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Hearing Research Jan 2023The time delay and/or malfunctioning of the Eustachian tube may cause pressure differences across the tympanic membrane, resulting in quasi-static movements of the... (Review)
Review
The time delay and/or malfunctioning of the Eustachian tube may cause pressure differences across the tympanic membrane, resulting in quasi-static movements of the middle-ear ossicles. While quasi-static displacements of the human middle-ear ossicles have been measured one- or two-dimensionally in previous studies, this study presents an approach to trace three-dimensional movements of the human middle-ear ossicles under static pressure loads in the ear canal (EC). The three-dimensional quasi-static movements of the middle-ear ossicles were measured using a custom-made stereo camera system. Two cameras were assembled with a relative angle of 7° and then mounted onto a robot arm. Red fluorescent beads of a 106-125 µm diameter were placed on the middle-ear ossicles, and quasi-static position changes of the fluorescent beads under static pressure loads were traced by the stereo camera system. All the position changes of the ossicles were registered to the anatomical intrinsic frame based on the stapes footplate, which was obtained from µ-CT imaging. Under negative ear-canal pressures, a rotational movement around the anterior-posterior axis was dominant for the malleus-incus complex, with small relative movements between the two ossicles. The stapes showed translation toward the lateral direction and rotation around the long axis of the stapes footplate. Under positive EC pressures, relative motion between the malleus and the incus at the IMJ became larger, reducing movements of the incus and stapes considerably and thus performing a protection function for the inner-ear structures. Three-dimensional tracing of the middle-ear ossicular chain provides a better understanding of the protection function of the human middle ear under static pressured loads as immediate responses without time delay.
Topics: Humans; Ear, Middle; Ear Ossicles; Incus; Stapes; Rotation
PubMed: 36462376
DOI: 10.1016/j.heares.2022.108651 -
Surgical and Radiologic Anatomy : SRA Feb 2021The aims of the present study were to identify detailed positional relationship between the auditory ossicles and to provide theoretic navigational guidelines for...
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.
Topics: Aged; Cadaver; Female; Humans; Imaging, Three-Dimensional; Intraoperative Complications; Male; Malleus; Ossicular Prosthesis; Prosthesis Implantation; Stapes; Stapes Surgery; Stereotaxic Techniques; Temporal Bone; X-Ray Microtomography
PubMed: 32812128
DOI: 10.1007/s00276-020-02556-x -
Developmental Dynamics : An Official... Oct 2022Asymmetries in craniofacial anomalies are commonly observed. In the facial skeleton, the left side is more commonly and/or severely affected than the right. Such...
BACKGROUND
Asymmetries in craniofacial anomalies are commonly observed. In the facial skeleton, the left side is more commonly and/or severely affected than the right. Such asymmetries complicate treatment options. Mechanisms underlying variation in disease severity between individuals as well as within individuals (asymmetries) are still relatively unknown.
RESULTS
Developmental reductions in fibroblast growth factor 8 (Fgf8) have a dosage dependent effect on jaw size, shape, and symmetry. Further, Fgf8 mutants have directionally asymmetric jaws with the left side being more affected than the right. Defects in lower jaw development begin with disruption to Meckel's cartilage, which is discontinuous. All skeletal elements associated with the proximal condensation are dysmorphic, exemplified by a malformed and misoriented malleus. At later stages, Fgf8 mutants exhibit syngnathia, which falls into two broad categories: bony fusion of the maxillary and mandibular alveolar ridges and zygomatico-mandibular fusion. All of these morphological defects exhibit both inter- and intra-specimen variation.
CONCLUSIONS
We hypothesize that these asymmetries are linked to heart development resulting in higher levels of Fgf8 on the right side of the face, which may buffer the right side to developmental perturbations. This mouse model may facilitate future investigations of mechanisms underlying human syngnathia and facial asymmetry.
Topics: Animals; Branchial Region; Fibroblast Growth Factor 8; Heart; Humans; Jaw Abnormalities; Maxilla; Mice; Mouth Abnormalities
PubMed: 35618654
DOI: 10.1002/dvdy.501 -
European Archives of... Aug 2019The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to...
PURPOSE
The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to clarify the nature of TM, tympanic bone and malleus to propose a new anatomic classification.
