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PubMed2004

Pathology of the ossicular chain: comparison between virtual endoscopy and 2D spiral CT-data.

OBJECTIVE: The purpose of this study was to assess the value of virtual endoscopy (VE) in the diagnosis of lesions of the ossicular chain and to compare virtual endoscopy and two-dimensional (2D) spiral computed tomography (CT) data. STUDY DESIGN: Retrospective study. SETTING: A university hospital. PATIENTS: Fifty-eight patients with suspected ossicular chain lesions underwent a high-resolution CT of the temporal bone with both 2D data and VE before surgery. MAIN OUTCOME MEASURES: Two views were chosen for VE. The CT data obtained (2D, VE, and both 2D and VE) were compared with the lesions noted during surgery. RESULTS: In the diagnosis of dislocation of the ossicles or prostheses, VE seemed to be a better technique than 2D CT. Views chosen for the VE proved to be ineffective for diagnosing epitympanic fixations. VE was not adapted to the study of otosclerosis. We found it necessary to use the data provided by the addition to 2D CT data in the diagnosis of ossicular lysis and minor aplasia. Radiologic analysis of the lesions of the long process of the incus and the incudostapedial joint was improved by performing both 2D CT and VE. VE reconstruction of the stapes proved to be difficult, especially in cases of inflammation of the middle ear. CONCLUSION: This study demonstrates the value of VE in the diagnosis of dislocation of the ossicles and ossicular prostheses. VE was less effective in diagnosing other pathologies of the ossicular chain.

Ear Ossicles↗
PubMed2005

Hush puppy: a new mouse mutant with pinna, ossicle, and inner ear defects.

OBJECTIVES/HYPOTHESIS: Deafness can be associated with abnormalities of the pinna, ossicles, and cochlea. The authors studied a newly generated mouse mutant with pinna defects and asked whether these defects are associated with peripheral auditory or facial skeletal abnormalities, or both. Furthermore, the authors investigated where the mutation responsible for these defects was located in the mouse genome. METHODS: The hearing of hush puppy mutants was assessed by Preyer reflex and electrophysiological measurement. The morphological features of their middle and inner ears were investigated by microdissection, paint-filling of the labyrinth, and scanning electron microscopy. Skeletal staining of skulls was performed to assess the craniofacial dimensions. Genome scanning was performed using microsatellite markers to localize the mutation to a chromosomal region. RESULTS: Some hush puppy mutants showed early onset of hearing impairment. They had small, bat-like pinnae and normal malleus but abnormal incus and stapes. Some mutants had asymmetrical defects and showed reduced penetrance of the ear abnormalities. Paint-filling of newborns' inner ears revealed no morphological abnormality, although half of the mice studied were expected to carry the mutation. Reduced numbers of outer hair cells were demonstrated in mutants' cochlea on scanning electron microscopy. Skeletal staining showed that the mutants have significantly shorter snouts and mandibles. Genome scan revealed that the mutation lies on chromosome 8 between markers D8Mit58 and D8Mit289. CONCLUSION: The study results indicate developmental problems of the first and second branchial arches and otocyst as a result of a single gene mutation. Similar defects are found in humans, and hush puppy provides a mouse model for investigation of such defects.

Animals↗
PubMed1986

Traumatic lesions of the middle ear: aetiology and results of treatment.

A retrospective investigation of the aetiology and results of treatment for traumatic, conductive hearing loss was performed in 122 patients treated from 1979 to 1983. The mean age at the time of the trauma was 25 years. The average treatment delay was 7 years. The patients were grouped according to the nature of the injury. The group with head injury (40 patients) was characterized by a frequent combination of young men and traffic accidents. Among direct trauma (16 patients) lesions to the tympanic membrane and/or the middle ear were caused by ear syringing or by the introduction of swabs or other instruments into the auditory canal. In the group exposed to indirect trauma (57 patients) the dominant single cause of the trauma in the present material consisted of a blow to the ear and was most often seen among young women. A subgroup exposed to blasts contained more young men. The dominant operative findings were rupture of the tympanic membrane, luxation of the incus, partial bone necrosis and fracture of the auditory ossicles. Ear surgery consisted of closure of the ruptured tympanic membranes and restoration of the sound-transmitting function of the ossicular chain. Normal hearing was restored in 78%, and hearing improved in another 10%. The hearing remained unchanged or deteriorated in 9% of the patients, a group often characterized by a long treatment delay and/or the development of chronic otitis.

