Measurement of stapes footplate thickness using ultra-high-resolution computed tomography: stapes axial plane correlates better with otosclerosis than lateral semicircular canal plane.

BACKGROUND, AIMS: Stapes footplate thickness measurement using ultra-high-resolution CT has been described only in the lateral semicircular canal plane. The purpose of this study was to compare stapes footplate thickness between the lateral semicircular canal and stapes axial planes in patients with otosclerosis compared to controls. MATERIAL AND METHODS: We performed a retrospective single-center study of patients undergoing high-resolution temporal bone CT. Two radiologists measured stapes footplate thickness in both the lateral semicircular canal and stapes axial planes. RESULTS: Between February 2020 and October 2022, we collected 81 ears from 49 patients (75% of women; mean age 51.22 ± 16.6 years, 17 otosclerosis, and 64 controls). In the stapes axial plane, there was a significant anterior thickening in otosclerosis patients (Reader 1: 0.52 ± 0.12 [0.3-0.7] vs. 0.41 ± 0.08 [0.3-0.6], p = 0.001; Reader 2: 0.54 ± 0.06 [0.5-0.7] vs. 0.39 ± 0.08 [0.2-0.6], P < 0.001) compared to controls. These differences were not significant using the lateral semicircular canal plane. CONCLUSION: The stapes footplate was thickened at its AC in otosclerosis patients using only the stapes axial plane. SIGNIFICANCE: We propose to use the stapes axial plane instead of the lateral semicircular canal plane when analyzing the stapes.

Congenital Absence of Stapes Suprastructure and Footplate: A Case Report.

INTRODUCTION: Congenital ossicular chain anomalies are rare conductive hearing loss conditions that remain difficult to diagnose even with high-resolution computed tomography (CT). The preoperative diagnosis is helpful for surgical planning and counseling patients regarding treatment outcomes. CASE PRESENTATION: We report a case involving a 14-year-old boy presenting with left conductive hearing loss without history of trauma for 5 years, physical examination showed normal otoscopic examination bilaterally and high-resolution CT showed absent of stapes suprastructure and footplate. Subsequent diagnosis was done via endoscopic middle ear exploration which revealed an absent long process of the incus, stapes suprastructure and footplate, but with intact oval window membrane. The residual incus was removed, and a tragal perichondrium graft was used over the oval window. A total ossicular replacement prosthesis was placed between the malleus and oval window to repair the chain. Postoperatively, the patient had no complications. Preoperative pure tone average revealed an air/bone result of 52/8 dB. Follow-up after surgery at 6 months showed a pure tone average air/bone result of 15/3 dB. The air-bone gap was reduced from 44 to 12 dB. CONCLUSION: Congenital absence of the stapes suprastructure and footplate remains a rare condition compared to the myriad of middle ear anomalies in the literature.

Ultra-high-resolution CT of the temporal bone: Comparison between deep learning reconstruction and hybrid and model-based iterative reconstruction.

PURPOSE: The purpose of this study was to evaluate the ability of ultra-high-resolution computed tomography (UHR-CT) to assess stapes and chorda tympani nerve anatomy using a deep learning (DLR), a model-based, and a hybrid iterative reconstruction algorithm compared to simulated conventional CT. MATERIALS AND METHODS: CT acquisitions were performed with a Mercury 4.0 phantom. Images were acquired with a 1024 × 1024 matrix and a 0.25 mm slice thickness and reconstructed using DLR, model-based, and hybrid iterative reconstruction algorithms. To simulate conventional CT, images were also reconstructed with a 512 × 512 matrix and a 0.5 mm slice thickness. Spatial resolution, noise power spectrum, and objective high-contrast detectability were compared. Three radiologists evaluated the clinical acceptability of these algorithms by assessing the thickness and image quality of the stapes footplate and superstructure elements, as well as the image quality of the chorda tympani nerve bony and tympanic segments using a 5-point confidence scale on 13 temporal bone CT examinations reconstructed with the four algorithms. RESULTS: UHR-CT provided higher spatial resolution than simulated conventional CT at the penalty of higher noise. DLR and model-based iterative reconstruction provided better noise reduction than hybrid iterative reconstruction, and DLR had the highest detectability index, regardless of the dose level. All stapedial structure thicknesses were thinner using UHR-CT by comparison with conventional simulated CT (P < 0.009). DLR showed the best visualization scores compared to the other reconstruction algorithms (P < 0.032). CONCLUSION: UHR-CT with DLR results in less noise than UHR-CT with hybrid iterative reconstruction and significantly improves stapes and tympanic chorda tympani nerve depiction compared to simulated conventional CT and UHR-CT with iterative reconstruction.