METHODS
This cadaveric study was performed in two human heads and six fresh temporal bones. A study of the temporomandibular joint, external acoustic meatus (EAM), TM and middle ear structures was conducted. A medical literature review englobing anatomy, embryology, histology and phylogeny of the ear was performed and the results were compared with the results of the dissection.
RESULTS
The external ear is constituted by the auricle and the EAM. This last segment is made by a cartilaginous and an osseous portion. The osseous portion of the EAM is constituted mainly by tympanic bone. The external ear is separated from the middle ear by the TM. Inside the middle ear, there are three ossicles: malleus, incus and stapes, which allow the conduction of sound to the cochlea. Based on the anatomic dissection and medical literature review of the tympanic bone, malleus and TM, we propose that these structures are interconnected like a joint, and named it "Tympanicomalleal joint".
CONCLUSIONS
It seems that the TM can be part of a joint that evolved to improve sound transmission and middle ear protection. Thinking TM has part of a joint may help in the development of more efficient reconstructive surgical techniques.
Topics: Anatomy, Regional; Cadaver; Ear, Middle; Humans; Malleus; Models, Anatomic; Temporal Bone; Temporomandibular Joint; Tympanic Membrane; Tympanoplasty
PubMed: 31004197
DOI: 10.1007/s00405-019-05434-4 -
The Laryngoscope Mar 2024To report the largest case series of isolated malleus fractures with systematic review to characterize the disease's presentation and natural history, and provide... (Review)
Review
OBJECTIVE
To report the largest case series of isolated malleus fractures with systematic review to characterize the disease's presentation and natural history, and provide suggestions for management.
DATA SOURCES
PubMed, Embase, Cochrane Library.
REVIEW METHODS
Retrospective cohort study was performed on 12 patients with isolated malleus fractures. History, physical exam, pre- and post-treatment audiograms, and imaging were obtained. Systematic review of the literature was performed.
RESULTS
Including the cases herein, 58 isolated malleus fractures were identified, the majority of which were published in the 21st century. Mean time to presentation after injury was 34.4 months. Most common etiology was external auditory canal (EAC) manipulation. Physical exam and imaging did not identify any abnormality at presentation in 16% and 21% of cases, respectively. The majority of fractures involved the manubrium. Air-bone gap (ABG) at initial presentation ranged from 16 to 26 dB, and was greater at higher frequencies. Thirty-six cases underwent surgery. ABG improvement was greater at all frequencies for those who underwent surgery. Final ABG was significantly less than initial ABG at nearly every frequency for those who underwent surgery (p < 0.05), while not at any frequency for those who were observed.
CONCLUSIONS
Isolated malleus fractures may occur more often than historical data suggests, and are perhaps underdiagnosed. Abrupt removal of a finger from the EAC with pain and hearing loss is nearly pathognomonic. Conductive hearing loss with ABG greater at higher frequencies is most often observed. Observation is unlikely to produce spontaneous improvements in hearing, while surgery demonstrates reliable decreases in ABG. Laryngoscope, 134:1032-1041, 2024.
Topics: Humans; Malleus; Hearing Loss, Conductive; Retrospective Studies; Hearing; Hearing Tests; Fractures, Bone; Treatment Outcome
PubMed: 37584374
DOI: 10.1002/lary.30962 -
Environment International Jan 2022Harbour porpoises are under pressure from increasing human activities. This includes the detonation of ammunition that was dumped in large amounts into the sea during...
Harbour porpoises are under pressure from increasing human activities. This includes the detonation of ammunition that was dumped in large amounts into the sea during and after World War II. In this context, forty-two British ground mines from World War II were cleared by means of blasting in the period from 28 to 31 August 2019 by a NATO unit in the German Exclusive Economic Zone within the marine protected area of Fehmarn Belt in the Baltic Sea, Germany. Between September and November 2019, 24 harbour porpoises were found dead in the period after those clearing events along the coastline of the federal state of Schleswig-Holstein and were investigated for direct and indirect effects of blast injury. Health evaluations were conducted including examinations of the brain, the air-filled (lungs and gastrointestinal tract) and acoustic organs (melon, acoustic fat in the lower jaw, ears and their surrounding tissues). The bone structure of the tympano-periotic complexes was examined using high-resolution peripheral quantitative computed tomography (HR-pQCT). In 8/24 harbour porpoises, microfractures of the malleus, dislocation of middle ear bones, bleeding, and haemorrhages in the melon, lower jaw and peribullar acoustic fat were detected, suggesting blast injury. In addition, one bycaught animal and another porpoise with signs of blunt force trauma also showed evidence of blast injury. The cause of death of the other 14 animals varied and remained unclear in two individuals. Due to the vulnerability and the conservation status of harbour porpoise populations in the Baltic Sea, noise mitigation measures must be improved to prevent any risk of injury. The data presented here highlight the importance of systematic investigations into the acute and chronic effects of blast and acoustic trauma in harbour porpoises, improving the understanding of underwater noise effects and herewith develop effective measures to protect the population level.
