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Biomedical subjects

W L Meyerhoff

Publications and source records attributed to W L Meyerhoff.

At least 127 records · Page 7Linked to original sources
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Use of an implantable hearing device.

PURPOSE: The purpose of this paper was to discuss our experiences with an implantable bone conduction hearing prosthesis, the XOMED Audiant Bone Conductor (Jacksonville, FL). PATIENTS AND METHODS: Twenty-four patients who had been implanted with the Audiant Bone Conductor were interviewed by telephone following implantation. Questions were asked regarding use of the device and subjective benefit. RESULTS: Eleven patients are using their devices, 12 patients are not using their devices, and one patient has been lost to follow-up. Patients using the device report satisfaction and prefer the Audiant to other amplification systems, whereas those not using the device indicate that insufficient amplification or weak magnetic attraction prevent its use. CONCLUSIONS: Analysis of failures has altered our criteria for implantation. With improvements that have been made by XOMED and stricter patient criteria, the Audiant should be considered a viable amplification alternative for certain hearing-impaired patients.

Adolescent↗
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Pathology of chronic otitis media.

A review of 800 pathological temporal bones collected from autopsy cases revealed 333 ((41.6%) to have some type of otitis media; purulent otitis media (52.5%), serous otitis media (6%), mucoid otitis media (4.5%), and chronic otitis media (36.9%). The 123 temporal bones with chronic otitis media were further studied and found to have granulation tissue, cholesteatoma, cholesterin granuloma, bone changes, and fibrosis. Other findings included tympanic membrane perforation, tympanosclerosis, metaplasia of the epithelium with subepithelial glandular formation, suppuration, labyrinthitis, and evidence of complications of chronic otitis media (meningitis, subdural abscess, brain abscess, petrositis, and endolymphatic hydrops). From this study it was concluded: 1) chronic otitis media occurred quite frequently, from a histological standpoint, in the absence of tympanic membrane perforation; 2) granulation tissue in temporal bones was found much more frequently in chronic otitis media than was cholesteatoma; and 3) complications and sequelae of otitis media tended to occur more commonly secondary to granulation tissue than to cholesteatoma.

Adult↗
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Inner ear pathology and otitis media. A review.

Insidious inner ear complications of otitis media have been and are being studied in our laboratory. The purpose of this paper is to review these studies, coordinate, capsulize and highlight the results with emphasis on the transport role of the round window membrane.

Animals↗
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Pneumococcal otitis media following middle ear deflation.

Temporal bone histology has been studied in chinchillas following middle ear deflation in the presence of nasopharyngeal colonization with S pneumoniae. All animals sacrificed within one hour following deflation had similar middle ear histology regardless of whether or not the animals had been colonized with S pneumoniae. All animals with negative nasopharyngeal culture for S pneumoniae sacrificed from 3-24 days following - 30 mm Hg negative middle ear pressure had negative middle ear cultures and normal morphology. During the same time period, however, nearly 60% of animals colonized with S pneumoniae developed acute otitis media with positive middle ear cultures for S pneumoniae. Histologic changes in the middle ear included the presence of effusion, leukocytes, granulation tissue, osteoneogenesis, mucosal metaplasia, and hemorrhage. Changes in the inner ear were much less frequent and included some leukocyte infiltration with hyperemia in the scala tympani and and endolymphatic hydrops.

Animals↗
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Use of tympanostomy tubes in otitis media.

Tympanostomy tubes (TT) are frequently employed as treatment for otitis media (OM) although there is little-clinical or experimental evidence of their efficacy. Potential detriments of TT include cost, risk of inhalation anesthesia, intraoperative complications, and tympanic membrane (TM) damage. Potential benefits include elimination of the conductive hearing loss (CHL), reduction in the occurrence of acute purulent OM, and avoidance of sequelae. The cost/benefit ratio of TT has never been accurately determined and morbid complications of inhalation anesthesia and the surgical procedure appear to be rate. There is evidence that TT significantly reduce the CHL of OM as well as reduce the incidence of recurrent acute purulent OM and help avoid sequelae. It is therefore determined that the risk of TT insertion for middle ear effusion (occasional TM changes) can be justified, in properly selected patients, by the benefits (immediate improvement in hearing and reduction in the incidence of recurrent acute purulent OM).

