Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Ear Ossicles”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Cold deformation elements for attaching an implantable hearing aid transducer to ear ossicles or perilymph].

Development and short-term implantation results of the Tübingen implantable hearing aid (TI = Tübingen implant) have been presented. The TI is designed for patients with sensorineural hearing loss due to a malfunction of the cochlear amplifier. This can be identified by the presence of positive recruitment and the absence of TEOAE (transitory evoked otoacoustic emissions). The Tübingen implant functions in two ways: it allows electronic amplification of the auditory signal and electromechanical signal transduction into a micromechanical vibratory stimulus. There are two paths by which vibratory stimulus reaches the cochlea: (1) directly through a perforation in the stapes foot plate into the perilymph or (2) via the ossicular chain. Made of pure titanium, the casing of the helium-tight welded transducer includes the piezoelectric actuator. An implantable manipulator device is designed for transducer positioning and anchoring in the mastoid cavity. Usually, the transducer probe tip is directly coupled to the body of the incus. This functions without a special coupling device by utilization of an Erbium-YAG laser. Special anatomical situations or the loss of incus and/or stapes suprastructure, however, requires coupling of the vibratory signal to other points of the ossicular chain or to the perilymph. A major problem, however, was an intraoperative, irreversible link between the titanium probe tip and coupling elements. To overcome this problem, the coupling elements were made of gold. A crimp technique was developed, allowing the surgeon to induce cold deformation of the gold. The cold deformation technique (crimp) results in an irreversible coupling between the titanium probe tip and the golden coupling element.

Cochlear Implantation↗
PubMed1994

[Calculated displacements of the middle ear ossicles in static load].

To investigate the dynamic properties of human hearing, experiments in vivo and with cadaver specimens can be carried out. Furthermore, electrical or mechanical models can also be used to study specific phenomena and parameter sensitivities. Present electrical and mechanical models are often based on crude structural and kinematic simplifications in which testing is restricted to static loading or simplified investigations. To investigate both static and dynamic behavior of normal and pathological ears spatial mechanical models have to be established. The different parts of sound transmission--i.e., airborne sound, elastic membranes, fluids, and ossicles have to be represented by different mechanical systems. In this investigations, a rigid body model of the middle ear was investigated. For verification, simulation results with respect to static loads were compared with measurements reported previously by Hüttenbrink. In further investigations, the dynamic behavior of the model will be evaluated. Models for the tympanic membrane and inner ear will also be formulated in order to create a compositive model that describes the whole hearing process. By so doing the successful development of prostheses as well as diagnostic methods will be supported.

Biomechanical Phenomena↗
PubMed1984

[An error in the Reichert-Gaupp theory. A contribution to onto- and phylogenesis of the temporomandibular joint and ear ossicles in mammals].

The theory of Reichert- Gaupp is refuted by A) new embryological, B) some teratological and C) a new morphological and functional interpretation of palaeontological findings: A) Before the formation of the chondrocranium the still fibrous anlagen of the Meckel's cartilage and of the hyoidal (!) malleus-incus-complex are still sharply outlined each against other. The hyomandibular boundary between them is yet distinctly visible. B) In the malformations being reconducted to an arrest of development the malleus-incus-complex regularly shares the fate of the outer ear (II. visceral arch) but never the destiny of the face (I. visceral arch). The ossicle-chain is not only a functional but also an ontogenetic unit and consequently also a phylogenetic unit. C) The phylogenetic changes of the temporomandibulary joint (tmj) of the Therapsida result by steps out of autochthon (!) structures. The functional background is discussed. We see the articulare as homologue to the processus condylaris and the quadratum to the articular disk. The phylogenetic older quadrato -articular hinge-joint is preserved in the inferior part and the phylogenetic younger quadrato - squamosal slide-joint, which in the human embryo also develops 2 weeks later than the first, is situated superior to the ginglymus . Thus the Mammals have 2 tmj on each side but no squamoso -dental joint.

Aging↗
PubMed1996

[Replacement of ear ossicles with titanium prostheses].

BACKGROUND: Titanium has been a well established implant material for many years. New material processing techniques now permit the manufacture of small implants for ossicular chain reconstruction. METHODS: Between November 1994 and September 1995, 100 titanium middle ear implants (55 PORP, 45 TORP) were used for reconstruction of the ossicular chain. A range of five different sizes for partial and total protheses suits all implantation needs. The shape of the implants can be altered by bending. Time consuming intraoperative shaping and trimming is avoided. RESULTS: At a follow-up time of three months (33 patients) and six months (17 patients), no adverse reactions or extrusions occurred. Biologic fixation between the foot of the partial prothesis and the head of the stapes was found eight months after implantation. A hearing result of 0-20 dB residual air-bone gap was achieved in 79%. CONCLUSION: Titanium middle ear implants show good bio-compatibility and are readily integrated into the ossicular chain. Although delicate in shape, they offer excellent mechanical properties in respect to sound conduction and implantation. Initial results show Titanium to be a perfect implant material for middle ear prostheses, although long-term results are not yet available.

Auditory Threshold↗
PubMed1993

[Animal experiment study of the biocompatibility of dentin and enamel as ear ossicle prosthesis].

