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Medicine International 2023The middle ear represents the anatomic space between the external auditory canal and the inner ear (Cochlea). It is comprised of the tympanic membrane, the ossicular... (Review)
Review
The middle ear represents the anatomic space between the external auditory canal and the inner ear (Cochlea). It is comprised of the tympanic membrane, the ossicular chain [malleus (hammer), incus (anvil) and stapes (stirrup)] with the corresponding muscles and ligaments and the cavity of the middle ear. The main function of the middle ear is to convey vibratory energy (sound pressure) from the air to the cochlear fluids of the internal ear via the ossicular chain. Tympanoplasty represents a number of procedures used to re-establish the continuity of sound transmission from the tympanic membrane to the inner ear. Ever since the beginning of otologic surgery, various materials have been tested for ossicular chain reconstruction (OCR). The present review aimed to present, in a chronological sequence, the evolution of knowledge regarding this field of medicine, and to also discuss the advantages and disadvantages of different materials and designs of ossicular prostheses. The constant search for more efficient, easily tolerated and lighter materials has improved the acoustic rehabilitation process and has markedly reduced the rate of functional failure of these small prostheses.
PubMed: 36875817
DOI: 10.3892/mi.2023.73 -
The Pan African Medical Journal 2021The purpose of this study was to evaluate the functional outcomes of ossiculoplasties. We conducted a retrospective study, in the department of ear, nose and throat... (Comparative Study)
Comparative Study Review
The purpose of this study was to evaluate the functional outcomes of ossiculoplasties. We conducted a retrospective study, in the department of ear, nose and throat (ENT) and congestive cardiac failure (CCF) at the University Hospital Mohammed VI, in Oujda, from October 2018 to March 2020. Out of 45 patients with secondary otitis, 30 had gone ossiculoplasty using endoscopic transmeatal approach. These patients were enrolled in the study. The average age of patients was 31.8 years, with a F/M sex ratio of 1.5. The examination of the eardrum showed type A otitis (18 cases) type B otitis (5 cases), type C otitis (3 cases) and type D otitis (4 cases), according to Austin classification; 70% of patients who had undergone surgery had hearing loss between 30 and 40 dB and 30% of patients had hearing loss of ≥40 dB. Type II ossiculoplasty was performed in 26 cases, using tragal cartilage in 18 cases. Autologous incus interposition graft and placement of titanium PORP were performed in 4 cases each, whereas ossiculoplasty type III was performed in 4 cases, with placement of titanium TORP. Type II ossiculoplasty group had a hearing gain of ≥20 dB (all cases), whereas type III ossiculoplasty group had a hearing gain of ≥1 dB (1 case). Success rate was 90%. The analysis of these results shows that the overall outcome is slightly worse in patients undergoing type III ossiculoplasty than in those undergoing type II ossiculoplasty. However, comparative studies between the placement of prostheses and autografts or between different types of materials have only shown minor differences reported by the same author or the same team. Many authors highlighted that the preservation of the handle of malleus could provide better functional results.
Topics: Adolescent; Adult; Cartilage; Child; Female; Hearing Loss; Humans; Male; Middle Aged; Ossicular Replacement; Otitis; Retrospective Studies; Titanium; Treatment Outcome; Tympanoplasty; Young Adult
PubMed: 33995793
DOI: 10.11604/pamj.2021.38.187.27449 -
Anatomical Record (Hoboken, N.J. : 2007) Sep 2019Incus angles of axes (the angle between "short process axis" and the "long process axis") are more open in humans than chimpanzees: 64.0 versus 55.7 degrees (Quam et...