Utility of machine learning for identifying stapes fixation on ultra-high-resolution CT.

PURPOSE: Imaging diagnosis of stapes fixation (SF) is challenging owing to a lack of definite evidence. We developed a comprehensive machine learning (ML) model to identify SF on ultra-high-resolution CT. MATERIALS AND METHODS: We retrospectively enrolled 109 participants (143 ears) and divided them into the training set (115 ears) and test set (28 ears). Stapes mobility (SF or non-SF) was determined by surgical inspection. In the ML analysis, rectangular regions of interest were placed on consecutive axial slices in the training set. Radiomic features were extracted and fed into the training session. The test set was analyzed using 7 ML models (support vector machine, k nearest neighbor, decision tree, random forest, extra trees, eXtreme Gradient Boosting, and Light Gradient Boosting Machine) and by 2 dedicated neuroradiologists. Diagnostic performance (sensitivity, specificity and accuracy, with surgical findings as the reference) was compared between the radiologists and the optimal ML model by using the McNemar test. RESULTS: The mean age of the participants was 42.3 ± 17.5 years. The Light Gradient Boosting Machine (LightGBM) model showed the highest sensitivity (0.83), specificity (0.81), accuracy (0.82) and area under the curve (0.88) for detecting SF among the 7 ML models. The neuroradiologists achieved good sensitivities (0.75 and 0.67), moderate-to-good specificities (0.63 and 0.56) and good accuracies (0.68 and 0.61). This model showed no statistical differences with the neuroradiologists (P values 0.289-1.000). CONCLUSIONS: Compared to the neuroradiologists, the LightGBM model achieved competitive diagnostic performance in identifying SF, and has the potential to be a supportive tool in clinical practice.

Assessment of the ability of the radiological incudo-stapedial angle to predict the stapedotomy technique type: a prospective case-series study.

PURPOSE: This study aimed to propose a radiological classification of the incudo-stapedial angle by preoperative high-resolution computed tomography (HRCT) images and to highlight its importance for predicting the use of reversal-steps stapedotomy (RSS) rather than the traditional non-reversal technique. METHODS: We included 83 candidates for stapedotomy operation. Two physicians measured the radiological incudo-stapedial joint angle in the preoperative HRCT. According to this measurement, the radiological incudo-stapedial joint was classified into three types: obtuse, right, and acute. In addition, this radiological classification was correlated with the intraoperative use of the stapedotomy technique, either reversal or non-reversal. RESULTS: The RSS technique was used in forty-two (97.7%) cases with an obtuse angle and twenty-six (89.7%) with a right angle. At the same time, the traditional non-reversal technique was used in all patients with an acute angle. The three groups differed significantly regarding the method used for stapedotomy (P value < 0.001). Moreover, Spearman's correlation coefficient revealed a significant correlation between the used technique and the radiological type of the incudo-stapedial angle (P value < 0.001). CONCLUSIONS: This prospective study proposed a preoperative radiological classification of the incudo-stapedial angle. This classification was significantly correlated with the type of stapedotomy technique. The RSS technique was feasible in most cases with an obtuse and right radiological incudo-stapedial angle. In contrast, the non-reversal method was used in all patients with an acute radiological incudo-stapedial angle. This radiological classification could predict the choice for the stapedotomy technique with an accuracy of 95.18%, a sensitivity of 73.33%, and a specificity of 100%.

Radiological and audiological predictors of stapes destruction in adherent pars tensa.

