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At least 325 records · Page 18Linked to original sources
PubMed2005

Shape-memory stapes prosthesis for otosclerosis surgery.

OBJECTIVES: The aim of this study was to determine the efficacy of a shape-memory alloy, Nitinol, as a component of an improved stapes prosthesis. STUDY DESIGN: Prospective laboratory and clinical study to develop a Nitinol stapes prosthesis. METHODS: Various diameters of Nitinol wire and temperature transition variants were analyzed with regard to ease of deformation, response to heating, and strength. The size and geometry of the closed hook was determined by measurement of 50 incus cadaver bones. Several heat sources for activating the shape memory were evaluated, including electrocautery, lasers, and warm water. Trial surgeries were then performed on human temporal bones in the laboratory. The closure characteristics of the Nitinol loop were studied. Magnetic resonance imaging (MRI) testing at 1.5 Tesla was performed to determine safety during MRI studies. Preliminary human subject trials were then instituted. RESULTS: In all cases, a low heat condition was ample to activate the shape memory characteristics of the hook and return it to a closed position after it had been opened. Laser power was generally set well below the power needed for removing bone. The Nitinol loop closed snugly around the incus with application to the top of the hook with a low temperature laser setting. Almost any heat source was effective. MRI testing at 1.5 Tesla showed no movement of the prosthesis. Preliminary results in human subjects showed excellent air-bone closure. The Nitinol loop holds uniform contact around the incus. CONCLUSIONS: The Nitinol piston greatly simplifies the stapedectomy procedure by taking the need for a hand operated instrument out of the surgeon's hands. Because of the nature of the Nitinol wire, it can never over-crimp. All these characteristics make the prosthesis advantageous for otosclerosis surgery.

Alloys↗
PubMed1978

Homograft stapes in middle ear surgery.

Descriptions are given of various uses of stapes homografts in tympanoplasty on ears with missing stapedial arch. The use of homograft stapes-incus assembly, placing the head of the homograft stapes on the patient's own footplate and on top of that an incus, is a method which at long sight has proved to afford better results than the use of an incus columella.

Ear Ossicles↗
PubMed1986

Studies on the mechanics of the reconstructed human middle ear.

Using a laser-Doppler interferometer the influence of different positions of an incus prosthesis on hearing performance was examined in human temporal bone preparations. The influence of position and tension of a malleus to footplate prosthesis (columella) was studied in the same way. It is concluded that an incus prosthesis should be placed along an imaginary line through the centre of the footplate and the head of the stapes. With a malleus to footplate prosthesis the position on the footplate is relatively unimportant. Tension between the malleus, prosthesis and footplate, however, is quite important and should be as low as possible, and compatible with a stable situation. The malleus to footplate prosthesis provides a columella type of prosthesis which for lower frequencies works better than an incus prosthesis, and occasionally even better than the normal ear.

Biomechanical Phenomena↗
PubMed1987

Reconstructing the absent lenticular process.

When a surgeon encounters an absent lenticular process of the incus, he must either reposition the incus or attempt to bridge the small gap between the remaining incus long process and the stapes capitulum. Our solution to this problem is to place a Lippy modified Robinson stapes prosthesis on the stapes footplate and attach it to the remaining long process, thus bypassing the stapes superstructure. This modified Robinson prosthesis has a portion of the well removed allowing the eroded long process to enter from the side. The hearing results of 63 cases at 6 months (two-thirds of which had a concurrent tympanoplasty) are 67% within 10 dB and 91% within 20 dB of the preoperative bone hearing level. The use of an existing and proven prosthesis provides both stability and, to date, the most successful hearing results for reconstructing the absent lenticular process.

Ear Ossicles↗
PubMed1985

Control of responding by the location of sound: role of binaural cues.

In auditory localization experiments, where the subject observes from a fixed position, both relative sound intensity and arrival time at the two ears determine the extent of localization performance. The present experiment investigated the role of binaural cues in a different context, the sound-position discrimination task, where the subject is free to move and interact with the sound source. The role of binaural cues was investigated in rats by producing an interaural imbalance through unilateral removal of the middle auditory ossicle (incus) prior to discrimination training. Discrete trial go-right/go-left sound-position discrimination of unilaterally incudectomised rats was then compared with that of normal rats and of rats with the incus of both sides removed. While bilateral incus removal affected binaural intensity and arrival times, the symmetry of sound input between the two ears was preserved. Percentage of correct responses and videotaped observations of sound approach and exploration showed that the unilateral rats failed to localize the sounding speaker. Rats with symmetrical binaural input (normal and bilaterally incudectomised rats) accurately discriminated sound position for the duration of the experiment. Previously reported monaural localization based upon following the intensity gradient to the sound source was not observed in the unilaterally incudectomised rats of the present experiment. It is concluded that sound-position discrimination depends upon the use of binaural cues.