Adolescent↗
PubMed1987

The predictive value of high resolution computerized tomography in chronic suppurative ear disease.

High resolution computerized tomographic scanning was used in the preoperative evaluation of 50 patients with chronic suppurative ear disease. The radiological predictions were compared with the operative findings in each case. This form of imaging proved to be highly accurate in depicting the extent of soft tissue within the middle ear cleft and mastoid. With the exception of the long process of the incus and the stapes superstructure, the state of the ossicular chain was correctly predicted in over 90% of cases. Erosion of the labyrinth was clearly depicted in 4 of the 5 cases in which it occurred. A correct pathological diagnosis was made radiologically in 44 cases (88%). The selective use of this modality in the evaluation of patients with chronic suppurative otitis media is valuable.

Adult↗
PubMed1991

Ossicular geometry and the choice of technique for ossiculoplasty.

The dimensions of the space between the handle of the malleus and the plane of the head of the stapes have been investigated in 31 preserved temporal bones and 20 patients with defects of the incus. The width (A) and depth (B) were measured directly and other dimensions were then calculated. In the preserved temporal bones A varied between 0.5 and 3 mm (mean 2.0 mm), while for the patients the range was 1.5-3.8 mm (mean 2.2 mm). The dimension B varied between 1 and 2.5 mm (mean 1.7 mm) in the temporal bones and between 0 and 2 mm in the patients (mean 0.9 mm). This difference is statistically significant (P less than 0.0001). The angle at which a graft placed directly between the stapes head and malleus handle would lie relative to the long axis of the stapes varied between 14 degrees and 71 degrees in the temporal bones (mean 49 degrees) and between 0 degrees and 79 degrees in the patients (mean 63 degrees). This difference is also statistically significant (P less than 0.001). These differences may be due to chronic Eustachian tube dysfunction or to a tendency of the malleus to become displaced medially when it is not supported by the incus/stapes complex. These findings have significant implications for the mechanical properties of different methods of ossiculoplasty, and the relative position of the malleus and stapes should be taken into account when choosing the technique to be used in an individual case.

Anthropometry↗
PubMed1994

Revision surgery in otosclerosis--operative findings in 186 patients.

Over a 14-year-period 186 revision operations for otosclerosis were performed. In 90% of the patients the indication for revision was too large an air-bone-gap. A number of different surgical techniques had been used at the primary operation. The purpose of the investigation was to describe the middle ear abnormality at the revision operation. Most often adhesions, acentric prosthesis, reobliteration and necrosis of the long process of the incus were found. The middle ear abnormality found at revision operation was correlated to the primary surgical technique used and the information obtained can be of value, when a revision operation is considered. The surgical technique used at revision operation was determined by the operative findings. The best hearing improvement was obtained when a small-fenestration-technique was used primarily or as the method for revision. In revision stapes surgery, the experience of the surgeon is important and centralization of this type of operation is recommended.

Ear Ossicles↗
PubMed1995

A 3-D finite element analysis of the natural frequencies of vibration of a stapes prosthesis replacement reconstruction of the middle ear.

In this work, the natural frequencies of vibration of two different stapes prosthesis replacement reconstructions have been analysed using the finite element method. Prosthesis 1 was constructed of fine stainless steel wire and a Teflon base, while prosthesis 2 was made entirely of Teflon. The results have indicated that generally, the first natural frequency of vibration falls as the prostheses become larger and more bulky. However, the fall in the first natural for prosthesis 1 was modest when compared with that of the isolated tympanic membrane. An important variable influencing frequencies and mode of vibration of the reconstruction was the tightness of fit of the prostheses within the remaining ossicular chain. The tightness of fit in this work was modelled as a range of spring constants applied at the stapes pseudo footplate, together with a series of joint elements at the incus tip/prosthesis head for the Teflon implant. When these spring constraints were below approximately 10 N/mm, the reconstruction exhibited normal mode 1 vibration behaviour, but at larger spring values, an abnormal mode 1 became established resembling the normal mode 2 vibration characteristics. The formation of new geometries and surfaces following reconstruction, introduces new constraints between umbo and stapes footplate particularly at the natural/artificial interfaces. These unnatural constraints may inhibit and modify the natural movements normally occurring at the stapes footplate leading to abnormal modes of vibration.

