Computer-integrated finite element modeling of human middle ear

 The objective of this study was to produce an improved finite element (FE) model of the human middle ear and to compare the model with human data. We began with a systematic and accurate geometric modeling technique for reconstructing the middle ear from serial sections of a freshly frozen temporal bone. A geometric model of a human middle ear was constructed in a computer-aided design (CAD) environment with particular attention to geometry and microanatomy. Using the geometric model, a working FE model of the human middle ear was created using previously published material properties of middle ear components. This working FE model was finalized by a cross-calibration technique, comparing its predicted stapes footplate displacements with laser Doppler interferometry measurements from fresh temporal bones. The final FE model was shown to be reasonable in predicting the ossicular mechanics of the human middle ear. Received: 18 February 2002 / Accepted: 6 June 2002 The preparation of temporal bone histological sections of Robert K. Dyer, Jr., MD is gratefully recognized. The Whitaker Foundation supported this work (Research Grant RG-98-0305).     

Computed tomography in the diagnosis of exudative otitis media

Temporal bone computed tomography (CT) was used to examine 37 patients aged 2 to 55 years who had exudative otitis media; in 27 patients of them, a pathological process was bilateral. An analysis of 58 temporal bone CT scans identified the CT signs of chronic exudative otitis media. These included a partial or complete block of the osseous foramen of the auditory tube; impaired pneumatization of the tympanic cavity, mastoid process fenestrae, and antrum; pathological drawing-in of the tympanic membrane. The preservation of the auditory ossicles and the absence of destructive changes in the walls of the cavities of the middle ear were observed in most cases. Repeated temporal bone CT study was performed in 10 patients (14 temporal bones) in different periods (from 2 months to 3 years) after surgery. The results of tympanostomy were visually assessed. These included recovered pneumatization of middle ear cavities (7 temporal bones), a cicatricial process in the tympanic cavity (5 temporal bones), recurrence of the CT manifestations of exudative otitis media (2 temporal bones).     

Potentialities of temporal bone CT in the diagnosis of chronic purulent otitis media and its complications

Temporal bone CT was used to examine a group of 87 patients with chronic purulent otitis media (103 temporal bones). The patients' age ranged from 2 to 74 years. A scheme was developed and proposed to evaluate the temporal bone by CT. The CT signs of chronic purulent otitis media uncomplicated by cholesteatoma and those of cholesteatomic purulent otitis were identified. The CT symptomatology of chronic purulent otitis includes: sclerotic changes in the bone tissue of the mastoid process, impaired pneumatization of the cavities of the middle ear, including the tympanic cavity, destructive changes in auditory ossicles, carious changes in the walls of the cavities of the middle ear. The CT semiotics of cholesteatoma depends on its site and spread into the temporal bone and includes as follows: deformation of the epitympanum due to soft tissue mass-induced destruction of the lateral wall; the dilated entrance into the antrum; the presence of a cavity with the sclerosed walls in the antromastoid area; carious changes in the auditory ossicles; the displacement of a chain of ossicles medially or laterally in relation to the initial site of cholesteatoma. CT reflects carious changes in the walls of the cavities of the middle ear, including the roof and labyrinthine wall of the tympanum, which allows labyrinthine fistula and intracranial cholesteatomic complications. The study of the temporal bone by the proposed scheme may reveal anomalies and the specific features of its structure: the presentation of the sigmoid sinus, the high elevation of the bulb of the jugular vein, diverticulum of the latter, the low standing of the bottom of the ACH.     

Simple technique for RNA purification from mouse inner ear hair cells

Obtaining a good quality of RNA from small population of cells remain an issue. Isolation for a special anatomic location such as inner ear placed in the temporal bone become a challenge, especially in terms of time needed for isolation of living tissue from the bone, which is a key factor to preserve the RNA. Due to limited accessibility to the technologies such as laser dissection, we present a simplified procedure for isolation of good quality of RNA from the inner ear for further studies.     

Preoperative computed tomography of temporal bones and its use in selecting patients with sensorineural deafness for cochlear implantation

Cochlear implantation (CI) involves the insertion of electrode systems in the inner ear in order to restore hearing in patients with sensorineural deafness. Positive CI results are closely related with careful selection of candidates. Preoperative computed tomography (CT) and its results are decisive in this selection. Temporal bone CT was made in 40 patients aged 1 to 57 years who had sensorineural deafness. The following changes were detected: malformations of the inner ear, the inner auditory canal, meningititis-induced cochlear obliteration, post-traumatic temporal bone changes, local auditory ossicle malformation, inflammatory middle ear changes, the high position of the jugular vein bulb, and its diverticula. Temporal bone CT plays an important role in selecting candidates for CI and circumvents potential difficulties and complications at CI.     

Atresia of the external acoustic meatus in prehistoric populations

A case of atresia of the external acoustic meatus is presented from a prehistoric Late Woodland site in Iowa. The affected individual was a female aged 30 to 40 years. The left temporal bone displayed a thin bony plate occluding the external acoustic canal. No evidence of middle ear or inner ear malformation was observed on the axial tomographs, although the external canal was shortened. The individual is diagnosed as having a mild case of congenital atresia. The report extends the geographical and temporal distributions of this archaeologically rare condition.     

