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At least 19 recordsLinked to original sources
PubMedDate not supplied

Incorporation of radioactive calcium into otolithic membranes and middle ear ossicles of the gerbil.

45CaCl2 was injected into gerbils in single or multiple doses, and the resulting radioactivity in serum, otoconial CaCO3, bone samples, and selected labyrinthine epithelium was determined by liquid scintillation spectrometry. Incorporation into both utricular and saccular otoconia occurred at the rate of 0.06-0.07 nmole Ca++ per day, corresponding to a fractional rate of uptake of 0.1%. The retention of radioactivity had a half-life of approximately 11 days. The rate of incorporation of calcium for the middle ear ossicles was 5-7 times that for otoconia and was similar to that for otic capsule and skeletal bone. The level of 45Ca++ was higher in the pigmented regions of the utricular membranous wall than in the non-pigmented areas of the utricular and ampullary wall and in the stria vascularis.

Animals↗
PubMed1992

[Ear ossicle transplants for reconstruction of sound transmission in the middle ear. A histologic long-term study].

In this study 130 ossicular middle ear transplants were studied. 33 remained in the middle ear for 10 years or longer, one for 21 years. The majority of the grafts show 5% to 40% bone new formation. Absence of vital bone or subtotal host bone replacement is exceptional. The amount of bone new formation appears independent the implantation time. 75% of the grafts show no bone resorption. In 15% sound transmitting might be impaired due to resorption. Grafts with a high degree of bone new formation show less resorption. 21% of the ossicles have signs of inflammation. Inflammation boosts bone turnover with resorption on one hand and new for resorption. Cholesteatoma is the main cause of resorption and inflammation. The critical phase for resorption of the graft are the first two to three years after transplantation. No considerable difference was found between autografts and allografts (homografts). Histological and metabolical properties of the ossicles seem to be responsible for the stability of the graft. Ossicular grafts have a good longterm stability which makes them very suitable for reconstruction of the ossicular chain.

Bone Resorption↗
PubMed1992

[New ceramic implants for reconstruction of the ear ossicle chain].

Due to new technologies it is now possible to produce more ingeniously shaped ceramic implants. The essential characteristics of our newly designed implants are perforations at the distal end of the shaft which allow a better medial anchorage. Intraoperatively they will be filled with small pieces of connective tissue or periosteum to improve the position of the implant on the stapes head or the foot plate. We also want to comment on the fundamental importance of a stable reconstruction of the tympanic membrane level, e.g. in cases of a missing handle of the malleus. With a judicious indication and correct techniques the functionel long-term results of ceramic implants will be excellent.

Aluminum Oxide↗
PubMed1978

Scanning electron microscopy of human ossicles.

Human middle ear ossicles removed from cadavers and during surgical procedures have been examined with scanning electron microscope (SEM). Two kinds of bone tissue compose ossicles: periosteal and endochrondral bone. Periosteal bone occurs in the form of external covering on the ossicles. In the middle of the ossicles there is endochrondral bone which shows various spatial arrangement of collagen bundles. Lamellar bone occurs also in this bone around vascular channels but rarely in the form of typical osteons. Surface appearance of periosteal, coarse-fibred bone and lamellar, fine-fibred bone is almost the same. Lamellar bone is composed of coarse collagen bundles arranged tightly in the rows. The space between the rows is filled by fine fibres which link the coarse bundles.

Ear Ossicles↗
PubMed1976

Pinna anomalies associated with congenital conductive hearing loss.

This paper compares the normal pinna with the abnormal congenitally malformed pinna. Then the abnormal pinna is related to case histories where a hearing loss was found due to a congenital malformation of the middle ear ossicles. Careful examination of the pinna, therefore, may be a simple diagnostic sign of an underlying potentially surgically correctable hearing loss. An abnormal pinna is more often associated with a middle ear anomaly than with any other congenital malformation including a urinary tract anomaly.

Child↗
PubMed1978

Use of plastipore for ossicular chain reconstruction: an evaluation.