PURPOSE: Progressive adherent pars tensa occasionally induces ossicular erosion. Specifically, stapes discontinuity adversely affects postoperative hearing. However, this irretrievable sequela is challenging to prove preoperatively, partly because perimatrix inflammation on the pars tensa can obscure the visibility of the ossicles or the partial volume effect of computed tomography (CT) imaging can hamper detailed ossicular visualization. Therefore, there is no consensus regarding the ideal timing for switching from a wait-and-see approach to a surgical one. Herein, we aimed to explore the potential predictors of stapes superstructure destruction in adherent pars tensa. METHODS: This retrospective cohort study enrolled consecutive patients who underwent primary tympanoplasty for adherent pars tensa categorized as grade IV on Sadé's grading scale between April 2016 and September 2021. The impact of features on otoscopy and CT and air-bone gap (ABG) on stapes superstructure destruction was assessed using uni- and multivariable logistic regression analyses. RESULTS: Sixty-four ears were included. Multivariate analysis revealed the presence of debris on the adherent pars tensa (odds ratio [OR] [95% confidence interval {CI}]): 4.799 [1.063-21.668], p = 0.0415), presence of soft-tissue density occupying the oval window (OR [95% CI]: 13.876 [3.084-62.437], p = 0.0006), and a ≥ 20-dB preoperative ABG at 3 kHz (OR [95% CI]: 7.595 [1.596-36.132], p = 0.0108) as independent predictors for stapes superstructure destruction. CONCLUSION: High preoperative awareness of the possibility of destruction of the stapes superstructure would enable the surgeon to make a timely decision to provide surgical intervention before progression to severe stapes destruction, thereby maintaining long-term satisfactory hearing.

Absent Stapedial Tendon: Imaging Features of an Underrecognized Entity : Clinical Neuroradiology.

PURPOSE: Congenital absence of the stapedial tendon is a rare entity with characteristic imaging findings, which can go unrecognized due the scarcity of the diagnosis and limited previous description in the imaging literature. We aim to characterize the imaging features of this entity. METHODS: A series of 9 cases with surgical confirmation of stapedial tendon absence were retrospectively reviewed and the most common abnormalities on high resolution computed tomography (CT) of the temporal bone described. RESULTS: Congenital fixation of the stapes footplate was present in nearly all cases of stapedial tendon absence (n = 8, 89%), a clinically important association because the stapes footplate abnormality was not detectable on preoperative CT. Absence or hypoplasia of the pyramidal eminence and aperture was identified in almost all cases (n = 8, 89%), which may be the sole imaging finding to suggest stapedial tendon absence and associated stapes footplate fixation prior to surgery. CONCLUSION: The most reliable indicator of stapedial muscle absence on temporal bone CT is the absence or hypoplasia of the pyramidal eminence and aperture. Importantly, most patients had congenital stapes footplate fixation confirmed intraoperatively with a normal stapes footplate on CT, meaning the pyramidal eminence/aperture abnormality was the only preoperative imaging finding that could have suggested the footplate fixation.

Cerebrospinal Fluid Leak During Stapes Surgery: The Importance of Temporal Bone CT Reconstructions in Oblique Anatomically Oriented Planes.

Stapes gusher is a massive flow of perilymph and cerebrospinal fluid leak that fills the middle ear immediately after surgical opening of the labyrinth, such as during stapedectomy. Stapes gusher usually occurs as the result of a congenital malformation that causes an abnormal communication between the perilymphatic space and the subarachnoid space involving the internal auditory canal or the cochlear duct. To date, the potential risk of stapes gusher cannot be assessed preoperatively, as there are not pathognomonic signs suggestive of this complication. However, high-resolution computed tomography scan (HRCT) of the temporal bone can provide information that may help recognizing patients at risk. Recently, an anatomic evaluation of the inner ear with oblique reformation at HRCT has been described. This reformation offers a new and more detailed topographic vision of temporal bone structures compared to the classic axial and coronal planes and may help identifying anatomical alterations otherwise not visible. In this article, we present a case of stapes gusher and the role of preoperative HRCT with oblique reformation in its prevention.

Unexpected Branch Malformation of the Facial Nerve during Stapes Surgery: Comparison between Intraoperative and Radiographic Findings.

