Differential effects of mass-loading the eardrum and stiffening the middle ear on wideband absorbance.

The current work investigated the effects of mass-loading the eardrum on wideband absorbance in humans. A non-invasive approach to mass-loading the eardrum was utilized in which water was placed on the eardrum via ear canal access. The mass-loaded absorbance was compared to absorbance measured for two alternative middle ear states: normal and stiffened. To stiffen the ear, subjects pressurized the middle ear through either exsufflation or insufflation concurrent with Eustachian tube opening. Mass-loading the eardrum was hypothesized to reduce high-frequency absorbance, whereas pressurizing the middle ear was hypothesized to reduce low- to mid-frequency absorbance. Discriminant linear analysis classification was performed to evaluate the utility of absorbance in differentiating between conditions. Water on the eardrum reduced absorbance over the 0.7- to 6-kHz frequency range and increased absorbance at frequencies below approximately 0.5 kHz; these changes approximated the pattern of changes reported in both hearing thresholds and stapes motion upon mass-loading the eardrum. Pressurizing the middle ear reduced the absorbance over the 0.125- to 4-kHz frequency range. Several classification models based on the absorbance in two- or three-frequency bands had accuracy exceeding 88%.

Disrupted harmony of the skull skeleton: Middle ear resonance in acromegaly.

OBJECTIVES: This study aims to investigate whether the middle ear resonance frequency (RF) is affected in acromegaly, which causes growth in the skull bone. METHODS: Thirty acromegaly patients and 38 volunteers were included in the study. Pure tone average scores and middle ear RF values of the groups that underwent pure tone audiometry, tympanometry, and multifrequency tympanometry tests were compared. RESULTS: The pure tone mean was 14.95 ± 12.13 in acromegaly patients and 5.70 ± 8.52 in the control group (p:0.18). Sensorineural hearing loss(SNHL) was observed in 16.6% of the patients. The average middle ear RF was calculated as 815 ± 179.05 Hz in patients with acromegaly and 773 ± 127.15 in the control group. (p = 0.0001). CONCLUSION: This study is the first to evaluate middle-ear RF in acromegaly patients. Acromegaly-induced changes in soft tissues and bone structures impact middle ear functions. In this patient group, we found an increase in middle ear RF without conductive-type hearing loss and a 16.6% rate of SNHL.

The A2ml1-Knockout mouse as an animal model for non-syndromic otitis media.

BACKGROUND: Inflammation and infection of the middle ear, known as otitis media (OM), is a leading cause of hearing loss and the most frequently diagnosed disease in children worldwide. Traditionally, mouse models for OM rely on inducing acute infection through inoculation of the middle ear, e.g. with the human otopathogen non-typeable Haemophilus influenzae (NTHi), and with very few genetic models with spontaneous or chronic OM. A2ML1 variants, including loss-of-function variants, were associated with susceptibility to OM in humans, but no animal model has been reported for A2ml1-related OM. Here, we report our middle ear findings in a mouse line with a CRISPR-induced knockout (KO) of A2ml1. METHODS: Mice were X-rayed prior to harvest to determine if there are craniofacial or skeletal abnormalities. Tissue from mouse middle ears, as well as other upper respiratory mucosal tissues, were harvested. The harvested middle ear bullae were examined under microscope and submitted for histologic preparation to study phenotypic indications of OM. RNA samples isolated from middle ear tissue were assayed for expression of genes correlated with A2ML1 expression in humans. RESULTS: Data from a total of 119 mice (35 wildtype, 40 heterozygous, 44 homozygous) are presented here, with each analyses being performed on subsets of these mice. There were no significant craniofacial differences by genotype (n = 22). Findings in mice with the A2ml1-KO indicated an increased incidence of OM (n=29; odds ratio = 11; CI: 1.1, 573.6; Fisher exact two-sided p = 0.02) with tympanic membrane perforations or thickening, as well as cases of middle ear effusion, inflammatory cells, or fluid from histologic sections. Dsp was upregulated in the middle ear tissues of homozygous mice (Wilcoxon test p = 0.001). CONCLUSION: Thus far, our results in this A2ml1-KO mouse line indicate spontaneous occurrence of OM and dysregulation of Dsp in the middle ear as a potential disease mechanism for A2ml1-related OM.

