions and their associated factors. Temporal bone specimens with SNHL and normal hearing were selected from Massachusetts Eye and Ear, University of Pittsburgh, and Hospital Nacional de Niños using the NIDCD National Temporal Bone Registry. Exclusion criteria included prior otologic surgery, middle ear disease, and congenital anomalies. Histopathologic analysis was performed. Two hundred seventy-nine temporal bones were analyzed (215 SNHL, 64 controls). Among adults, 43.2% had pseudomembranes and 19.2% had tissue plugs. Among children (age ≤18), 10.0% had pseudomembranes and 50.0% had tissue plugs. Results did not differ by hearing status. Pseudomembranes were significantly associated with age older than 18 [odds ratio (OR): 8.01] and reactive middle ear mucosa (OR: 1.83). Tissue plugs were associated with age 18 or younger (OR: 9.03) and presence of mesenchyme (OR: 2.53). Meniere disease (OR: 0.07) and ototoxicity (OR: 0.11) were associated with fewer pseudomembranes. RWM obstructions are common, with pseudomembranes or tissue plugs present in 2/3 of ears. Adults were more likely to have pseudomembranes, while children were more likely to have tissue plugs. These findings may impact inner ear drug delivery strategies.

To evaluate the presence and measure the depth of newly found air space located posteriorly to the basal turn of the cochlea-retrocochlear recess (RCR). The area of subtympanic sinus was explored bilaterally using multi-planar reconstruction tools in 280 temporal bone computed tomography scans. We searched for RCR and measured its depth whenever present. We evaluated the presence of subcochlear canaliculus and the position of the jugular fossa bordering the RCR. The RCR in 192 out of 280 evaluated temporal bones (69%), more commonly in children under 2years old than aged three to five (p < 0.001). The mean depth of the RCR for the whole studied group measured from posterior pillar of the round window niche was 3.9 ± 1.8mm, and from promontory -6.6 ± 1.8mm. The influence of the jugular fossa on the shape of the RCR was confirmed in 88 out of 192 temporal bones with RCR present (46%), more commonly on the right side (p < 0.001). We found subcochlear canaliculus in only 7.5% of examined bones. The RCR is a commonly found anatomical space in the vicinity of subtympanic sinus. Its final shape may be affected by the jugular fossa, especially on the right side. The RCR may play role in preoperative evaluation for cholesteatoma surgery or cochlear implantation.

Roughly 5% of the population is affected by hearing loss. In case of a functional middle ear impairment with decreased transmission, different types of active middle ear implants may restore hearing. To drive the round window membrane (RWM) for example, bone anchored actuators or floating mass transducer (FMT) have been used in clinics. Bone anchored devices are usually too big for the round window niche and FMTs display low displacement and force at low frequencies. This paper focuses on the stimulation of the RWM by a stator-based actuator that combines small size and bone anchoring. The design features a rotational-symmetric balanced armature core with flexible membrane parts manufactured micro technologically. Membranes and assembled prototypes were evaluated on the bench in the range of 0.1 kHz – 10 kHz and prototypes tested in human temporal bones. We demonstrate the feasibility of a balanced armature actuator of appropriate size for RW placement. With 1.4 mm outer diameter and 4.9 mm length, the actuator fits the anatomical constraints. Acoustic stimulation of the RWM resulted in a maximum output of approximately 80 eq. dB SPL at 300 Hz increasing to > 100 eq. dB SPL above 5 kHz. The measured output is comparable to clinically used devices. The design lacked sufficient robustness leading to a low yield in manufacturing and failures in experiments, although the output level was insensitive to static force loading up to 30 mN. Future developments require an increased maximum output level and improved robustness.Graphical abstractSupplementary InformationThe online version contains supplementary material available at 10.1007/s10544-025-00766-x.

To determine the in vivo radiological prevalence of the round window niche veil (RWNV) using the ultra-high-resolution (UHR) mode of photon-counting detector computed tomography (PCD-CT) and to assess variations in its prevalence across different age groups in a Japanese cohort. This retrospective study analyzed temporal bone PCD-CT scans from 191 consecutive patients (382 temporal bones), aged 0 to 79 years. After excluding temporal bones with middle ear opacification or prior surgery, 261 temporal bones were included in the final analysis. All imaging was performed on a clinical dual-source PCD-CT scanner using a standardized, noncontrast UHR protocol. The presence of an RWNV was evaluated based on established radiologic criteria, requiring visualization of the characteristic soft-tissue shadow on both axial and coronal reformatted images. The primary outcome was the radiologic prevalence of the RWNV, calculated for the entire cohort and stratified by decadal age groups. An RWNV was identified in 66 of 261 temporal bones, yielding an overall prevalence of 25.3% (95% CI: 20.4%-30.9%). Prevalence varied across age groups, ranging from 5.3% (30-39y) to 33.3% (40-49y), but no consistent monotonic trend was observed with advancing age. This study provides the first large-scale, in vivo quantification of RWNV radiologic prevalence using UHR PCD-CT. The findings establish this advanced imaging modality as a valuable tool for noninvasively identifying this anatomic barrier, which has significant implications for predicting and potentially improving the efficacy of intratympanic drug delivery for inner ear disorders.