Ear Ossicles↗
PubMed2004

Audiometric evaluation of an attempt to optimize the fixation of the transducer of a middle-ear implant to the ossicular chain with bone cement.

Typically, an implantable hearing device consists of a transducer that is coupled to the ossicular chain and electronics. The coupling is of major importance. The Vibrant Soundbridge (VSB) is such an implantable device; normally, the VSB transducer is fixed to the ossicular chain by means of a special clip that is crimped around the long process of the incus. In addition to crimping, bone cement was used to optimize the fixation in six patients. Long-term results were compared to those of five controls with crimp fixation alone. To assess the effect of bone cement (SerenoCem, Corinthian Medical Ltd, Nottingham, UK) on hearing thresholds, long-term post-surgery thresholds were compared to pre-surgery thresholds. Bone cement did not have any negative effect. Next, to test the hypothesis that aided thresholds might be better with the use of bone cement, aided thresholds were studied. After correction for the severity of hearing loss, only a small difference was found between the two groups at one frequency, viz. 2 kHz. It was concluded that there was no negative effect of using bone cement; however, there is also no reason to use bone cement in VSB users on a regular basis.

Adult↗
PubMed1996

Audible in utero sound caused by the ultrasonic radiation force from a real-time scanner.

While investigating in utero sound levels during vibro-acoustic stimulation on the maternal abdomen it was noticed that noise level increased when the real-time ultrasonic scanner beam was directed at the sensing hydrophone. The noise was recorded and later analysed for frequency content and waveform. It appeared related to the scanning and frame rate frequencies of the scanner used. Sounds may originate from radiation pressure produced when the ultrasound beam is absorbed by tissue or reflected from bone or the metal hydrophone. This implies that although ultrasound cannot be heard per se, any modulation of its intensity will produce vibrations in the maternal tissues or reflecting structures such as skull bone, and especially stapes, malleus and incus, that would be heard as sound by the fetus. The intensity of the sound produced varied with orientation of the transducer beam and this may itself produce a stimulation. Based on our recordings (Fig. 1), it was calculated (please see Appendix) that the fetus would hear a sound corresponding to 84dB noise pressure level in air.

Acoustic Stimulation↗
PubMed1982

Input impedance of the cochlea in cat.

Tones were delivered directly to the stapes in anesthetized cats after removal of the tympanic membrane, malleus, and incus. Measurements were made of the complex amplitudes of the sound pressure on the stapes PS, stapes velocity VS, and sound pressure in the vestibule PV. From these data, acoustic impedance of the stapes and cochlea ZSC delta equal to PS/US, and of the cochlea alone ZC delta equal PV/US were computed (US delta equal to volume velocity of the stapes = VS X area of the stapes footplate). Some measurements were made on modified preparations in which (1) holes were drilled into the vestibule and scala tympani, (2) the basal end of the basilar membrane was destroyed, (3) cochlear fluid was removed, or (4) static pressure was applied to the stapes. For frequencies between 0.5 and 5 kHz, ZSC approximately equal to ZC; this impedance is primarily resistive ([ZC] approximately equal to 1.2 X 10(6) dyn-s/cm5) and is determined by the basilar membrane and cochlear fluids. For frequencies below 0.3 kHz, [ZSC] greater than [ZC] and ZSC is primarily determined by the stiffness of the annular ligament; drying of the ligament or changes in the static pressure difference across the footplate can produce large changes in [ZSC]. For frequencies below 30 Hz, ZC is apparently controlled by the stiffness of the round-window membrane. All of the results can be represented by an network of eight lumped elements in which some of the elements can be associated with specific anatomical structures. Computations indicate that for the cat the sound pressure at the input to the cochlea at behavioral threshold is constant between 1 and 8 kHz, but increases as frequency is decreased below 1 kHz. Apparently, mechanisms within the chochlea (or more centrally) have an important influence on the frequency dependence of behavioral threshold at low frequencies.