[Features of otosurgery in children after blast injuries]. / Osobennosti rekonstruktivnoi otokhirurgii u detei posle minno-vzryvnykh ranenii.

An explosion is a process that rapidly releases a huge amount of energy in the form of heat, kinetic energy, and high-pressure shock waves. Since the organ of hearing is most susceptible to pressure changes, damage to the sound-conducting or sound-receiving systems is inevitable in case of an explosive injury. This article examines the mechanism of formation of explosive injuries of the middle and inner ear in children and adolescents, the features of diagnosis and tactics of surgical reconstructive treatment of explosive ear injuries based on the data available in the scientific literature and their own experience.

Long-term outcomes following pediatric endoscopic titanium ossiculoplasty: A single-institution experience.

INTRODUCTION: Endoscopic ossicular chain reconstruction (OCR) in adults has demonstrated equivalent outcomes to the traditional microscopic approach. Less data exist on endoscopic OCR outcomes in children, who have unique considerations including a smaller transcanal corridor and variable pathology. The purpose of this study was to investigate surgical and audiometric outcomes in children undergoing fully endoscopic and endoscopic-assisted OCR in both the short and long-term. METHODS: Retrospective review of all children (<17 years) who underwent endoscopic OCR at one tertiary care center between 2017 and 2021. Children undergoing primary and revision endoscopic OCR with either partial (PORP) and total ossicular reconstruction prostheses (TORP) were included. Children undergoing surgery for juvenile otosclerosis or congenital stapes fixation, or any child receiving a stapes prosthesis were excluded. Primary outcome measures were post-operative change in 4 frequency (500 Hz, 1, 2, 4 KHz) air conduction pure tone average (AC PTA) and change in air-bone gap (ABG). Secondary measures included need for readmission and/or revision surgery, complication rate, and surgery duration. RESULTS: Seventeen patients met inclusion criteria. Average age was 11.3 years (range, 5-17 years); 14 were male. A variety of fixed length, titanium total and partial prostheses were used. The most common prosthesis length was 2 mm (range 2-5 mm), and there were no intra- or perioperative complications. Mean long-term follow-up was 2.6 years. Most common pathology was congenital cholesteatoma (11/17, 64%), followed by chronic otitis media with tympanic membrane perforation (5/17, 29.4%), and extruded prosthesis (1/17, 5.9%). Intraoperatively, the most common finding was incus erosion (10/17, 58.8%), followed by malleus erosion (6/17, 35.3%), stapes erosion (4/17, 23.5%), and stapes absence (4/17, 23.5%). Eight children (47%) were reconstructed with PORPs, and 9 children (52.9%) were reconstructed with TORPs. Average ABG improved from 36.8 dB preoperatively to 19.9 dB postoperatively in the short-term and remained stable at 19.5 dB in the long-term. Average short-term ABG improvement was 4.2 dB for PORPs and 18 dB for TORPs. In the long-term, average ABG improved by 2.3 dB in PORPs and 13.4 dB in TORPs. PORPs had higher rates of ABG closure and lower AC PTAs than TORPs in the long-term. DISCUSSION: Endoscopic ossiculoplasty is a viable option in children presenting with ossicular erosion from various causes. Audiometric improvement following endoscopic partial and total ossicular reconstruction remains stable over time, with a preference towards partial in the long-term, and mirrors published outcomes for microscopic surgery.

Measuring absorbed energy in the human auditory system using finite element models: A comparison with experimental results.

BACKGROUND: There are different ways to analyze energy absorbance (EA) in the human auditory system. In previous research, we developed a complete finite element model (FEM) of the human auditory system. OBJECTIVE: In this current work, the external auditory canal (EAC), middle ear, and inner ear (spiral cochlea, vestibule, and semi-circular canals) were modelled based on human temporal bone histological sections. METHODS: Multiple acoustic, structure, and fluid-coupled analyses were conducted using the FEM to perform harmonic analyses in the 0.1-10 kHz range. Once the FEM had been validated with published experimental data, its numerical results were used to calculate the EA or energy reflected (ER) by the tympanic membrane. This EA was also measured in clinical audiology tests which were used as a diagnostic parameter. RESULTS: A mathematical approach was developed to calculate the EA and ER, with numerical and experimental results showing adequate correlation up to 1 kHz. Another published FEM had adapted its boundary conditions to replicate experimental results. Here, we recalculated those numerical results by applying the natural boundary conditions of human hearing and found that the results almost totally agreed with our FEM. CONCLUSION: This boundary problem is frequent and problematic in experimental hearing test protocols: the more invasive they are, the more the results are affected. One of the main objectives of using FEMs is to explore how the experimental test conditions influence the results. Further work will still be required to uncover the relationship between middle ear structures and EA to clarify how to best use FEMs. Moreover, the FEM boundary conditions must be more representative in future work to ensure their adequate interpretation.

