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At least 127 records · Page 7Linked to original sources
PubMed1996

[Postmortem changes in ear canal resonance and tympanic membrane impedance in the human ear].

BACKGROUND: The human temporal bone preparation is a common model for research of physical processes of the ear canal and middle ear. In the past decade only a few reports were published discussing changes of the vibration behaviour of the tympanic membrane, as well as the ear canal resonance, during the time between death and preparation of the temporal bone. The aim of our study is to verify whether measurements at the temporal bone of dead humans can be really applied to the in vivo situation. METHODS: We investigated whether changes of the ear canal resonance and the vibration of the tympanic membrane depend on temperature and time after death. In a female human body we defined the resonance of the outer ear and the impedance of the tympanic membrane using a tympanometer and a real ear measurement system during nine hours post mortem. RESULTS: We were able to prove that before the preparation of the temporal bone none of the parameters changed significantly. CONCLUSIONS: In conclusion, the method of preserving the bone after its preparation is decisive for the validity of measurements at the isolated (post mortem) human temporal bone.

Acoustic Impedance Tests↗
PubMed1984

[Computed tomographic volumetry of the pneumatic system of the ear. Comparison of normal subjects and patients with ear diseases].

The volume of the pneumatised portion of the ear was determined by computed tomography in 235 patients. Amongst the 470 ears examined, 320 had no disease in the ear, nose or throat. Normal pneumatisation of the ear can be quantified by CT and strict correlation has been demonstrated between the air content and age from ten to 17 years. Chronic inflammatory processes of the middle ear occurring during childhood interfere with pneumatisation on one or both sides. The most severe failure of pneumatisation occurs with congenital abnormalities of the ear, most cases never showing significant pneumatisation. Chronic infection of the tonsils or adenoids causes much less interference with pneumatisation.

Adolescent↗
PubMed1988

Aggressive papillary middle-ear tumor. A clinicopathologic entity distinct from middle-ear adenoma.

A 29-year-old woman had a middle-ear mass that resulted in hearing loss and seventh-nerve palsy. The tumor invaded the petrous bone, the mastoid, at least one semicircular canal, and then extended into the posterior fossa. Microscopically, it consisted of complex, interdigitating papillae lined by uniform, cuboidal to low columnar cells. The cells resembled the epithelium of the normal middle ear and middle-ear adenoma, but the papillary architecture distinguished this neoplasm from the latter, nonpapillary tumors. Papillary middle-ear tumors are locally invasive. We propose the term "aggressive papillary middle-ear tumor" (APMET). Nine other examples of APMET have been reported under various diagnostic terms. All have been locally destructive with frequent intracranial invasion. Although none of the tumors has metastasized, one patient died of uncontrolled local disease. For this reason, APMET must be distinguished from nonpapillary middle-ear tumors.

Adenocarcinoma↗
PubMed1995

Middle ear gas composition and middle ear aeration.

Partial pressures of the gases in the middle ears of 14 guinea pigs were measured continuously on-line with a specially designed mass spectrometer. The average values were carbon dioxide 67.55 mm Hg, oxygen 48.91 mm Hg, and nitrogen 596.54 mm Hg. These values confirm earlier measurements and show that the gas composition of the middle ear differs basically from that of air and resembles that of venous blood. These findings are indicative of bilateral diffusion between the middle ear cavity and the blood. We propose that under physiologic as well as under pathologic (ie, atelectatic) conditions, the gas content of the middle ear is also controlled by diffusion. This mechanism fits well with the fluctuating character of atelectatic ears. Thus, a negative middle ear pressure could be secondary to excessive loss of gases through increased and excessive diffusion, although additional mechanisms are probably also involved. A likely contributing factor is poor pneumatization of the mastoid, with consequent absence of a physiologic pressure regulation mechanism by its pneumatic system.

Animals↗
PubMed1998

Effect of increased inner ear pressure on middle ear mechanics.

