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At least 19 recordsLinked to original sources
PubMedDate not supplied

Cholesteatoma in children: histopathologic findings in middle ear ossicles.

Middle ear ossicles removed during ear surgery in 40 patients were examined in order to compare the histopathologic changes in children with those observed in adults. Bone resorption, mainly localized at the level of the periosteum and haversian canals in adults, was much more extensive in children. Replacement of bone by fibrous granulation tissue was observed in 60% of children's ossicles and in 27% of those belonging to adults. In children, extensive active resorptive osteitis of the ossicles was frequently associated with intensive round cell infiltration, which seems to play an important role in bone absorption and in the aggressiveness of cholesteatoma.

Adolescent↗
PubMed1989

[Movement of the ear ossicles by middle ear muscle contraction].

Up to now, the function of the middle ear muscles has mainly been investigated from an acoustical point of view. However, the primary function of the middle-ear muscles, namely the induction of ossicular movements, has never been investigated systematically. For this purpose, the displacements of the ossicles, as induced by simulated muscle contractions, were measured microscopically in 13 fresh temporal bone preparations. Both muscles move all ossicles. The tensor tympani muscle pulls the umbo inwards about 100 microns. Due to the gliding motion in the malleus-incus joint, the stapes is thus pushed inwards by at the most 10 microns and, additionally, displaced anteriorly, antagonistic to the pull of the stapedius muscle. This muscle pulls the stapes backwards, lifting the anterior crus outwards and pushing the posterior crus inwards. This reduces the pressure on the cochlear fluids significantly as compared to our former concepts of the movement of the footplate, tilting outwards as a whole around an axis at the posterior pole. Furthermore, this outward displacement of the stapes is not prerequisite for the outward movement of the malleus-drumhead complex, which typically appears at the contraction of the stapedius muscle. The basic motion of the stapes is the movement backwards, which is 5 times greater and which matches the anatomic direction of the pull of the stapedius muscle. This explains the otherwise unlogical position of the stapedius muscle parallel to the footplate. Due to the gliding movement in the malleus-incus joint, this motion changes at the umbo into outward rotation, counteracting the tensor tympani muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Ear Ossicles↗
PubMed1989

Densitometry of implanted allograft ear ossicles.

Densitometry measurements of allograft ear ossicles implanted in humans middles ears for more than 10 years have been performed by means of High Resolution Computerized Tomography and compared with similar measurements made in the opposite normal middle ear ossicles. Eight patients operated for unilateral chronic ear disease were selected for this study. Densitometry findings have been also correlated with histological observations made in allograft ossicles removed after a long-term implantation period.

Cholesteatoma↗
PubMed1997

[First comparisons with laser vibrometry measurements and computer simulation of ear ossicle movements].

The dynamic behavior of the ossicular chain is very complex and is frequency-dependent. To date, this has still not been fully investigated or understood. There remains a lack of measurement procedures to pick up the motion of the ossicles and ear drum simultaneously with sufficient resolution. The presented paper reports simultaneous measurements with laser-Doppler vibrometry at two points of the ossicular chain of cadaver specimens. Motions not observed were derived using mechanical simulation models on a computer and then evaluating appropriate mathematical equations. Using a sound stimulus, the displacement velocities of the umbo and stapes footplate were measured, and the corresponding transfer functions were derived by Fourier transform. Results were used for verification of the computer models. In the current investigations these models were refined and allow for the detailed investigation of the dynamic behavior of the ossicular chain, facilitating the optimal design of passive and active middle-ear implants.

Computer Simulation↗
PubMed1997

Scanning laser Doppler vibrometry of the middle ear ossicles.

This paper describes measurements of the vibratory modes of the middle ear ossicles made with a scanning laser Doppler vibrometer. Previous studies of the middle ear ossicles with single-point laser Doppler measurements have raised questions regarding the vibrational modes of the ossicular chain. Single-point analysis methods do not have the ability to measure multiple points on the ossicles and, consequently, have limited ability to simultaneously record relative phase information at these points. Using a Polytec Model PSV-100, detailed measurements of the ossicular chain have been completed in the human temporal bone model. This model, when driven with a middle ear transducer, provides detailed three-dimensional data of the vibrational patterns of the middle ear ossicles. Implications for middle ear implantable devices are discussed.

Cadaver↗
PubMed2002

Ontogenetic and phylogenetic transformations of the ear ossicles in marsupial mammals.

