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PubMed2004

Comparison of the mechanical performance of ossiculoplasty using a prosthetic malleus-to-stapes head with a tympanic membrane-to-stapes head assembly in a human cadaveric middle ear model.

HYPOTHESIS: Ossiculoplasty using prosthetic reconstruction with a malleus assembly to the stapes head will result in better transmission of vibrations from the eardrum to the stapes footplate than reconstruction with a tympanic membrane assembly to the stapes head. Both types of reconstruction will be affected by tension of the prosthesis. BACKGROUND: Theories (and some clinical studies) that the shape of the normal tympanic membrane is important suggest that prosthetic reconstruction to the malleus performs better than reconstruction to the tympanic membrane. This has not been previously tested by directly measuring vibration responses in the human ear. Our previous work suggests that tympanic membrane assembly to the stapes head type prostheses performed best under low tension. This had not been previously tested for malleus assembly to the stapes head type prostheses. METHODS: Hydroxyapatite prostheses were used to reconstruct a missing incus defect in a fresh cadaveric human ear model. Two types of prostheses were used, one from the stapes head to the malleus (malleus assembly to the stapes head), the other from the stapes head to the tympanic membrane (tympanic membrane assembly to the stapes head). Stapes footplate center responses were measured using a laser Doppler vibrometer in response to calibrated acoustic frequency sweeps. RESULTS: Tension had a very significant effect on both types of prostheses in the lower frequencies. Loose tension was best overall. The malleus assembly to the stapes head type prostheses consistently performed better than the tympanic membrane assembly to the stapes head type prostheses when stratified for tension. CONCLUSION: Tension has a significant effect on prosthesis function. Malleus assembly to the stapes head type prostheses generally result in better transmission of vibrations to the stapes footplate than tympanic membrane assembly to the stapes head type prostheses.

Biomechanical Phenomena↗
PubMed1978

Modified technique of tympanoplasty with functional results of 494 cases after 3 years.

This paper gives the functional preliminary and final results of tympanoplasty as modified by Khan in types I--III in the form of a comparison. We examined 494 patients who were operated according to our modified technique. It is emphasized that in reconstruction of the middle ear, the use of a prepared fascial graft, homograft incus cartilage and external auditory meatal flap is sufficient. The preliminary and final results were documented with the aid of audiograms which were described and critically appraised according to two different types of evaluation. The evaluation did not only include the hearing results of tympanoplasty, but also the change in individual frequencies for all types. According to our appraisal of the operations with regard to social hearing the functional results of operations performed in our clinic may be considered above average. The hearing gain achieved from the preliminary postoperative control to the final examination is especially satisfying, since it also includes an improvement in bone conduction values.

Auditory Threshold↗
PubMed1978

Some observations on cochlear mechanics.

A set of experiments was conducted using the Mössbauer effect to determine the vibratory characteristics of the basilar membrane, Reissner's membrane, the malleus, incus, and oval window in squirrel monkey. A few measurements were also made in guinea pig in the basal cochlear region. The nonlinear vibration properties of the basilar membrane are described in detail for the midfrequency region in the squirrel monkey. Only in this region have nonlinear effects been observed. A comparison of mechanical and neural data indicates good qualitative agreement.

Animals↗
PubMed1987

Attenuation and protection provided by ossicular removal.

Behavioral studies of hearing loss produced by exposure to ototraumatic agents in experimental animals, combined with the anatomical evaluation of end-organ pathology, have provided useful information about the relation between dysfunction and pathology. However, in order to attribute a given hearing loss to some pattern of cochlear damage, it is necessary to test each ear independently. The objective of the present study was to evaluate attenuation measured behaviorally and protection to the cochlea provided by removal of the malleus and incus in noise-exposed chinchillas. Results from one behaviorally trained chinchilla with ossicular removal indicated a conductive hearing loss that varied from 41 dB at 0.125 kHz to 81 dB at 4.8 kHz and averaged 60 dB. Counts of missing sensory cells in ears of seven chinchillas with unilateral ossicular removal and exposure to noise (octave band centered at 0.5 kHz, 95 dB SPL, for durations up to 216 days, or centered at 4.0 kHz, 108 dB SPL, for 1.75 h) showed no more cell loss on the protected side than in age-matched control ears. From these data it is concluded that ossicular removal provides enough attenuation to protect the chinchilla cochlea from damage during these noise exposures, and that it will insure monaural responses behaviorally as long as the hearing loss in the test ear does not exceed that in the ear with ossicular removal by approximately 50 dB at any frequency.

