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PubMed1998

[Therapeutic results of surgery for exostoses of the ear canal].

A relatively high complication rate in surgery for ear canal exostoses is reported in the literature. It was found of interest to review our long-term results of surgery in ear-canal exostosis, using case-report review and clinical and audiological re-evaluation. Nineteen of 26 patients, 24 ears, operated in the 20-year period 1976-1996 were re-evaluated, mean time from surgery 7.3 years. All patients were found preoperatively to have occluding ear canal exostoses with a variety of related symptoms, all were in most cases operated via the trans-canal approach. At the re-evaluation all patients were completely free of symptoms, even though exostosis remnants were found in 19 of 24 operated ears. The complication rate was 12.5%. In conclusion, in order to avoid the complications found in this material as well as in other reports a less radical removal of exostoses is proposed.

Adolescent↗
PubMed1992

Effect of ear-canal air pressure on evoked otoacoustic emissions.

The effect of ear-canal air pressure on click-evoked otoacoustic emissions was measured for pressures ranging from 200 to -200 daPa and stimulus levels ranging from 60-90 dB PeSPL. Positive and negative ear-canal pressures (relative to ambient pressure) reduced the emission amplitude by 3-6 dB. A spectral analysis of the emissions revealed that the effect of ear-canal air pressure is that of a high-pass filter with a cutoff frequency of 2600 Hz and a slope of 4 dB/oct. The spectral changes are the expected effect of an increase in stiffness of the middle ear and were independent of pressure polarity and click level. Ear-canal air pressure substantially reduced the reproducibility of the emission waveform, in many cases rendering the emission indistinguishable from background noise. The implication of these findings for hearing screening applications is that a high false alarm rate may occur in normal-hearing patients with intratympanic air pressures that are significantly different from ambient pressure.

Adult↗
PubMed1988

Three-dimensional acoustic waves in the ear canal and their interaction with the tympanic membrane.

The long and slender geometry of the ear canal supports an infinite number of cross-sectional acoustic modes. The lower mode(s) travel along the length of the ear canal, while the higher modes are trapped near the ends of the canal. Many of these waves are introduced as a result of the complex vibrational shape of the eardrum. A three-dimensional mathematical model of the ear canal is formulated that includes this acoustic interaction. The coupled system is solved using matched asymptotic expansions that take advantage of the small slenderness ratio. This solution in the ear canal is in the form of a series of modes, the first being the plane-wave solution. As an illustrative example, the analysis is applied to a geometry that partially represents the ear canal and eardrum of a cat. The results indicate that the plane-wave solution is supplemented by multidimensional trapped modes at low frequencies and by a limited number of traveling waves at high frequencies. The magnitude of these higher modes generally increases with frequency and can significantly influence the acoustic coupling of the ear.

Acoustic Stimulation↗
PubMed2002

Cavernous hemangioma of the external ear canal.

OBJECTIVE: To document the occurrence of a cavernous hemangioma of the external ear canal and to review the relevant literature. STUDY DESIGN Case report and literature review. METHODS: Review of a patient chart, imaging studies, operative report, and histologic findings. RESULTS: A cavernous hemangioma of the external ear canal not involving the tympanic membrane was surgically excised without complication. This is the third documented cavernous hemangioma of the external ear canal without tympanic membrane involvement in the English literature. Computed tomography scan is invaluable to narrow the differential diagnosis. Complete removal is curative. CONCLUSIONS: Cavernous hemangioma of the external ear canal with or without tympanic membrane involvement is a rare otologic entity amenable to surgical treatment. Temporal bone computed tomography scan imaging is an important preoperative diagnostic tool.

Ear Canal↗
PubMed1986

Acoustics of ear canal measurement of eardrum SPL in simulators.