Animals↗
PubMedDate not supplied

A topographic quantitative analysis of the post-natal bone formation in the auditory ossicles of the dog.

The amount and distribution of the post-natal bone deposition in the auditory ossicles and in the left tibia of dogs of varying ages were studied by means of alizarin labelling. The relative amount of fluorescent new-formed bone was expressed as a percentage ratio NB/(NB+PB) of new bone (NB) on the pre-existing bone (PB). The result was that the post-natal bone deposition (1) was larger in the tibia than in the incus, malleus and stapes; (2) significantly decreased with age both in the ossicles and in the tibia; (3) in the stapes it stopped at 3 months, while it was present in the tibia, incus and malleus even at 12 months. In the ossicles the post-natal bone deposition takes place both on the periosteal surfaces of the ossicles and on the internal surfaces of the haversian systems. The first process produces an appositional growth that stops in all three ossicles within the 1st month of post-natal life, the second one produces an internal growth that continues until the age of three months in the stapes, while in the incus and malleus it occurs in small amounts, even in the 12th month of life. In the ossicles all the new-formed bone tissue, periosteal and osteonic, is built up by primary bone (addition bone). In the tibia from 50 days of age the primary bone is gradually replaced by secondary haversian systems as a consequence of remodelling processes.

Age Factors↗
PubMed2004

[Surgery for tympanosclerotic stapes fixation accompanied by malleus fixation at the anterior malleus: report of 2 cases].

Most tympanosclerotic stapes fixation involves fixation or erosion of the malleus and/or incus. This status of the ossicular chain is one reason that ossiculoplasty for tympanosclerotic stapes fixation is more difficult than that for otosclerosis. In some cases, the malleus is fixed only at the anterior, while the incus is intact. In such cases, anterior spinotomy can recover mobilization of the malleus, then a prosthesis can be used for the long process of the incus during ossiculoplasty. We conducted stapedectomy with anterior spinotomy on 3 ears in 2 patients. Over 15 dB of hearing was regained in all 3 ears 6 months after surgery. No significant sensorineural hearing loss was seen in any ear. To adapt this surgical procedure, it is necessary to evaluate preoperative CT findings and the status of the ossicular chain during surgery.

Adult↗
PubMed1995

[Classification of middle ear anomalies by a correspondence analysis method].

We studied on 70 cases of middle ear anomalies by a standard correspondence analysis method. The external meatus of these cases was open. We classified these 70 cases into the following four groups: type D: disruption between the long process of the incus and the movable oval window (54.3%), type F: immovable oval window with no disruption between the long process of the incus and the oval window (14.3%), type DF: anomalies with both immovable oval window and disruption between the long process of the incus and the oval window (18.6%), type O: anomalies of neither type D nor type F (12.9%). Half of these 70 cases had other miscellaneous anomalies, however, they did not affect the present results.

Ear, Middle↗
PubMed1990

Reconstruction of the middle ear with hydroxylapatite implants: long-term results.

The results are reported of reconstructions of the middle ear with hydroxylapatite implants performed between 1980 and 1986 with an average follow-up of 5 years. The findings concern 120 canal wall prostheses made of hydroxylapatite. It was possible to reconstruct a radical cavity with a new ear canal. The results obtained with ossiculoplasty in 170 patients are reported. In patients lacking an incus, an incus prosthesis made of hydroxylapatite gave air-bone gap closure to within 20 dB in 83.3% of the patients. Extrusion was not observed. In cases with the stapes superstructure and incus both missing, an incus/stapes prosthesis made of hydroxylapatite gave an air-bone gap closure to within 20 dB in 75.7% of the cases, when used as an assembly. Extrusion was not observed. When the prosthesis was used as a columella, the results were less favorable (41.1%), and two prostheses were extruded during the postoperative control period. Recurrent cholesteatoma was not seen in cases in which eradication and reconstruction were staged.

Adolescent↗
PubMed1977

Histologic fate of tympanic membrane and ossicle homografts.

1. The biologic behavior and usefulness of homologous incus grafts preserved in Cialit compare favorably with that of ossicular autografts. 2. Reconstruction of the transplanted incus correlates with the period of its immersion in preservative: the briefer the period of exposure to fixative, the more rapidly resorption and substitution occur. The longer the preservation time, the slower the rate of incus transplant reconstruction. 3. The preserved heterograft bone chip is unsuitable, since it disintegrates completely irrespective of the duration of its preservation. 4. The configuration of all bone chips is extensively altered after implantation. Autograft and homograft bone chips are both poorly tolerated. Chemical fixation does not alter this reaction. Fragments are shortened, softened, and rounded off. Heterologous bone chips are completely resorbed.

Animals↗
PubMed1987

[Technic and spate results of stapedotomy].

