Induced and genetic mouse middle ear ossicular malformations: a model for human malformative ossicular diseases and a tool for clarifying their normal ontogenesis

Summary Oral administration of 13-cis retinoic acid (RA) to pregnant mice on the 9th gestation day provokes important malformations of the middle ear ossicles, associated with a general kind of craniofacial dysmorphogenesis evoking the human mandibulofacial dysostosis. The malleus, incus and stapes are affected. The malleus exhibits a handle separated from its head and keeping a persistant relationship with the tubotympanic recess. The stapes makes no contact with the otic capsule. The malformation pattern is visible early as shown by the appearance of an abnormally curved Meckel's cartilage at day 12, followed by the development of atypically shaped ossicular anlagen. The mouse far (first arch malformation) mutation is responsible for minor ossicular abnormalities which disrupts the normal relationships between the stapes, Reichert's cartilage and stapedial muscle. The administration of RA to pregnant mice and the comparison with a genetically induced malformation (the mutation far) provides some interesting information about the postulated mechanisms of human middle ear dysmorphogenesis, as well as precious data about the features of normal ossicular primordia formation. The comparison of these features with human middle ear abnormalities as revealed by medical imaging sheds light on human malformation patterns and provides a better understanding of normal and abnormal radiologic ossicular aspects.

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Malformations des osselets de l'ouïe de la souris d'origine génétique et induite : un modèle pour les malformations ossiculaires humaines et une aide pour la compréhension de leur ontogenèse normale

Résumé L'administration orale d'acide rétinoïque (AR) à des souris gravides à 9 jours de gestation est responsable d'importantes malformations des osselets de l'oreille moyenne, associées à une dysmorphose d'ensemble de la sphère maxillo-faciale évoquant la dysostose mandibulo-faciale humaine. Le malleus, l'incus et le stapes sont affectés. Le malleus présente un manche séparé de sa tête et conservant un rapport constant avec le récessus tubo-tympanique. Le stapes peut ne présenter aucun contact avec la capsule otique. L'atteinte malformative est précocement visible par l'apparition d'un cartilage de Meckel anormalement arciforme au douxième jour, suivie du développement d'ébauches ossiculaires présentant d'emblée une forme anormale. L'administration d'AR à des souris gravides et la comparaison des résultats obtenus avec un modèle génétique (la mutation far) est source d'informations très intéressantes relatives aux mécanismes supposés caractériser les dysmorphoses de l'oreille moyenne dans l'espèce humaine. Cette méthodes nous fournit en outre de précieux renseignements relatifs aux caractéristiques de l'ontogenèse ossiculaire normale.

     

耳内镜下新西兰兔中耳的解剖研究

目的　耳内镜下观察兔中耳解剖结构,探讨兔作为耳内镜解剖训练模型的可行性,为兔中耳相关的其他实验研究提供解剖学依据。 方法　5只（10耳）新西兰兔麻醉处死后,耳内镜下经外耳道入路观察兔鼓膜、中耳鼓室结构,辨别听小骨、上中下鼓室、面神经等。 结果　与人对比,新西兰兔听小骨由锤砧联合体和镫骨组成;上鼓室外侧壁部分骨质缺如,由鼓膜向上延续并覆盖;听泡类似于人的中、下鼓室,包含咽鼓管、面神经、鼓岬、前庭窗、蜗窗以及鼓室神经等结构,乳突为听泡尾侧的板障型骨管;面神经鼓室段水平走行于上鼓室下方骨壁内,后经锥隆起垂直走行于听泡后壁,经茎乳孔出听泡。 结论　新西兰兔中耳结构与人相似,既可作为耳科医生练习耳内镜操作的解剖模型,也可作为耳部三维解剖结构的教学标本。     

耳内镜下新西兰兔中耳的解剖研究

目的　耳内镜下观察兔中耳解剖结构,探讨兔作为耳内镜解剖训练模型的可行性,为兔中耳相关的其他实验研究提供解剖学依据。 方法　5只（10耳）新西兰兔麻醉处死后,耳内镜下经外耳道入路观察兔鼓膜、中耳鼓室结构,辨别听小骨、上中下鼓室、面神经等。 结果　与人对比,新西兰兔听小骨由锤砧联合体和镫骨组成;上鼓室外侧壁部分骨质缺如,由鼓膜向上延续并覆盖;听泡类似于人的中、下鼓室,包含咽鼓管、面神经、鼓岬、前庭窗、蜗窗以及鼓室神经等结构,乳突为听泡尾侧的板障型骨管;面神经鼓室段水平走行于上鼓室下方骨壁内,后经锥隆起垂直走行于听泡后壁,经茎乳孔出听泡。 结论　新西兰兔中耳结构与人相似,既可作为耳科医生练习耳内镜操作的解剖模型,也可作为耳部三维解剖结构的教学标本。     