Velocity of malleus, umbo, and stapes footplate in response to stepwise increases up to +400 mm H2O in hydrostatic pressure of the inner ear was investigated in 10 fresh human temporal bones by using a laser Doppler interferometer. The sound-pressure input was 114 dB SPL, and the frequency range was 0.4 to 5.0 kHz. Static displacement of these sites was also measured by a video measuring system. When the inner ear pressure was increased, the malleus and stapes moved outward. Amplitude of umbo velocity decreased below 1.0 kHz with a slight increase around 2.0 kHz, whereas stapes velocity decreased at all frequencies with the major effect below 1.0 kHz. The phase angle of malleus umbo velocity advanced markedly in response to the increased inner ear pressure between 1.0 and 1.4 kHz. Change in the vibration of the umbo was thought to be primarily caused by an increased stiffness of the middle ear conduction system, and that of the stapes was caused by distention of the annular ligament and increased cochlear impedance produced by the increased inner ear pressure. These changes in TM vibration and its phase angle may help detect indirectly an elevation of inner ear pressure.

Aged↗
PubMed1992

A comparison of the efficacy of two ear drop preparations ('Audax' and 'Earex') in the softening and removal of impacted ear wax.

Thirty-six patients with symptoms of impacted ear wax were recruited to an open, randomized, parallel group study of 'Audax' ear drops and 'Earex' ear drops. Patients had had their symptoms for several weeks and they were assessed on entry for the degree of impaction in each ear. After using the drops, morning and evening for 4 days, they were assessed on the fifth day for degree of impaction, ease of syringing, side-effects or discomfort, and the investigator's and patient's own global impression of efficacy of the ear drops. A trend was seen showing less impaction post-treatment in the 'Audax' group than in the 'Earex' group although the difference did not reach statistical significance. A significant difference was seen in favour of 'Audax' for the frequency and ease of syringing (p < 0.005). No patients in the 'Audax' group reported any side-effect or discomfort although 1 patient using 'Earex' reported slight irritation whilst another found the smell unacceptable. The results of the investigators' and patients' own global impression of efficacy were significantly in favour of 'Audax' ear drops (p < 0.01).

Adolescent↗
PubMed2001

Ear deformity in children following high ear-piercing: current practice, consent issues and legislation.

In this presentation we examine the practice of high ear-piercing in children, the issue of informed consent and current legislation. We sampled current practice and consent policy by visiting nine establishments in Sheffield providing this service. There were two high street department stores, two fashion accessory outlets and five body-piercing studios. Enquiries were made as to the technique used, knowledge of complications, customer counselling and consent policy. A photograph of an ear with a cosmetic deformity following high ear-piercing was shown and awareness of this possible outcome was noted. Two ear-piercing techniques were identified, either a spring-loaded gun firing a blunt stud or the use of a body-piercing needle. The fashion accessory outlets were prepared to pierce any part of the ear using a spring-loaded gun in children under 16 years of age. There was a general lack of knowledge about possible serious complications. Two of the body piercers would not perform high ear-piercing on clients under the age of 16 years. The body piercers use a disposable needle and were of the opinion that using a spring-loaded gun shatters the cartilage and increases the risk of infection. The best technique is open to debate and it may be that the perceived unsavoury environment of the body-piercing studio represents a safer option than the more respectable or cheaper alternatives. The practice of body piercing in the UK remains uncontrolled.

Adolescent↗
PubMedDate not supplied

Inner ear disturbances following inoculation of endotoxin into the middle ear.

Inner ear function was assessed by a frequency-specific (+/-100 Hz) auditory brainstem response (ABR) technique after a single instillation of a suspension of purified E. coli lipopolysaccharide in sterile water into the round window (RW) niche in rats. Instillation of endotoxin caused a transient concentration and tonotopically dependent dysfunction of the inner ear. The largest threshold impairment occurred in the high-frequency region anatomically located close to the RW. At 31.5 kHz the threshold impairment persisted throughout the study. Morphologic damage to the inner ear was not detected at the light microscopic level when using serial sections from decalcified specimens. Our study supports the clinical hypothesis that remnants of non-viable bacteria such as endotoxins, when trapped in the middle ear, can promote middle ear effusion and dysfunction of the inner ear.