Topics: Animals; Blast Injuries; Explosions; Lung; Phocoena; Porpoises; World War II
PubMed: 34883460
DOI: 10.1016/j.envint.2021.107014 -
Anatomical Record (Hoboken, N.J. : 2007) Nov 2023The placental order Dermoptera, which includes two extant species, the Philippine and Sunda flying lemurs, Cynocephalus volans and Galeopterus variegatus, respectively,...
The placental order Dermoptera, which includes two extant species, the Philippine and Sunda flying lemurs, Cynocephalus volans and Galeopterus variegatus, respectively, is generally held to be the sister group of Primates. Yet, little has been reported on their cranial anatomy. Here, the anatomy of the ear region is described and illustrated for a juvenile and adult C. volans based on CT scans. The inclusion of a juvenile is essential as nearly all cranial sutures are fused in the adult. Soft tissues are reconstructed based on sectioned histological pre- and postnatal specimens previously reported by the author. Numerous unusual features are identified, including: a small parasphenoid beneath the basisphenoid, a tensor tympani fossa on the epitympanic wing of the squamosal, a cavum supracochleare for the geniculate ganglion of the facial nerve that is not enclosed in the petrosal bone, a secondary facial foramen between the petrosal and squamosal, a secondary posttemporal foramen leading to the primary one, a subarcuate fossa that is floored in part by a large contribution from the squamosal, a body of the incus larger than the head of the malleus, and a crus longum of the incus that lacks an osseous connection to the lenticular process. Documentation of the anatomy of the Philippine flying lemur ear region is an essential first step in morphological phylogenetic analyses where features of the basicranium are widely sampled.
Topics: Pregnancy; Animals; Female; Phylogeny; Lemur; Philippines; Placenta; Primates; Chiroptera
PubMed: 36897245
DOI: 10.1002/ar.25174 -
Anatomical Record (Hoboken, N.J. : 2007) Nov 2019Development of mouse gonial bone and initial ossification process of malleus were investigated. Before the formation of the gonial bone, the osteogenic area expressing...
Development of mouse gonial bone and initial ossification process of malleus were investigated. Before the formation of the gonial bone, the osteogenic area expressing alkaline phosphatase and Runx2 mRNA was widely recognized inferior to Meckel's cartilage. The gonial bone was first formed within the perichondrium at E16.0 via intramembranous ossification, surrounded the lower part of Meckel's cartilage, and then continued to extend anteriorly and medially until postnatal day (P) 3.0. At P0, multinucleated chondroclasts started to resorb the mineralized cartilage matrix with ruffled borders at the initial ossification site of the malleus (most posterior part of Meckel's cartilage). Almost all CD31-positive capillaries did not run through the gonial bone but entered the cartilage through the site where the gonial bone was not attached, indicating the forms of the initial ossification site of the malleus are similar to those at the secondary ossification center rather than the primary ossification center in the long bone. Then, the reducing process of the posterior part of Meckel's cartilage with extending gonial bone was investigated. Numerous tartrate-resistant acid phosphatase-positive mononuclear cells invaded the reducing Meckel's cartilage, and the continuity between the malleus and Meckel's cartilage was completely lost by P3.5. Both the cartilage matrix and the perichondrium were degraded, and they seemed to be incorporated into the periosteum of the gonial bone. The tensor tympani and tensor veli palatini muscles were attached to the ligament extending from the gonial bone. These findings indicated that the gonial bone has multiple functions and plays important roles in cranial formation. Anat Rec, 302:1916-1933, 2019. © 2019 American Association for Anatomy.