A comparative immunohistochemical study of cytokeratin and vimentin expression in middle ear mucosa and cholesteatoma,and in epidermis

Summary Cytokeratin expression was studied in human middle ear cholesteatoma lesions, using a variety of immunohistological techniques and a wide range of polyclonal antisera and monoclonal antibodies against cytokeratin (CK) subgroups or individual CK polypeptides. The expression of the other cytoskeletal proteins, vimentin and desmin, was also investigated. Middle ear mucosa and epidermal tissues were used as reference tissues. Our investigations also included epithelial structures present in the cholesteatoma perimatrix and in dermal tissues.The results indicate that, compared with epidermal tissues, the expression profile of CKs in cholesteatoma matrix is representative of a hyperproliferative disease. Evaluating the presence of a marker of terminal keratinization - the 56.5 kD acidic CK n^o 10 - we found supportive evidence of a pronounced retardation of its expression, which did not parallel histological differentiation. In epidermal tissues, the first prickle cell layers are CK10 positive whereas in many cholesteatomas this finding was observed near the stratum granulosum only. Probing the early stages of keratinization -the 58 kD basic CK n^o 5 and the 50 kD acidic CK n^o 14 - we regularly observed an extended staining area in the cholesteatoma matrix. In epidermal reference tissues, only the basal and nearest suprabasal layers were convincingly labeled.As a rule, non-epidermal CKs did not belong to the cholesteatoma CK set. However, exceptions to that rule were noticed as a focal or more extended expression of one or more non-epidermal CKs in about half of the cases. Together with the extended CK5 topography, this is further evidence that CK expression is seriously affected by the diseased state. CK expression in the perimatrix is limited to mucous glands, either normal, atrophic or hyperplastic. CKs n^o 4, 5, 7, 14, 18 and 19, also displayed by middle ear mucosa, were consistently observed. Where ductal arrangements were present, CK10 was also detected, in analogy with the CK10 registration in ductal portions of mucous glands in the external ear canal skin. The absence of CK8 in mucous glands of the perimatrix, however, strongly differentiates these structures from the mucous gland acini and ducti in the external ear canal, where CK8 is systematically expressed. Vimentin staining was restricted to dendritic cells of the matrix (Langerhans cells) and to perimatrix fibroblasts, blood cells and vascular endothelium. Coexpression of CK and vimentin was not observed.     

Finite element analysis of the middle ear transfer functions and related pathologies

With developments in software and micro-measurement technology, a three-dimensional middle ear finite element (FE) model can now be more easily constructed to study sound transfer function. Many FE models of the middle ear have been constructed to date, and each has its own particular advantages and disadvantages. In this article, we review the latest developments and technologies in the field of the FE models of the middle ear, and the use of FE in the study of middle ear pathology. Proposals are made for future developments in the field of finite element analysis of middle ear transfer function.     

高压下中耳结构动力损伤研究

目的研究高压对中耳结构造成的损伤。方法基于CT扫描建立中耳结构有限元数值模型,对模型施加随时间变化的压力,分析鼓膜以及镫骨足板的应力、应变和位移变化。结果获得的计算结果与相关文献中的试验数据吻合,验证了所建中耳模型的准确性。高压会对中耳造成损伤,随着压力的增加,损伤加重;快速加压使得中耳损伤严重,对内耳的影响较小;慢速加压也能导致中耳损伤,但在中耳损伤前,内耳会损伤。结论高压容易导致人耳出现损伤,为避免听力受到影响,在加压过程中要控制好加压速率。     

