Outer Ear Canal Research Articles

Titanoxidkeramik als Implantationsmaterial in der Ohrchirurgie: Tierexperimentelle Ergebnisse zur Operationstechnik

For the experimental animal study to evaluate a new ossicular chain replacement prosthesis, we developed a new technique for surgical implantation into the middle ear of rabbits. The selection of the species was based on its similarity to human middle ear anatomy and the favored, standardized, microsurgical approach to the middle ear cavity. For the study we included a total of 34 approximately 6-month-old female white rabbits (New Zealand) with a weight of 3.2 to 4.4 kg. The implants used were constructed of ceramic materials TiO(2) (titania) with different pore size. Directly before the implantation of the TORPs, as well as at 28, 84 and 300 days after implantation, electric response audiometry was used to determine the hearing thresholds of the animals (bone conduction click stimulus nHL). The Erbium Yag-Laser was used to cut out the originally ossicular chain. After implantation we could not detect any stenosis of the outer ear canal or perforation of the tympanic membrane. The conductive hearing threshold was in the range of 4.21 +/- 6.68 dB nHL (n = 131). The hearing level showed no significant difference before and after surgery (p > 0.05). The laser surgery is a very safe procedure for prosthesis implantation in the middle ear of rabbits..

Bacteriemia During Mastoidectomy and/or Tympanoplasty

To investigate the risk of bacteriemia development during surgery in patients who underwent mastoidectomy and/or tympanoplasty for chronic otitis media. A total of 59 patients with chronic otitis media who were undergoing tympanoplasty operation with or without mastoidectomy were enrolled in this study. Smear cultures were obtained from outer ear canal and/or middle ears of all patients before the operation. Venous blood samples were obtained before and after the operation for bacteriologic analysis. Smear cultures were also obtained from the pressure dressing material that was applied during the operation for retrieval of the outer ear canal pressure. There was a 13.5% difference between the outer ear canal and/or middle ear smear cultures and ear pressure dressing smear cultures of the same case. There was no growth in the blood cultures obtained before tympanoplasty in any of the involved cases, however, in 5 (8.4%) of the culture samples obtained immediately after the tympanoplasty operation, there was bacteriemia. In the pressure dressing smear cultures obtained after the operation, 11 patients had microbial growth. Risk of bacteriemia should be considered in the preoperative period for the patients undergoing mastoidectomy especially in patients with cardiovascular diseases, this is of importance for the dramatic consequences that might arise after the operation. We also think that bacteriemia is also one of the factors that influences graft success rate.

The Allen-Fahey experiment extended

An ingenious experiment has been performed by Allen and Fahey [J. Acoust. Soc. Am. 92, 178-188 (1992)], in which they attempted to estimate the gain of the cochlear amplifier by comparing responses to the 2 f1-f2 distortion product (DP) in the outer ear canal (otoacoustic emissions) and from an auditory-nerve fiber. Results were essentially negative: no evidence of cochlear amplification was found in that experiment. A variation of that experiment is reported here, where DP responses in the outer ear canal are compared with mechanical responses of the basilar membrane. This variation does not suffer from the major limitation in the original experiment in the choice of possible frequency ratios. Results confirm and extend those of Allen and Fahey entirely. Apparently, the gain of the cochlear amplifier cannot be measured in this way. It is argued that the retrograde wave going to the stapes is most likely reduced in magnitude by wave interference when the two primary frequencies approach each other. Such a reduction does not take place in the forward-going wave to the location tuned to the DP frequency. This explanation is illustrated on the basis of results of earlier experiments on the movements of the basilar membrane.

Messungen zum Lärmschutz bei der funktionellen MR-Tomographie

Functional magnetic resonance imaging (fMRI) can detect changes in oxygen saturation of the brain. Fast changing high gradient fields are necessary which produce high levels of noise. In studies of the auditory cortex, auditory stimuli have to be perceived and discriminated against the noise level of the activated tomograph. The generated frequency bands and their intensities during fMRI with a Siemens Magnetom Vision, 1.5 T, EPI sequence were measured in the outer ear canal of a dummy head. Noise attenuation was evaluated with four different noise muffs (simple/inexpensive products, quality product, specialized fMRI muffs). Without protection, peak noise levels reached up to 111 dB(A) near 1000 Hz in the dummy ear canal. Major noise attenuation was only found at higher frequencies (4000 Hz by about 25 dB; 8000 Hz by about 35 dB) with the quality product and the specialized fMRI muffs. Only quality noise products can sufficiently protect patients from high sound pressure levels of tomograph noise. If in the future higher gradient fields are applied at faster slew rates, acoustic stimuli can safely be applied only in combination with increased hearing protection systems in order to minimize the risk of noise trauma.