Anesthesia, Inhalation↗
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Silent otitis media: an animal study.

Recent clinical and laboratory observations suggest that otitis media can occur in the absence of visible tympanic membrane changes (silent otitis media). Temporal bone histopathology was studied in 38 chinchillas that had been subjected to conditions known to predispose these animals to otitis media. Morphological changes were compared to a control group of 25 nonmanipulated animals. The tympanic membranes were examined at intervals and during the immediate premortem period with the operating microscope. Thirty-one tympanic membranes in the experimental group and all tympanic membranes in the control group were judged to be normal (gray and translucent) throughout the study period. The middle ears from the experimental group histologically manifested varying amounts of effusion, mucosal edema, granulation tissue, hyperemia of the subepithelial space, hemorrhage in the middle ear space, and abundant polymorphonuclear leukocytes in the middle ear cleft. These findings were not present in the control group.

Animals↗
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Auditory and temporal bone abnormalities in CHARGE association.

CHARGE association is a recently described cluster of congenital defects including ocular coloboma, heart disease, choanal atresia, retarded development and/or CNS abnormalities, genital hypoplasia, and ear anomalies. Although congenital hearing loss has been reported in CHARGE association, no information regarding the underlying temporal bone disease is available in the literature to date. The authors evaluated four patients with multiple anomalies consistent with CHARGE syndrome. Two surviving patients have bilateral severe hearing loss on auditory brain stem response testing. Two patients did not survive, and their temporal bones were obtained at autopsy for histologic examination. All four temporal bones showed severe middle ear defects including ossicular deformities, absence of the stapedius muscle, absence of the oval window, aberrant course of the facial nerve, and dehiscence of the facial nerve canal. In the more severely affected case, a Mondini-type malformation of the cochlea was present, together with multiple anomalies of the vestibular apparatus. Vestibular defects also occurred in the other case; however, the cochleae were found to be normally developed.

Abnormalities, Multiple↗
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Morphologic effects of glycerol and urea on cochlear tissues of the chinchilla.

Glycerol and urea are used as test agents in confirming the diagnosis of endolymphatic hydrops. Although both substances act as osmotic diuretics, recent evidence suggests that they may have differing physiologic effects on the inner ear. This study was designed to compare the morphologic effects of urea and glycerol on cochlear tissues, using the chinchilla as an experimental model. Animals were given subcutaneous injections of glycerol (2 g/kg) or urea (1.2 g/kg) over periods of 3 hours, 4 days, or 1 week. Both agents were found to produce ultrastructural changes, including spiral ligament vacuolization, intracellular alterations of the stria vascularis, and increased numbers of Hensen's bodies in outer hair cells. These alterations appeared indicative of metabolic stress, but not toxicity. The morphologic findings provided no evidence that glycerol and urea affect the inner ear by fundamentally different mechanisms of action.

Animals↗
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Anatomic considerations in the posterior approach to the internal auditory canal.

We dissected 30 human temporal bones in order to establish a reliable method for avoidance of the membranous labyrinth in acoustic neuroma surgery. We believe that the variability of the surgical landmarks is sufficient to make complete reliance on anatomic measurements quite treacherous. Fine-cut computed tomograms were evaluated, and it was determined that measurements taken from such scans can define the anatomy of individual temporal bones. We conclude that hearing conservation surgery for acoustic neuroma is a relatively difficult surgical exercise and that complete familiarity with the anatomy and use of all available landmarks is required for successful tumor removal and hearing conservation. Success can be improved further by using measurements taken from the individual patient's preoperative CT scan.

Dissection↗
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Acute mastoiditis and cholesteatoma.

