Conduction of thermal stimuli in the human temporal bone

Summary Temperature changes at different locations in the labyrinth were measured in human temporal bone preparations after syringing with water. In order to simulate physiological conditions, the preparations were placed in a water bath at 37°C. The maximum temperature changes in the horizontal semicircular canal after syringing with temperatures symmetrical to body temperature (44° or 30°C) were found to be clearly asymmetrical (with mean values of 0.6 and –0.3 K). From measurements in the external auditory meatus, findings showed that the reference temperature was 34°C in front of the tympanic membrane, which explains the asymmetry recorded. Measurements at different locations showed that the temperature first changes in the regions of the ampullae of the horizontal and the superior semicircular canals. In the vestibule the onset and decay of the temperature change is delayed. The time courses of the temperature difference between locations demonstrate that the temperature difference across the horizontal semicircular canal, which would be responsible for any convective effect in the endolymph, is of shorter duration than the absolute temperature change, which would be responsible for any temperature-mediated volume changes.     

Vascular anatomy of the human temporal bone

Summary The vascular pattern inside the otic capsule was studied by injecting colored compounds into human temporal bones.In specimens from individuals of all age groups, one could fill the vascular network of the otic capsule by means of the following injections:Injections from the anterio-inferior cerebellar artery system (a.i.c.a.) or the common carotid artery respectively. Injections from both mentioned origins with differently colored compounds into the same specimen revealed numerous end to end anastomoses between the intra- and extracranial vessels. These were found too between the inferior petrosal sinus and the ad.c.a. branches.By means of the different injections one could observe an especially dense vascularity inside an area, which was named the vascular key area. It included the basal part of the bony separation between the cochlear coils plus the adjacent bony area between the cochlea, the middle ear promontory, the vestibule and the inferior part of the internal auditory canal fundus.The main route for vascular connections between the membranous cochlear structures and remote regions as par example the middle ear structures and the carotid artery network occured here too.The possible clinical importance of these data was discussed in the case of otosclerosis, vascular embolism, intracanalicular acoustic neurinomas und presbyacusis.

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Zusammenfassung Das Gefäßmuster innerhalb der Labyrinthkapsel wurde durch Injektion von Farbstoffen in menschliche Schläfenbeine untersucht. In Präparaten von Individuen aller Altersgruppen konnte man die Gefäßnetze der Labyrinthkapsel mit Hilfe folgender Injektionen füllen: Von der A. cerebelli ant. inf. (A.c.a.i.) aus odor von der A. carotis communis aus.Injektionen von diesen beiden erwähnten Ursprüngen, mit verschiedenen Farbstoffen am gleichen Präparat, ergaben zahlreiche End-zu-End-Anastomosen. Sie warden auch zwischen dem Sinus petrosus inf. und den Ästen der A.c.a.i. gefunden. Mittels dieser verschiedenen Injektionen konnte man die besonders dichte Gefäßverbindung innerhalb eines Gebietes feststellen, das vascular key area genannt wurde. Es umschließt den basalen Toil der Knochentrennwand zwischen den Schneckenwindungen und der angrenzenden Knochenzone zwischen der Cochlea, dem, Promontorium, dem Vestibulum and dem unteren Toil des Fundus des inneren Gehörganges.Auch die Hauptgefäßverbindung zwischen dem membranösen Labyrinth und den entfernteren Regionen, wie z. B. Mittelohrstrukturen und Carotis-Netz wird hier besprochen.Die mögliche klinische Bedeutung dieser Befunde in bezug auf Otosklerose, Gefäßembolien, intracanaliculäre Acusticusneurinome und Presbyacusis wird diskutiert.

     

Efferent system degeneration in the human temporal bone

Sense organ deposits have been described in temporal bones from patients with vestibular neuronitis, Meniere's disease, and benign paroxysmal positional vertigo that are not found in a comparable series of temporal bones without vestibulopathy. Because the recurrent vestibulopathies are caused by vestibular ganglionitis and the vestibulocochlear anastomosis was degenerated in these temporal bones, the deposits may represent the end buds of regenerating efferent axons injured in passage through the vestibular ganglion. Such neural buds have been described with transmission electron microscopy in animals after vestibular nerve transection and in a human temporal bone with endolymphatic hydrops. The buds may be visible by light microscopy, because their size is comparable to that of hair cell nuclei and they stain blue with hematoxylin because of their nucleic acid content. The variable location and size of these deposits (buds) in the labyrinthine sense organs is described to aid in the recognition of efferent system injury in human temporal bones.     

Observations of the anterior epitympanic recess in the human temporal bone

The structure of the anterior epitympanic recess was examined in 50 human temporal bones. The recess was found in 48 temporal bones (96%) and showed three different structural types. In type A, the least developed type (38%), a main cavity is seen above the tensor tympanic fold. The recess is divided into two cavities by the tensor tympanic fold, which stretches to the anterosuperior tympanic tegmen in type B, the intermediate type (40%). The tensor tympanic fold is fused with the superior mallear fold in type C, the best-developed type (18%), with the recess being contiguous with the eustachian tube. The shape of the anterior epitympanic recess is influenced by the ratio between the cavities above and below the tensor tympanic fold, ie, by the embryologic development of the saccus anticus and the anterior saccule of the saccus medius. The structural variations in this recess must be kept in mind during the surgical management of middle ear diseases.     

