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At least 343 records · Page 19Linked to original sources
PubMed1995

[Ear prostheses in burns of the external ear. Technical notes].

Ear reconstruction is best performed with autologous tissue. However, there are selected cases in which a prosthesis may be preferred. Some patients are unwilling to undertake multiple surgical procedures, others do not accept the chest wall scar. More importantly, in severe post burn cases, the scars in the periauricular region can truly compromise the outcome of an autologous reconstruction. In such cases, the authors perform a prosthetic reconstruction which is anchored to the cranial bone by means of osteointegrated titanium screws. The method described here has been modified compared to the original Bränemark system. A new microscrew design allows the implants to be inserted in a single surgical procedure. A magnetic anchoring system avoids cumbersome external rods, and the overall size of the masses emerging from the skin is significantly reduced. These improvements increase patient comfort and compliance.

Bioprosthesis↗
PubMed1977

[A proposition for mutual genesis of hearing loss, recruitment and ear murmurs in the case of acute inner ear alterations (author's transl)].

Pathological changes on the stereocilia of cochlear hair cells observed by Bredberg et al. (1972) after noise exposure and in the early stages of antibiotic intoxication are suggested to cause a mechanical decoupling between the tectorial membrane and the hair cells. During acute episodes of endolymphatic hydrops a similar decoupling is suggested to occur, although for different reasons. Harris (1968) calculated the noise generated at the input to the hair cells on account of the Brownian motion of air particles in front of the tympanic membrane. For tight coupling, he obtained a level of (--)22 dB re auditory threshold. For loose coupling this noise was found to increase to +33 dB, i.e., for 55 dB. These two independent findings are used to account for the combination of hearing loss, recruitment, and tinnitus observed with the inner-ear pathologies mentioned. The proposed hypothesis is in good agreement with clinical observations.

Anti-Bacterial Agents↗
PubMed1997

[Active electronic hearing implants for middle and inner ear hearing loss--a new era in ear surgery. II: Current state of developments].

Active hearing implants have been developed to varying degrees for conductive hearing loss as well as for sensorineural hearing loss. Implants for conductive hearing loss match impedance transformation by the middle ear. They will be referred to as ITI (impedance transformation implants). Three partial ITIs have been developed for routine clinical use: the Swedish transcutaneous BAHA, the American subcutaneous AUDIANT, and the Japanese P-MEI. Of greater importance with respect to the number of patients are electronic implants for sensorineural hearing loss. These implants are designed to replace parts of the function of the cochlea amplifier (CA). Therefore, in this study, they will be called CAI (cochlea amplifier implant). The CAI consist of four parts: (1) transducer, (2) microphone, (3) control unit, and (4) battery. A CAI for routine clinical use does not yet exist. Two transducer principles have thus far been developed for use in CAIs: the electromagnetic (EM) and the piezoelectric (PE) principle. Most of the transducers that have been described are EM transducers. The American Maniglia implant and the American floating mass transducer have been tested in humans. Both belong to the category of high energy consuming (HEC) implants with a limited frequency range that does not contain the whole speech spectrum. This is in contrast to the Canadian electromagnetic Fredrickson-HEC implant which is capable of transmitting broad band signals of up to 10 kHz. All ot he HEC-EM transducers lack an implantable microphone and an implantable battery. The German CAI, one of the piezoelectrical implants, was recently implanted acutely in humans. It consists of a piezoelectrical, ossicle coupled, low energy consuming (LEC) transducer, as well as an implantable microphone. It allows a broadband signal of up to 10 kHz, yet at a considerably lower level of energy.

Deafness↗
PubMed1997

Dissecting the frog inner ear with Gaussian noise. II. Temperature dependence of inner ear function.