Animals↗
PubMed1976

The inclined lateral projection: a new view in temporal bone tomography.

Radiographic findings in the inclined lateral projection are presented. This view provides detail of the malleus and incus which is not provided on any other view and also preserves the visualization of temporal bone anatomy seen by routine lateral projection. The frequent occurrence of ossicular pathology in inflammatory and traumatic diseases of the ear requires the meticulous radiographic examination of the ossicles provided by this projection. Patient positioning is uncomplicated and comfortable.

Ear, Middle↗
PubMedDate not supplied

Measurements of ossicular vibrations in the middle ear.

The vibrations of the ossicles were measured with a laser Doppler vibrometer in temporal bone specimens. The data contradicted the generally accepted view that the malleus and incus rotate about a fixed axis. The vibrations of the ossicles show a more complex pattern and, consequently, a more sophisticated model is needed to portray the behaviour of the middle ear in a satisfactory manner. But in turn models with many degrees of freedom make the identification process a very difficult task. This dilemma can be resolved if the system is divided into subsystems of less complexity where each subsystem can be studied in an appropriate manner. The excitation by electrostatic forces, as applied in this study, seems to be a powerful tool to make possible a study of parts of the ossicular chain.

Acoustic Stimulation↗
PubMed1975

Artificial stapes - a fourteen-year report.

This paper is based on 3,500 cases of otosclerosis operated on during the past 14 years restoring the continuity of the ossicular chain by means of an artificial stapes. Eighty percent showed practically a closure of the air-bone gap. There was no hearing gain in 17 percent of the patients, many of which showed reversal to preoperative levels. Three percent of the patients suffered sensori-neural hearing loss and 1 percent cophosis. Necrosis of the incus occurred in 0.3 percent of the patients and perilymphatic fistula in 0.2 percent. Only one case of inflammatory granuloma was observed as a complication of stapedectomy.

Artificial Organs↗
PubMed1992

Diagnosis of the ossicular chain in the middle ear by high-resolution CT.

This study was conducted to assess the usefulness and limitations of high-resolution CT for diagnosing the ossicular chain in the middle ear. The CT images in this study were obtained in as much detail as possible and 2 direction images. Preoperative CT findings of the ossicular chain were compared with operative findings in 26 patients with ossicular defects. Preoperative detection of the complete defect of the malleus head and the body and long process of the incus by high-resolution CT was possible in all cases, while detection of the defect of the manubrium of the malleus and superstructure of the stapes could be made in 33.3 and 60%, respectively. The defect of the incudostapedial joint (1 case) and partial defect of the stapes crus (2 cases) could not be diagnosed correctly by preoperative estimation.

Cholesteatoma↗
PubMed2003

Congenital conductive hearing loss in dyschondrosteosis.

Conductive hearing loss was detected in a boy with a previous diagnosis of dyschondrosteosis. Dyschondrosteosis is a rare inherited condition characterized by mesomelic dwarfism and Madelung's deformity. The syndrome can be caused by mutations in the SHOX gene, and in that case, the pattern of inheritance is pseudoautosomal dominant. Indeed, SHOX mutation analysis in our patient revealed a deletion. The combination of dyschondrosteosis and conductive hearing loss has been reported in 2 previous cases. In our patient, exploratory tympanotomy revealed ankylosis of the stapes and a malformed incus. A substantial gain in hearing threshold was obtained by a stapedectomy in combination with a malleovestibulopexy.

Abnormalities, Multiple↗
PubMedDate not supplied

Atelectasis and secretory otitis media.

