Osteoradionecrosis of external auditory canal in nasopharyngeal carcinoma.
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BACKGROUND: Osteoradionecrosis (ORN) is one of the most serious complications of radiotherapy of nasopharyngeal carcinoma (NPC). ORN rarely occurs in the external auditory canal. METHODS: This is a retrospective review of 11 NPC patients who had ORN in the external auditory canal. Exposed necrotic bone over the external auditory canal was the diagnostic hallmark. Three patients wore hearing aids and 2 had had previous otological surgery. ORN was detected between 2 and 15 years after radiation therapy (mean 8 years). The radiation dose ranged from 6480 to 8460 rads in 8 patients. RESULTS: The symptoms of external auditory canal ORN were crust (100%), otorrhea (91%), otalgia (91%), hearing impairment (73%), foul odor (45%) and retroauricular discharging fistula (9%), all of which mimicked those of chronic otitis media. After treatment, the diagnoses of 2 patients were rectified to external auditory canal malignancy and external auditory canal cholesteatoma, and the other 9 (82%) patients' diagnoses remained as ORN. After combined treatment with local cleansing, hyperbaric oxygen therapy, sequestrectomy and ear drops, resolution of symptoms was achieved in all the patients. Three patients who underwent sequestrectomy were free of disease. CONCLUSIONS: External auditory canal ORN is rare in NPC patients. The clinical presentation mimics that of chronic otitis media and differentiation is difficult. The disease is prone to occur in patients who wear hearing aids or have had previous surgery. A high index of suspicion is mandatory for early diagnosis. The disease may lead to disastrous complications and should never be neglected by clinicians. (+info)
A mechano-acoustic model of the effect of superior canal dehiscence on hearing in chinchilla.
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Superior canal dehiscence (SCD) is a pathological condition of the ear that can cause a conductive hearing loss. The effect of SCD (a hole in the bony wall of the superior semicircular canal) on chinchilla middle- and inner-ear mechanics is analyzed with a circuit model of the dehiscence. The model is used to predict the effect of dehiscence on auditory sensitivity and mechanics. These predictions are compared to previously published measurements of dehiscence related changes in chinchilla cochlear potential, middle-ear input admittance and stapes velocity. The comparisons show that the model predictions are both qualitatively and quantitatively similar to the physiological results for frequencies where physiologic data are available. The similarity supports the third-window hypothesis of the effect of superior canal dehiscence on auditory sensitivity and mechanics and provides the groundwork for the development of a model that predicts the effect of superior canal dehiscence syndrome on auditory sensitivity and mechanics in humans. (+info)
A previously unidentified Chorioptes species infesting outer ear canals of moose (Alces alces): characterization of the mite and the pathology of infestation.
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BACKGROUND: During the past decade, Chorioptes mites occupying the outer ear canals have been a common finding at routine necropsies of moose (Alces alces) in Sweden, but neither the taxonomy of the mites nor lesions from the infestation have been investigated. In this study, the mites are characterized by morphological and molecular techniques, and the histopathology of the skin of the outer ear canal is described. METHODS: External auditory meatuses from 53 necropsied moose were examined for the presence of Chorioptes, and samples from outer ear canals were taken for histopathological and microbiological examination. A proportion of the mites from each moose was identified to species. The DNA was extracted from mites from three moose, and their ITS-2 sequences were determined; these sequences were compared phylogenetically to sequences from other Chorioptes taxa. RESULTS: Chorioptes mites were found in 43 (81%) of the 53 moose. The mites had morphological and genetic characteristics distinct from those of C. texanus and C. bovis, the two species generally accepted within the genus. Morphology also did not argue for a diagnosis as C. crewei, C. mydaus or C. panda. On histopathology, lesions were characterized by a hyperplastic perivascular to interstitial dermatitis with epidermal hyperkeratosis and crust formation. Dermal inflammatory infiltrates were composed of mixed T- and B-lymphocytes, plasma cells and macrophages, whereas eosinophils were notably uncommon. Staphylococcus aureus was grown from the infested epidermis of five of 14 examined moose. CONCLUSION: Chorioptes mite infestation was frequently detected in the outer ear canals of moose in Sweden. The mites were evidently pathogenic, being associated with inflammatory lesions of the external auditory meatus. Our studies indicate infestations with a previously undescribed Chorioptes species. (+info)
Non-ossicular signal transmission in human middle ears: Experimental assessment of the "acoustic route" with perforated tympanic membranes.