The aim of this study was to determine the prevalence of facial nerve (FN) bifurcation in patients who undergo stapes surgery, and to ascertain the correlation between the intraoperative and radiographic findings in cases where an unexpected branch malformation for patients undergoing stapes surgery. Patients who underwent stapes surgery were retroactively examined for confirmed FN bifurcation. Among the 887 patients, 10 had a bifurcated FN confirmed during surgery and had a preoperative high-resolution computed tomography (HRCT) scan. The HRCT scans were examined by two radiologists who were blinded to the operational findings. The diagnostic accuracy of HRCT imaging was examined along with their preoperative audiometry. In total, 887 patients underwent stapes surgery and among them the prevalence of FN bifurcation was 1.13%. These 10 patients had a 1:1 male-female ratio with a mean age of 17.9 ± 7.0 years. From a surgical review, all cases had bifurcation at the horizontal segment of FN, including 1 case of FN trifurcation. The diagnostic difference between HRCT imaging and intraoperation observations for malformations in the middle ear varies widely depending on the location, ranging from 0% to 90%. The prevalence of incus and stapes malformations was high in both imaging and operation findings (≥60%). The detection rate of abnormal positioning and bifurcation of the FN during HRCT imaging was 30% and 0%, respectively. The mean air-bone gap hearing threshold for patients was significantly improved from 42.3 dB preoperatively to 15.6 dB postoperatively without any complications. These results showed that it is extremely difficult to predict the FN bifurcation prior to surgery with a detection rate of 0%. The diagnostic difference between HRCT imaging and intraoperation observations for malformations of different parts of the middle ear varies widely. These results highlight the importance of being vigilant in regard to FN anatomical variation during stapes surgery for any unexpected malformations that are not detected during HRCT evaluation. In addition, the surgical outcomes for these patients were optimal when treatment was performed by senior surgeons.

Persistent Stapedial Artery Resulting in Direct Communication Between the Middle Meningeal and Basilar Arteries: Clinical Image.

A persistent stapedial artery originates from the petrous segment of the internal carotid artery due to failure of the regression of the embryonic stapedial artery. During embryologic development, the stapedial artery supplies the middle meningeal artery through the ventral pharyngeal artery. The presence of a persistent stapedial artery can result in direct communication between the basilar and middle meningeal arteries. We present a cerebral angiogram image of an adult patient that shows a right-sided persistent stapedial artery with communication between the right middle meningeal and basilar arteries. It is important to recognize such rare anatomic variants during endovascular interventions to avoid catastrophic complications such as nontarget embolization of the posterior circulation.

Stapes visualization by ultra-high resolution CT in cadaveric heads: A preliminary study.

PURPOSE: This study aimed to assess stapes visualization using an ultra-high resolution computed tomography (U-HRCT). METHOD: Sixty ears from 30 cadaveric human heads were scanned by both U-HRCT and 128-section multislice CT (MSCT) with clinical parameters. Image quality of the stapes head, anterior and posterior crura, footplate, incudostapedial joint and stapedial muscle within the pyramidal eminence was scored using a 3-point Likert scale. Linear measurements of the stapes configuration were performed on U-HRCT. RESULTS: The interobserver agreement for image qualitative score on U-HRCT was good to excellent (interobserver agreement coefficients 0.65-0.86). With the exception of the stapes head, U-HRCT achieved significantly higher qualitative scores than MSCT across all anatomical structures (Ps < 0.05). The total height of the stapes was measured to be 3.48 ±â€¯0.33 mm. The height and width of the obturator foramen were 1.77 ±â€¯0.28 mm and 2.19 ±â€¯0.33 mm, respectively. The widths of the anterior and posterior crura were 0.20 ±â€¯0.06 mm and 0.22 ±â€¯0.06 mm, respectively. The thickness of the footplate was 0.22 ±â€¯0.06 mm, and the angle of the incudostapedial joint was 95.91 ±â€¯10.69°. CONCLUSIONS: U-HRCT is capable of delineating fine structures of the stapes and provides linear data on dimensions of the stapes, which could be helpful for detecting stapes disease and making individualized surgical plans in the clinical setting.

Isolated Incudostapedial Cholesteatomas: Unique Radiologic and Surgical Features.