That condition where the tympanic membrane is displaced toward the promontory is termed atelectasis. Thirty-seven patients (61 ears) showing various degrees of atelectasis graded from stage 1 to stage 4 were studied. Atelectatic drums are an inflammatory phenomenon occurring in underventilated ears. This conclusion is reached by considering the reversibility of the atelectasis upon ventilation; while the inflammatory factor can be deduced from the history and histopathology of the atelectatic drum, as well as the histology of the necrosed incus, the latter occurs in over a third of our cases. Also pneumatization of the mastoid is almost never present. Twelve (21%) of the ears treated did indeed develop a perforation at one time or another (two had cholesteatomas). Chronic granulating external otitis with specific features occurred in 15% of cases. The characteristics of these ears and their case histories lead us to view atelectatic ears as part of the otitis media syndrome, where their place is somehow transitional between secretory otitis media on the one hand and chronic otitis media on the other.

Adult↗
PubMedDate not supplied

The sleeve autograft in congenital cholesteatoma.

An epithelial cyst behind an intact tympanic membrane with no previous history of ear infections is an unusual but not infrequent finding in children. If it is recognized early and completely removed, a permanent cure is obtained. However, if it is unrecognized or poorly treated, there may be far-reaching complications. The conventional technique of creating a tympanomeatal flap to remove the congenital cholesteatoma is often unsatisfactory. This is because the cyst may be located in the anterior-superior quadrant and extend beneath the malleus. It therefore becomes impossible to accomplish a complete removal and still preserve auditory function. This leads to incomplete removal with recurrence and subsequent radical removal with loss of auditory function and alteration of normal anatomy. A technique is presented whereby the canal skin, malleus, and cholesteatoma are removed en bloc. Once outside the confines of the bony ear canal, the tympanic membrane is inverted and the epithelial cyst removed under direct vision. The eardrum-malleus-canal skin autograft is then replaced in anatomical position and the hearing reconstructed with a homograft notched incus. This technique has been utilized in nine cases over the past 10 years. Case reports demonstrate the anatomical and functional results.

Child↗
PubMedDate not supplied

Comparison of ossicular replacement materials in a mouse ear model.

Four biomaterials, UF45S5 Bioglass, Silastic, Plasti-Pore, and Proplast, were used to replace the incus in a mouse ear model. Bioglass, a bioactive glass ceramic, compared favorably with the other test materials in maintaining surgical positioning between malleus and stapes and remaining stable to a blast of nitrogen gas and to pick manipulation. In a short-term animal study, Bioglass showed histocompatibility comparable to that of these other implant materials now used in ossicular replacement surgery in humans.

Animals↗
PubMed1994

Imaging of ossicular prostheses.

The prostheses available for reconstruction of the ossicular chain have expanded to include a variety of synthetic materials. Hydroxyapatite contains the inorganic constituents found in human living bone and is currently being incorporated into many new prostheses. This study demonstrates the computed tomography and magnetic resonance image characteristics of eight middle ear prostheses, a block of dense hydroxyapatite, and a human incus. Imaging of ossicular prostheses is more informative with computed tomography.

Bone Substitutes↗
PubMed1976

Glomus tympanicum--excision by radical mastoidectomy exposure with autograft reconstruction.

Wide surgical exposure, total tumor removal and anatomic and functional reconstruction are the goals of tumor management. These goals are met by radical mastoidectomy exposure for the removal of glomus tympanicum tumors and reconstruction by autograft replacement of the posterior osseous canal, and if the tympanic membrane, malleus and incus are removed for tumor exposure, autograft replacement may also be accomplished. The history, physical findings, X-rays and details of surgical management of two patients with glomus tympanicum are reviewed. Wide removal of the posterior osseous canal, just lateral to the VIIth nerve with total replacement of this segment gives excellent exposure of the middle ear space and affords total reconstruction of the posterior osseous canal.

Ear Diseases↗
PubMed1979

Hypermobility of the incudostapedial joint: a clinical entity.