Incus angles of axes (the angle between "short process axis" and the "long process axis") are more open in humans than chimpanzees: 64.0 versus 55.7 degrees (Quam et al.: J Anat 225 (2014) 167-196). However, Flohr et al. (Anat Rec 293 (2010) 2094-2106) raise concern about interobserver agreement of the axes. The concern is important as phylogenetic relationships of mammals are inferred from the incus (and malleus and stapes). We sought to check (1) interobserver agreement; and (2) if the angles of the axes of incudes (incuses) exhibit bilateral symmetry, which is expected if the axes are genetically determined. We studied incudes from 41 modern adult crania with clinically normal temporal bones. Angles of axes were determined on rectilinear digital photographs of incudes in standard lateral orientation. Two observers independently drew the axes and measured the axes. Interobserver agreement was within 4 degrees for 24 of 34 left-sided incudes and for 27 of 35 right-sided incudes. The mean of the two observers' angle determinations were used. Left incudes' median was 67 degrees, range 60-73; right 67.5 degrees, range 58-77. Bilateral symmetry of angles of axes was found: r = 0.55, N = 31, 95% CI 0.24-0.75. Angles of axes of modern human incudes are probably genetically determined features, but are of doubtful physiologic or evolutionary advantage in modern humans. Interobserver agreement of angles of modern human axes is concerning and must be specified in reports. Consideration should be given to a convention to designate axes in ambiguous cases. Anat Rec, 302:1615-1619, 2019. © 2019 American Association for Anatomy.
Topics: Adult; Humans; Incus; Mastoid; Observer Variation; Temporal Bone
PubMed: 31120197
DOI: 10.1002/ar.24178 -
Frontiers in Bioscience (Landmark... Jan 2011The middle ear is a composite organ formed from all three germ layers and the neural crest. It provides the link between the outside world and the inner ear, where sound... (Review)
Review
The middle ear is a composite organ formed from all three germ layers and the neural crest. It provides the link between the outside world and the inner ear, where sound is transduced and routed to the brain for processing. Extensive classical and modern studies have described the complex morphology and origin of the middle ear. Non-mammalian vertebrates have a single ossicle, the columella. Mammals have three functionally equivalent ossicles, designated the malleus, incus and stapes. In this review, I focus on the role of genes known to function in the middle ear. Genetic studies are beginning to unravel the induction and patterning of the multiple middle ear elements including the tympanum, skeletal elements, the air-filled cavity, and the insertion point into the inner ear oval window. Future studies that elucidate the integrated spatio-temporal signaling mechanisms required to pattern the middle ear organ system are needed. The longer-term translational benefits of understanding normal and abnormal ear development will have a direct impact on human health outcomes.
Topics: Amphibians; Animals; Birds; Chondrogenesis; Ear, Middle; Epithelial-Mesenchymal Transition; Eustachian Tube; Humans; Mammals; Neural Crest; Organogenesis; Osteogenesis; Reptiles; Signal Transduction; Tympanic Membrane
PubMed: 21196256
DOI: 10.2741/3813 -
PloS One 2021To assess the feasibility of radiologic measurements and find out whether hearing outcome could be predicted based on computer tomography (CT) scan evaluation in...
OBJECTIVES
To assess the feasibility of radiologic measurements and find out whether hearing outcome could be predicted based on computer tomography (CT) scan evaluation in patients with temporal bone fractures and suspected ossicular joint dislocation.
METHODS
We assessed 4002 temporal bone CT scans and identified 34 patients with reported ossicular joint dislocation due to trauma. We excluded those with no proven traumatic ossicular dislocation in CT scan and patients with bilateral temporal bone fractures. We measured four parameters such as malleus-incus axis distance, malleus-incus angle at midpoints, malleus- incus axis angle and ossicular joint space. The contralateral healthy side served as its own control. Hearing outcome 1-3 months after the index visit was analyzed. We assessed diagnostic accuracy and performed a logistic regression using radiologic measurement parameters for outcome prediction of conductive hearing loss (defined as >20dB air-bone gap).
RESULTS
We found excellent inter-rater agreement on the measurement of axis deviation between incus and malleus in CT scans (interclass correlation coefficient 0.81). The larger the deviation of incus and malleus axis, the higher probability of poor hearing outcome (odds ratio (OR) 2.67 per 0.1mm, p = .006). A cut-off value for the axis deviation of 0.25mm showed a sensitivity of 0.778 and a specificity of 0.94 (p < .001) for discrimination between poor and good hearing outcome in terms of conductive hearing loss.