显示中耳和内耳细微结构的标准化标本制作方法

目的 探索显示中耳和内耳细微结构直视标本的标准化制作方法。 方法 使用人颞骨材料,在颅内和颅底面画出标准锯路的标志线,选择细齿窄条钢弓锯,沿标志线锯开颞骨显示中耳结构。再用手握式玉石磨钻分别研磨显示内耳结构。最后完成对鼓膜、听小骨、面神经、鼓索神经和颈内动脉等结构的仿真复原,并用合页连结锯开的两半颞骨。 结果 在锯开的颞骨内可清晰显示中耳鼓室的6个壁,以及锥状隆起、咽鼓管、前庭窗和蜗窗等细微结构。磨制后的内耳可见3个打开的骨半规管和耳蜗的剖面。复原后的听骨链、面神经、鼓索神经、颈内动脉和鼓膜等结构,均以三维方式显示原有结构的特征和位置关系。由合页连结的颞骨标本,既可打开观察内部结构,也可合拢显示整体形态。 结论 采用锯开和研磨技术制作耳标本可以取得满意的结果,标准化的锯路标志和标准的定位研磨是成功制作的关键。     

Glycoconjugates in the middle ear and eustachian tubal epithelium

Glycoconjugates in the middle ear and eustachian tubal epithelium were investigated using lectin histochemical techniques. A comparison of the affinity of lectins demonstrated the heterogeneity of glycoconjugates in the secretory cells of the middle ear and eustachian tubal epithelium. Lectin histochemical analysis of sialoglycoconjugates in the developing murine tubotympanum showed that terminal galactose residues are masked by sialic acids around birth, and that sialic acids are important for mucociliary function.     

Carcinoid tumor of the middle ear: a case report and review of literature

Carcinoid tumors of the middle ear are very rare. Here we describe a 37-year-old man with multiple recurrent carcinoid tumor of the right middle ear. The CT demonstrated the recurrent mass that filled the tympanum and mastoid with osteolytic invasion, and the tumor was removed by surgery. The pathological findings showed the tumor cells, without necrosis and mitotic activity, had round, oval, or slightly irregular nuclei and finely-dispersed chromatin, arranged in cords, nests, and glandular structures. They were strongly positive for synaptophysin and CD56, but were negative for S-100 and chromogranin A. Ki-67 proliferation activity was low (<2%). With a review of the literature, the clinical, pathological characteristics and treatment modalities of this rare tumor are discussed.     

Finite element analysis of the effects of a floating mass transducer on the performance of a middle ear implant

Experimental evidence has shown that floating mass transducers (FMTs) play a key role in the performance of middle ear implants. However, because of the tiny size and complex structure of the middle ear, systematic experimental study of the influences of FMTs is difficult to carry out. In this paper we develop a FMT-attached middle-ear finite element model to investigate some effects of a FMT on the performance of a middle ear implant. This model was constructed based on a complete set of computerized tomography section images of a healthy volunteer's left ear. The validity of the developed model was verified by comparing the model-predicted motion of the tympanic membrane and stapes footplate with published experimental data. The result shows that the FMT produces a mass loading effect prominently at high frequencies, the force required to drive the incus to the equivalent of 100 dB sound pressure level (SPL) is about 89?μN, and setting the attachment position of the FMT close to the incudostapedial joint can enhance the driving effect.     

国人颞中静脉的解剖学研究及意义

目的　研究国人颞中静脉的解剖学特征和标志,为临床应用提供解剖学依据。 方法　26侧（左12侧,右14侧,男性18,女性3）经10%福尔马林灌注固定的人头标本,解剖颞区颞中静脉及属支,观察其走行分布,测量主干到各解剖标志距离及管径,计数属支数目并测量管径。比较左、右侧差异。 结果　所有标本存在颞中静脉,主干管径平均2.91 mm（0.72~5.88 mm）,属支0~7支,属支管径平均2.05 mm（0.54~5.30 mm）,可有2级属支（3.8%,1例）。主干汇入颞浅静脉的位置不完全一致,汇点高者在颧弓根部（42.3%,11例）,低者位于颧弓下缘9.02~21.00 mm处。主干大致有3种分布类型：①经典型53.8%（14例）,②分裂聚合型30.8%（8例）,③直角型15.4%（4例）。转折处到耳屏内侧缘的垂直距离平均18.69 mm,主干到颧弓中点、眶外缘与颧弓交界处、眼外眦、眉弓外端距离的平均值,左侧分别为：（17.23±7.29）、（18.82±9.00）、（21.14±6.96）、（9.62±8.87）mm,右侧分别为：（17.28±5.74）、（18.34±7.63）、（19.40±6.98）mm、（8.17±5.53）mm;相对应的管径平均值分别为左：（3.75±1.63）、（3.34±1.00）、（3.08±1.18）、（2.81±1.23）mm;右：（4.29±2.93）、（2.90±1.29）、（2.89±1.20）、（2.57±1.21）mm。左、右侧无统计学差异。 结论　对国人颞中静脉的走行分布进行解剖学类型划分,以丰富解剖学资料;掌握颞中静脉的解剖学特征和标志,于颞区手术具有指导意义。     