Animals↗
PubMed1993

Multiple frequency tympanometry: effects of ear canal volume compensation on static acoustic admittance and estimates of middle ear resonance.

Three methods for compensating multiple frequency acoustic admittance measurements for ear canal volume were studied in 26 men with normal middle ear transmission systems. Peak compensated static acoustic admittance (magnitude of y) and phase angle (phi) were calculated from sweep frequency tympanograms (226-1243 Hz in 113 Hz increments). Of the procedures used to compensate for volume in rectangular form, the ear canal pressure used to estimate volume had the largest effect on the estimate of middle ear resonance. Median resonance was 800 Hz for admittance measurements compensated at 200 daPa versus 1100 Hz for measurements compensated at -350 daPa. The remaining two methods, compensation of susceptance only versus both susceptance and conductance and compensation using the minimum volume versus separate volumes at each frequency, did not affect estimates of middle ear resonance. Estimates of middle ear resonance from compensated phase angle measurements also were compared with estimates of resonance from admittance and phase difference curves. Although resonance could not be estimated from the phase difference curve, resonance estimated from the admittance difference curve agreed with the estimate from compensated phase angle.

Acoustic Impedance Tests↗
PubMed1976

Collapsing ears and acoustic reflex measurement with circumaural ear cushions.

Ears that collapse from audiometer ear cushion pressure may show elevated stapedial reflex thresholds. In such cases, erroneous judgments about the status of a patient's hearing are possible. Experiments on 15 normal ears suggest that the use of a circumaural ear cushion on the impedance audiometer headset is an effective method of eliminating outer ear closure and the resulting spurious thresholds, when the proper correction values by frequency are applied to the audiometer dial reading. In this study, correction values for reflex-eliciting stimuli are established and their use in a child with collapsing ears is reported.

Acoustic Stimulation↗
PubMed2002

[Thiel method fixed cadaver ears. A new procedure for graduate and continuing education in middle ear surgery].

BACKGROUND AND OBJECTIVE: An efficient training program in ear surgery needs suitable models to learn the specific preparation techniques. However, conventionally fixed or fresh frozen ears of human corpses do not meet all demands. Therefore we investigated the feasibility of ears fixed according to Thiel for surgical training in the temporal bone lab. METHODS: Various surgical techniques on external and middle ears were evaluated on ears from cadavers fixed according to Thiel. Structure and consistency of the tissues were compared to vital conditions by means of a standardized questionnaire. RESULTS: Structure and consistency of the tissues of the auditory canal, the tympanic cavity and the mastoid were comparable to vital conditions. Merely the cartilage of the auricle was considerable softened. This enabled a surgical preparation under conditions close to the intravital situation. CONCLUSIONS: Under the aspects of quality assurance and efficiency of continuous medical education in middle ear surgery, the Thiel fixation technique provides an excellent prerequisite.

Cadaver↗
PubMed1999

Standardized measurements of the sound transmission of middle ear implants using a mechanical middle ear model.

Several ways to evaluate the sound transmission properties of middle ear implants are now established. Besides computer-based simulations using acoustic and electrical analog circuits or finite element analysis, measurements can be performed with temporal bone preparations. Experiments with these preparations consider various anatomical properties, but a large number of parameters influence the outcome of measurements. To facilitate standardized measurements, a mechanical middle ear model was developed that allows comparison of the transfer function of middle ear implants on defined conditions. The model approximates the impedances of the tympanic membrane and inner ear with the aid of thin, flexible membranes. The implants are fit between the membranes, and displacement at an artificial stapes foot-plate is measured with an optical probe. Fundamental influences on the sound transmission properties of nine different middle ear implants (total ossicular replacement prostheses) were examined. Although the material and shape were different, some of the prostheses revealed very similar transfer functions. The mass of the implant showed the largest influence on sound conduction. With a higher mass, the frequency area above approximately 1 kHz was found to be significantly deteriorated. The lightest implant used was 4 mg and showed the best overall results. These findings show that middle ear prostheses should be as light as possible for optimum high-frequency transmission.