The ossicles are often destroyed in patients with chronic otitis media. After removal of inflammatory tissue the surgeon may be confronted with the need to reconstruct the ossicular chain. Apart from homologous ossicles, implants of different materials have been used for this purpose but often without finding the best solution for the problem encountered. As such, we implanted pieces of human dentin and enamel into the middle ears and mandibles of guinea pigs. After staged placements of the grafts in the animal hosts, specimens were removed and prepared for morphological evaluation by embedding in acrylic without prior decalcification. In a mobile unloaded position within the middle ears, implanted specimens were covered by mucosa and showed no evidence for fibrosis or fixation. A joint-like connection to the bony capsule of the middle ear develops as necessary for a type III tympanoplasty. In a mobile, loaded site with contact to bone, implants were surrounded by connective tissue. In connection with the mucosal envelope, this finding confirms the suitability of the materials for ossiculoplasty. When stable within the mandible, implants were surrounded by new bone formation that originated from the host's tissue only, indicating a favorable result for the obliteration of a mastoid cavity. On the surface of both biomaterials, a cell-mediated resorption could be detected, which was more significant in the mandibular site than in the middle ear. However, the long-term biostability of dentin and enamel seems questionable. The synthetic material hydroxyapatite proved less susceptible to biodegradation when tested under identical conditions in a previous experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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↗
PubMedDate not supplied

[A experimental device for ultrasonic control of ear ossicle prosthesis function].

A device designed by the author is intended for functional control over prosthetic auditory ossicle efficacy in experiment. The device employs Doppler effect and lies inside the frame adjusted for the experimental conditions. The device provides standard conditions for determining amplitude-frequency characteristics and signal transmission factor in the range 128-2000 Hz. As illustration, measurements of transmission from the T-shape prosthesis are described.

Doppler Effect↗
PubMedDate not supplied

[Bioceramic prosthesis of the ear ossicles in tympanoplasty].

Anvil bones bioceramic prostheses were used in tympanoplasty performed in 60 patients with chronic otitis media purulenta (COMP). Complete and partial variants of the prostheses were tried. Follow-up results available for 60 patients demonstrate that the above tympanoplasty improved hearing in 41 out of 60 patients, made possible complete cavity epidermization, arrested inflammation, secured safety of the tympanic transplant in 51 patients. Bioceramic prostheses of the anvil bones provide stable hearing improvement even in COMP cases with severe impairment of the anvil bones.

Acute Disease↗
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↗
PubMed1998

Morphometric investigation on osteocytes in human auditory ossicles.

An osteocyte lacunae differential count (1-lacunae with live osteocytes, 2-lacunae with degenerating osteocytes, 3-empty lacunae) was carried out on ear ossicles and clavicles from cadavers as well as on stapes removed by stapedotomy. The distance of the three types of lacunae from the vascular source was also determined by a computer-assisted light microscope. Results showed that the delayed fixation of bone from cadavers does not significantly interfere with osteocyte preservation, at least with the scope of this investigation. The results of osteocyte differential count show that the number of empty lacunae and lacunae with degenerating osteocytes: (a) is significantly higher in ear ossicles than in clavicles, (b) increases with age, (c) is higher in stapes than in incuses and mallei, (d) increases with the distance from the vascular sources in both ear ossicles and clavicles. Additionally it appeared that the process of osteocyte degeneration in ear ossicles is very rapid and widespread, over 40% of the cells being dead within the 2nd year of age. In the light of the recent literature and personal findings, which ascribe to osteocytes the function of mechanical detectors, and considering that bone remodeling occasionally occurs in ear ossicles, it is postulated that osteocyte death in these bones could be a programmed phenomenon (apoptosis?), due to which they lose the ability to react to strains and stresses and achieve the structural stability they need to perform their peculiar stereotyped function.

Adult↗
PubMed2001

Modeling whale audiograms: effects of bone mass on high-frequency hearing.

In a previous paper (Hemilä et al., Hear. Res. 133 (1999) 82-97) we have presented a mechanical model, based on species-specific anatomical data, for the toothed whale middle ear. For five odontocete species of six we found that the model quite well predicted published behavioral audiograms. Here we report that new published data indicate that the audiogram of the sixth and deviating species, the killer whale Orcinus orca, was from a specimen with deficient high-frequency hearing. A new published killer whale audiogram is similar to other odontocete audiograms and does fit our four-bone model. With certain general conditions, a model with isometric (middle) ears results in uniform audiograms for different species, when presented in a log-log plot; with larger ears the audiogram curves are just moved towards lower frequencies. The audiograms coincide in case all frequencies are scaled by a factor 1/m3, where m is the mass of the ear ossicles. Odontocete ears are isometric enough to show that the corresponding audiograms are indeed similar after such mass scaling. Specifically, this scaling factor can be used to predict the high-frequency hearing limits of all odontocete species. Our anatomical data and models support the notion that ossicular mass is a crucial factor limiting high-frequency hearing in both terrestrial mammals and toothed whales.

Animals↗
PubMedDate not supplied

Semibiologic middle ear prostheses: ossicle cup and ossicle columella.

As a natural step in ossicular reconstruction technique, two semibiologic prostheses are introduced. The prosthesis designed for incus replacement is called the "ossicle cup." A hole is drilled in the body of an incus or head of the malleus, and the synthetic shaft of the ossicle cup is placed into the hole. The synthetic cup fits over the stapes capitulum, forming a joint. The ossicle keeps the synthetic portion from touching the tympanic membrane. The prosthesis designed for total ossicular replacement is called the "ossicle columella." In like manner, the shaft is inserted into a shaped ossicle and placed on the remaining footplate. The ossicle columella has a synthetic footplate that rests on the remaining footplate and provides stability and safety. The adaptability of the semibiologic prostheses solves the problems of a laterally healed tympanic membrane, absent stapes capitulum, remaining footplate crura, low-lying stapes, and retracted malleus. The hearing results of the ossicle cup prosthesis indicate 87% of cases with successful hearing at one year. The ossicle columella results in 71% of cases with successful hearing at one year. To date, the extrusion rate is less than 1%.

Bioprosthesis↗