OBJECTIVES: Congenital cholesteatomas originate from epithelial tissue present within the middle ear in patients with an intact tympanic membrane, no history of otologic surgery, otorrhea, or tympanic membrane perforation. They are diagnosed by a pearl-like lesion on otoscopy and computed tomography (CT) scan showing an expansile soft-tissue mass. We describe a series of patients with no prior otologic history presenting with progressive unilateral conductive hearing loss and normal otoscopy. The CT scans showed ossicular erosion without obvious soft-tissue mass. Surgery confirmed incudostapedial erosion found to be cholesteatoma. In this study, we characterize the clinical course of patients diagnosed with isolated incudostapedial cholesteatoma (IIC) and review possible pathologic mechanisms. METHODS: Retrospective review of IIC cases treated by the Department of Pediatric Otolaryngology, Rady Children's Hospital, San Diego, 2014 to 2020. Data included patient demographics, clinical features, imaging, surgical findings, and audiologic data. RESULTS: Five patients were diagnosed with IIC (3 [60%] female; mean age at presentation 10.7 years [range 5.5-16.0]). All patients presented with postlingual unilateral conductive hearing loss and normal otoscopy without any past otologic history; delay in diagnosis ranged from 4 months to several years. The CT scans showed ossicular chain erosion with an absent long process of the incus and/or stapes superstructure. All patients underwent middle ear exploration, revealing a thin layer of cholesteatoma in the incudostapedial region, confirmed by histopathology. Mean preoperative speech reception threshold was 55 dB and improved to a mean of 31 dB in the 4 patients who underwent ossicular chain reconstruction. CONCLUSION: Isolated incudostapedial cholesteatoma should be included as a possible etiology in pediatric patients with insidious onset of unilateral conductive hearing loss with normal otoscopy, unremarkable otologic history, and a CT scan showing ossicular abnormality/disruption without notable middle ear mass. These patients should be counseled preoperatively regarding the possibility of cholesteatoma and should undergo middle ear exploration with possible ossiculoplasty.

Navigational guidelines and positional relationships of the human auditory ossicles from three-dimensional topography for ensuring safe and effective malleostapedotomy : Stereotactic topography of the auditory ossicles and its clinical implication.

PURPOSE: The aims of the present study were to identify detailed positional relationship between the auditory ossicles and to provide theoretic navigational guidelines for optimal prosthesis adaptation and effective malleostapedotomy. METHODS: Fifty sides of the temporal bone from donated cadavers were scanned by MicroCT and the malleus, incus, stapes and tympanic membrane were materialized three dimensionally using computer software. Dimensions between the auditory ossicles closely related to malleostapedotomy were measured twice. RESULTS: The grip site of malleus handle was mean 1.8 mm superior and mean 1.3 mm anterior, and linear distance between the grip site of malleus handle and the footplate of the stapes was mean 6.5 mm. The stapes was not parallel to the tympanic membrane and rotated mean 10.7° posteriorly relative to the tympanic membrane. CONCLUSION: Surgeons should start with at least 8.75 mm prosthesis to cover the upper limits of potential anatomy and then trim down to the individualization to the case. The ideal loop morphology has to be oval shape more than 1.4 mm in the long diameter and 1.0 mm in the short diameter. The wire of the prosthesis has to be bended at the two points: about 10° anteriorly at the most proximal point of the wire and about 50° superiorly at the stapes head point.

Measurement of stapes footplate thickness in otosclerosis by ultra-high-resolution computed tomography.

BACKGROUND: Ultra-high-resolution computed tomography (U-HRCT) utilizes a 1024 × 1024 matrix with 0.25-mm section thickness, offering better spatial resolution than conventional multi-detector row CT to detect anatomic data for otologic surgery. AIMS: We examined stapes footplate thickness using U-HRCT in relation to stapedotomy to predict the difficulty of the surgical procedure. MATERIALS AND METHODS: Subjects were 12 otosclerosis patients and 25 controls who underwent diagnostic U-HRCT. A profile curve (Hounsfield units) was used to measure stapes footplate thickness along a perpendicular line across the stapes footplate in a plane parallel to the lateral semicircular canal. RESULTS: Footplate thickness was smaller at the midpoint than just before the anterior crus and just after the posterior crus. Interobserver variability was lowest at the midpoint, where foot plate thickness was significantly greater in the affected ear in otosclerosis patients compared with controls (0.60 ± 0.09 mm vs 0.46 ± 0.04 mm; p < .001). Otosclerosis patients were detected using U-HRCT with a high area under the curve. Difficulty in the stapes opening procedure correlated with stapes footplate thickness. CONCLUSIONS: Footplate thickness on U-HRCT correlated with temporal bone anatomy and corresponded to surgical difficulty. Significance: U-HRCT-derived anatomic data is useful for evaluating the stapes.