Prevalence of microfissures in the human temporal bone: A report of 1000 temporal bones

A total of 1000 human temporal bones were studied to determine the prevalence of two microfissures: 1. the one between the facial canal and the vestibule, 2. the microfissure between the round window niche (RWN) and the posterior semicircular canal (PSC). Additionally, this study compares the prevalence according to temporal bone age and sex The microfissure between the facial canal and the vestibule was observed in 470 (47%) temporal bones, with a bilateral presence of 77.2%. The prevalence of this microfissure increases linearly with age. It was not found in any bone within the 0 to 2 age group. It was present in 3 (7.3%) bones from the 2 to 9 age group, as opposed to 374 (54.8%) bones from the 40 and over group The microfissure between the RWN and the PSC was detected in 915 (91.5%) temporal bones. This second microfissure was found to be an overwhelmingly bilateral entity. The prevalence of this other microfissure also increases with age. This microfissure was also not present in any temporal bone within the 0 to 2 age group. It was found in 28 (68.3%) bones from the 2 to 9 age group, in contrast to 678 (99.4%) temporal bones from the 40 + group In addition to a review of the literature, the possible clinical significance of these microfissures is discussed.     

High-resolution magnetic resonance imaging of the human temporal bone.

A magnetic resonance imaging (MRI) system (Hitachi, Naka, Japan) with a superconductive magnet running at 2.11 T was used to obtain 2-mm-thick slices of fixed, decalcified and celloidin-embedded human temporal bone. The temporal bone was then sectioned and stained for routine histological evaluation. Both the MR images and the histological sections were in the mid-modiolar slice plane, and comparable images and sections were analyzed to confirm the identity of the inner-ear structures visualized on the MR images. The cochlear duct, scala tympani, scala vestibuli and basement membrane of all three cochlear turns were clearly imaged on MRI. In addition, the vestibule and three semicircular ducts were also clearly seen. This study raises the possibility of some day using MRI for the diagnosis of inner-ear diseases.     

Preparation of human temporal bone for immunohistochemical investigation

Successful treatment of progressive sensorineural hearing loss with corticosteroids and cyclophosphamide has promoted the notion of a new entity 'autoimmune hearing loss'. In this context, we have examined sera of patients suffering from idiopathic sensorineural hearing loss, in order to study the binding of humoral antibodies to structures of the normal human inner ear. Investigations were carried out with indirect fluorescence techniques on temporal bones obtained at autopsy. To minimize the possibility of artifacts, we suggested that indirect immunofluorescence with the patients' sera should yield a reproducible positivity on sections of at least three normal temporal bones. In this study, we describe a method for removal and preparation of human temporal bone which ensures reproducible immunohistochemical results.     

Various types of suprameatal spines and depressions in the human temporal bone

Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep. Received: 5 January 1998 / Accepted: 19 March 1998     

Sclerotic changes in ossicular ligaments in human temporal bone pathology

When tympanoplasty is performed for conductive hearing loss due to otitis media, hearing recovery may not be as good as anticipated preoperatively. Sclerotic changes may therefore exist in the conduction system of the middle ear. To clarify the relationship between middle ear inflammation and sclerotic changes of middle ear sound conduction, particularly of the ossicular ligaments, specimens of human temporal bones were studied. Histology of the anterior malleal ligament, posterior incudal ligament, and stapediovestibular ligament was examined in 636 ears from 367 individuals (postmortem) ranging from infancy to 90 years old and without blood disease, neoplasm, anomaly, or cholesteatoma. Only small numbers of acute and subacute inflammatory were identified, but sclerotic changes in ligaments were compared between normal and chronically inflamed ears. In anterior malleal and posterior incudal ligaments, the severity of sclerotic hyalinization and calcification increased with age in normal ears, but sclerotic changes in chronically inflamed ears were more severe than in normal ears and displayed a reduced association with age. Conversely, sclerosis of the stapediovestibular ligament was less severe than that of the anterior malleal and posterior incudal ligaments in both normal and chronically inflamed ears, and displayed a reduced relationship with age. The sclerotic changes apparent in the anterior malleal and posterior incudal ligaments therefore seem to be more readily influenced by inflammation than by age. Sclerotic changes of the stapediovestibular ligament are not as severe as those of anterior malleal and posterior incudal ligaments. For cases in which tympanoplasty of inflamed ears is planned, mobility of the anterior malleal and posterior incudal ligaments should be tested independent of testing of the stapediovestibular ligament. When mobility of anterior malleal and posterior incudal ligaments is not as good as mobility of the stapediovestibular ligament, surgical modification of the anterior malleal and posterior incudal ligaments may be advisable.     