Acoustic Impedance Tests↗
PubMed1992

Analysis of dynamic behavior of human middle ear using a finite-element method.

Applying the general-purpose finite-element package program (ISAP), a three-dimensional finite-element method (FEM) model of a human right middle ear, which included ossicles, was made and the mechanical properties and boundary conditions of the middle ear were determined by a comparison between the numerical results obtained from the FEM analysis and the measurement results of the fresh cadavers, normal subjects and patients, which were obtained by our developed sweep frequency middle ear analyzer (MEA). The "Elastic" boundary condition consisting of linear and torsional springs at the eardrum attachments to the annular ligament was more appropriate for the actual condition than "fully clamped" one. Rotational axis of the ossicular chain was assumed to be a fixed straight line from the anterior process of the malleus to the short process of the incus, and a load of the ossicular chain and cochlea was simplified to be expressed by the stiffness of the cochlea. Vibration patterns of the eardrum and ossicles at the first resonance frequency, obtained under these assumptions, were in agreement with the experimental results obtained by means of time-averaged holography and by using a video measuring system, except for the relatively large displacements at the tympanic ring.

Auditory Perception↗
PubMed1996

Some acoustical properties of the otic bones of a fin whale.

The otic bones in this report are the tympanic bulla, the periotic, and the three ossicles (malleus, incus, and stapes) of an adult fin whale (Balaenoptera physalus). The purpose was to determine if the periotic was denser than the other otic bones. It was found in one male adult fin whale that the density of all the otic bones is approximately the same, 2.50 kg/m3 with a maximum of 2.58. The lowest density was observed in the stapes (2.36). The sonic velocity seems to vary as the density but there also seems to be a structural effect. The maximum sonic velocity was 4.89 km/s in the malleus. The specific acoustic impedance was as high as 12.5 megarayles in the periotic. These values compare with those for human femur of 1.95 for the density, 3.73 for the sonic velocity, and 7.33 for the specific acoustic impedance. The ossicles weigh as much as 200 times as much as human ossicles. The density of whale ossicles are about ten percent greater than human ossicles. The mechanical natural frequency of the whale ossicles must be very low. The approximate uniformity of the properties of this whale's otic bones may be characteristic of the middle ear. The density of the otic bones of land mammals is less than for whales. The density of the horse petrosal (2.29 g/cc) is essentially the same as the density of adult human ossicles (2.23-2.27 g/cc). The high density of the otic bones for all mammals suggests it may be related to hearing acuity perhaps by increasing the specific acoustic impedance, which increases the acoustic contrast with the other body tissues.

Acoustics↗
PubMedDate not supplied

CT evaluation of prosthetic ossicular reconstruction procedures: what the otologist needs to know.

Postoperative otologic evaluation of patients who have undergone ossicular reconstruction is often difficult. However, thin-section computed tomography (CT) can help determine the type of prosthesis used for reconstruction and adequately assess for complications that may be causing postoperative conductive hearing loss. A variety of prostheses may be used in ossicular reconstruction (eg, stapes prosthesis, incus interposition graft, Applebaum prosthesis, Black oval-top prosthesis, Richards centered prosthesis, Goldenberg prosthesis) and can usually be identified at CT by their shapes and locations. Several causes of prosthetic failure are readily demonstrated at CT, including recurrent cholesteatoma and otitis media, formation of granulation tissue or adhesions, and various mechanical problems (eg, subluxation, dislocation, extrusion, fracture, bending). Perilymphatic fistula can be difficult to identify at CT but may be suggested by the presence of pneumolabyrinth, unexplained middle ear effusion, or fluid accumulation within the mastoid air cells. The presence of soft tissue within the oval window niche 4-6 weeks following surgery may indicate poststapedectomy granuloma or fibrosis. Familiarity with the normal and abnormal CT appearances of ossicular prostheses will enable the radiologist to assist the otologist in identifying patients in whom revision surgery is most appropriate.

Equipment Failure Analysis↗
PubMed1987

Ossicular erosions in the dry ear: CT diagnosis.