Pathogenesis of otitis externa and otitis media in dogs and cats

Diseases of the outer and middle ear (Otitis externa and Otitis media) are a frequent clinical problem which is mostly approached in the wrong way. We believe that the approach to a diseased ear in dogs or cats by practicing veterinarians in our country is most often incorrect. Namely, the conventional approach to inflammation of the outer ear is narrowed down to cleaning the ear, usually with cotton wool and hydrogen peroxide, and then by applying ear drops for veterinary or human use over the next few days. A somewhat more conscientious approach implies treatment using antibiotics, topical and/or systemic, but based on an antibiogram. If the presence of a foreign body is suspected, the veterinarian will use an otoscope, and this is where the entire diagnostic approach in our conditions usually ends. Such procedures most often fail to resolve the problem, so that the disease recurs after a certain time or becomes chronic recurrent Otitis externa, which is one of the biggest problems in dog dermatology. Experience shows that veterinarians here are generally not familiar with the pathogenesis of outer and middle ear infection, and that this is the reason why they approach diagnostics and therapy in the wrong way. The most important thing is to have in mind that bacteria and fungi linked with a pathological process in the ear canal are merely opportunistic microorganisms, and never primary pathogens, themselves responsible for Otitis externa. Antibiotic or antimycotic treatment does not cure the basic disease which led to the inflammation, but only its consequences. A large number of factors involved in the inflammation of the outer or middle ear are traditionally divided into primary, predisposing, secondary, and underlying. The basis for the successful treatment of Otitis externa and Otitis media is the recognition, elimination or control of the primary factors (atopy, nutritive allergy, keratinization disorders, parasitic infestations). The predisposing factors should be observed in order to reduce the incidence of recurrence. The most frequent predisposing factor are hairs in the ear canal or on the concave side of pendulous ear conches. There are also frequent damages or excessive humidity in the canal as a consequence of irregular treatment of the outer ear. Among the predisposing factors are also abnormalities in the structure of the ear canal, such as stenosis which is often present in shar-pei-dogs. Secondary factors - bacteria and fungi, are in our conditions wrongly considered causes of ear inflammations. Their control leads to a clinical improvement, but not to the lasting cure of the process of this disease. Supportive factors are the main reason for the poor response to therapy. They are expressed as progressive pathological changes in the outer ear canal itself, changes in the tympanic membrane, and changes in the middle ear. The effect of therapy can be positive only provided the listed factors, which participate in the ear inflammation to a greater or smaller degree, are kept in mind and treated as such, but, unfortunately, this is often not the case.

Digital hearing aids for high-frequency sensorineural hearing loss: Preliminary experience with the RetroX® device

Conclusions. The RetroX® outer ear hearing aid seems to represent a means of overcoming problems with understanding speech in noise in patients with high-frequency sensorineural hearing loss (SNHL) without the need to wear conventional completely-in-the-canal (CIC) hearing aids, which are usually reported to annoy patients as a result of the occlusion effect. Objective. To present preliminary data from a study carried out to compare the efficacy, in the same individual, of a standard digital CIC hearing aid and a new implantable outer ear canal device, the RetroX. Material and methods. Three out of 15 adults affected by high-frequency SNHL who were candidates for auditory rehabilitation were evaluated by using speech audiometric tests in quiet and noise as well as a questionnaire shortly after use of a CIC hearing aid and the RetroX device, i.e. at 7 and 14 days. The efficacy of the RetroX was anticipated by testing all the subjects using a RetroX simulating system before starting the study protocol. Results. In all three implanted patients, the RetroX provided better audiological benefit for speech understanding in noise. These findings were corroborated by the results of the questionnaire, which showed greater satisfaction with the RetroX, especially regarding the absence of the occlusion effect.

