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At least 55 records · Page 3Linked to original sources
PubMed1992

Alterations of bone conducted hearing in cases of modified middle ear mechanics. Conclusions from an electrical model.

In clinical diagnosis bone conduction thresholds can be used to assess impaired hearing caused by pathological function of the inner ear. The effects of changed mechanical properties of the middle ear on bone conduction are usually not considered in patients who simultaneously suffer from middle ear and inner ear diseases. This procedure is only partially correct. An exact determination of the effects of altered middle ear mechanics on bone conduction in patients with otosclerosis or after middle ear operations is rather difficult, but such determinations can improve diagnostic validity. Therefore, a special electrical model was constructed to simulate the oscillation pattern of the basilar membrane for bone conduction and variable middle ear impedance. Results from the model and possible conclusions on bone conducted hearing in vivo are discussed. Further steps to ensure measurements of inner ear function in cases with modified middle ear mechanics are proposed.

Basilar Membrane↗
PubMed2006

[Useful imaging of the ear].

Good anatomical knowledge is necessary to make an effective diagnosis in ear pathology. The purpose of this article is to summarize the main landmarks of the ear. Anatomic definitions of the external ear, middle ear, and bony labyrinth are described on routine spiral CT, and the anatomic definition of the membranous labyrinth and the cochleovestibular nerve on MRI is reviewed.

Auditory Pathways↗
PubMed2002

Fetal development of the human tympanic ossicular chain articulations.

OBJECTIVES: To obtain further knowledge on the morphogenesis of the articulations in the tympanic ossicular chain in humans. MATERIAL AND METHODS: In 25 temporal bones of human fetuses the structural development of incudomallear, incudostapedial and stapediovestibular articulations was studied. The chronological ages were between the 7th week (21 mm) and the 29th week (270 mm). RESULTS AND DISCUSSION: Incudomallear articulation showed diarthrosis and sellar joint characteristics. It showed a homogenous interzone in the 7th week of development, a three-layered interzone in the 8th week, the first cavitation signs in the 9th week and the presence of an articular cavity in the 10th week. The presence of a hyaline cartilage covering articular surfaces was observed starting in the 20th week of development. Incudostapedial articulation showed typical characteristics of a diarthrosis and spheroidal joint with a homogenous interzone at the 7th week, showing similar characteristics for 12 weeks, and completed its cavitation at the 16th week. We observed hyaline cartilage on articular surfaces from 29 weeks. Stapediovestibular articulation showed typical characteristics of syndesmosis. The annular ligament primordium derived from cartilage differentiation, both from stapedial footplate and from the surrounding otic capsule, into mesenchyme and its subsequent transformation into fibrous tissue, reaching definitive characteristics from the 12th week.

Body Patterning↗
PubMed1994

Perilymph pressure during hypobaric conditions--cochlear aqueduct obstructed.

Nine cats with the cochlear aqueduct surgically blocked were anaesthetised, put in a pressure chamber, and stepwise exposed to hypobaric pressure, each of the two steps lasting 5 min. The chamber pressure was reduced to -5 and -7 kPa. Concluding the experiment the cats were observed for 5 min after restoration of atmospheric pressure. The perilymph, tympanic cavity, cerebrospinal fluid, central venous, arterial and surrounding chamber pressures were continuously recorded. Reduced chamber pressure caused relative overpressure within the tympanic cavity, thereby inducing pressure gradients between the chamber, the tympanic cavity, the labyrinth and the cerebrospinal fluid and vascular pressures respectively. Our results demonstrate that hypobaric effects on the labyrinth are mediated via pressure changes in the tympanic cavity and not by systemic, vascular or cerebrospinal fluid influence. Substantial perilymph overpressure lasted throughout the hypobaric conditions. The magnitude and the duration of this overpressure were influenced by the patency of the Eustachian tube whereas the rate of the pressure change in the chamber was of little importance. As atmospheric pressure was restored in the chamber the overpressure in the labyrinth was reversed to underpressure--relative to pre-experimental conditions.

Animals↗
PubMed1981

Surgical anatomy and pathology of the round window.