The effect of standing waves on the ear canal measurement of eardrum sound pressure level (SPL) was determined by both calculation and measurement. Transmission line calculations of the standing wave were made using the dimensions of the ANSI S3.25-1979 ear simulator and three different eardrum impedances. Standing wave curves have been obtained for the standard eardrum impedance at 1-kHz intervals in the range of 1-8 kHz. The changes in standing wave position due to each of the three eardrum impedances and their effects on ear canal measurements of SPL were computed for each of the eardrum impedances. Ear canal SPL measurements conducted on simulators modified to correspond to the eardrum impedances used in the calculations were compared to the computed values. Differences between eardrum SPLs and those measured at different locations in the ear canal approached a standing wave ratio (SWR) of 10-12 dB as the position of the measuring probe approached the standing wave minimum at each frequency. These maximum differences compared favorably with data developed by other investigators from real ears. Differences due to the eardrum impedance were found to be significant only in the frequency region of 2-5 kHz. Calibration of probes in a standard or modified ANSI simulator at the same distance from the eardrum as in the real ear reduces the eardrum SPL measurement errors to those resulting from differences in eardrum impedance.

Acoustic Stimulation↗
PubMedDate not supplied

Traumatic ear canal separations and para-aural abscessation in three dogs.

Three dogs were presented for para-aural abscessation. Ear canal separations were suspected preoperatively, based on histories of trauma, physical examination findings of minimally inflamed external ear canals with abrupt endings, and radiographic evidence of discontinuity of the ear canals. Concurrent otitis media, based on radiographic findings, was diagnosed in all three dogs. Disruptions of the external ear canals were confirmed at surgery, and the dogs each responded to total ear canal ablation and lateral bulla osteotomy.

Abscess↗
PubMed1992

Ear canal cholesteatoma.

Although cholesteatomas are more commonly found in the middle ear and the mastoid, the disease can occur in the external ear canal. All cases of ear canal cholesteatoma treated by the author were reviewed. There were nine ears in seven patients, who had an average age of 62 years. The lesions ranged in size from a few millimeters to extensive mastoid destruction. Smaller lesions can be managed by frequent cleaning as an office procedure. Larger lesions require surgery, either canaloplasty or mastoidectomy. The otolaryngologist should suspect this disease in the elderly. Microscopic examination of the ear with meticulous cleaning of all wax, especially in elderly patients, is most useful in detecting early disease. Frequent applications of mineral oil to the canal should be used in the management of the disease and to prevent recurrence.

Adolescent↗
PubMed1993

Bacterial flora in the external ear canal and in induced cholesteatoma in the Mongolian gerbil.

We report on the bacterial flora of the external ear canal and of induced aural cholesteatoma in 14 Mongolian gerbils (Meriones unguiculatus). In the control, nonmanipulated external ear canal, gram-positive and gram-negative organisms were isolated. In the contents of the cholesteatoma sac, only monomicrobial, gram-negative isolates were found; in each animal they were different from the isolates from the nonmanipulated external ear canal. Obligate anaerobes were absent in all cases. Ligation of the external ear canal in the left ear provoked cholesteatoma in all cases.

Animals↗
PubMed2005

Prevention of cerumen impaction by treatment of ear canal skin. A pilot randomized controlled study.

OBJECTIVES: To evaluate the effect of topical skin treatment of the ear canal in the prevention of impacted earwax. DESIGN: The study was prospective, randomized and controlled. SETTING: Secondary ORL care and Institute for the Mentally Retarded. PARTICIPANTS: Thirty-nine consecutive patients aged 1-74 years. Selection criteria were impacted earwax more than once a year and impacted earwax completely obstructing the lumen of the ear canal at the time of inclusion. Patients were randomized to active therapy or no intervention. The active therapy was Ceridal lipolotion instilled in the ear canal with a syringe once a week for 12 months. In the control group, earwax was removed without other intervention. The lipolotion was administered by the participants themselves with exception of the mentally retarded who were treated by nurses. Follow-up visits were at 3 and 12 months. MAIN OUTCOME: The main outcome was recurrence of impacted earwax with complete obstruction of the ear canal. There was significantly lower recurrence rate of impacted earwax in the treated compared with the control group (23%versus 61%, P < 0.05). CONCLUSIONS: This study suggests that prophylactic treatment of the ear canal with a topical emollient may prevent formation of impacted earwax.

Administration, Topical↗
PubMed1989

Specification of the geometry of the human ear canal for the prediction of sound-pressure level distribution.