Preservation of the dissected and surgical anatomic detail in the human temporal bone

Preservation and usefulness of human gross temporal bones that have been dissected or drilled have always been a problem. This article describes application of the technique of plastination developed by von Hagens to the temporal bone. The use of this technique permits development of a collection of both anatomically dissected and surgically drilled temporal bones which can be studied by the otolaryngologist at any level. The procedure involves impregnation of the specimen with uncured polymers--a silicone rubber of medium viscosity followed by curing in a vapor bath. The advantages of this technique are that the plastinated temporal bone can be studied and handled without any unpleasant odor and there is no need for liquid preservation. The potential problem of the specimen drying out and becoming useless is thus avoided.     

Flexible fiberoptic endoscopy of the cochlea: human temporal bone studies

New bone formation within the cochlea has been found more frequently than expected during cochlear implantation. Although implantation of partially ossified cochleas with long multichannel electrodes is possible, in practicality it may be difficult to determine whether electrode insertion is feasible prior to attempting it. In spite of use of high resolution computerized tomography, the presence, nature, and extent of new bone formation in the scala tympani is often difficult to ascertain. Flexible fiberoptic otologic endoscopes, 0.7 mm and 1.0 mm in diameter, were developed for the purpose of visualizing the fluid-containing scalae of the cochlea. In order to determine the efficacy of the device in visualizing the interior of the cochlea, as well as determining possible damage caused by its use, ten formalin fixed human temporal bones were studied. The flexible fiberoptic otologic endoscope was found to be capable of passage through the scala tympani of the cochlea in the inferior segment and of identifying normal and abnormal structures. Passage beyond this point resulted in damage to the spiral ligament. We conclude that human trials of use of the endoscope during cochlear implantation on previously deafened individuals is feasible.     

Application of unbiased stereology on archival human temporal bone

OBJECTIVE: The current report presents unbiased stereological sampling and counting strategies for estimating the total number of neurons in the spiral and vestibular ganglia of the archival human temporal bone. STUDY DESIGN: Application of unbiased stereology using archival human temporal specimens. Observational study. METHODS: The practical sampling and counting strategies for estimating the number of neurons are presented. To illustrate the method described, the total number of neurons in spiral and vestibular ganglia from archival human temporal bone was estimated. RESULTS: The study found, on average, 41,643 (coefficient of variation = 0.12) spiral ganglion neurons in the subjects with an average age of 35.6 years (age range, 22-60 y) and, on average, 27,635 (coefficient of variation = 0.10) vestibular ganglion neurons in the subjects with an average age of 28.6 years (age range, 2-58 y). CONCLUSIONS: The total number of primary auditory and vestibular ganglion neurons from the current study differs significantly from the previously published data using assumption-based methods. The unbiased stereological technique presented in the current report thus would be invaluable for future studies on such specimens, including the study of the changes of neurons during aging and various pathological conditions.     

Localization of inflammation of tympanic cavity in human temporal bone pathology

When we treat patients of otitis media, it is important to know the pathogenesis of otitis media. Therefore histopathological change of epithelium and bone in each site of tympanic cavity was observed using human temporal bones. Histopathological change of epithelium was classified as: acute, subacute and chronic in eighteen sites of tympanic cavity. Histopathological change of bone was observed in thirteen sites of tympanic cavity. And the frequency of histopathological change of epithelium and bone in each site was compared. A review of 350 temporal bones collected from autopsy cases revealed 171 (49.1%) to have otitis media, and a review of 170 temporal bones of otitis media cases revealed 165 (97.1%) to have bone changes. Differences in frequency of histopathological change of epithelium and bone existed in each site. Histopathological change in inferior portion of mastoid cells, round window niche and tympanic sinus was more frequent than in the other sites. Change of epithelium: in acute inflammation, no differences in frequency of histopathological change existed; in subacute inflammation and chronic inflammation, differences in frequency of histopathological change existed in each site. Change of bone: most changes were bone formation and bone reconstruction, but there was no clear finding that bone formation narrowed tympanic cavity without mastoid cells. Osseous destruction was found in mastoidectomy cases and cholesteatoma cases. It is thought that the frequency of inflammation is related to structure of cavity, aeration, immunologic activity or structure of the epithelium, and that the pathogenesis of otitis media, especially in chronic otitis media, is different in each site of tympanic cavity. It is thought that because the subjects of this study were not operated cases but autopsy cases, slight bone change was very frequent, but severe bone change, was rare. And we examined the pathogenesis of tympanic cavity of each case of acute inflammation and chronic inflammation of pars tensa and cases where there were no findings of inflammation in the pars tensa. In most cases of acute inflammation of pars tensa, inflammation of tympanic cavity was acute; in chronic inflammation of pars tensa, chronic. It was interesting that, in cases of normal pars tensa, inflammation was frequently found in tympanic cavity. Therefore, it is important to pay attention to the possibility of inflammation in tympanic cavity, even if the tympanic membrane appears normal.