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At least 235 records · Page 13Linked to original sources
PubMed1998

Double-evoked otoacoustic emissions. II. Intermittent noise rejection, calibration and ear-canal measurements.

Measurements of double-click-evoked otoacoustics emissions (2CEOAEs) and double-chirp distortion products (2ChDPs) are reported for normal-hearing adults based upon theory presented in an earlier report [Keefe, J. Acoust, Soc. Am. 103, 3489-3498 (1998)]. The nonlinear acoustic response of a probe assembly used in ear-canal measurements in tested in a calibration cavity to compare the double-evoked (2E) technique with existing OAE techniques. The 2E technique reduces the peak distortion by approximately 30 dB relative to existing click-evoked techniques. The 2E subtraction of click responses is partially analogous to current techniques in that the linear response is eliminated, but differs in that high-frequency measurements are improved by eliminating time gating of the cochlear response, and low-frequency measurements are improved by reducing probe distortion, especially when two acoustic sources are used. Because time gating is eliminated, it is straightforward to measure the onset of a click-evoked OAE. The nonlinear coherence function is used to measure the nonlinear distortion signal-to-noise ratio (DNR) for the 2ChDPs and 2CEOAEs. The DNR is typically 20-30 dB. An intermittent noise rejection technique is implemented in real time that compares a currently acquired ear-canal response with a stored response. Dissimilar responses indicate the presence of intermittent noise, and the noise-contaminated responses are thereby discarded before ensemble averaging.

Acoustic Stimulation↗
PubMed1992

Temporal bone resections for carcinoma of the middle ear and the external ear canal.

Petrosectomy has been used in the management of carcinoma of the external ear canal and the middle ear for the last 45 years. In recent years, there have been conflicting reports; some authors advocate a conservative approach, whereas others support an ultraradical approach. Most retrospective studies report patients who have been treated with radiotherapy or surgery as having undergone the primary modality depending on where the patient first presented. No selection criteria seem to have been employed. Although radiotherapy was used postoperatively, the problems of wound healing were not addressed. This study presents our experience with temporal bone resection as described by Lewis and shows that, in combination with patient selection and proper choice of incision, reconstruction and timely postoperative radiotherapy can achieve better results, and the patient's quality of life can be preserved.

Combined Modality Therapy↗
PubMed2003

Ear-canal acoustic admittance and reflectance effects in human neonates. I. Predictions of otoacoustic emission and auditory brainstem responses.

This report describes the extent to which ear-canal acoustic admittance and energy reflectance (YR) in human neonates (1) predict otoacoustic emission (OAE) levels and auditory brainstem response (ABR) latencies, and (2) classify OAE and ABR responses as present or absent. Analyses are reported on a subset of ears in which hearing screening measurements were obtained previously [Norton et al., Ear. Hear. 21, 348-356 (2000a)]. Tests on 1405 ears included YR, distortion-product OAEs, transient-evoked OAEs, and ABR. Principal components analysis reduced the 33 YR variables to 5-7 factors. OAE levels decreased and ABR latencies increased with increasing high-frequency energy reflectance. Up to 28% of the variance in OAE levels and 12% of the variance in ABR wave-V latencies were explained by these factors. Thus, the YR response indirectly encodes information on inter-ear variations in forward and reverse middle-ear transmission. The YR factors classify OAEs with an area under the relative operating characteristic (ROC) curve as high as 0.79, suggesting that middle-ear dysfunction is partly responsible for the inability to record OAEs in some ears. The YR factors classified ABR responses less well, with ROC areas of 0.64 for predicting wave-V latency and 0.56 for predicting Fsp.

Brain Stem↗
PubMed1992

Chondrocalcinosis of the temporomandibular joint: an external ear canal pseudotumor.