Safe and Reliable Sound Threshold Measures with Direct Vibration of the Ossicular Chain

The aim of the study was to evaluate the safety and feasibility of piezoelectric malleus vibration audiometer (MVA), which presents micromechanical vibrations to the umbo membranae tympani. Phase I study performed in a tertiary referral center (University Hospital). The coupling rod of the MVA was moved slowly through the outer ear canal toward the eardrum with a micromanipulator. Coupling was completed when the rod tip touched the umbo membranae tympani. Basic audiologic measures of sound threshold obtained with direct stimulation of the malleus are presented. We used MANOVA (multivariate repeated measures ANOVA) to investigate the repeatability of MVA thresholds from one day to the other and when decoupling and retracting the coupling rod 2 mm off the umbo. We also selected the MANOVA to test for unwanted bone-conduction threshold shifts after MVA application. We assessed normality of the data by quantile-quantile plots of the residuals. Twenty-eight male and 10 female subjects with normal hearing, 22.2 to 34.6 years old (median age, 27.2 yr) underwent an examination. Thirty-six subjects underwent MVA, because 2 of the 38 subjects who volunteered for the study have not undergone the procedure due to the external auditory canal anatomy preventing application of the MVA. The results show that it is possible to safely and reliably measure thresholds of direct vibration of the ossicular chain. Using pure tone audiograms, no pure tone bone- and/or air-conduction threshold shifts occurred after the procedure. None of the subjects reported any other ear-related symptoms such as vertigo, tinnitus, or dizziness. Geometric mean vibratory displacements at threshold ranged from 0.55 nm at 250 Hz to 0.03 nm at 6 kHz. MANOVA demonstrated a repeatability of MVA thresholds. Malleus vibration audiometry will not allow exact linkage of actual implantable hearing aid. But the present study demonstrates that MVA can provide an audiometric tool for assessing ossicular function and integrity prior to implantation of an electronic hearing amplifier.

Experience of uni- and bilateral cochlear implant users with a microphone positioned in the pinna

Cochlear implant systems use different microphone positions and characteristics, none of which provide sound detection as normal hearing listeners experience it. The T-Mic, a microphone located in the pinna, close to the outer ear canal and thus taking advantage of some favourable outer ear properties, was developed in order to better mimic natural hearing. The T-Mic has been assessed by eight unilaterally implanted users. Sound quality, wearing comfort and ease of listening in different situations were evaluated by a questionnaire. The results highlight several advantages: easier listening in group conversation as well as in background noise, as noise from the rear is further attenuated. Telephone use is enhanced without further accessories since the sound is conducted via a sealed volume between telephone receiver and the outer ear canal. Speech perception measured over the telephone shows the T-Mic is comparable to direct coupling via the telephone adapter. For bilaterally implanted subjects, the T-Mic offers superior directional hearing compared to the forward facing BTE microphone; the lower error is being found for the T-Mic. It appears that the new T-Mic enables CI users to benefit from the characteristics of the pinna and to be both comfortable and practical for everyday use.

Antibiotic prophylaxis in clean and clean-contaminated ear surgery.

Ear surgery may be performed in the treatment of chronic otitis media, ossicular chain disorders, tympanic membrane perforations and otitis media with effusion. Postoperative infection in ear surgery may result in: Wound infections Infection of the middle ear or mastoid resulting in discharge from the ear canal Failure of the tympanic membrane to close Labyrinthitis due to infection in, or adjacent to, the inner ear These complications may be associated with discomfort and inconvenience for the patient, an increase in morbidity and an increase in the costs of medical care. The objective of this review was to assess the effects of local and/or systemic antibiotics for preventing complications such as postoperative discharge, graft failure and labyrinthitis in patients undergoing clean or clean-contaminated ear surgery. We searched MEDLINE (searched January 1966 to December 2002), EMBASE (searched January 1980 to December 2002), the Science Citation Index, The Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 4 2002); the Cochrane Acute Respiratory Infections Group and Cochrane Ear, Nose and Throat Group Specialised Registers and proceedings of scientific meetings. The date of the last search was December 2002. We also contacted investigators in the field (Govaerts, Antwerp). Bibliographies of identified articles were screened for further relevant trials. No language restriction was applied. Randomised or quasi-randomised trials involving: patients undergoing clean or clean-contaminated types of ear surgery. Skull base surgery was excluded. any regimen of local and/or systemic antibiotic prophylaxis administered at or around the time of surgery compared to placebo, no antibiotic, or an alternative intervention group. infection, discharge, graft failure, labyrinthitis, adverse effects of prophylaxis. When possible, investigators were contacted for additional information on data and methodological issues. At least two reviewers independently extracted data and assessed trial quality. Eleven studies were included in the review. The methodological quality of the trials was fair to good. However, most studies presented insufficient detail on methodological data. Although definitions of outcome measures were heterogeneous, pooling of results was possible. There were no significant differences between antibiotic prophylaxis groups and control groups in terms of reduction of postoperative infections, graft failures, draining outer ear canals and adverse drug effects. There is no strong evidence that the large scale use of prophylactic of antibiotics in clean and clean-contaminated ear surgery is helpful in reducing postoperative complications such as wound infection, discharge from the outer ear canal, labyrinthitis and graft failure.