The geometry of 15 human ear canals has been studied. Silicone rubber molds were made of the ear canals of human cadavers, and a mechanical probe system was used to obtain approximately 1000 coordinate points over the surface of each mold. The data points were accurate to about 0.03 mm in each of the three space directions, allowing ample resolution of surface detail. The measurements have been summarized as individual ear canal area functions, the area of cross-sectional slices normal to a curved central axis following the bends of the canal. Large intersubject differences were found, but several overall trends were evident in the area functions. Accurate specification of the canal geometry has lead to improved predictions of the sound-pressure distribution along the human ear canal at frequencies greater than 8 kHz. Such predictions are relevant to the development of high-frequency audiometric methods, high-fidelity hearing aids, and to the interpretation of experiments in physiological and psychological acoustics.

Ear Canal↗
PubMed2002

[Advanced squamous carcinoma of external ear canal].

Squamous carcinoma of the external ear canal (CEEC) is an uncommon neoplasm which prognostic changes following the tumour spread. Because of its location in ECC as well as the anatomical fissures between osseous and cartilaginous parties it's possible the spread to areas of surgical accessibility complicated restricting the complete tumoral removal. We report one of those cases, when first visited had already meningeal infiltration and was accordingly treated with radiotherapy. Analysis of the case and review of the literature.

Aged↗
PubMedDate not supplied

The use of a miniature microphone in the ear canal for the verification of hearing aid performance.

An individual head, auricle, and ear canal can alter signals from a hearing aid other sources of acoustic stimulation compared to artificial couplers. The most realistic method for quantifying or verifying certain parameters of acoustic simulation delivered to the ear by a hearing aid is to measure the sound pressure level of a signal in the ear canal of an individual while wearing an aid. Probe microphone measurements have been conducted and reported for the past 33 years. Until now, such microphone measurements have used a hollow tube inserted into the ear canal which leads to a transducer outside the canal. This paper describes our preliminary clinical application of a new wide range, flat response, miniature electret microphone, measuring 4 x 5 x 2 mm for measurement of insertion gain in a patient's ear canal. We believe the information from these recordings can be useful in developing objective clinical procedures for the selection and monitoring of wearable amplification for hearing-impaired patients.

Acoustics↗
PubMed1990

Total ear canal ablation combining bulla osteotomy and curettage in dogs with chronic otitis externa and media.

Ear canal ablation combining bulla osteotomy and curettage was performed on 44 dogs (n = 72 ears). Indications for the procedure included one or more of the following: chronic nonresponsive otitis externa and/or media (n = 71), tumor in the horizontal portion of the ear canal (n = 1), failed lateral ear resection (n = 11), ossified auricular cartilages secondary to chronic otitis externa (n = 22), failed previous total ear canal ablation (n = 1), and otitis interna (n = 1). In 40 dogs, the surgery was successful in alleviating all clinical signs of otitis externa and media. During the immediate postoperative period, 2 dogs died of causes unrelated to otitis. Complications related to the surgery developed in 9 of the surviving 42 dogs. Ultimately, 95% (40 of the surviving 42) of the dogs were cured by use of this procedure. Surgery successfully resolved the original problems in 97% (66 of 68) of the surgically treated ears of these dogs.

Animals↗
PubMed2004

Keratosis obturans and external ear canal cholesteatoma: how and why we should distinguish between these conditions.

Keratosis obturans and external ear canal cholesteatomas have been considered as separate entities for the last 20 years, after being regarded as variations of the same disease for at least 87 years. While both disorders are distinct, they do have some overlapping characteristics which may make it difficult to reach a definite diagnosis. This review explores the diagnostic dilemmas which may arise, and discusses the classification, aetiology, pathogenesis and management of these conditions. We concur that external ear canal cholesteatoma and keratosis obturans are different conditions and conclude that the presence of osteonecrosis and focal overlying epithelial loss are the most reliable features favouring the diagnosis of external ear canal cholesteatoma over keratosis obturans. Furthermore, whilst keratosis obturans can be managed successfully by regular aural toilet, external ear canal cholesteatoma may require surgical intervention depending on the extent of the disease.

Cholesteatoma↗
PubMed2002

Inner ear pressure changes following square wave intracranial or ear canal pressure manipulation in the same guinea pig.