Introduction: Optimizing inner ear access is necessary for the genetic and regenerative treatment of sensorineural hearing loss. This is a descriptive histological study, with three-dimensional modeling of the microanatomy of minimally invasive transcanal access routes to the scala tympani through the round window, and suggested form and dimensions of injection needles for inner ear drug delivery. Methods: Three-dimensional models of eight human temporal bone histological sections were created to measure key anatomical relationships and optimal needle trajectories. Results: To spare the inner ear structures and reach the greatest depth in the scala tympani, the optimal trajectory via the round window is achieved with a needle leaned on and bent at the superiormost point of the round window niche operculum. The length of the needle’s medial part is between 1.375 mm (1.2–1.6 mm) and 3.49 mm (2.8–4.3 mm), with a bend angle of 147° (123–167°). The penetration point of the round window membrane is its vertical axis center, reducing the risk of damage to the inner ear structure and avoiding the crista fenestra. The crista may shift the penetration point inferiorly when visible and not found behind the round window membrane. In all eight temporal bones, the crista never reached the center of the round window membrane, with the horizontal distance between the crista edge and the center being 0.55 mm (0.4–0.75 mm). Conclusion: The data reveal the form and size factors for optimal transcanal access to the inner ear for structure- and function-preserving drug delivery.

Although computed tomography (CT) can predict round window (RW) visibility at posterior tympanotomy pre-operatively, there is a trend towards the application of using magnetic resonance imaging (MRI) alone for cochlear implant (CI) planning. This study assessed the potential of a novel "Black Bone" (BB) MRI sequence to determine RW visibility during posterior tympanotomy. Patients underwent BB MRI as part of pre-operative CI planning. Two independent radiologists performed 5 landmark-based MRI measurements. RW visibility was recorded during posterior tympanotomy as > 50% or < 50% visibility. Patients with undefinable landmarks or absent surgical grading were excluded. Mann-Whitney U or t-tests compared MRI measurements to RW visibility whilst step wise logistic regression determined significant predictors. 86 patients (40 male; median 10.5 years) and 129 implanted ears (43 unilateral, 43 bilateral; 52 adult, 77 paediatric) were evaluated. There were 109/129 ears with > 50% and 20/129 ears with < 50% RW visibility. The external auditory canal (EAC) angle was increased in paediatric patients with > 50% RW visibility (P = 0.033; AUROC 0.689; 73.4% sensitive, 69.2% specific with threshold 6.2o) with ICC = 0.598. The facial recess distance, facial nerve location, and modified RW niche angle were increased in adult patients with > 50% RW visibility but only modified RW niche angle was significant on stepwise regression (P = 0.016; AUROC 0.805; 82.2% sensitive, 71.4% specific with threshold 17.95o) with ICC = 0.578. The visibility of RW at posterior tympanotomy may be determined with pre-operative BB MRI. The optimal predictive measurements differ between adult and paediatric patients and there is superior performance in adults.

The human cochlea, which encapsulates the hearing organ, remains difficult to image using current medical tools due to its delicate structure and location behind dense bone. Optical coherence tomography (OCT) has become an essential technology for imaging cochlear morphology and function in animal models, offering high spatial and temporal resolution. Our previous work demonstrated OCT's ability to image cochlear structures in mouse models and to measure sound-induced vibrations at a nanometer scale. Translating this approach to human patients, however, requires overcoming challenges such as accessing the cochlea non-invasively through the ear canal. We previously designed a hand-held OCT endoscope for this purpose, but the initial design and lack of a camera made it very difficult to use in a clinical setting. In this paper, we present a redesigned OCT endoscope to image the human cochlea that addresses these limitations by reducing its size, improving visibility, and incorporating a forward-looking fiber bundle and camera for better navigation. We validated the device using both an opal checkerboard target and a cadaver temporal bone, demonstrating the ability to navigate to the round window niche via the ear canal. These advancements allow for detailed, real-time imaging of cochlear structures and represent a step toward the clinical application of OCT for diagnosing and treating hearing disorders of the inner ear.