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Direct acoustic stimulation of the cochlea by the sound-pressure difference between the oval and round windows (called the "acoustic route") has been thought to contribute to hearing in some pathological conditions, along with the normally dominant "ossicular route." To determine the efficacy of this acoustic route and its constituent mechanisms in human ears, sound pressures were measured at three locations in cadaveric temporal bones [with intact and perforated tympanic membranes (TMs)]: (1) in the external ear canal lateral to the TM, P(TM); (2) in the tympanic cavity lateral to the oval window, P(OW); and (3) near the round window, P(RW). Sound transmission via the acoustic route is described by two concatenated processes: (1) coupling of sound pressure from ear canal to middle-ear cavity, H(P(CAV) ) identical withP(CAV)P(TM), where P(CAV) represents the middle-ear cavity pressure, and (2) sound-pressure difference between the windows, H(WPD) identical with(P(OW)-P(RW))P(CAV). Results show that: H(P(CAV) ) depends on perforation size but not perforation location; H(WPD) depends on neither perforation size nor location. The results (1) provide a description of the window pressures based on measurements, (2) refute the common otological view that TM perforation location affects the "relative phase of the pressures at the oval and round windows," and (3) show with an intact ossicular chain that acoustic-route transmission is substantially below ossicular-route transmission except for low frequencies with large perforations. Thus, hearing loss from TM perforations results primarily from reduction in sound coupling via the ossicular route. Some features of the frequency dependence of H(P(CAV) ) and H(WPD) can be interpreted in terms of a structure-based lumped-element acoustic model of the perforation and middle-ear cavities. (+info)
Sound pressure distribution and power flow within the gerbil ear canal from 100 Hz to 80 kHz.
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Sound pressure was mapped in the bony ear canal of gerbils during closed-field sound stimulation at frequencies from 0.1 to 80 kHz. A 1.27-mm-diam probe-tube microphone or a 0.17-mm-diam fiber-optic miniature microphone was positioned along approximately longitudinal trajectories within the 2.3-mm-diam ear canal. Substantial spatial variations in sound pressure, sharp minima in magnitude, and half-cycle phase changes occurred at frequencies >30 kHz. The sound frequencies of these transitions increased with decreasing distance from the tympanic membrane (TM). Sound pressure measured orthogonally across the surface of the TM showed only small variations at frequencies below 60 kHz. Hence, the ear canal sound field can be described fairly well as a one-dimensional standing wave pattern. Ear-canal power reflectance estimated from longitudinal spatial variations was roughly constant at 0.2-0.5 at frequencies between 30 and 45 kHz. In contrast, reflectance increased at higher frequencies to at least 0.8 above 60 kHz. Sound pressure was also mapped in a microphone-terminated uniform tube-an "artificial ear." Comparison with ear canal sound fields suggests that an artificial ear or "artificial cavity calibration" technique may underestimate the in situ sound pressure by 5-15 dB between 40 and 60 kHz. (+info)
Isolation and antimicrobial susceptibility of bacteria from external ear canal of cancer patients at Shafa Cancer Hospital-Ahwaz.
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A bacteriological study of external ear canal was performed in 52 hospitalized cancer patients and 42 non hospitalized cancer patients at Shafa hospital, Ahwaz. Study was under taken to find out the normal flora changes in the external ear canals and to observe the prevalence of external otitis among these cancer patients. The control group consisted of 40 non-cancer patients. We observed the following bacteria among hospitalized cancer patients. Staphylococcus Coagulase negative (51.9%), Staphylococcus aureus (15.7%) and Streptococcus pneumoniae (11.9%). Similarly, among non hospitalized cancer patients, Staphylococcus Coagulase negative (45.2%), S. aureus (9.5%) and Streptococcus pneumoniae (4.7%). Incidence of Staphylococcus Coagulase negative and Streptococci pneumoniae is higher in control group than that in cancer patients. We have concluded that cancer patients probably suffer from external otitis more frequently because of enhanced colonization by S. aureus (P < 0.05). The antimicrobial susceptibility of these organisms to various antibiotics was determined by disk diffusion method using Muller Hinton agar. In hospitalized cancer patients Staphylococcus Coagulase negative was 25% and 85% resistant to Vancomycin and Penicillin G and in non hospitalized cancer patients, Staphylococcus Coagulase negative were 45% and 80% resistant to Vancomycin and Penicillin G. S. aureus of both the groups (hospitalized & non hospitalized) were resistant to Penicillin G. Similarly, both the groups were 55% and 50% resistance to Vancomycin. (+info)
Metastatic hepatocellular carcinoma of the external auditory canal.
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This report describes a rare case of metastatic hepatocellular carcinoma (HCC) presenting a huge mass in the left external auditory canal (EAC). The patient was a 55-year-old man with hepatitis B virus-related HCC. He presented to our department with a three-month history of increasing left otalgia, and hearing loss with recent fresh aural bleeding. Histopathologic examination indicated that the tumor was secondary to HCC. Although external irradiation was not effective, the tumor was treated with surgical debulking and high dose rate 192 Ir remote afterloading system (RALS) for postoperative intracavitary irradiation. A review of the literature revealed only five other cases of HCC metastasis to the temporal bone, all of which mainly metastasized in the internal acoustic meatus. The present case is the first report of HCC metastasis to the EAC. (+info)
An atypical presentation of recurrent temporal lobe meningioma with external auditory canal mass.
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Extracranial spread of recurrent meningiomas involving the middle ear is rare. We present the case of a 59-year-old woman with headache and swelling of scalp over the right temporal region. MRI revealed a lesion in the right temporal lobe suggestive of meningioma. She underwent complete surgical excision of the lesion followed by post-operative radiotherapy. After 1 year, she presented with right-sided otalgia and a middle-ear mass extruding into the external auditory canal. She was re-operated and histopathology was anaplastic meningioma. We are discussing this unusual pattern of recurrence in our patient with a review of literature. (+info)