CONCLUSION
Adequate assessment of high resolution CT scans of temporal bone in which ossicular chain dislocation had occurred after trauma was feasible. Axis deviations of the incus and the malleus were strongly predictive for poor hearing outcome in terms of air conduction 1-3 months after trauma. We propose a 3-level classification system for hearing outcome prediction based on radiologic measures.
Topics: Ear Ossicles; Feasibility Studies; Female; Hearing; Humans; Male; Middle Aged; Prognosis; Retrospective Studies; Tomography, X-Ray Computed
PubMed: 33556107
DOI: 10.1371/journal.pone.0245796 -
Proceedings of the National Academy of... Dec 2006At frequencies above 3 kHz, the tympanic membrane vibrates chaotically. By having many resonances, the eardrum can transmit the broadest possible bandwidth of sound with...
At frequencies above 3 kHz, the tympanic membrane vibrates chaotically. By having many resonances, the eardrum can transmit the broadest possible bandwidth of sound with optimal sensitivity. In essence, the eardrum works best through discord. The eardrum's success as an instrument of hearing can be directly explained through a combination of its shape, angular placement, and composition. The eardrum has a conical asymmetrical shape, lies at a steep angle with respect to the ear canal, and has organized radial and circumferential collagen fiber layers that provide the scaffolding. Understanding the role of each feature in hearing transduction will help direct future surgical reconstructions, lead to improved microphone and loudspeaker designs, and provide a basis for understanding the different tympanic membrane structures across species. To analyze the significance of each anatomical feature, a computer simulation of the ear canal, eardrum, and ossicles was developed. It is shown that a cone-shaped eardrum can transfer more force to the ossicles than a flat eardrum, especially at high frequencies. The tilted eardrum within the ear canal allows it to have a larger area for the same canal size, which increases sound transmission to the cochlea. The asymmetric eardrum with collagen fibers achieves optimal transmission at high frequencies by creating a multitude of deliberately mistuned resonances. The resonances are summed at the malleus attachment to produce a smooth transfer of pressure across all frequencies. In each case, the peculiar properties of the eardrum are directly responsible for the optimal sensitivity of this discordant drum.
Topics: Animals; Cats; Hearing; Models, Biological; Tympanic Membrane
PubMed: 17170142
DOI: 10.1073/pnas.0603898104 -
Saudi Medical Journal Jun 2021Malleostapedotomy (MS) is an evolving otology procedure that involves attaching prosthesis to the malleus on one end and the stapes footplate on the other end. It has... (Review)
Review
Malleostapedotomy (MS) is an evolving otology procedure that involves attaching prosthesis to the malleus on one end and the stapes footplate on the other end. It has multiple indications and requires skills and experience. We present 2 cases operated in our center (King Abdullah Ear Specialist Center, Riyadh, Saudi Arabia) in which intraoperative incus injury occurred, and MS was used to reconstruct the ossicular chain with good postoperative outcomes and patient satisfaction. As the procedure was surgically difficult and time consuming, many otologists prefer not to do it. Nevertheless, we believe that all surgeons dealing with stapes surgery should be familiar and gain confidence in performing MS considering that intraoperative incus dislocation is a complication that can happen even with great caution.