Dizziness and Head Injury

Dizziness, whether vague or specifically rotational, is a common sequel to head injury, and is often postural. One hundred and sixty-five patients with this symptom were examined. The simple posture tests employed to detect positional nystagmus are described. This physical finding was present in one-quarter of the entire group, and in nearly one-half of cases of longitudinal fracture of temporal bone. In such cases, it is an objective finding that corresponds precisely to the patient''s complaint of vertigo.Transverse fracture of temporal bone destroys the inner ear in both cochlear and vestibular parts. Longitudinal fracture is commoner and causes bleeding from the ear; inner-ear damage is usually minor.In the rare cases where persisting postural vertigo and positional nystagmus are disabling, relief of the symptom may be achieved by vestibular denervation of the affected side.     

An attempt at comparing CT images of petrous bone with analogical sections of anatomical specimens

The purpose of the paper was to present comparative laminar anatomy of human temporal bone on the basis of cross-sections of autopsy specimens and CT scans made in identical thin layers. The investigations were made on 20 temporal bones taken during anatomopathological dissections of cadavers of men and women (aged 40 to 60 a) without visible pathological changes in the skull. The CT examinations were made by means of a Siemens Somatom DR 2 apparatus, using high resolution programme, on 10 patients who had pathological changes in the ear. The obtained scans were compared with temporal bone cross-sections, schemas of regular anatomical relation of 8 layers corresponding to routine CT examinations were worked out.     

Endotemporal branching of the facial nerve

Out of 400 specimens of temporal bone the authors found two cases of branching of the facial nerve in the mastoid course, i.e., 0.5%. Knowledge of this anomaly has a certain practical value in surgical intervention of the middle ear.     

Potentialities of temporal bone computed tomography in the identification of causes of hypoacusis of postinflammatory genesis

Temporal bone computed tomography (CT) was used to examine 64 patients with impaired hearing due to inflammatory diseases of the middle year. In 21 patients, the pathological process was bilateral. A total of 85 series of temporal bone CT scans were analyzed. The patients' age ranged from 2 to 66 years. CT verified adhesive otitis media in 62 cases, otosclerosis in 7, local malformation of the auditory ossicles and/or the labyrinthine fenestrae in 11. No CT changes were revealed in 5 cases. The CT symptoms of adhesive otitis media were identified. These included soft tissue bands and/or soft tissue-density portions that fix the auditory ossicles or block the niches of the labyrinthine fenestrae (31 temporal bones); sclerosis or ossification of the ligaments and tendons of the middle ear (7 temporal bones); calcification foci in the tympanic cavity (9 cases); osteosclerotic changes in the epitympanus (2 cases); cicatricial changes in the tympanic membrane (24 cases); destructive changes in the auditory ossicles (19 temporal bones). There has been evidence that CT may be used for the differential diagnosis of adhesive otitis media from otosclerosis and congenital malformations of the structures of the middle ear.     

Evaluation of temporal bone computed tomography and paranasal sinuses magnetic resonance images in acromegalic patients

OBJECTIVE: Acromegaly is a rare disease, which symptoms are caused by excess secretion of a growth hormone (GH) from the anterior pituitary benign tumor - adenoma. Authors present an evaluation of computed tomography (CT) and magnetic resonance (MR) images of temporal bone and paranasal sinuses of patients with acromegaly. CONCLUSIONS: 1. In all patients with acromegaly, morphological changes in paranasal sinuses were shown. They were mostly pronounced within the maxillary sinuses including the mucosa thickening up to 6 mm and encysted fluid occurrence. 2. CT of temporal bone did not reveal structural changes of internal and median ear. 3. There is a need for further studies on hearing impairment in patients with acromegaly.     

Pneumatization and mesenchyme in the human middle ear

The normal pneumatization in human middle ears from Wittmaack's temporal bone collection (ENT Clinic, University of Hamburg Medical School) is investigated by means of light microscopy and compared with electron-microscopic findings in the rat. The fetal middle ear in man and rats is completely filled with mesenchyme. The compartmentalization of the middle ear by the associated mucosal folds of the ossicular chain and the middle ear pneumatization are results of the resorption of the mesenchyme present. Ultrastructural findings in the rat's middle ear reinforce light-microscopic studies and provide evidence of the fibrillogenesis which characterizes the transformation of the mesenchyme into the tunica propria of the middle ear mucosa. The microtopography of mesenchymal remnants in middle ears of neonates and in children during the first year of life, and their relevance as to the pathogenesis of the primary acquired keratoma (cholesteatoma) are discussed.     