Morphogenesis of the middle ear ossicles and spatial relationships with the external and inner ears during the embryonic period

We describe the three‐dimensional morphogenesis of the middle ear ossicles (MEOs) according to Carnegie stage (CS) in human embryos. Seventeen samples including 33 MEOs from CS18 to 23 were selected from the Kyoto Collection. The primordia of the MEOs and related structures were histologically observed and three‐dimensionally reconstructed from digital images. The timing of chondrogenesis was variable among structures. The stapes was recognizable as a vague condensation of the mesenchymal cells in all samples from CS18, whereas the malleus and incus were recognizable at CS19. Chondrogenesis of all MEOs was evident in all samples after CS21. The chondrocranium was recognizable in all samples by CS18, and the perichondrium border of the auricular cartilage and otic capsule was distinct in all samples at CS23. At CS19, the MEOs were positioned in the anterior to posterior direction, following the order malleus, incus, stapes, which adjusted gradually during development. The MEOs connected in all samples after CS22. The stapes was located close to the vestibular part of the inner ear, although the basal part was not differentiated into the “footplate” form, even at CS23. The handles of the malleus were close to the tubotympanic recess at CS23, but were distant from the external auditory meatus. Determining the timeline of the formation of MEOs and connection of the external and inner ears can be informative for understanding hearing loss caused by failure of this connection. These data may provide a useful standard for morphogenesis, and will contribute to distinguishing between normal and abnormal MEO development. Anat Rec, 299:1325–1337, 2016. © 2016 Wiley Periodicals, Inc.     

Effect of anterior tympanomeatal angle blunting on the middle ear transfer function using a finite element ear model

The anterior tympanomeatal angle (ATA) blunting is clinically defined as a certain degree of the ATA obliteration due to excessive fibrous tissue formation, which is a relatively common complication of external auditory canal (EAC) related operations. The aim of this study was to examine the effect of ATA blunting on the middle ear transfer function using a finite element (FE) model. Results showed that the displacements at the tympanic membrane (TM), at the manubrium and at the stapes footplate, and also the ratio of stapes footplate velocity to the sound pressure in the EAC were decreased to various degrees from ATA blunting of Grades 1–4. This was more significant with TM thickening at the frequencies below 3.2 kHz, particularly in Grades 3 and 4 when analyzing the anterior region of the TM. The phase differences of TM and stapes footplate increased with the ATA blunting from Grades 1 to 4 in relation to normal ATA. It is noteworthy that the vibration mode of the malleus does not show obvious change, compared to the displacement reduction at the TM with ATA blunting Grades 1–4. These results suggest that FE analysis of ATA blunting effect appears to be effective.     

Effects of posture,hypotension and locally applied vasoconstriction on the middle ear microcirculation in anaesthetized humans

Studies by laser-Doppler flowmetry of middle ear microcirculation changes induced by physical and chemical stimuli in the animal have only recently been made. This prospective study, performed in humans, was designed to compare the effects of a postural manoeuvre (headup tilt 30°), hypotension and locally applied vasoconstriction on middle ear blood flow during anaesthesia. Circulatory changes provoked by a headup tilt of 30°, and successive intravenous boluses of potent vasodilators, were compared with circulatory changes provoked by locally applied adrenaline, in ten healthy patients in good physical states undergoing middle ear surgical repair. Heart rate and direct arterial pressure were continuously recorded via a radial artery cannula. Middle ear blood flow was continuously recorded via a laser-Doppler probe placed on the promontorium cavi tympani. Metabolic parameters (partial pressure of O₂ and CO₂ in arterial blood, pH, arterial lactate concentrations) and arterial concentrations of propofol were measured just before and just after the experiment. Headup tilt did not modify heart rate, mean arterial pressure or middle ear blood flow. Vasodilators (nicardipine, nitroprusside, nitroglycerin) provoked a fall in arterial pressure (P<0.0001,P<0.0001,P<0.019, respectively), but did not induce any significant variations in heart rate; variations occurred in middle ear blood flow (P>0.05, not significant) which were different according to patients and agents. Locally applied adrenaline provoked a fall in the middle ear blood flow (P<0.0012), with no effect on heart rate and arterial pressure. There were no significant changes in metabolic values, or propofol serum concentrations. The behaviour of the middle ear blood flow submitted to hypotension, posture, or to vasoconstriction could be related to counteracting regulatory responses and/or to direct vascular effects.     