Erosions of the ossicular chain that occurred as a complication of noncholesteatomatous chronic otitis media were studied with computed tomography (CT) in 55 patients. The incus (particularly the long and lenticular processes) was the ossicle most commonly involved (50 cases). Coronal and axial CT sections were complementary in the diagnosis of these erosions. Fibrous replacement of the incudostapedial articulation was diagnosed in four cases on axial CT scans when an unusually wide joint was present.

Ear Diseases↗
PubMed1992

High-resolution CT of the temporal bone: a modified baseline.

High-resolution computed tomography (CT) of the temporal bone, particularly axial scanning on a baseline parallel to the orbitomeatal line, produces radiation exposure to the patient's lenses. The authors evaluated the radiation dose to the lens and the visualization of temporal bone structures with use of scanning along the orbitomeatal line and on a line parallel to the hard palate. Evaluation of visualization was performed by five radiologists, with high-resolution CT scans of 45 healthy patients, and the chi 2 test was performed for comparison. The change of the baseline from the orbitomeatal line to a line parallel to the hard palate decreased the radiation dose to the lens from 12.7 cGy to 0.274 cGy and improved visualization of the stapes superstructure and the tympanic portion of the facial nerve canal, although visualization of the incus body, incudostapedial joint, lateral semicircular canal, and oval window was of equal quality. Therefore, the authors recommend a new baseline parallel to the hard palate for use at high-resolution CT of the temporal bone.

Health Personnel↗
PubMedDate not supplied

Modelling of components of the human middle ear and simulation of their dynamic behaviour.

In order to get a better insight into the function of the human middle ear it is necessary to simulate its dynamic behaviour by means of the finite-element method. Three-dimensional measurements of the surfaces of the tympanic membrane and of the auditory ossicles malleus, incus and stapes are carried out and geometrical models are created. On the basis of these data, finite-element models are constructed and the dynamic behaviour of the combinations tympanic membrane with malleus in its elastic suspensions and stapes with annular ligament is simulated. Natural frequencies and mode shapes are computed by modal analysis. These investigations showed that the ossicles can be treated as rigid bodies only in a restricted frequency range from 0 to 3.5 kHz.

Computer Simulation↗
PubMedDate not supplied

Middle ear imaging using virtual endoscopy and its application in patients with ossicular chain anomaly.

Virtual endoscopy (VE) is a recently developed technique to provide a realistic surface rendering of various organs, which can be applied to the use of three-dimensional (3D) studies of several lesions. However, its advantages in otological disease have not been well investigated. In this study, we evaluated the application of VE in patients with ossicular chain anomalies. Virtual middle ear endoscopy was a time-saving method, however, we needed the appropriate technical procedures of algorithm and reconstruction spacing to generate accurate 3D images of ossicles. We obtained virtual surgical views of middle ear structures and related anomalies, and confirmed by intraoperative findings that these images were mostly compatible with the actual lesions of ossicles. VE allowed an identification of the anatomy of the ossicles and adjacent structures simultaneously. The elements of the stapedial crura were clearly visualized with VE images in 93.3% of normal ears. Pathological ossicular chain findings such as malleus or incus fixation, dislocation and disruption, except footplate fixation were investigated successfully. One possible procedure, using alterable CT value in the obtained VE images on the monitor, is proposed for further detection of fine lesions of the ossicles. These observations suggest that virtual middle ear simulations accurately represent major intraoperative findings. This technique may have an important role in preoperative planning, surgical training, and/or postoperative evaluation in otology.

Adult↗
PubMedDate not supplied

Long-term results of a new stapedotomy prosthesis.

The long-term results of a new, home-made stapedotomy prosthesis are presented. The innovations of this prosthesis concern both portions, design for attachment to the incus and shaft. Our series include a total number of 42 individuals with stapes fixation, operated using the new prosthesis, with a medical follow-up period between eighteen months and five years. Our innovations offer a proper and safe insertion of the prosthesis into the oval window associated with excellent manipulation and handling. These advantages could be of major importance for younger surgeons and trainees. Postoperative hearing results are similar to those achieved with other commercially available pistons.

Adult↗