Paleopatología neurológica en las culturas precolombinas de la costa y altiplano andino (I). Deformaciones craneales intencionales

The aim of this work was to study the cranial trepanations and deformations carried out by the ancient Paraca, Huari, Tiahuanaco and Inca cultures. To do so, we conducted a field study involving visits to archaeological remains and anthropological museums on the Andean plateau and the Peruvian coast.Cranial deformation was more common in the Andean regions and was performed by putting little pieces of wood or compressive bandages on newborn infants' heads in order to modify the growth axis of the cranial cavity. Cranial deformations were performed for aesthetic and magic religious reasons, but were also used as a means of ethnic or social identification, as a symbol of nobility or to distinguish the ruling classes. The immediate consequence of such deformation was the modification of the normal process by which the cranial sutures close. There is a significant correlation between the presence of posterior and lateral wormian bones, according to the degree of artificial deformation. The persistence of metopic suture and exostosis of the outer ear canal have been found in 5% of the skulls belonging to pre Columbine mummies. Other paleopathological findings include cranial fractures (7%), porotic hyperostosis (25% of children's skulls), spina bifida occulta, signs of spinal disk arthrosis and Pott's disease.Artificial cranial deformation was a very widespread practice in the Andean regions in pre Columbine times.

Culture-independent molecular analysis of microbial constituents of the healthy human outer ear.

Molecular-phylogenetic sequence analyses have provided a new perspective on microbial communities by allowing the detection and identification of constituent microorganisms in the absence of cultivation. In this study we used broad-specificity amplification of ribosomal DNA (rDNA) genes to survey organisms present in the human outer ear canal. Samples were obtained from 24 individuals, including members of three extended families, in order to survey the resident microbiota and to examine microbial population structures in individuals related by familial or household associations. To examine the stability of the microbial populations, one individual was sampled four times and another twice over a 14-month period. We found that a distinct set of microbial types was present in the majority of the subjects sampled. The two most prevalent rDNA sequence types that were identified in multiple individuals corresponded closely to those of Alloiococcus otitis and Corynebacterium otitidis, commonly thought to be associated exclusively with infections of the middle ear. Our results suggest, therefore, that the outer ear canal may serve as a reservoir for normally commensal microbes that can contribute to pathogenesis upon introduction into the middle ear. Alternatively, culture analyses of diseases of the middle ear may have been confounded by these contaminating commensal organisms.

On the safety of Aspergillus niger--a review.

Aspergillus niger is one of the most important microorganisms used in biotechnology. It has been in use already for many decades to produce extracellular (food) enzymes and citric acid. In fact, citric acid and many A. niger enzymes are considered GRAS by the United States Food and Drug Administration. In addition, A. niger is used for biotransformations and waste treatment. In the last two decades, A. niger has been developed as an important transformation host to over-express food enzymes. Being pre-dated by older names, the name A. niger has been conserved for economical and information retrieval reasons and there is a taxonomical consensus based on molecular data that the only other common species closely related to A. niger in the Aspergillus series Nigri is A. tubingensis. A. niger, like other filamentous fungi, should be treated carefully to avoid the formation of spore dust. However, compared with other filamentous fungi, it does not stand out as a particular problem concerning allergy or mycopathology. A few medical cases, e.g. lung infections, have been reported, but always in severely immunocompromised patients. In tropical areas, ear infections (otomycosis) do occur due to A. niger invasion of the outer ear canal but this may be caused by mechanical damage of the skin barrier. A. niger strains produce a series of secondary metabolites, but it is only ochratoxin A that can be regarded as a mycotoxin in the strict sense of the word. Only 3-10% of the strains examined for ochratoxin A production have tested positive under favourable conditions. New and unknown isolates should be checked for ochratoxin A production before they are developed as production organisms. It is concluded, with these restrictions, that A. niger is a safe production organism.