With the exception of stapes prostheses, previous use of implantable alloplastic materials in reconstructing the sound conducting mechanism in middle ear surgery has been uniformly unsuccessful. A new material composed of ultra-high molecular weight polyethylene has been developed as a replacement for middle ear ossicles. This implant, called the Plastipore total ossicular replacement prosthesis (TORP), and the Plastipore drum to the stapes prosthesis were inserted in 87 patients, all of whom had a long history of extensive middle ear disease and/or surgery. One TORP patient was lost to follow-up. The overall average hearing gain was 14.8 db. The overall follow-up was 12.4 months with a range of from 3 to 25 months. Eleven of the 15 patients receiving the drum-to-stapes prosthesis had hearing gain; 55 of 71 patients receiving the TORP had hearing gain. Eight prostheses were extruded. Nine patients had no improvement in hearing. Eight patients had subsequent decrease in hearing after initial gains. All ears are now dry and aerated. Early evaluation appears to demonstrate that the Plastipore prosthesis shows promise for use in difficult reconstructive middle ear problems.

Ear Diseases↗
PubMed1992

An empirical bound on the compressibility of the cochlea.

Effects of a possible inner-ear compressibility on middle-ear transfer functions are explored and a small upper bound on the magnitude of that compressibility established. Consequently. the traditional two-port representation of middle-ear mechanics remains valid to within a few percent. If the compressibility of the cochlea is small but finite, a simple phenomenological model of that compressibility correctly predicts hearing thresholds in the "middleless" ear at low frequencies. Experiments to establish the value of cochlear compressibility and to explore further its possible contributions to residual hearing in patients with missing or disarticulated middle-ear ossicles are suggested.

Animals↗
PubMed1991

Ossicular erosion by cholesteatoma: investigation by scanning electron microscopy utilizing a new preparation technique.

A new technique for removing the soft tissues from middle ear ossicles to prepare them for scanning electron microscopy is described. The technique involved use of a solution of hypochlorite. The bony surface of normal ossicles was studied as a control group after preparation by the technique and no morphological distortion was observed. Ossicles eroded by cholesteatoma were then studied, and we propose that the erosion occurs in three stages; pumicing, pitting and cavitating. The mucoperiosteum of normal ossicles and otosclerotic foci were also studied.

Cholesteatoma↗
PubMed1979

Experimental viral infections of the temporal bone. I. Experimental otitis media due to vaccinia virus in hamsters.

Clinical and pathologic studies of patients with smallpox suggest that conductive hearing loss is a frequent complication of smallpox and that it is due to otitis media. A possible experimental model for this hearing loss has been developed by study of the pathogenesis of acute vaccinia virus infections of hamster middle ears. Infant hamsters developed severe necrotic otitis media, and vaccinia viral antigen was demonstrated by fluorescent antibody staining in large confluent areas of epithelial cells lining the middle ear. Juvenile hamsters developed a patchy, less severe infection of the middle ear, most of which present along the tympanic membrane and middle ear ossicles, Adult hamsters did not develop middle ear infection. These findings support the argument that variola (smallpox) virus can cause otitis media in humans and that viral infection of the middle ear may be the cause of hearing loss.

Acute Disease↗
PubMed1975

[Homologous transplants in the middle ear (author's transl)].

The original concept of tympanoplasty included besides the closure of the middle ear, the removal of pathological middle ear components leaving intact the functional and healthy components. The special conditions that prevail in the middle ear (aeration, absence of intrinsic trauma) allow the reconstruction of the middle ear mechanics to a great extent. Animal experiments and clinical experience reveal good transplantation properties of denatured and preserved ear ossicles. They are partly replaced by the body's own true tissue, and preserve the original form over a period of years. Denatured dear drums with malleus, incus, and parts of the stapes give astounding acoustic results. The posterior bony canal wall in old radical cavities can be replaced by the posterior wall of the human temporal bone which has been preserved in Cialit.

Bone Transplantation↗
PubMed1992

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

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.

Abnormalities, Drug-Induced↗