There is an increasing clinical interest in the human round window region through the arise of novel medical treatments such as cochlear implantation (CI), middle ear pharmacotherapy, and gene therapy strategies. Here, we analyzed anatomic variations of the round window niche (RWN) and membrane (RWM) using synchrotron phase-contrast imaging (SR-PCI) of human cadaveric specimens. Results were combined with light (LM) and electron microscopy (TEM) investigations of optimally preserved human tissue. SR-PCI and 3D reconstructions of the round window region were accomplished in 66 human cadaveric temporal bones. RWN and RWM morphology was analyzed and correlated with light and electron microscopy studies of human cochleae. SR-PCI showed the wide variations in both size and shape of the human RWN. A pseudomembrane was present in 80% of the specimens, of which 20% were complete. In 3%, the RWN contained dense tissue or secrete plugs partly or entirely obstructing the niche. Bone channels communicated between the spiral ganglion and RWM and were found in all specimens. Tympanic-meningeal fissures and infra-labyrinthine clefts are described. The human RWN forms a highly variably shaped corridor to the RWM and cochlear base. It may be subdivided and partially closed by a pseudomembrane or soft tissue obscuring the RWM. The RWM seems to be invariably reached by channels containing neural or stretch-receptor-like structures from the spiral ganglion believed to be involved in perilymph pressure regulation.

3D printing of dexamethasone-loaded polycaprolactone-enhanced alginate hydrogels for individualized implants in inner ear therapy.

To investigate the anatomical diversity of the round window (RW) in the pediatric population, focusing on its transcanal trajectory and anatomical angles. The study aims to provide insights into how RW accessibility changes with age, which may impact surgical planning and drug delivery approaches. Retrospective radiologic review of pediatric patients who underwent high-resolution CT scans of the temporal bone. Tertiary care center. Ninety-one pediatric ears from 50 patients with normal anatomy between the ages of 0 and 15 years were analyzed. Radiologic measurements: Using OsiriX MD, scans were reformatted to measure RW access angles, depth, and volume. Using 3D Slicer for 3D reconstruction, RW niche segmentation and volumetric analysis were performed. Main outcome measures included evaluation of transcanal angle to the RW membrane, depth and opening angle of the RW, volume and shape variability, and its three-dimensional localization relative to the umbo. The results demonstrated that the mean transcanal angle to the RW membrane was 98.8° ± 7°. The transcanal angle to the RW increased significantly with age, with the ≥24-month age group demonstrating a mean increase of 6.2° compared to the younger cohort ( p < 0.0001). Additionally, the RW position was found to shift inferiorly as age increased, with a mean difference of 0.47 mm ( p = 0.01). This study provides valuable anatomical insights into changing pediatric RW morphology. These results may have implications for future surgical approaches, particularly for transcanal drug delivery and gene therapy in pediatric patients.

To address the challenge of observing the round window niche during exoscopic cochlear implantation, an assisted endoscopic underwater drilling technique was developed. To improve visibility, we introduced an endoscopic underwater technique after posterior tympanotomy for enhanced visualization of round window area. The procedure transitions between the exoscope and endoscope, with saline irrigation clearing bone dust and blood. Operation times were slight longer, but it offered enhanced safety and ergonomic advantages. This technique enhances clarity for safe manipulation of the round window area, improving cochlear implantation outcomes by optimizing surgical precision and reducing complications.

Modeling and analysis of ear dynamics with a round-window stimulating active middle ear implant

To assess whether the ultrahigh-resolution (UHR) mode of photon-counting detector (PCD) CT can consistently visualize the round window niche veil (RWNV) in human ex vivo specimens. This ex vivo study was conducted on nine human cadaveric temporal bones (four male and five female body donors) with an average age of 72 years (range of 56-83 yr). Imaging with a dual-source PCD-CT scanner in ultrahigh-resolution (UHR) mode. Two blinded, independent board-certified radiologists reviewed CT images in axial and coronal reformations to determine the presence and extent of an RWNV (complete or partial). The performance of the PCD-CT was evaluated by comparing the readings of the radiologists to inspection of the dissected specimens with a surgical endoscope and microscope. The UHR mode of PCD-CT provided consistent visualization of the RWNVs. Five out of six RWNVs were accurately identified, and all three specimens without RWNVs were correctly recognized. All complete RWNVs were correctly identified. The readers missed one partial RWNV due to its close proximity and minimal fluid next to the round window membrane. The visualization of the RWNV was superior in the coronal plane compared with the axial plane. This study is the first to demonstrate that the UHR mode of PCD-CT enables a consistent visualization of the RWNV in ex vivo specimens. The promising results of the current study support verification of the results in prospective patient studies.