On Simulation Models in Otology

The perception of a sound event is a very complex process. A sound wave reachingthe concha of external ear is conveyed through the outer ear canal to the eardrum which is connected to the ossicular chain. The spatial motions of malleus,incus and in particular of the stapes are the main input to the liquid-filledinner ear where the receptor cells are located.

M-meatoplasty: results and patient satisfaction in 125 patients (199 ears).

Is M-meatoplasty the solution for chronic otitis externa caused by wax retention? This study discusses acceptance of this operation and whether sedation is necessary. Between October 1994 and October 1997, 199 successive M-meatoplasties (125 patients) were studied, and 79% of the patients completed a questionnaire in which patient satisfaction with the procedure and outcome was assessed. Local hospital, functioning as a secondary referral center. All patients had narrowing of the lateral part of the outer ear canal resulting from anterior displacement of the cavum conchae cartilage. The aim of M-meatoplasty is to increase the lumen of the entrance to the external ear canal by reducing the conchal cartilage on the posterior wall Reduction of visits to the outpatient clinic, patient satisfaction on a scale from 1 (very bad) to 10 (excellent). The number of preoperative visits was 7 (range 1-153). The median number of postoperative visits for the same problems more than 3 months after surgery was 1 (range 0-14). The patient score for the surgery and the final result was a median of 9 (very good). Wax obstruction and related external otitis can be cured by M-meatoplasty if the conchal cartilage is too prominent on the posterior wall. It is a simple outpatient operation and is very well tolerated. After the operation, there is an enormous reduction in outpatient visits.

Effects of amplified and damped auditory feedback on vocal characteristics

This study tested two possible methods for reducing vocal load e.g. during classroom speech. Six female subjects read aloud from a text (1) under normal circumstances, (2) while hearing their own voice amplified (through headphones) and (3) with auditory feedback damped by foam plastic earplugs inserted in the outer ear canal. Fundamental frequency (F0) and sound pressure level (SPL) decreased during both amplified and damped feedback. Additionally, during amplification the relative level of F0 compared to that of the first formant diminished, likewise the alpha ratio. These changes may indicate reduced vocal fold adduction. The results suggest that both amplification and damping of auditory feedback may reduce vocal load during phonation.

Noise attenuation of an insertion-type hearing protector by mathematical model and experimental verification

The experimental real ear attenuation at threshold (REAT) method is based on the standards ANSI S12.6-1997 and ISO 4869-1990 which consider measurements on qualified subjects, in a qualified acoustic chamber. The REAT method is very expensive, time consuming, and has a very poor frequency resolution. Mathematical and numerical models, such as the one-dimensional plan wave model, finite-element method, and boundary-element method offer cheap, quick, and high-resolution results, especially for comparison and product development. In this paper, the outer ear canal is considered as a straight tube with an open end and the other end closed with an eardrum membrane of human acoustic impedance. For the open ear canal case (without hearing protector on), plan acoustic waves are considered as incident and reflected waves. In the case of a blocked ear (with the insertion hearing protector on), a model of three mediums is considered; air hearing protector air. In this model only one longitudinal wave propagation is considered. Material density and speed of sound are the only parameters considered. The noise insertion loss is calculated as the difference of the sound pressure level at the eardrum without and with the protector on. The results are compared with controlled experimental measurements.

An automated procedure for identifying spontaneous otoacoustic emissions.