Topics: Humans; Incus; Malleus; Ossicular Prosthesis; Saudi Arabia; Stapes Surgery
PubMed: 34078733
DOI: 10.15537/smj.2021.42.6.20200460 -
Clinical Significance of Körner's Septum in Relation to Occurrence of Squamous Chronic Otitis Media.Cureus Nov 2022The Körner's septum (KS), persistent petrosquamosal lamina, is a bony lamina (developmental remnant) that extends from the articular fossa to the mastoid apex, above... (Review)
Review
The Körner's septum (KS), persistent petrosquamosal lamina, is a bony lamina (developmental remnant) that extends from the articular fossa to the mastoid apex, above the middle ear, and runs inferiorly and laterally to the facial nerve canal. The petrous and squamous bones meet at this septum. The anatomical structure of KS, which most frequently occurs at the level of the head of the malleus and/or the anterior semicircular canal, is described in depth in this work. The embryological elements of the temporal bone development that result in the formation of KS are taken into consideration. Clinically KS is considered an important anatomical variation, in the development of chronic diseases of the ear like chronic otitis media, especially attic retraction pockets, and cholesteatoma as it can contribute to attic blockage. Also, studies have found a significant association between tympanosclerosis and KS. High-resolution computed tomography (HRCT) and cone-beam computed tomography are the two imaging methods most commonly used to identify KS. It is observed that KS was associated with an increased risk for chronic otitis media, and residual cholesteatoma. The purpose of this review article is to provide a general overview of the KS and its clinical implication, as well as to summarize and discuss the latest clinical data regarding this entity.
PubMed: 36475185
DOI: 10.7759/cureus.31070 -
Journal of the Association For Research... Aug 2014In previous studies, 3D motion of the middle-ear ossicles in cat and human was explored, but models for hearing research have shifted in the last few decades to smaller...
In previous studies, 3D motion of the middle-ear ossicles in cat and human was explored, but models for hearing research have shifted in the last few decades to smaller mammals, and gerbil, in particular, has become a popular hearing model. In the present study, we have measured with an optical interferometer the 3D motion of the malleus and incus in anesthetized gerbil for sound of moderate intensity (90-dB sound pressure level) over a broad frequency range. To access the ossicles, the pars flaccida was removed exposing the neck and head of the malleus and the incus from the malleus-incus joint to the plate of the lenticular process. Vibration measurements were done at six to eight points per ossicle while the angle of observation was varied over approximately 30 ° to enable calculation of the 3D rigid-body velocity components. These components were expressed in an intrinsic reference frame, with one axis along the anatomical suspension axis of the malleus-incus block and a second axis along the stapes piston direction. Another way of describing the motion that does not assume an a priori rotation axis is to calculate the instantaneous rotation axis (screw axis) of the malleus/incus motion. Only at frequencies below a few kilohertz did the screw axis have a maximum rotation in a direction close to that of the ligament axis. A slight slippage in the malleus-incus joint developed with increasing frequency. Our findings are useful in determining the sound transfer characteristics through the middle ear and serve as a reference for validation of mathematical middle-ear models. Last but not least, comparing our present results in gerbil with those of previously measured species (human and cat) exposes similarities and dissimilarities among them.
Topics: Animals; Cats; Finite Element Analysis; Gerbillinae; Hearing; Humans; Imaging, Three-Dimensional; Incus; Malleus; Models, Animal; Models, Theoretical; Rotation; Vibration
PubMed: 24691793
DOI: 10.1007/s10162-014-0452-1 -
Developmental Dynamics : An Official... Dec 2020The mammalian middle ear comprises a chain of ossicles, the malleus, incus, and stapes that act as an impedance matching device during the transmission of sound from the... (Review)
Review
The mammalian middle ear comprises a chain of ossicles, the malleus, incus, and stapes that act as an impedance matching device during the transmission of sound from the tympanic membrane to the inner ear. These ossicles are derived from cranial neural crest cells that undergo endochondral ossification and subsequently differentiate into their final functional forms. Defects that occur during middle ear development can result in conductive hearing loss. In this review, we summarize studies describing the crucial roles played by signaling molecules such as sonic hedgehog, bone morphogenetic proteins, fibroblast growth factors, notch ligands, and chemokines during the differentiation of neural crest into the middle ear ossicles. In addition to these cell-extrinsic signals, we also discuss studies on the function of transcription factor genes such as Foxi3, Tbx1, Bapx1, Pou3f4, and Gsc in regulating the development and morphology of the middle ear ossicles.
Topics: Animals; Bone Morphogenetic Proteins; Cell Differentiation; Chemokines; Ear Ossicles; Ear, Middle; Fibroblast Growth Factors; Humans; Neural Crest; Signal Transduction; Transcription Factors
PubMed: 33058336
DOI: 10.1002/dvdy.260