Acoustics↗
PubMed2000

Middle ear volume and pressure effects on tympanometric middle ear pressure determination: model experiments with special reference to secretory otitis media.

OBJECTIVE: Middle ear pressure (P(m)) measured by tympanometry has revealed high negative values in patients with secretory otitis media (SOM) in contrast to direct measurement. This may be explained by errors in tympanometry caused by volume displacement of the tympanic membrane (TM) affecting the volume of the middle ear (V(m)) and the P(m) according to Boyle's Law. Such errors are susceptible to the size of V(m). METHODS: A realistic middle ear model based on previous clinical studies of normal pressure-volume relations of the middle ear system (MES) was constructed. In this model non-linear behaviour and hysteresis of the MES was imitated and P(m) as well as V(m) could be controlled. RESULTS: Tympanometrically estimated P(m) decreased on average 38 daPa, when V(m) was changed from 21 to 1 cm(3). The decrease was most pronounced, when V(m) became smaller than 5 cm(3). Moreover, tympanometry showed a linear numerical overestimation of P(m) by a factor 2.31 compared with model P(m). CONCLUSION: A curve fit was derived describing the tympanometric P(m) as a function of V(m). This demonstrated that tympanometric P(m) approached -infinity daPa, when middle ear volume approached 0 cm(3), which indicates that negative tympanometric recordings and B curves can be found in ears with normal P(m) entirely due to very small V(m)'s. This explains the discrepancy between direct and tympanometric measurements of P(m) in SOM, since the effusion replaces the air filled expandable volume resulting in a very small 'functional' V(m). Numerical overestimation of P(m) by tympanometry was explained by hysteresis, which reflected the viscoelastic properties of the MES. These results question the significance of negative P(m)'s as a pathogenetic factor in SOM.

Acoustic Impedance Tests↗
PubMedDate not supplied

Middle ear status at myringotomy and its relationship to middle ear immitance measurements.

Middle ear status at myringotomy was compared to middle ear immitance measurements in 76 ears. Clinical features examined included plane and mobility of the tympanic membrane, amount of effusion, and status of the middle ear mucosa. Middle ear effusion yielded the strongest relationship with immitance results. Plane and mobility of the tympanic membrane were not strongly related with clinical immitance data. Tympanometry and acoustic reflex threshold were found to be the best indicators of the presence of middle ear effusion.

Acoustic Impedance Tests↗
PubMed1995

Probe-tube microphone measures with very young infants: real ear to coupler differences and longitudinal changes in real ear unaided response.

OBJECTIVE: The feasibility and practicalities of performing probe-tube microphone measures with infants is addressed, as well as two aspects of acoustic functioning of infant ears: the real ear unaided response (REUR) and the real ear to coupler difference (RECD). DESIGN: Part 1 is a longitudinal study involving 12 infants. Serial measures of REUR were obtained over an 18-mo period. Infants were < or = 3 mo for the first test and < or = 21 mo at the last test visit. Practicalities of probe-tube microphone testing of unsedated infants and changes in the position (i.e., frequency) of the primary REUR peak were addressed. For part 2 of the project, 33 infants under 12 mo of age took part. A comparison of real ear hearing aid gain versus coupler gain was made. Test-retest differences for real ear aided response were estimated. RESULTS: Part 1 results indicate that probe-tube microphone measures in unsedated infants are feasible and show good within-subject repeatability. REUR measures for the more alert and mobile older subjects, as for the younger infants, showed an acceptably small degree of intersubject variability. The frequency of the primary REUR peak decreased during the first year of life, with a group mean of 2932 Hz reached at the end of the first year. However, thereafter, instead of stabilizing at around this value there was considerable fluctuation in the frequency of REUR peak. For Part 2, results a) confirmed the large RECD value for infants in the first year of life and b) showed a high degree of intersubject variability. Test retest measures of real ear aided response (REAR) gave values small enough to indicate the clear potential of probe-microphone use with infants during the hearing aid selection and fitting process. CONCLUSION: These findings should encourage attempts to carry out individual probe-tube microphone measurements with very young infants. They point to the need for infant hearing aid fitting procedures which involve such measurements to secure appropriate amplification.