Quantitative evaluation of middle ear radiopacity in French bulldogs using X-ray imaging.

Background: Radiographic examination of the middle ear in French bulldogs can be challenging due to their small ear cavity and thick walls. Quantifying opacity on radiographic images is required to determine normal or abnormal results. Aim: To quantify the radiographic opacity of the middle ear in French bulldogs and create a threshold for objective diagnosis. Methods: A study was conducted on 32 French Bulldogs using radiographic images. Significant difference tests were performed on the ears of patients with unilateral and bilateral middle ear filling on computed tomography. A threshold was established for detecting left-right asymmetry in the same individuals. In addition, comparisons were made between the filling and nonfilling middle ear groups to establish a threshold of pixel values that could determine single middle ear filling and nonfilling for different patient images. Results: Significant differences were observed in the left-right difference in max, left-right difference in max-ave, and left-right ratio of max-ave between unilateral and bilateral filling groups. The max-ave left-right ratio had the highest area under the curve value with a cutoff of 1.077% and 92.3% sensitivity. The item that showed a significant difference between middle ear groups with and without filling was corrected for nasopharyngeal pixel values with a cutoff of 1.028% and 85% sensitivity. Conclusion: Pixel value ratios in the middle ear region can detect asymmetries in ear densities. The max value in the region compared to the same image's nasopharyngeal region can determine the filling. Combining individual ear evaluations and symmetry improves accuracy.

Integration of 3D-printed middle ear models and middle ear prostheses in otosurgical training.

BACKGROUND: In otosurgical training, cadaveric temporal bones are primarily used to provide a realistic tactile experience. However, using cadaveric temporal bones is challenging due to their limited availability, high cost, and potential for infection. Utilizing current three-dimensional (3D) technologies could overcome the limitations associated with cadaveric bones. This study focused on how a 3D-printed middle ear model can be used in otosurgical training. METHODS: A cadaveric temporal bone was imaged using microcomputed tomography (micro-CT) to generate a 3D model of the middle ear. The final model was printed from transparent photopolymers using a laser-based 3D printer (vat photopolymerization), yielding a 3D-printed phantom of the external ear canal and middle ear. The feasibility of this phantom for otosurgical training was evaluated through an ossiculoplasty simulation involving ten otosurgeons and ten otolaryngology-head and neck surgery (ORL-HNS) residents. The participants were tasked with drilling, scooping, and placing a 3D-printed partial ossicular replacement prosthesis (PORP). Following the simulation, a questionnaire was used to collect the participants' opinions and feedback. RESULTS: A transparent photopolymer was deemed suitable for both the middle ear phantom and PORP. The printing procedure was precise, and the anatomical landmarks were recognizable. Based on the evaluations, the phantom had realistic maneuverability, although the haptic feedback during drilling and scooping received some criticism from ORL-HNS residents. Both otosurgeons and ORL-HNS residents were optimistic about the application of these 3D-printed models as training tools. CONCLUSIONS: The 3D-printed middle ear phantom and PORP used in this study can be used for low-threshold training in the future. The integration of 3D-printed models in conventional otosurgical training holds significant promise.

Deep Learning for Automated Image Segmentation of the Middle Ear: A Scoping Review.