A study of the surgical anatomy and pathology of the round window was performed on a total of 292 serially sectioned temporal bones. The surgical approach to the round window is discussed with consideration of the anatomical findings. In the pathological study obliteration of the round window niche occurred as a congenital anomaly, in otosclerosis, chronic otitis media and as an end result in suppurative labyrinthitis. Clinical reports seem to indicate that obliteration of the window is associated with significant hearing loss, contrary to the findings in experimental animals. In chronic otitis media the round window is a pathway for spread of infection to the labyrinth, but also the finding of perilymphatic precipitates to the window in some ears suggests that certain inflammatory products may enter the scala tympani through the round window and so lead to high tone sensorineural hearing loss.

Adolescent↗
PubMed1988

[Personal experiences with tympanoscopy in sudden deafness].

The rupture of the round window membrane with consecutive perilymph fistula has gained in importance in the discussion of the pathogenesis of sudden hearing loss. In a retrospective study, the results of 23 tympanoscopies performed at the ENT Department of the University of Hamburg are reported. Two confirmed perilymph fistulas were seen, whereas in three cases they could not be excluded. After obliteration of the window niches with connective tissue an improvement of the hearing loss was seen in 9 cases. In comparison with our intraoperative findings, the number of perilymphatic fistulas mentioned in literature often seems very high. Nevertheless, tympanoscopy and obliteration of the window niches have their definite place in the therapeutic concept of sudden hearing loss, although the indication must be severely restricted.

Adolescent↗
PubMed1997

Mechanics of type IV tympanoplasty: experimental findings and surgical implications.

In a type IV tympanoplasty, the stapes footplate is directly exposed to incoming sound while the round window is "shielded," usually with a fascia graft. Postoperative hearing results are quite variable, with air-bone gaps ranging from 10 to 60 dB. A cadaveric human temporal bone preparation was developed to investigate the middle ear mechanics of this operation to identify causes of variable results and to test predictions of a recently described theoretic model of type IV tympanoplasty. The ear canal, tympanic membrane, malleus, and incus were removed so as to expose the stapes and round window to the sound stimulus. A "cavum minor" chamber (air space adjacent to the round window) was constructed around the round window niche. The round window could be isolated from sound by placing an acoustic shield over this chamber. The mechanical properties of the shield, cavum minor, annular ligament, and round window membrane were varied experimentally. Stapes velocity as determined by an optical motion sensor was used as a measure of hearing level. The largest stapes velocity occurred with a mobile stapes and round window, a stiff shield, and a well-aerated cavum minor. Partial fixation of the stapes or round window caused a decrease in stapes velocity. Acoustic shields of conchal cartilage or Silastic silicone rubber sheeting (approximately 1 mm thick) provided near-optimal shielding. A temporalis fascia shield resulted in a stapes velocity 10 to 20 dB less than that seen with a cartilage or Silastic silicone rubber shield at low frequencies. A cavum minor air space as small as 16 microL was sufficient for unrestricted stapes motion, provided the air was in contact with the round window membrane. These results qualitatively matched predictions of our model, but there were some quantitative differences. The clinical implications of our results are that in order to optimize postoperative hearing, the surgeon should 1) preserve normal stapes mobility, preferably by covering the footplate with a very thin split-thickness skin graft, not a fascia graft; 2) reinforce a fascia shield with cartilage or Silastic silicone rubber; 3) create conditions that promote aeration of the round window niche; and 4) preserve the mobility of the round window membrane.

Adult↗
PubMed2000

Acoustic impedances at the oval window, and sound pressure transformation of the middle ear in Norwegian cattle.