This study is based on the examination of histological sections of specimens of different ages and of adult ossicles from macerated skulls representing a wide range of taxa and aims at addressing several issues concerning the evolution of the ear ossicles in marsupials. Three-dimensional reconstructions of the ear ossicles based on histological series were done for one or more stages of Monodelphis domestica, Caluromys philander, Sminthopsis virginiae, Trichosurus vulpecula, and Macropus rufogriseus. Several common trends were found. Portions of the ossicles that are phylogenetically older develop earlier than portions representing more recent evolutionary inventions (manubrium of the malleus, crus longum of the incus). The onset of endochondral ossification in the taxa in which this was examined followed the sequence; first malleus, then incus, and finally stapes. In M. domestica and C. philander at birth the yet precartilaginous ossicles form a supportive strut between the lower jaw and the braincase. The cartilage of Paauw develops relatively late in comparison with the ear ossicles and in close association to the tendon of the stapedial muscle. A feeble artery traverses the stapedial foramen of the stapes in the youngest stages of M. domestica, C. philander, and Sminthopsis virginiae examined. Presence of a large stapedial foramen is reconstructed in the groundplan of the Didelphidae and of Marsupialia. The stapedial foramen is absent in all adult caenolestids, dasyurids, Myrmecobius, Notoryctes, peramelids, vombatids, and phascolarctids. Pouch young of Perameles sp. and Dasyurus viverrinus show a bicrurate stapes with a sizeable stapedial foramen. Some didelphids examined to date show a double insertion of the Tensor tympani muscle. Some differences exist between M. domestica and C. philander in adult ossicle form, including the relative length of the incudal crus breve and of the stapes. Several differences exist between the malleus of didelphids and that of some phalangeriforms, the latter showing a short neck, absence of the lamina, and a ventrally directed manubrium. Hearing starts in M. domestica at an age in which the external auditory meatus has not yet fully developed, the ossicles are not fully ossified, and the middle ear space is partially filled with loose mesenchyme. The ontogenetic changes in hearing abilities in M. domestica between postnatal days 30 and 40 may be at least partially related to changes in middle ear structures.

Animals↗
PubMed1989

Mechanics of a single-ossicle ear: I. The extra-stapedius of the pigeon.

The motion of the conical peak of the tympanic membrane (TM) at the tip of the extra-stapedius (ES) and of the columella footplate (CFP) were measured in the pigeon using the Mössbauer technique. The dimensions of middle-ear structures were measured in some of the experimental animals. The averaged velocity response at the ES for frequencies of 0.25-2.378 kHz was that of a second order, mass and stiffness controlled, resonant system with resonant frequency of 1.2 kHz and Q3 dB of 1.2. The mean velocity amplitude at resonance was 3.7 mms-1 at 100 dB SPL, which is approximately equal to the theoretical value of 3.5 mms-1 required for maximum energy transfer from a uniform plane acoustic wavefront in air. For the frequency regions 0.125-0.25 kHz and 2.378-5.657 kHz, the mean amplitude slopes for the velocity at the ES were 2 dB oct-1 and -3 dB oct-1, respectively. Above 5.657 kHz there was considerable inter-animal variation in the ES velocity responses. The direction of motion at the ES was frequency dependent above 1 kHz. For frequencies up to 1 kHz the ratio of CFP to ES velocity was independent of frequency; the mechanical lever ratio was 2.7, which was attributed to the geometry of the middle ear. At these frequencies the total transformer ratio for the middle ear, expressing the ratio of fluid pressure at the CFP to sound pressure at the ES, was estimated to be 35 dB.

Acoustic Stimulation↗
PubMed1989

Mechanics of a single-ossicle ear: II. The columella footplate of the pigeon.

The motion of the columella footplate (CFP) was measured in the pigeon using the Mössbauer technique. At the upper frequency limit of the cochlea the measured CFP response exhibited anti-resonant phenomena. These high-frequency responses were dependent on the orientation of the radiation detector, in a way which could not be explained by the cosine effect. The dependence of the recorded phase response on the measurement axis implies an additional vibration mode, which was out of temporal phase and non-colinear with the presumed translational vibration mode. The anti-resonant phenomena were not observed when the cochlear labyrinth was extirpated, thus excluding an explanation in terms of extraneous vibrations in the experimental apparatus or of loading by the Mössbauer source. Intra-cochlear reflection is proposed as the origin of the interference mode.

Acoustic Stimulation↗
PubMed2003

[Experimental investigations of CO2 laser application in middle ear ossicles].

BACKGROUND: During the last few years, several laser systems have been applied for procedures in middle ear surgery. In this study, we determined the technical parameters for the dissection of the middle ear ossicles with the CO(2) laser and analyzed the histological findings. METHODS: The malleus necks of 16 human temporal bones were dissected under standardized conditions using a CO(2) laser with a power output between 35 and 55 kW/cm(2). The specimens were fixed and histological probes of 50- micro m thickness were prepared. RESULTS: The laser outputs led to crater diameters from 0.14 to 0.55 mm. As an analogy between laser energy and thermal tissue destruction, three zones of thermal damage were differentiated: a cinder zone, a carbonization zone, and a zone of dehydration. The metrical dimensions of these zones did not show any correlation to the applied laser energy. CONCLUSIONS: The data of this study show that commercially available CO(2) lasers are sufficient for a safe and effective partial resection of middle ear ossicles using a power output of 35 kW/cm(2).

Ear Ossicles↗