Treacher Collins syndrome: A novel TCOF1 mutation and monopodial stapes.

Treacher Collins syndrome (TCS: OMIM 154500) is an autosomal dominant craniofacial disorder belonging to the heterogeneous group of mandibulofacial dysostoses. OBJECTIVE: To investigate four Treacher Collins syndrome patients of the Sgaw Karen family living in Thailand. METHOD: Clinical examination, hearing tests, lateral cephalometric analyses, Computed tomography, whole exome sequencing and Sanger direct sequencing were performed. RESULTS: All of the patients affected with Treacher Collins syndrome carried a novel TCOF1 mutation (c.4138_4142del; p.Lys1380GlufsTer12), but clinically they did not have the typical facial gestalt of Treacher Collins syndrome, which includes downward-slanting palpebral fissures, colobomas of the lower eyelids, absence of eyelashes medial to the colobomas, malformed pinnae, hypoplastic zygomatic bones and mandibular hypoplasia. Lateral cephalometric analyses identified short anterior and posterior cranial bases, and hypoplastic maxilla and mandible. Computed tomography showed fusion of malleus and incus, sclerotic mastoid, hypoplastic middle ear space with a soft tissue remnant, dehiscence of facial nerve and monopodial stapes. CONCLUSION: Treacher Collins syndrome in Sgaw Karen patients has not been previously documented. This is the first report of monopodial stapes in a TCS patient who had a TCOF1 mutation. The absence of a common facial phenotype and/or the presence of monopodial stapes may be the effects of this novel TCOF1 mutation.

High-resolution imaging of the human incudostapedial joint using synchrotron-radiation phase-contrast imaging.

The incudostapedial joint (ISJ) of the middle ear is important for proper transmission of sound energy to the cochlea. Recently, the biomechanics of the ISJ have been investigated using finite-element (FE) modelling, using simplified geometry. The objective of the present study was to investigate the feasibility of synchrotron-radiation phase-contrast imaging (SR-PCI) in visualising the ISJ ultrastructure. Three human cadaveric ISJs were dissected and scanned using SR-PCI at 0.9 µm isotropic voxel size. One of the samples was previously scanned at 9 µm voxel size. The images were visually compared and contrast-to-noise ratios (CNRs) were calculated (of both bone and soft tissues) for quantitative comparisons. The ISJ ultrastructure as well as adjacent bone and soft tissues were clearly visible in images with a 0.9 µm voxel size. The CNRs of the 0.9 µm images were relatively lower than those of the 9 µm scans, while the ratio of bone to soft tissue CNRs were higher, indicating better discernibility of bone from soft tissue in the 0.9 µm scans. This study was the first known attempt to image the ISJ ultrastructure using an SR-PCI scanner at submicron voxel size and results suggest that this method was successful. Future studies are needed to optimise the contrast and test the feasibility of imaging the ISJ in situ. LAY DESCRIPTION: The human middle ear consists of the eardrum, three small bones (the malleus, incus and stapes) and two joints connecting the bones (the incudostapedial joint and the incudomallear joint). The role of the middle ear is to amplify and transfer sound energy to the cochlea, the end organ of hearing. The incudostapedial joint (ISJ) of the middle ear is a synovial joint which is important for proper transmission of sound energy to the cochlea. Similar to other synovial joints it consists of meniscus, fluid and articulating surfaces. Recently, the biomechanics of the ISJ have been investigated using computational models, using grossly simplified geometry. Synchrotron radiation phase contrast imaging (SR-PCI) is a high-resolution imaging technique used to visualise small structures in three dimensions. The objective of the present study was to investigate the feasibility of using SR-PCI in visualising the ISJ ultrastructure. Three human cadaveric ISJs were dissected and scanned using SR-PCI at 0.9 µm isotropic voxel size. One of the samples was previously scanned at 9 µm voxel size. The images were both qualitatively and quantitatively compared. This study was the first known attempt to image the ISJ ultrastructure using an SR-PCI scanner at submicron voxel size and results suggest that this method was successful. Future studies are needed to optimise the contrast and feasibility of imaging the ISJ in situ.