In 15 cadaver ears from Norwegian cattle, sound pressure transfer functions have been measured (1) for sound input to the tympanic membrane, (2) for sound input to the oval window with the footplate in place, but with the ossicular chain removed, and (3) for sound input to the oval window with also the footplate removed. The output pressure was measured in an enclosure cemented to the round window. The data allow calculation of equivalent sound pressures at the input positions, as well as the acoustic input impedances at the oval window with intact footplate, Z(sc), and with the footplate removed, Z(c). The difference Z(s)=Z(sc)-Z(c) is the acoustic impedance contribution of the footplate and annular ligament. Z(sc) is mainly determined by the stiffness of the annular ligament at low frequencies, and by the cochlear input impedance Z(c) at higher frequencies. Z(c) is predominately resistive, a minor reactive part at low frequencies is attributed to the stiffness of the round window membrane. Z(s) and Z(c) are equal in magnitude at about 0.4 kHz. Rather close RLC fits have been obtained for all the three impedances, Z(sc), Z(s), and Z(c). The fitted values for the resistive parts of Z(sc) and Z(c) are 62.9 and 58.2 acoustic Gomega, respectively. The relatively small difference, 4.7 Gomega, is attributed to the resistance of the annular ligament. The fitted resistance of Z(s) is somewhat larger, 8.6 Gomega, but is anyway of minor importance relative to the dynamic stiffness of the annular ligament. This stiffness depends on the static pressure difference across the footplate. Each of the averaged Z(sc) corresponds to minimum stiffness. The fitted acoustic compliance is 6.89 x 10(-15) m3/Pa. The acoustic inertance plays a minor role. It is attributed to the mass of the footplate and the co-vibrating liquid in the inner ear, and has a fitted value of 4.7 x 10(5) Pa s2/m3. A sound pressure at the eardrum is equivalent to a larger pressure at the footplate, about 16 dB larger at frequencies below 100 Hz, increasing to about 30 dB at 10 kHz. In the vestibulum at the inner side of the footplate, the sound pressure at 20 Hz is about 20 dB below the equivalent pressure at the outer side. The two pressures approach toward higher frequencies, and above 1 kHz they are nearly equal.

Acoustic Impedance Tests↗
PubMed2003

[Surgical management of Mondini dysplasia with cerebrospinal fluid leakage].

OBJECTIVE: To evaluate the clinical manifestation and surgical technique of Mondini dysplasia with cerebrospinal fluid (CSF) leakage. METHOD: Three Mondini dysplasia with spontaneous cerebrospinal fluid leakage were treated by the authors. A transcanal tympanotomy were used to pack the vestibular cavity with muscle. RESULT: Three children were first manifested with recurrent meningitis and spontaneous cerebrospinal fluid rhinorrhea. Further examinations found that the leakages were otogenic. One side or both sides Mondini dysplasia were confirmed by CT scanning of temporal bones. The leakages were all stopped by the primary surgical closure. CONCLUSION: Mondini dysplasia should be considered in children with spantaneous cerebrospinal fluid otorhinorrhea. A temporal bone CT scan can confirmed the diagnosis. A transtympanic closure is very effective in the management.

Cerebrospinal Fluid Otorrhea↗
PubMed2006

Relationship between CT densitometry with a slice thickness of 0.5 mm and audiometry in otosclerosis.

The appropriate cutoff Hounsfield unit (HU) value for the diagnosis of otosclerosis was determined and the correlation between the bone conduction threshold and the findings of computed tomography (CT) densitometry investigated. CT images, 0.5-mm thick, were evaluated in 24 ears with otosclerosis and 19 control ears. Eight regions of interest were set around the otic capsule. The mean HU values in the area anterior to the oval window (A-OW) and anterior to the internal auditory canal (A-IAC) were significantly lower in otosclerosis than in controls. Based on receiver operating characteristic (ROC) analysis, the cutoff HU value in A-OW was determined to be 2,187.3 HU. The mean HU value in retrofenestral otosclerosis was significantly lower in the area A-OW, A-IAC and around the cochlea than in controls. Based on ROC analysis, the cutoff HU value in the latter was determined to be 2,045 HU. A statistically significant correlation was found between the density of the area A-OW and the hearing level at 500 and 1,000 Hz, and between the density of the area around the cochlea and the hearing level at most frequencies. These results suggest the semi-automated diagnosis of otosclerosis may be possible.

Absorptiometry, Photon↗
PubMed1987

[The "window-fistula symptom" in lesions of the round and oval window].