To determine which anatomical parameters of the round window (RW) influence the surgical approach for cochlear implantation and in which plane they should be measured. Sixty-six patients (40females and 26males; mean age: 60.4±17.7 [26-84] years) who underwent preoperative ultra-high resolution CT underwent cochlear implantation between February 2020 and March 2024. Two radiologists reviewed the anatomical parameters of the RW niche (type, minimal width), membrane (size, inclination) and bony overhang (size, inclination) in the axial, parasagittal and Stenvers planes. The RW membrane size in the Stenvers plane was the most reproducible and the only difference between patients requiring a promontory cochleostomy approach and those with an easy RW approach, with an optimal cut-off value of 1.55mm for the need for a cochleostomy. The RW membrane size in the parasagittal and Stenvers planes were highly correlated. The minimum width and type of the RW niche and the size and inclination of the RW bony overhang did not influence the surgical approach and had variable interobserver agreement. The size of the RW membrane should be measured in the Stenvers plane. Other anatomical parameters of the RW do not influence the surgical approach.

ABSTRACTObjectiveTo clarify the feasibility and the anatomical characteristics related to round window exposure via the external auditory canal (EAC) without bony removal.MethodsSurgical videos and radiological data from 50 adult patients who underwent endoscopic tympanoplasty type I were collected. According to surgical videos, round window niche (RWN) exposure was classified as “Certainly,” “Possibly,” and “None,” and round window membrane (RWM) exposure was classified as “Clear visualization,” “Incomplete visualization,” “Just perceptible” and “Invisible.” Basing on CT reconstruction, distances among RWM, RWN, tympanic annulus (TA), width, and orientation of scala tympani (ST) were measured under the Coordinate System of Cochlea, and anatomic features of EAC under the Coordinate System of EAC.Results60% of RWNs were “Certainly,” 24% “Possibly,” and 16% “None” exposed. RWM exposure was 32% “Clear visualization,” 22% “Incomplete visualization,” 14% “Just perceptible,” and 32% “Invisible.” Longer distances between RWM and TA (RWM‐TA), and the Width of ST in x and z sections were related to RWM exposure (RWM‐TA: Spearman‐r = 0.663, p < 0.001, ST in x: Spearman‐r = −0.337, p = 0.017, z: Spearman‐r = −0.586, p < 0.001). RWM‐TA longer than 7.06 mm indicated a possibility of RWM exposure (AUC = 0.784, p = 0.011). Widths of ST in x and z sections shorter than 1.85 mm and 1.84 mm, respectively, indicated better RWM exposure (AUC = 0.887, p < 0.001). The size of EAC in axial and coronal sections could significantly predict RWM exposure (axial: AUC = 0.726, p = 0.011, coronal: AUC = 0.798, p = 0.001).ConclusionIn adults, 54% of RWM could be partially visualized via EAC without bony removal. There are reliable pre‐operative predictors for RWM exposure, which are helpful for future inner ear therapy.Level of Evidence3

Cochlear Implantation by classical Trans-mastoid Posterior tympanotomy approach for Round window insertion using microscope is often difficult due to limited visualization of Round window membrane niche. Our study aims to use Endoscope as an adjunct to classical microscopic technique to overcome this difficulty. Our study is a Double blinded Randomised controlled trial with patients undergoing Cochlear implantation & having St Thomas Hospital classification IIb and III intraoperatively included in study. They were divided into two groups. Group A underwent Microscopic Cochlear Implantation while Group B underwent Endoscope assisted Cochlear Implantation. Based on visibility Round window niche structural visibility index (RSVI) score was recorded using both microscope and Endoscope. In Endoscope assisted group mean RSVI score was 8.44 ± 1.37 as compared to microscopic group was 5.47 ± 2.56 and it was Statistically significant with p < 0.05. Intraoperative mean electrically evoked compound action potentials(ECAP) for electrodes 1 to 8 was 187.9 ± 2.84 in microscopic group as compared to 179.44 ± 2.30 in Endoscopic group and the same for electrode 9 to 15 was 178.69 ± 3.16 & 175.3 ± 3.65 respectively but ECAP for electrode 16-22 was statistically insignificant between the groups considering p-value < 0.001. Endoscope assisted Cochlear Implantation was found to be associated with Statistically significant(p < 0.05) chances of Round window insertion with Chi square value of 15.45. Microscope is the tool of choice for Cochlear Implantation but in cases with difficult visualization Endoscope can adjunct microscope in better visualization thus increasing chances of Round window insertion and promoting hearing preservation.

Evaluating round window niche visibility in cochlear implantation: anatomical insights and electrode insertion strategies