During exploratory tympanotomy for conductive deafness, the surgeon is occasionally perplexed to find no apparent cause for the air-bone gap. This unexplained deafness has been called "inner ear conductive hearing less" because of the apparent absence of pathology in the middle ear. The incudostapedial joint was studied in 68 vertically sectioned temporal bones and the anatomy is presented. Varying amounts of laxity is observed in the normal joint capsule at the time of surgery. A theory is suggested in which an elongated capsule allows incus motion without energy transmission to the stapes. It is proposed that hypermobility of the incudostapedial joint may exist and explain conductive hearing loss of undetermined etiology.

Audiometry↗
PubMed1990

Congenital absence of the oval window.

From 1983 to 1987, seven patients with conductive hearing loss were found to have congenital absence of the oval window. Six of these patients underwent vestibulotomies and reconstruction with House wires or total ossicular reconstruction prostheses. Surgical findings included absent or rudimentary stapes in all cases, abnormal facial nerves in four cases, and abnormal long processes of the incus in four cases. All patients had normal external ear canals and tympanic membranes. Hearing initially improved 20 to 45 dB in four of the six patients reconstructed. Over time, however, much of this initial hearing gain was lost. A marked difference in hearing results was evident between this series of absent oval window cases and a recent series of major atresia cases.

Adolescent↗
PubMedDate not supplied

Holographic vibration analysis of the ossicular chain.

The mechanics of movement of the ossicular chain has been investigated on human temporal bone preparations by means of time average holography. The malleus and incus moved like a lever around an axis, which position was somewhat dependent upon frequency. Simulation of contraction of the muscles of the middle ear gave as result a change in the pattern of movement of the ossicular chain. The position of the rotatory axis was changed, and the amplitudes of vibration were reduced. This should be a protecting mechanism.

Autopsy↗
PubMed1988

The mechanics of the middle-ear at static air pressures: the role of the ossicular joints, the function of the middle-ear muscles and the behaviour of stapedial prostheses.

In an experimental study, the mechanical behaviour of the ossicle-chain during changes of the static air pressure was analyzed microscopically and with a radiographic magnification technique in temporal bone preparations. Several preliminary experiments served to pinpoint methodological problems, like exsiccation-artifacts, storage procedures, preparation defects, missing air-cushion effect with the opened middle-ear cavity, absent labyrinthine pressure, relation of the optical axis to middle-ear structures and statistical reproducibility of the measured values. Variations of the static air pressure in the external ear canal ranging from 0 to +/- 400 mmH2O induce an inward-outward movement of the malleus. In the regular middle-ear, the direction of this movement is changed within the ossicular chain into a predominantly upward-downward direction of the lenticular process, due to a gliding function of the incudo-malleal (IM) joint. This results in a gliding movement of the surfaces of the incudostapedial joint (IS). In this way, the stapes and the inner-ear are decoupled from the excessive displacements of the drum membrane and malleus. This change in the mode of motion explains many former results of ossicle vibration, aroused by unphysiologically high sound pressures, like v. Békésy's description of the tilting footplate. This mode of motion, however, changes completely if the gliding function of the IM-joint is cancelled by experimental ankylosis. In that case, the predominant direction of movement at the incus and stapes is inward and outward, too. This mode of motion has been the generally accepted concept of the ossicle-chain mechanics up to now. This isodirectional motion also occurs with progressive exsiccation of the temporal bone preparations, explicable with drying and shrinking of the capsular ligament of the IM-joint. It is conceivable, therefore, that our concepts of the mechanics of the ossicle-chain were partly based on experiments with insufficiently moistened temporal bone preparations, as the methodological problem of the exsiccation became known only during recent decades. In further experiments with static air pressure, the mechanics of the reconstructed ossicle-chain, i.e. tympanoplasty and stapedial prostheses, were studied. In the columella-like chain reconstruction, the displacement of the stapes equals the values measured with the ankylosed IM-joint. This displacement is limited by the strength of the annular ligament, whose function, however, is eliminated in the case of stapedial prostheses. Now the displacement is limited by the friction of the piston at the perforation in the footplate.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