The long-term results of 253 stapedotomies and of 444 stapedectomies were compared. Stapedotomy yielded significantly better and more stable results for the higher frequency range (1-4 kHz) than stapedectomy. Reversal of the classic sequence of the surgical steps of stapedectomy has improved the precision of the technique and reduced the possibility of inner ear trauma. Perforation of the footplate and the introduction of the prosthesis into the stapedotomy opening and its crimping to the long process of the incus are performed before separating the incudostapedial joint and removing the stapes arch. For optimal results the 0.4 mm platinum teflon prosthesis should protrude 0.5 mm into the vestibule. If the incus is too short or the oval window niche too narrow the prosthesis is attached directly to the malleus handle, bypassing the incus.

Follow-Up Studies↗
PubMed2004

Functional morphology of the ear in fossorial rodents, Microtus arvalis and Arvicola terrestris.

Functionally relevant features and parameters of the outer, middle, and inner ear were studied morphologically and morphometrically in two species of voles, smaller Microtus arvalis and larger Arvicola terrestris. The findings in these fossorial (i.e., burrowing) rodents with components of surface activity were compared with respective findings reported for taxonomically related muroid rodents representing the same size classes but different eco-morphotypes: obligate subterranean rodents (Ellobius talpinus and Spalax ehrenbergi superspecies) and generalized rodents (Mus domesticus and Rattus norvegicus). The ear in voles was characterized by traits reported for subterranean rodents. The eardrum was round, without a distinct pars flaccida, and had an area of 5.4 mm2 in M. arvalis and 9 mm2 in A. terrestris. The middle ear exhibited reduced goniale, enlarged incus nearly parallel to the manubrium of the malleus. The malleus-incus lever ratio amounted to 2.1 (M. arvalis) and 2.0 (A. terrestris). The malleus-incus complex weighed about 0.8 mg in both vole species. The stapedial footplate had an area of 0.3 mm2 in M. arvalis and 0.4 mm2 in A. terrestris. The cochlea had 2.3 coils in both vole species; the basilar membrane was 8.5 mm and 10.5 mm long in M. arvalis and A. terrestris, respectively. There were on average 1,030 (M. arvalis) and 1,220 (A. terrestris) inner hair cells, and 3,760 (M. arvalis) and 4,250 (A. terrestris) outer hair cells in the organ of Corti. In quantitative terms, all these (as well as some further) traits and parameters were intermediate (related to body size) between those reported for generalized rodents on the one hand and subterranean ones on the other. The sound transmission system of the ear seems to be best tuned to frequencies of about 8-16 kHz with a high-frequency cut-off at about 50-60 kHz. The ear of A. terrestris seems to be tuned to somewhat lower frequencies than that in M. arvalis. In this aspect as well as regarding hearing sensitivity (as judged from the mechanical transmission parameters), voles can be considered intermediate not only in their lifestyle but also in their hearing abilities between the subterranean rodents (mole-vole and blind mole-rat) and the surface dwellers (house mouse and Norway rat).

Animals↗
PubMed1996

Allograft stapes surgery for conductive hearing loss in patients with ossicular chain anomalies.

An allograft stapes was used during surgical intervention for conductive hearing loss due to ossicular malformations in 11 ears of seven patients. The external auditory canal and tympanic membrane were normal in all ears. The surgical findings for the ossicles were stapes fixation (7 ears), stapes fixation with discontinuity of the incudostapedial joint (in both ears of one patient), a deformed incus and stapes crura compressed by the facial nerve (one ear in which the stapes was not fixed) and an anomaly of the incus and stapes combined with a dermoid cyst (in one ear in which the stapes was also not fixed). In all ears, the following procedures were performed: stapedectomy followed by sealing the oval window with a vein graft and placing an allograft stapes between the oval window and the lenticular process of the incus or the handle of the malleus. The allograft stapes was placed with its capitulum on the oval window in all cases, and fibrin glue was used for stabilizing the seal and the allograft stapes. The indications for stapedectomy for conductive hearing loss due to ossicular chain anomalies and the utility of allograft stapes are discussed.

Adolescent↗
PubMed1989

Middle ear and cochlear receptors in the subterranean mole-rat, Spalax ehrenbergi.

The eardrum and the auditory ossicles of the middle ear, and the population of cochlear receptors in subterranean mole-rats of Spalax ehrenbergi complex were qualitatively and quantitatively analyzed. The area of the eardrum was 10.2 (S.D. = 0.9) mm2, that of the stapedial footplate 0.6 (S.D. = 0.07) mm2, the malleus: incus lever ratio was 1.25:1. The malleus is simply built, not attached to the tympanic ring. The incus is large; its long process is almost parallel to the manubrium of the malleus. The short process of the incus is provided with a peculiar bony cap, a structure thus far undescribed in mammalian auditory ossicles. Firmness of mutual connection of the ossicles may vary among different forms of Spalax. The size and form of the stapes are characterized by a large variability as well. The length of the basilar membrane was 12.6 (S.D. = 0.7) mm. The mean density of inner hair cells amounted to 93.3 that of outer hair cells to 386.4 cells per mm of the basilar membrane length. In general, the density increased from the base towards the apex. On average there were 415 outer, 100 inner hair cells in the organ of Corti; the ratio being constant along the basal 65% of the length and decreasing in the apical part of the organ of Corti. The radial width of the triad of outer hair cells increased and remained constant along the apical half of the Corti organ. Based on available findings of comparative and functional morphology, most of the studied features may be considered correlates of low-frequency tuning of the hearing organ in mole-rats.