Topics: Animals; Bone Development; Cartilage; Female; Malleus; Mandible; Mice; Mice, Inbred ICR; Ossification, Heterotopic; Osteogenesis
PubMed: 31197954
DOI: 10.1002/ar.24201 -
Otology & Neurotology : Official... Jan 2021This study aimed to evaluate success rates after ossicular chain reconstruction using different materials.
OBJECTIVE
This study aimed to evaluate success rates after ossicular chain reconstruction using different materials.
STUDY DESIGN
Retrospective cohort study.
SETTING
Tertiary referral center.
PATIENTS
Four hundred forty-three participants who underwent ossiculoplasty at a tertiary medical center were included.
INTERVENTION
Ossicular chain reconstruction using five materials: autologous malleus, incus, and cortical bone, as well as Hydroxyapatite (HA) and titanium.
MAIN OUTCOME MEASURES
Hearing data were measured 1 day preoperatively and 6 months postoperatively. Successful hearing outcomes were defined by the fulfillment of more than one of the following criteria: postoperative air-bone gap of 20 dB or less, hearing air conduction (AC) gain of 15 dB or more, or postoperative AC hearing less than 30 dB.
RESULTS
Preoperative median AC values (95% confidence interval) among participants with malleus, incus, cortical bone, HA, and titanium transplants or prostheses were 50 (39.6-54.6) dB, 51.3 (48.1-51.8) dB, 50 (45.2-52.2) dB, 56.3 (50.9-57.6) dB, and 54.3 (48.5-56.0) dB, respectively (p = 0.092). The success rates in malleus, incus, cortical bone, HA, and titanium were 53.3%, 60.3%, 51.7%, 61.6%, and 69.7%, respectively. Titanium had the highest success rate among the five materials, but the differences between the materials were not statistically significant (p = 0.283). Titanium had highest success rate among the participants with erosive stapes suprastructure or obstructed Eustachian tubes (p = 0.042 for erosive stapes suprastructure and p = 0.010 for obstructed Eustachian tubes).
CONCLUSION
Our study demonstrated that titanium prostheses would be a good alternative for ossiculoplasty in cases wherein autologous material is unavailable, especially in association with unfavorable conditions, such as with the presence of cholesteatoma, erosive stapes suprastructure, edematous middle ear mucosa, and obstructed Eustachian tube.
Topics: Humans; Ossicular Prosthesis; Ossicular Replacement; Otitis Media; Retrospective Studies; Treatment Outcome; Tympanoplasty
PubMed: 33201076
DOI: 10.1097/MAO.0000000000002847 -
Indian Journal of Otolaryngology and... Dec 2023The temporal bone is a complex anatomical space that houses the middle ear and its ossicles, as well as the inner ear, which includes the vestibule, cochlea, and the...
The temporal bone is a complex anatomical space that houses the middle ear and its ossicles, as well as the inner ear, which includes the vestibule, cochlea, and the semicircular canals. Henle's spine, also known as the suprameatal spine/spina suprameatica/ is found to guide the lateral wall of the mastoid antrum [J Res Med Dent Sci 8(7):420-422, Stat-Pearls Publishing, Treasure Island. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559153/]. It is found that the Henle's spine is present in 85% of the human skulls and when present, it could be used as a reliable anatomical landmark for isolating various foramina during skull base surgeries [J Laryngol Otol 119:856-861], and to assess the location of handle of malleus and subsequently the mastoid antrum, in many cases. We present here 3 cases in which tympanoplasty was planned, and the position of spine of Henle was found to be anterosuperior and so was the handle of malleus. Antrostomy was done by following the spine of Henle in all cases to establish patency and maintain ventilation in the post-operative ear. These 3 cases had a much more anteriorly placed spine. Such cases need to be reported so that it creates a paradigm shift in the way that mastoid surgeries are being done. Any variation in the positioning of the spine of henle points to variability in the position of the mastoid antrum. This is extremely important while drilling the mastoid in the correct position and also to prevent drilling over the sigmoid sinus or the dura. To conclude, an anteriorly placed spine of Henle corresponds to anteriorly placed mastoid antrum.
PubMed: 37974806
DOI: 10.1007/s12070-023-04017-4