An algorithm is described for objectively identifying and measuring spontaneous otoacoustic emissions (SOAEs) using the spectrum that results from transformation of the acoustic waveform measured in the outer ear canal. Prior to spectral analysis, the rms level is calculated for successive short segments of the waveform and only the weakest 25% of the segments are retained for the spectral analysis [the quietest 150 when using 16k-point fast Fourier transforms (FFTs)]. The resulting initial spectrum is scanned for peaks (potential SOAEs) which are then deleted from the spectrum. New values are estimated for the deleted values using linear extrapolations from frequency ranges on either side of the deleted values. The end result is a smoothed spectrum devoid of all local peaks. The initial spectrum is then compared peak-by-peak with the smoothed spectrum, and those peaks having differences that exceed an objectively determined decision criterion are identified as likely SOAEs. The effects of varying some of the important parameter values of the algorithm are described, and the sensitivity of the procedure is evaluated by measuring the detection rate for a Lorentzian peak of known amplitude added to a spectrum otherwise devoid of SOAEs.

Middle-ear dynamics before and after ossicular replacement

The mechanism of hearing involves conduction of mechanical vibrations along the ossicular chain to the inner ear. An acoustic wave is collected and transformed as it passes down the ear canal and impacts on the tympanic membrane (ear drum). The drum is connected to the inner-ear by three ossicle bones (malleus, incus, and stapes) in a complex arrangement, which serves to further transform the mechanical vibration before it reaches the cochlea of the inner ear. What is the mechanical function of the ossicular chain, and what are the biomechanical consequences of surgical reconstruction with prostheses? To answer these questions, a three-dimensional finite element model of the outer ear canal and middle ear was generated. The dynamical behaviour was predicted for the normal ear, and an ear reconstructed with partial and total ossicular replacement prostheses. For the normal ear, stapes amplitudes of 1×10 −8 m at low frequencies decrease to 4×10 −10 m at approximately 3 kHz with several resonance peeks in between, most significantly at approximately 1 kHz. Thereafter a further resonance is predicted at 4 kHz associated with the ear canal. The behaviour is changed fundamentally by adding a prosthesis; the partial replacement increases the vibratory coupling of the drum and the stapes compared to the normal ear whereas the total replacement does the opposite, and is predicted to have the disadvantage of bringing several new resonances of the ossicular chain into the hearing range. It is hypothesised that the function of the malleus–incus–stapes arrangement is to link the drum to the oval window with the flexibility required for impedance matching but the rigidity to prevent unconstrainable resonances from occurring in the hearing range. If this is true, then the structural stiffness of ossicular chain is the critical design variable for middle-ear replacement prostheses.

Antimycotic therapy in otomycosis with tympanic membrane perforation

Especially after prolonged antibiotic ototopic therapy otomycosis is not rare. An inoculation of fungi into the tympanic cavity however may have serious sequelae. Therefore an eradication of fungi from the external auditory canal is imperative before surgery. In addition to thorough cleaning of the outer ear canal antimycotic preparations are recommended in treating otomycosis. However, all of the commercially available ear drops contain ototoxic agents. In the case of defects of the tympanic membrane a damage of the inner ear may result. Alternatively, we suggest an aqueous solution of Miconazol 0,5%.

Improvement in the objective diagnosis of hearing disorders by a new technique of simultaneous recording of acoustic and electrical responses of the auditory system

The measurements of transitory evoked otoacoustic emissions (TEOAE) and auditory brainstem responses (ABR) are widely used in objective audiometry for the diagnosis of conductive or sensorineural hearing losses. In some cases only one of these signals is required for a complete diagnosis, while other cases may require both methods to define findings. With conventional equipment the measurement of TEOAE and ABR is performed with different devices at different times. Devices for simultaneous recording of both signals are currently not available or described, although the physiological circumstances and apparatus requirements would favor such an approach. In the present work a prototype for the simultaneous measurement of TEOAE and ABR is presented and its application tested in 33 normal-hearing adults. The equipment used was based on a general purpose laboratory computer connected to an acoustic stimulator and a dual-channel data acquisition system. Stimuli were composed of click sequences for the cancellation of linear signal components and were presented by an ear canal probe (Otodynamics) which also picked up the microphone signal within the outer ear canal. The EEG activity containing the ABR was recorded through surface electrodes fixed at the patient's vertex and mastoid. Acoustic and electric signals were processed simultaneously, resulting in three independent records representing a non-linear TEOAE and the low and high level ABR. The main advantages of the new approach are an improvement in information output and enhancement in the accuracy of determining the site and extent of a hearing impairment.