Prefabricated galeal flap based on superficial temporal and posterior auricular vessels

Scalp layers are widely used in reconstructive procedures. The authors used prefabricated galeal flaps based on the superficial temporal or postauricular vessels for ear, cheek, mandible, and cranium reconstructions in three cases. In case 1, synchronous beard and ear reconstructions were accomplished by using the temporoparietal and retroauricular flaps. In case 2, a buccomandibular defect was reconstructed by transposing the supra-auricular and retroauricular galea with prefabricated bone and skin. In case 3, an epidural hematoma in the left frontoparietal area was evacuated after a circular craniectomy. The harvested bone was not put back on the defect area but buried between the periosteal and galeal layers because of brain edema. These layers were raised as an osteogaleoperiosteal flap and transposed onto the defect area after 7 weeks. When used with a prefabrication method, scalp layers offer versatile options for repairing composite defects of the head region. A galeal flap based on the posterior auricular vessels is practical and reliable in reconstructive procedures. The authors suggest that this flap is an option in cases in which the temporoparietal fascia artery or the superficial temporal artery is not available. Prefabrication of the harvested cranial bone inside the adjacent tissues offers several advantages in that a viable bone is provided at the end of the procedure, intervention at a distant area is avoided, the graft is placed on osteogenic tissue (periosteum) that is also transposed onto the defect, and sophisticated procedures such as microsurgical techniques are not needed.     

Lumped parametric model of the human ear for sound transmission

A lumped parametric model of the human auditoria peripherals consisting of six masses suspended with six springs and ten dashpots was proposed. This model will provide the quantitative basis for the construction of a physical model of the human middle ear. The lumped model parameters were first identified using published anatomical data, and then determined through a parameter optimization process. The transfer function of the middle ear obtained from human temporal bone experiments with laser Doppler interferometers was used for creating the target function during the optimization process. It was found that, among 14 spring and dashpot parameters, there were five parameters which had pronounced effects on the dynamic behaviors of the model. The detailed discussion on the sensitivity of those parameters was provided with appropriate applications for sound transmission in the ear. We expect that the methods for characterizing the lumped model of the human ear and the model parameters will be useful for theoretical modeling of the ear function and construction of the ear physical model.Supported by Oklahoma Center for the Advancement of Science and Technology.     

儿童腺样体肥大程度与分泌性中耳炎发生的相关性研究(英文)

目的:探讨儿童腺样体肥大程度与分泌性中耳炎发生及预后的相关性,指导临床医师对分泌性中耳炎作出早期诊断和治疗。方法:239例住院手术切除腺样体的儿童,常规行鼻咽侧位片、声导抗检查;部分伴耳部症状、声导抗显示C型曲线或查体可疑鼓室积液征者行颞骨CT检查或术中行鼓室穿刺。经统计学分析,比较分泌性中耳炎与腺样体肥大程度及咽鼓管咽口情况的相关性。结果:在239例腺样体肥大儿童中,经鼓室穿刺证实合并分泌性中耳炎者34例(63耳,14.2%),其中鼓室曲线呈B型者33耳(52.4%),C型(-200 dapa)者10耳(15.9%),C型(-200 dapa)者20耳(31.7%)。结果表明分泌性中耳炎的发生与腺样体肥大程度及咽鼓管园枕受压迫的程度呈正相关。结论:声导抗检查不能作为分泌性中耳炎诊断的金标准,必要时可行颞骨CT明确诊断;对腺样体肥大伴分泌性中耳炎的儿童鼻内镜下腺样体切除为其主要疗法,配合鼓室穿刺多可治愈,对反复发作的分泌性中耳炎行鼓室置管术,避免术后并发症的发生。     

Role of N-acetyl-beta-d-hexosaminidase in cholesteatoma tissue

Cholesteatoma is a destructive disease characterized by the progressive expansion of keratinizing squamous epithelium in the middle ear and mastoid, and chronic inflammatory reaction of the subepithelial connective tissue. N-Acetyl-beta-d-hexosaminidase (HEX) catalyzes the release of terminal non-reducing N-acetyl-d-hexosamine residues acting on glucosides and galactosides in glycoproteins, G(M2)-gangliosides and glycosaminoglycans (GAGs). In this study the activities of HEX were measured in cholesteatoma tissue and in normal skin to demonstrate a possible role of HEX in bone resorption in the area adjacent to cholesteatoma. Cholesteatomas (n = 21) and normal adult retroauricular skin (controls, n = 21), were collected from patients during surgery due to chronic otitis media. In 20 of 21 specimens a significantly higher activity of HEX was observed in cholesteatoma tissue compared with that in normal skin. Mean release of HEX from the activated cells was 68.55 +/- 30.77 nkat/g wet tissue in cholesteatoma and 31.79 +/- 10.02 nkat/g wet tissue in skin specimens. It may explain the process of bone resorption in the area adjacent to cholesteatoma, i.e. ossicles or temporal bone. This study suggests that drugs inhibiting HEX activity, such as iminocyclitols, may be useful in cholesteatoma treatment.     

Computerized x-ray tomography of fossil hominid skulls

The newest generation of Computerized Tomography (CT) scanning appears to provide x-ray pictures of the internal structures of a rather heavily mineralized Homo erectus skull, i.e., Pithecanthropus IV, notably of its temporal bones, that reveal more details than traditional x-ray procedures. An analysis of the right temporal bone shows that it is extremely pneumatized, that the oval shape of the external meatus does not result from fractures as previously suggested, and that the middle ear and the internal auditory meatus have probably been damaged during restoration. Labyrinthine structures can be seen, and the facial nerve canal appears to be of a relative small size.