OBJECTIVE: Convolutional neural networks (CNNs) have revolutionized medical image segmentation in recent years. This scoping review aimed to carry out a comprehensive review of the literature describing automated image segmentation of the middle ear using CNNs from computed tomography (CT) scans. DATA SOURCES: A comprehensive literature search, generated jointly with a medical librarian, was performed on Medline, Embase, Scopus, Web of Science, and Cochrane, using Medical Subject Heading terms and keywords. Databases were searched from inception to July 2023. Reference lists of included papers were also screened. REVIEW METHODS: Ten studies were included for analysis, which contained a total of 866 scans which were used in model training/testing. Thirteen different architectures were described to perform automated segmentation. The best Dice similarity coefficient (DSC) for the entire ossicular chain was 0.87 using ResNet. The highest DSC for any structure was the incus using 3D-V-Net at 0.93. The most difficult structure to segment was the stapes, with the highest DSC of 0.84 using 3D-V-Net. CONCLUSIONS: Numerous architectures have demonstrated good performance in segmenting the middle ear using CNNs. To overcome some of the difficulties in segmenting the stapes, we recommend the development of an architecture trained on cone beam CTs to provide improved spatial resolution to assist with delineating the smallest ossicle. IMPLICATIONS FOR PRACTICE: This has clinical applications for preoperative planning, diagnosis, and simulation.

[A study of mismatched negative in normal hearing patients of different ages].

Objective:To study the characteristics of Mismatch negativity（MMN） in normal hearing patients of different ages, and to compare the MMN of normal hearing subjects at different ages to explore the differences in MMN between different ages. Methods:MMN test was performed on both ears using the classic Oddball mode. A frequency of 1 000 Hz（standard stimuli） and 2 000 Hz（deviant stimuli） was used to evoked the MMN. According to different age groups: the juvenile group（7-17 years old）, the youth group（18-44 years old）, the middle-aged group（45-59 years old）, and the elderly group（60-75 years old）, with 25 cases in each group. The MMN characteristics of normal hearing subjects in different age groups were analyzed statistically and the differences between groups were compared. All subjects underwent pure tone threshold test, tympanic reactance test and ABR test before MMN test. Results:MMN waveform could be elicited from both ears of 100 subjects. Among them, the average latency of the juvenile group was（159.70±20.34） ms while the average amplitude was（4.34±2.26） µV, For the youth group, the average latency was（166.01±28.67） ms and the average amplitude was（3.70±2.28） µV. Then in the middle-aged group, the average latency was（175.16±37.24） ms, meanwhile, the average amplitude was（2.69±0.84） µV. Finally, the elderly group has an average latency of（178.03±14.37） ms and an average amplitude of（2.11±0.70） µV. Therefore, there was no statistical difference in latency and amplitude between all groups（P>0.05）, and there was no statistical difference in latency and amplitude between left and right ears among all subjects as a whole（P>0.05）. However, when the left and right ears of all groups were compared, it was found that the latency between the left and right ears of the Juvenile group had statistical significance（P<0.05）, and the amplitude difference was not statistically significant（P>0.05）, while the latency and amplitude differences between the left and right ears of other groups had no statistical significance（P>0.05）. There were also no significant differences in latency and amplitude between men and women（P>0.05）. Conclusion:There was no statistically significant difference in the latency and amplitude of mismatched negative among normal hearing subjects of different ages, and no statistically significant difference in the MMN latency and amplitude between the left and right ears of subjects and between men and women. Therefore, the study inferred that the auditory cerebral cortex of subjects aged 7-75 years old maintained a stable state for a long time after maturity, and the latency and amplitude of mismatched negative waves were relatively stable. It is not affected by age, gender and ear side, and can stably reflect the auditory cortex function of the subjects. It has broad application prospects in clinical practice, and provides a reliable detection means for future research on the changes of the auditory cerebral cortex of patients, which is worthy of our further research and clinical promotion.

[Clinical features of congenitally enlarged bony portion of Eustachian tube].

Objective:To investigate the clinical features of patients with congenitally enlarged bony portions of the Eustachian tube（ET）. Methods:The medical history, physical examination, hearing test, temporal bone high resolution computed tomography（HRCT） of six patients（nine ears） with congenitally enlarged bony portion of the ET were retrospectively analyzed. Results:Four patients were men and two were women. The minimum, maximum, and average ages were 5, 21, and（14.7±6.4） years, respectively. Three malformations were bilateral and three were left-sided. Three ears had conductive hearing loss（average bone and air conduction thresholds were 13.7 dB and 71.3 dB）, three had mixed hearing loss（average bone and air conduction thresholds were 27.7 dB and 83.7 dB）, and one had extremely severe sensorineural hearing loss. The average maximum length and width of the enlarged bony ET on temporal bone HRCT were（22.61±2.94） mm and（6.50±2.33） mm, respectively. The enlargement was combined with an external auditory canal malformation in six ears, narrow tympanic cavity in six, tympanic antrum malformation in five, ossicular chain malformation in seven, cochlear malformation in six, helicotrema malformation in three, vestibule widening in two, semicircular canal malformation in three, vestibular window malformation in six, facial nerve abnormality in five, internal auditory meatus malformation in two, low middle cranial fossa in eight, and severe internal carotid artery malformation in one. Conclusion:Bony ET enlargement is a rare congenital middle ear malformation which could combined with other ear malformations. Patients can have no ET dysfunction but different patterns of hearing loss. The defect is usually found unintentionally during imaging, and the HRCT of temporal bone is significant.