22 tympanoscopies in suspected perilymph fistulas with clinical symptoms such as sudden hearing loss, tinnitus, vertigo, fluctuating hearing etc., histories and intraoperative findings were registered. In some cases a remarkable interval between the implicated event and the clinical manifestation of the symptoms was noticed. Besides on case history and audiometric data the diagnosis was based on vestibular investigations. In 14 of 22 cases the window-fistula-symptom was positive. The window-fistula-symptom is defined as a provocation nystagmus with maximal intensity in the lateral head position lying on the affected ear and in the head hanging position with the head rotated to the affected side. After abandoning these positions the nystagmus is decreased. Mostly the nystagmus is directed to the healthy side. With regard to the preoperative and postoperative findings a generous indication for tympanoscopy in suspected fistulas of the round and oval window membrane is recommended.

Cochlea↗
PubMed1989

Treacher Collins syndrome: an otologic challenge.

Patients with Treacher Collins syndrome have severe middle ear malformations that render operation difficult. We have evaluated 43 patients with Treacher Collins syndrome, on whom only 11 were operated. Computed tomography, the single most important study done preoperatively, routinely showed an underdeveloped temporal bone with islands of bone marrow and absent mastoid pneumatization. The middle ear space was often underdeveloped. Ossicular dysjunction was often noted in which the fused malleus/incus remnant was found 3 to 4 mm distant to the stapes. A common finding was severe dysplasia of the stapes-facial nerve complex that often made the middle ear malformation uncorrectable. Hearing results were much less predictable than in patients with isolated atresia/stenosis of the ear.

Adolescent↗
PubMed1991

Otosclerosis: the University of Minnesota temporal bone collection.

A study of 1452 human temporal bones revealed a previously unpublished material of 144 bones with otosclerosis. After exclusion of infants and individuals of races other than white, the incidence of otosclerosis was 12.75%. Of the bones with otosclerosis, 56.1% belonged to men and 43.9% to women. The incidence of clinical and histologic otosclerosis was practically the same for men (44.7% to 55.3%) as for women (47% to 53%). However, the incidence of bilateral otosclerosis was higher in women (88.9%) than in men (65.2%). Bilateral otosclerosis was present in 75.6%, whereas it was unilateral in 24.4%. Sixty-six (66) ears (45.8%) had clinical otosclerosis, whereas 78 (54.2%) had histologic otosclerosis--frequently unifocal lesions. The most common site was anterior to the oval window (117 ears, 81.25%), followed by round window niche (52 ears, 36.11%), apical and medial cochlear wall (31 ears, 21.52%), and anterior wall of the internal auditory canal (27 ears, 18.75%). The activity of lesions was directly related to their size. Smaller lesions were predominantly inactive, whereas medium and larger lesions were predominantly active. There was a positive correlation when the size of the lesions, activity, and degree of cochlear endosteal involvement were compared with bone conduction thresholds (37 cases). Correlations between size and activity, and between activity and associated sensorineural hearing loss did not necessarily follow the sequence of an initial active stage (spongiotic) to a final inactive one (sclerotic). Comparison of cases of otosclerosis with equivalent age groups of the normal population yielded worse bone conduction thresholds for the otosclerosis cases only in the age group 60 to 69 years and older. Comparison of average bone conduction thresholds between bones with one site of endosteal involvement (28.26 dB HL) revealed no significant differences. Bones with two or more sites of endosteal involvement had significant differences. Bones with two or more sites of endosteal involvement had significantly worse bone conduction thresholds (62 dB HL). The overall results are not suggestive of an association of sensorineural hearing loss with otosclerosis without stapedial fixation.

Adolescent↗
PubMedDate not supplied

[Introduction to the surgery of the middle ear: general principles].

We study the basic guidelines of the middle ear surgery, having as target the recuperation of the anatomic functional integrity of ear. There are different important elements in the quality/quantity of the functional results as follows: The surgery technical method used. The actual pathology in the middle ear. The quality of eustachian tube function. The surgeon's experience and ability and several factors. We review the concept introduced by Wullstein called it tympanoplasty from 1952 till nowadays. Finally, we described the most frequent surgery procedures used in the daily practice.

Ear Diseases↗