Inner ear pressure was measured in scala tympani with a micropipette during square wave pressure manipulation of the intracranial compartment and, subsequently, of the external ear canal (EEC) in the same guinea pig. As expected, the combination of the cochlear aqueduct and the inner ear behaves as a low-pass filtering system for intracranial pressure manipulation and as a complementary high-pass system for ear canal pressure manipulation. Time constants for pressure equalization were in the order of seconds and depended on the direction of flow through the cochlear aqueduct. Pressure equalization curves could not be fitted to a single exponential function; more complicated functions were needed for good fits, showing that the pressure equalization process is nonlinear. This means that the flow resistance of the cochlear aqueduct and/or the compliance of the cochlear windows is not constant, which is in accordance with a flow-direction dependent resistance of the cochlear aqueduct. An explanation for this can be found in the special structure of the periotic duct inside the aqueduct.

Animals↗
PubMed1981

Stimulated acoustic emissions in the ear canal of the gerbil.

Ear-canal sound pressure and cochlear potentials were monitored inthe anesthetized gerbil to study the origins of acoustic emissions produced by transient and continuous stimuli. No evidence was found of any delayed emissions (echoes) originating within the cochlea in the acoustic or cochlear microphonic (CM) waveforms. However, strong acoustic and CM distortion products occurred when two primary tones of moderate levels were presented to the ear; the site of origin of these products was traced to the cochlea. Further, the levels of distortion followed a complex time course after anoxia, often becoming stronger after animal death for up to one hour, then decaying to the noise floor of the system. The disappearance of the distortion products was coincident with elimination of both the negative endocochlear potential and the CM response to a fundamental tone.

Acoustic Stimulation↗
PubMed1989

Electrocochleographic effects of ear canal pressure change.

A series of Swedish studies has shown that the application of middle ear over-pressure may be effective in ameliorating the symptoms associated with Meniere's disease. Other studies have shown that electrocochleography (ECochG) is an effective tool in the identification of Meniere's disease, especially in the presence of active symptoms. Based on the therapeutic potential of middle ear overpressure as a treatment for Meniere's symptoms and on the relationship between these symptoms and ECochG, we investigated the effects of ear canal pressure change on human electrocochleographic components in normally hearing subjects. An experimental system combining an immittance audiometer probe and ear canal electrode was utilized to record extratympanic ECochG when different atmospheric pressures were applied indirectly to the middle ear via the sealed ear canal. All ECochG parameters except for the duration of the whole nerve action potential (AP) of the auditory nerve were significantly affected by pressure changes in the ear canal. Effects included an enlargement of the summating potential (SP) amplitude and of the SP:AP amplitude ratio at pressures above and below 0 decaPa (daPa). An important implication of our findings is that the status of the middle ear must be taken into account in the interpretation of ECochG results.

Action Potentials↗
PubMed1997

[Correlation between ear canal resonance and tympanic membrane impedance in relation to age and body mass and postmortem changes].

The human temporal bone preparation is an acknowledged model for research of the physical processes affecting the outer ear canal and eardrum. Changes affecting the oscillation and resonance behavior of the tympanic membrane and ear canal between death and temporal bone preparation presently exist in only a few studies. Since the influence of age and physique, as well as the width of ear canal on the ear canal resonance may be important, we prepared two separate studies to analyze these questions. The goal of our first test series involved children and was devised to determine if changes in the outer auditory canal resonances differed according to age. In so doing, canal resonance was recorded with a real ear measurement system. Further, we recorded middle ear pressure, impedance of the tympanic membrane, ear canal volume, height, weight and surface of the body, head and ear size. We found a significant decrease in the resonance frequency of the outer ear which was age-dependent and was 2.75 kHz in the 7-year-old child. In a separate study we wanted to know if results found in the postmortem temporal bone reflected in vivo relationships. A tympanometer and real ear measurement system was used to test the resonance behavior of the auditory canal as well as the vibration of the eardrum in dependence on temperature and the time after death for 9 h. We then proved the absence of significant changes in the auditory canal and eardrum oscillation in this time period before possible postmortem changes occurred. Our findings show that the method of bone preservation after its preparation is decisive for the validity of measurements in the isolated human temporal bone.

Acoustic Impedance Tests↗