Animals↗
PubMed1992

Middle ear development. III: Morphometric changes in the conducting apparatus of the Mongolian gerbil.

Middle-ear structural ontogeny was examined in 12 age groups of Mongolian gerbils between 2 and 42 days after birth. Measurements of tympanic membrane surface area; depth of the tympanic membrane cone; the lengths of the malleus and incus long processes; and stapes footplate, annular space, and oval window areas were obtained using video micrographs and computer digitization techniques. The incus long process matured first at 3.5 days after birth, while the pars flaccida surface area was the last middle-ear variable studied to reach adult size (26 days after birth). The incus long process increased its length by 30% from 0.5 mm to 0.65 mm. The malleus long process, however, demonstrated much more relative growth (47%). Pars tensa area expanded from 6.35 mm2 at two days after birth to its adult size of 16.9 mm2 and the stapes footplate expanded by 50%. The developmental changes observed in middle-ear anatomy are then discussed with regard to their contribution to the functional maturation of both the middle ear and more central auditory function.

Animals↗
PubMed2002

The incudo-malleolar joint and sound transmission losses.

The question as to whether the incudo-malleolar joint (IMJ) is mobile or immobile at moderate sound pressure levels (SPLs) is addressed. Referring to the mechanical properties of elastic tissue, we suggest that the IMJ is mobile at any SPL. In order to test this hypothesis, we investigated the dynamics of the IMJ in nine temporal bones by means of laser scanning doppler vibrometry. The dynamic behavior of both ossicles, malleus and incus is described by three degrees of freedom, and transfer functions (TFs) are shown for each motion component [corrected]. We show that there is indeed relative motion between the malleus and the incus. This transmission loss affects the middle ear TF and results in a frequency dependent sound transmission loss. Some characteristics of our results are in agreement with middle ear TFs described in the literature. The increasing transmission loss towards higher frequencies is caused by relative motion between malleus and incus at the IMJ. The concept that the IMJ is functionally mobile is consistent with the physical properties of elastic tissues which most likely define the mechanics of this joint. Since the IMJ is indeed mobile at moderate sound intensities and audible frequencies the theory of the lever ratio being responsible for the characteristics of the middle ear TF must be reconsidered.

Aged↗
PubMed1979

Pathology of the ossicular chain in various chronic middle ear diseases.

In a collection of 1,100 operated ears, 426 of which had cholesteatoma and 674 had not, the various defects of the ossicular chain are described and related to the nature of the disease and the site of perforation. The analysis showed marked differences between the various diseases and in the frequency of the individual ossicular defects or combinations of defects. Defects of the head of the malleus and of the body of the incus were found exclusively in chiolesteatomas, most often those affecting the attic. Isolated defects of the malleus handle were most common in cholesteatoma of the parts tensa and in total perforations. Defects of the long process of the incus occurred in 74--88 per cent of cholesteatomatous diseases, defects of the stapedial arch in 47 per cent of ears with sinus cholesteatoma. In granulating otitis without cholesteatoma and in sequelae to otitis there was less ossicular pathology, and 57 per cent of these ears had an intact ossicular chain. Total or posterior perforations were associated with pathology of the ossicles more often than inferior or anterior perforations. All cases with destruction of the body of the incus and the head of the malleus showed squamous epithelium in close relation to the ossicular defect, indicating a marked--presumably enzymatic--influence by the squamous epithelium upon the bone resorption.

Bone Resorption↗
PubMed1993

Origin of underwater hearing in whales.

All described fossil and Recent cetaceans have relatively similar ear bones (malleus, incus and stapes) that strongly diverge from those of land mammals. Here we report that the hearing organ of the oldest whale, Pakicetus, is the only known intermediate between that of land mammals and aquatic cetaceans (whales, dolphins and porpoises). The incus of Pakicetus is intermediate with respect to inflation, crural proportions, and position of the mallear joint. The incus and mandible of Pakicetus indicate that the path of soundwaves to its ear resembled that of land mammals. These fossils suggest that the first whale was amphibious, and corroborate the hypothesis that artiodactyls (for example, pigs, camels and ruminants) are the closest extant relatives of cetaceans.

Animals↗