Anatomy of the neural endocranium, parasphenoid and stapes of Diadectes absitus (Diadectomorpha) from the early Permian of Germany based on the high-resolution X-ray microcomputed tomography.

A detailed anatomy of the braincase and stapes of the subadult specimen of Diadectes absitus from early Permian sediments of Germany are described for the first time based on the high-resolution X-ray microcomputed tomography. In contrast to previous studies of Diadectes, the bones of the braincase (opisthotic, prootic, supraoccipital, basioccipital, exoccipital, basisphenoid, and sphenethmoid), and parasphenoid of D. absitus are not co-ossified, but suturally defined. This has allowed for a reconstruction of a complete braincase with all sutures between the individual bones. The opisthotic, prootic, and supraocciptal contain a well-preserved endosseous labyrinth. The three-dimensional-reconstruction of its cavities shows a well-preserved vestibule, three semicircular canals, and well-developed cochlear recess. In addition, a shallow subarcuate fossa is present on the ventral surface of the supraoccipital, which lies medial to the anterior semicircular canal. A typical feature of the diadectid braincase is the presence of the otic tube leading from the fenestra vestibuli to the vestibule. A revision of the topology of this structure is presented here. Here, we describe new structures of the stapes, especially in its proximal portion, as well as its position to the fenestra vestibuli. These structures are described for the first time not only in D. absitus, but for the genus.

Hypothalamic hamartomas and inner ear diverticula with X-linked stapes gusher syndrome - new associations?

X-linked stapes gusher syndrome is a genetic form of deafness with distinct radiographic features on temporal bone CT. Hypothalamic hamartoma is a congenital glioneuronal anomaly of the hypothalamus. We report a potential association between these two rare anomalies that, to our knowledge, has not been reported. Two brothers presented with sensorineural hearing loss and almost identical inner ear and hypothalamic abnormalities, consistent with a diagnosis of X-linked stapes gusher syndrome and hypothalamic hamartoma. Genetic testing revealed identical mutations in the POU3F4 gene associated with X-linked stapes gusher syndrome. Furthermore, multiple vestibular diverticula were seen in both brothers, which have also not been reported with X-linked stapes gusher syndrome. This case suggests that POU3F4 mediated X-linked stapes gusher syndrome may also lead to multiple vestibular diverticula and hypothalamic hamartoma and, therefore, brain magnetic resonance imaging (MRI) could be considered in patients presenting with these inner ear findings.

[Observation of human stapes and simulated stapedial lesion based on Micro-CT scanning].

Objective:The aim of this study is to understand the imaging morphology of the humerus morphology and its associated simulated lesions, and to provide information for related research. Method:Six adult cadaveric heads fixed by formaldehyde solution (12 sides of the tibia) were used. One of the cadaveric heads (two sides of the tibia) was perforated and fractured under the microscope.The remaining 5 (10 sides) were used. The humerus was used for morphological measurements of the tibia.The tibia (12 sides) was taken out, Micro-CT scan was performed, and two-dimensional and three-dimensional reconstruction were performed using software such as Mimics 17.0 software. Result:①Stapedial morphologic observation:the head,curs and footplate of the stapes and the adjacent structures can be well displayed on two dimensional structures.②Quantitative measurements and statistics: There were no significant statistic differences about the data that had been measured between the right ears and the left ears.③Micro-CT was more clearly in displaying the precise structure of human stapes and the stapedial minute lesion comparing with that of HRCT. Conclusion:Micro-CT can accurately and clearly display the structure, morphology and simulated lesions (model) of the tibia, which provides important reference materials and methods for related research.