An unusual case of calcium pyrophosphate arthropathy (pseudogout) involving the temporomandibular joint of a 53-year-old woman presented clinically as an ear canal tumor. Further evaluation and surgical exploration disclosed chondrocalcinosis of the temporomandibular joint with involvement of the bones at the left base of the skull. This case report emphasizes the importance of recognizing the lesion by frozen-section examination because excellent results can be obtained by intraoperative curettage of the calcareous deposits and local irrigation with saline solution.

Calcium Pyrophosphate↗
PubMed1995

Blood group phenotype determines lectin-mediated adhesion of Pseudomonas aeruginosa to human outer ear canal epithelium.

Pseudomonas aeruginosa is the most frequent bacterial pathogen causing acute diffuse otitis externa. In a recent prospective phase II study we demonstrated that lectin-mediated bacterial adhesion can be blocked by receptor-analogue carbohydrates in patients suffering from Pseudomonas aeruginosa-induced acute otitis externa. In this investigation, human ABO blood group antigens were analysed on outer ear canal epithelial cells with standard routine histological procedures by monoclonal antibodies for the blood groups A and B, and with Ulex europaeus I lectin for the blood group O, respectively. In all cases (n = 20) the blood groups could be shown immunohistologically. P. aeruginosa-specific adhesion and inhibition assays were performed in the presence of N-acetylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), D-mannose and A-like substance. Outer ear canal tissue sections were incubated with P. aeruginosa (strain PA 60), presenting lectin-specificity for GalNAc. Sections from patients presenting with blood group A were closely settled with bacteria in the presence of non-specific GlcNAc, D-mannose and PBS however, GalNAc and A-like substance inhibited the microbial adhesion. Amongst others, P. aeruginosa present adhesion molecules (lectins) with specificity for GalNAc. Thus, the correlation between blood group A phenotype and P. aeruginosa-induced acute diffuse otitis externa was investigated. Statistical evaluation proved a highly significant association. These data support the hypothesis that P. aeruginosa lectins with GalNAc specificity apparently adhere to GalNAc moieties, representing the terminal blood group A-determinant and further indicate that patients presenting with blood group A may have a genetic disposition for this form of otitis externa.

ABO Blood-Group System↗
PubMedDate not supplied

[Benign necrotizing osteitis of the external ear canal. A report of a clinical case].

Benign necrotizing osteitis of the external ear canal is a process of unknown origin. This necrotic process with sequestration of the tympanic bone occurs in healthy, non-diabetic patients. It should be differentiated from malignant otitis externa and radionecrosis of the tympanic bone. A case is reported and the literature on this rare clinical entity is discussed.

Aged↗
PubMed2001

Chronic otitis externa/media with total ear canal ablation and bulla curettage in a North American bison (Bison bison).

An adult female North American bison (Bison bison) with a chronic otitis externa/media of the right ear was examined because of a 4-mo history of intermittent anorexia, apparent painful behavior, and auricular discharge from the right ear. Computerized tomography (CT) demonstrated osteolysis of the tympanic, petrous, and squamous aspects of the temporal bone with soft tissue replacement and sclerosis of the right bulla. A total ear canal ablation with bulla curettage was performed, and cefazolin-impregnated polymethacrylate beads were left within the right bulla and the remnant temporal bone. Six months after the surgery, the bison had no clinical signs of otitis media.

Animals↗
PubMed2002

[Giant cholesteatoma of the external ear canal after myringoplasty].

Cholesteatoma are specially localized in middle ear and mastoid process, although sometimes is the external ear canal which shows the disorder. Usually its a appearance is spontaneous. We report a rare case of gigantic cholesteatoma which origin was the previous otologic surgery done because of the inclusion of a bit of epithelial tissue inside the surgical incision. Similar outcomes justify periodical checking after ear surgery with outlining a tympanomeatal flap.

Adult↗
PubMed1981

Management of the ear canal seborrhea with cerumen.