典型中耳病变对圆窗激振听力补偿性能影响的数值分析

目的研究典型中耳病变对圆窗激振听力补偿效果的影响,为圆窗激振式人工中耳的优化设计提供参考。方法利用CT扫描和逆向成型技术建立包括中耳和耳蜗的有限元模型,并验证模型的可靠性。再基于该模型,通过改变相应组织的材料属性,分别模拟镫骨环韧带硬化、镫骨不正常发育和锤骨前韧带硬化3种典型中耳病变。通过对比相应的基底膜响应,分析这3种病变对圆窗激振听力补偿效果的影响。结果镫骨不正常发育主要在高频处降低圆窗激振的效果,镫骨环韧带硬化和锤骨前韧带硬化主要恶化圆窗激振低频段的响应。3种病变中,镫骨环韧带硬化对圆窗激振听力补偿效果影响较大,等效声压的减小量可高达17 d B。结论中耳病变恶化圆窗激振的听力补偿效果,且恶化量较大,故在设计圆窗激振式人工中耳时需要针对性地提高其作动器的输出量。     

Morphometric study of ear lobule in northwest Indian male subjects

A total of 260 male subjects between 1 and 80 years of age of north-west region of India were studied with regard to morphometry of the ear lobule. The purpose of the present study was to obtain average values and range of measurements of several parameters of the ear lobule and the differences between right and left lobules. Female subjects were excluded from the study due to piercing. Various measurements of lobule were taken with the help of Vernier and Lange's calipers. The results of the aforementioned measurements were analyzed statistically using Student's t-test. The maximum length of the lobule increased appreciably between 6-15 years and 41-80 years. The breadth of the ear lobule increased up to the age of 15 years and was almost static between the ages of 16 and 40 years and increased again from 41 years onwards. Length of the lobule showed significant growth from the age group of 6-10 to 11-15, 21-40 to 41-60 and 41-60 to 61-80 years on the right side and 6-10 to 11-15 and 21-40 to 41-60 years on the left side. Breadth and thickness of ear lobule also showed statistically significant growth pattern in some age groups. On comparing the ear lobe dimensions with the studies available in other populations of the world, it was observed that north-west Indians have smaller ear lobules as compared to Caucasian and Japanese populations. In the present study, the frequency of attached (square) type of lobules was the maximum, followed by free (pendulous) type and tapering lobules. These findings were similar to those found among the Onge tribe of Andhra (India) and Newars of Nepal.     

Morphometry of auditory ossicles in medieval human remains from Central Europe

Human auditory ossicles, the malleus, the incus, and the stapes, are located in the tympanic cavity in the temporal bone and through forming a chain for the sound transmission from the tympanic membrane to the cochlea, they play an important role in the hearing process. Despite their clinical, phylogenetic, and evolutionary significance, the morphometry of the human ear bones has not been examined systematically. The ear ossicles are the smallest bones of the human skeleton, attaining their final size and morphology already at birth. Initially, they have been found to exhibit minimal morphometric variation, but further studies brought the opposite results. The aim of this study was to examine the morphometric variation of human auditory ossicles recovered from medieval and postmedieval subadult skeletons from Poland, Central Europe. The analysis involved in a total of 166 ear bones. Their measurements were performed on microscopic images using CorelDraw x4, according to a protocol of Quam and Rak with modification of Flohr et al. and Wadhwa et al. Our study showed a significant metric variation in the measurements taken at areas of the greatest morphological variability of the ossicles. We found that greater linear dimensions were associated with lower values of angular measurements. These results reveal the inherent variation found in these supposed functionally constrained structures. Representation of even greater number of populations, time periods, and developmental stages are needed. Further study will expand our understanding of the global scope of variation found in ear ossicular morphology and its functional implications for paleoanthropology.