The temperature dependence of the response of single primary auditory nerve fibers (n = 31) was investigated in the European edible frog, Rana esculenta (seven ears). Nerve fiber responses were analyzed with Wiener kernel analysis and polynomial correlation. The responses were described with a cascade model, consisting of a linear bandpass filter, a static nonlinearity, and a linear lowpass filter. From the computed Wiener kernels and the polynomial correlation functions, the characteristics of the three model components were obtained. With increasing temperature (1) tuning of the first filter increased in the majority (n = 16) of amphibian papilla fibers (best excitatory frequency, BEF < 1 kHz, n = 21) but remained unchanged in the majority (n = 10) of basilar papilla fibers (BEF > 1 kHz, n = 11), (2) the gain of the first filter remained unchanged, (3) the shape of nonlinear IO function remained unchanged, (4) the combined gain of the static nonlinearity and the second filter usually increased, but displayed considerable scatter across fibers (from -0.7 dB/degrees C to 3 dB/degrees C), and (5) the cutoff frequency of the second lowpass filter increases, with average 0.13 oct/degrees C. The immunity of the shape of the nonlinearity is considered evidence of a temperature independent gating mechanism in the transduction channels. The temperature dependence of the second filter may have resulted from a decrease of the hair cell membrane resistance, but may also reflect changes in subsequent staging of nerve fiber excitation.

Acoustic Stimulation↗
PubMed1985

Evaluation of inner ear damage during conditions with middle ear effusion by use of brainstem audiometry.

The method of auditory evoked brainstem responses (AEBR) was applied on an animal model with two types of well defined middle ear effusions--serous otitis media (SOM) and purulent otitis media (POM). The animals with SOM exhibited fairly normal interpeak latencies but a considerably increased auditory threshold. In contrast, POM mainly affected the latencies of the brainstem evoked potential but also caused a slight increase of the auditory threshold. The results indicate that SOM chiefly causes a conductive hearing loss, while POM also affects the neural circuit.

Animals↗
PubMed1965

LATERALIZATION OF SOUNDS AT THE UNSTIMULATED EAR OPPOSITE A NOISE-ADAPTED EAR.

We have discovered conditions of monaural stimulation under which a sound image can be located toward the contralateral, unstimulated ear; the phenomenon helps to clarify divergent experimental results. A tentative model is presented, together with some testable psychophysiological consequences.

Adaptation, Physiological↗
PubMed2005

Comparison of ear notch immunohistochemistry, ear notch antigen-capture ELISA, and buffy coat virus isolation for detection of calves persistently infected with bovine viral diarrhea virus.

Two techniques performed on skin biopsy samples (ear notches), immunohistochemistry (IHC) and antigen-capture ELISA (AgELISA), were compared for detection of bovine viral diarrhea virus (BVDV) persistent infection (PI) in 559 Angus calves between the ages of 1 and 5 months. The calves also were tested for BVDV infection using virus isolation (VI) and reverse transcription (RT)-PCR on buffy coat samples and for antibodies to BVDV types la and 2 by serum neutralization (SN). Sixty-seven of 559 (12.0%) calves tested positive at initial screening by IHC, AgELISA, or VI, and all 67 were kept for a minimum of 3 months and retested monthly by IHC, AgELISA, VI, RT-PCR, and SN. Of the calves positive at initial screening, 59/67 (88.1%) were determined PI and 8/67 (11.9%) were determined acutely infected. Both IHC and AgELISA detected 100% of PI calves; however, IHC and AgELISA also detected 6 and 8 acutely infected calves, respectively, at initial screening. Furthermore, IHC and AgELISA continued to detect 3 and 4 acutely infected calves, respectively, 3 months after initial screening. Three acutely infected calves had IHC staining indistinguishable from PI calves at initial screening. Both IHC and AgELISA are accurate at detecting BVDV-infected calves, but veterinarians and producers should be advised that both tests detect some calves acutely infected with BVDV in addition to PI animals. Repeat testing using VI or RT-PCR on buffy coat samples should be performed at 30 days after initial screening to conclusively discriminate between acute and PI.

Acute Disease↗
PubMed2002

Middle ear status in ears showing high admittance tympanograms. Clinical value of the use of the two-component 678 Hz oto-admittance tympanogram.

The present paper reports on the results of a retrospective study using 678 Hz susceptance-conductance tympanometry performed on abnormally high admittant middle ears. High admittance was proven to be caused by (partial) disruption or lysis of the ossicular chain. Retrospective analysis shows that 678 Hz tympanometry seems to be more accurate in the differential diagnosis of ossicular chain disruptions compared to CT-imaging of the ossicular chain (88% versus 81% correct identification respectively). Classic tympanometry using a probe frequency of 226 Hz was abnormal in only 43% of the cases.

Acoustic Impedance Tests↗