For the past 20 years, the author has been treating recurrent chronic seborrheic dermatitis with a suspension of human cerumen in glycerine. The cerumen is obtained from healthy children and young adults in which there is an over-production which requires removal. If the cerumen contains debris it is not used. The collected cerumen is suspended in 50% glycerine and left for several weeks to sterilize. It is then strained through a fine filter having been heated so that its is workable. The material is dispensed to the patient in a small dropper bottle and the patient is instructed to place two drops in the external ear canal once a week. The chronicity of seborrheic dermatitis must be explained carefully to the patient and the necessity for avoiding water, cosmetics and other materials must be stressed. The patient must be made aware that the cause of the condition is unknown and that periodic inspection of the ear canal is necessary in addition to the topical application of the cerumen suspension.

Cerumen↗
PubMed2001

Surgical repair of bone defects of the ear canal wall with flexible hydroxylapatite sheets: a pilot study.

OBJECTIVE: Evaluation of suitability of flexible composite sheets (hydroxylapatite and polymer) for outer ear canal (OEC) wall reconstruction in tympanoplasty. STUDY DESIGN: Prospective, open label pilot study. SETTING: University and regional hospital. PATIENTS: Forty-two randomly selected patients with chronic otitis media (n = 20) and cholesteatoma (n = 22) among 356 patients admitted between 1996 and 1997. INTERVENTIONS: Eradication of disease through a partial or total canal wall down mastoidectomy; immediate reconstruction of canal wall with flexible composite sheet (hydroxylapatite and polymer) and connective tissue graft. OUTCOME MEASURES: Anatomic integrity of the OEC and neotympanum, extrusion rate, complications. RESULTS: At minimum follow-up of 24 months: recurrent cholesteatoma (n = 0), residual cholesteatoma (n = 3/22) (13.6%) in the mesotympanum (none behind the hydroxylapatite sheet or in the attic or antrum). The neotympanum was intact in 38 ears (90.4%), reperforated in 2, and severely retracted and lateralized in 1, respectively. Anatomic integrity of the OEC was obtained in 37 (88%) of 42 patients; stenosis or membranous synechiae were observed in 5 ears and treated in the office. Extrusion of the hydroxylapatite sheet occurred in 7 patients (16.6%) because of purulent otorrhea and granulation tissue formation. Surgical revision achieved complete epithelialization of the rebuilt canal wall in 33 ears (78.6%). CONCLUSIONS: A dry, disease-free ear and normal anatomy may be expected 2 years postoperatively in more than three-fourths of the patients treated using the described surgical technique. Complete protection with a connective tissue graft is essential to avoid extrusion of the implant. The failure rate is significantly higher if otorrhea is present at the time of the operation.

Adolescent↗
PubMed1998

Energy reflectance in the ear canal can exceed unity near spontaneous otoacoustic emission frequencies.

There is some controversy in the literature over whether the so-called "active mechanism" or "cochlear amplifier" is actually a power amplifier that can produce an output signal with more power than its input, or whether it simply minimizes dissipative losses within the cochlea without providing an actual power gain greater than unity. A corollary of this controversy is whether spontaneous otoacoustic emissions (SOAEs) represent the output of a nonlinear oscillator mechanism, i.e., a power amplifier which can produce an oscillatory output signal in the absence of an input oscillatory signal, or whether they represent the output of a noise-driven, passive, nonlinear system. This paper describes measurements of energy reflectance, and acoustic impedance in the ear canals of human subjects with strong SOAEs. The reflectance, and the resistive and reactive parts of the acoustic impedance, all show a frequency fine structure which correlates with SOAE frequencies, and which becomes more pronounced at low stimulus levels. In some ears at some SOAE frequencies, energy reflectance exceeds unity, and correspondingly, acoustic resistance is negative. This result demonstrates that there is a power gain at these frequencies: The power reflected from the cochlea to the ear canal exceeds the power incident. It is also consistent with the theory that these SOAEs are produced by a nonlinear oscillator mechanism in the cochlea.

Ear Canal↗