Amplifiers, Electronic↗
PubMed2001

COCH5B2 is a target antigen of anti-inner ear antibodies in autoimmune inner ear diseases.

OBJECTIVE: This study was designed to identify the 58-kDa inner ear protein against which the sera of some patients with idiopathic, progressive sensorineural hearing loss or Ménière's disease strongly react. BACKGROUND: We and other groups have previously demonstrated that a 58-kDa protein extracted from guinea pig or bovine inner ear tissue is a target of antibodies in serum samples from some patients with autoimmune inner ear diseases. METHODS: After separation of inner ear proteins by 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis, the bands corresponding to 58 kDa were localized and excised from the gel. The concentrated protein was then digested with trypsin, and the peptide fragments were separated by high-pressure liquid chromatography. Three fractions were subjected to amino acid sequencing by the classic Edman degradation. RESULTS: The sequence of a stretch of 14 amino acids of the first fragment was identical to that of amino acids 526 to 539 of the COCH5B2 protein. The sequences of 11 and 10 amino acids of the second and third fragments, respectively, also were identical to residues 417 to 427 and 396 to 405 of the COCH5B2 protein. These data, together with two-dimensional gel electrophoresis followed by Western blot experiments, confirmed that the 58-kDa inner ear protein is the COCH5B2 protein. DISCUSSION: These findings indicate that the 58-kDa target protein of antibodies in serum samples of patients with autoimmune inner ear diseases is the COCH5B2 protein, a molecule that is highly and specifically expressed in the cochlea and vestibule.

Animals↗
PubMed2006

Effects of middle-ear immaturity on distortion product otoacoustic emission suppression tuning in infant ears.

Distortion product otoacoustic emission (DPOAE) measures of cochlear function, including DPOAE suppression tuning curves and input/output (I/O) functions, are not adultlike in human infants. These findings suggest the cochlear amplifier might be functionally immature in newborns. However, many noncochlear factors influence DPOAEs and must be considered. This study examines whether age differences in DPOAE I/O functions recorded from infant and adult ears reflect maturation of ear-canal/middle-ear function or cochlear mechanics. A model based on linear middle-ear transmission and nonlinear cochlear generation was developed to fit the adult DPOAE I/O data. By varying only those model parameters related to middle-ear transmission (and holding cochlear parameters at adult values), the model successfully fitted I/O data from infants at birth through age 6 months. This suggests that cochlear mechanics are mature at birth. The model predicted an attenuation of stimulus energy through the immature ear canal and middle ear, and evaluated whether immaturities in forward transmission could explain the differences consistently observed between infant and adult DPOAE suppression. Results show that once the immaturity was compensated for by providing infants with a relative increase in primary tone level, DPOAE suppression tuning at f2= 6000 Hz was similar in adults and infants.

Acoustic Stimulation↗
PubMed1988

Ear canal acoustic distortion at 2f1-f2 from human ears: relation to other emissions and perceived combination tones.

Two aspects of the intermodulation distortion product at 2f1-f2 generated by normal human ears and measured acoustically in the ear canal were studied: (1) its relation to tone-evoked and spontaneous otoacoustic emissions, and (2) its relation to the perceived combination tone at the same frequency. With regard to (1), substantial differences among ears in the detectability of emissions were observed; ears tended to exhibit all or none of the emission types that were sought. Within ears possessing emissions, the magnitudes of tone-evoked emissions and acoustic distortion showed a similar dependence on frequency. With regard to (2), a three-primary-tone stimulus was employed to ask whether the ear canal acoustic distortion tone is canceled under the same stimulus conditions that produce perceptual cancellation. Simultaneous cancellation of perceptual and acoustic distortion was produced rarely. Results are interpreted qualitatively with a model in which primary tones produce distortion at their interaction region within the cochlea; this distortion propagates to the distortion-frequency place where it mediates perception. This same distortion wave produces emission components at additional locations, including the primary-tone interaction region, which sum vectorially to mediate the emitted acoustic distortion product.

Acoustic Stimulation↗