The impact of size on middle-ear sound transmission in elephants, the largest terrestrial mammal.

Elephants have a unique auditory system that is larger than any other terrestrial mammal. To quantify the impact of larger middle ear (ME) structures, we measured 3D ossicular motion and ME sound transmission in cadaveric temporal bones from both African and Asian elephants in response to air-conducted (AC) tonal pressure stimuli presented in the ear canal (PEC). Results were compared to similar measurements in humans. Velocities of the umbo (VU) and stapes (VST) were measured using a 3D laser Doppler vibrometer in the 7-13,000 Hz frequency range, stapes velocity serving as a measure of energy entering the cochlea-a proxy for hearing sensitivity. Below the elephant ME resonance frequency of about 300 Hz, the magnitude of VU/PEC was an order of magnitude greater than in human, and the magnitude of VST/PEC was 5x greater. Phase of VST/PEC above ME resonance indicated that the group delay in elephant was approximately double that of human, which may be related to the unexpectedly high magnitudes at high frequencies. A boost in sound transmission across the incus long process and stapes near 9 kHz was also observed. We discuss factors that contribute to differences in sound transmission between these two large mammals.

Fossils document evolutionary changes of jaw joint to mammalian middle ear.

The dual jaw joint of Morganucodon1,2 consists of the dentary-squamosal joint laterally and the articular-quadrate one medially. The articular-quadrate joint and its associated post-dentary bones constitute the precursor of the mammalian middle ear. Fossils documenting the transition from such a precursor to the mammalian middle ear are poor, resulting in inconsistent interpretations of this hallmark apparatus in the earliest stage of mammaliaform evolution1-5. Here we report mandibular middle ears from two Jurassic mammaliaforms: a new morganucodontan-like species and a pseudotribosphenic shuotheriid species6. The morganucodontan-like species shows many previously unknown post-dentary bone morphologies1,2 and exhibits features that suggest a loss of load-bearing function in its articular-quadrate joint. The middle ear of the shuotheriid approaches the mammalian condition in that it has features that are suitable for an exclusively auditory function, although the post-dentary bones are still attached to the dentary. With size reduction of the jaw-joint bones, the quadrate shifts medially at different degrees in relation to the articular in the two mammaliaforms. These changes provide evidence of a gradual loss of load-bearing function in the articular-quadrate jaw joint-a prerequisite for the detachment of the post-dentary bones from the dentary7-12 and the eventual breakdown of the Meckel's cartilage13-15 during the evolution of mammaliaforms.

The influence of tympanic-membrane orientation on acoustic ear-canal quantities: A finite-element analysis.

Assuming plane waves, ear-canal acoustic quantities, collectively known as wideband acoustic immittance (WAI), are frequently used in research and in the clinic to assess the conductive status of the middle ear. Secondary applications include compensating for the ear-canal acoustics when delivering stimuli to the ear and measuring otoacoustic emissions. However, the ear canal is inherently non-uniform and terminated at an oblique angle by the conical-shaped tympanic membrane (TM), thus potentially confounding the ability of WAI quantities in characterizing the middle-ear status. This paper studies the isolated possible confounding effects of TM orientation and shape on characterizing the middle ear using WAI in human ears. That is, the non-uniform geometry of the ear canal is not considered except for that resulting from the TM orientation and shape. This is achieved using finite-element models of uniform ear canals terminated by both lumped-element and finite-element middle-ear models. In addition, the effects on stimulation and reverse-transmission quantities are investigated, including the physical significance of quantities seeking to approximate the sound pressure at the TM. The results show a relatively small effect of the TM orientation on WAI quantities, except for a distinct delay above 10 kHz, further affecting some stimulation and reverse-transmission quantities.