Acute coalescent mastoiditis is an uncommon sequela of acute otitis media. It occurs principally in the well-pneumatized temporal bone. The findings of fever, pain, postauricular swelling, and otorrhea are classic. Cholesteatoma, on the other hand, being associated with chronic infection, usually occurs in the sclerotic temporal bone. The signs and symptoms are isidious in nature and consist of chronic discharge and hearing loss which result from its mass, bone erosion, and secondary infection. Of 17 consecutive cases of acute mastoiditis over a six-year period, four were atypical because they were complications of chronic otitis media and cholesteatoma, yet they had the physical findings of acute mastoiditis-subperiosteal abscess and purulent otorrhea, plus radiographic evidence of mastoid coalescence.

Acute Disease↗
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Rabies: otolaryngologic manifestations.

Rabies is a rare, fatal viral infection, usually transmitted by the bite of an infected animal. Some 30,000 Americans are immunized annually, however, so public health considerations are common. The development of a new vaccine, grown in human diploid cell culture, is discussed. It appears to have high antigenicity with no serious morbidity. A case of a patient with fatal rabies who had fever, delirium, dysphagia, and cervical and pectoral subcutaneous emphysema is presented.

Adolescent↗
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Experimental pneumococcal otitis media: a histopathologic study.

An animal model for pneumococcal otitis media was studied histologically at varying intervals postinoculation. Histologic changes generally associated with acute inflammation (edema, diffuse infiltration with polymorphonuclear leukocytes, and hemorrhage) occurred early in the disease while the ears were culture positive. Changes generally associated with chronic otitis media (lymphocyte infiltration and osteoneogenesis) occurred later in the course of the disease when the ears were culture negative. Metaplasia of middle ear mucosa and middle ear granulation tissue were observed as early as five days following inoculation. Middle ear granulation tissue was identified in 82% of all cases; cholesteatoma was seen in only one ear. Tympanic membrane perforation did not occur. Labyrinthitis and endolymphatic hydrops were fairly common findings. The former was identified in 56% of ears examined, and the latter, in 45%. These two conditions coexisted in 34% of ears studied, while endolymphatic hydrops alone occurred in 11%.

Acute Disease↗
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Otitis media, cleft palate, and middle ear ventilation.

Chinchillas with unilateral tympanostomy tubes in place underwent palate-clefting in an effort to determine the histologic and bacteriologic effects of using tympanostomy tubes in the treatment of otitis media. The tympanostomy tube appeared to almost totally eliminate the occurrence of middle ear effusion but had much less, if any, effect on eliminating the middle ear inflammation which occurs in the clefted chinchilla.

Animals↗
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Experimental cholesteatoma. Epidermal ingrowth through tympanic membrane following middle ear application of propylene glycol.

This study was designed to investigate morphological changes in the tympanic membrane (TM) associated with cholesteatoma formation in experimental animals following application of propylene glycol to the middle ear. A 50% solution of propylene glycol was applied bilaterally to the middle ear cavities of 30 young-adult chinchillas. The animals were sacrificed for light and electron microscopic study at intervals of 2 days to 6 weeks after a single application of 0.2 ml of the propylene glycol solution. At 2 days there was complete destruction of the epidermal and mucosal layers of the TM. The denuded lateral surface rapidly became re-epithelialized by hyperplastic epidermal cells and by 2-3 weeks, keratinizing epidermis penetrated damaged areas of the fibrous layer of the lamina propria to reach the medial surface of the TM. These epidermal cells proliferated in the middle ear cavity, forming cholesteatomas. Our observations indicate that invasion of the intact, but structurally altered, tympanic membrane by hyperplastic epidermis is a primary mechanism of cholesteatoma formation in the animal model.

Animals↗
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Effects of middle ear ventilation on cholesteatoma development in experimental animals.

This study was designed to evaluate the effect of middle ear ventilation on cholesteatoma formation following propylene glycol application in experimental animals. Fifteen chinchillas had stainless steel ventilation tubes chronically implanted in their bullae and 60% propylene glycol was subsequently instilled into the middle ear cavities. The animals were kept alive for 4 weeks, during which time the middle ear pressure was monitored tympanometrically and the tubes were frequently inspected to verify patency. Of the 30 ears in the study, 20 (66.6%) developed middle ear cholesteatoma--a rate of occurrence comparable to that found in earlier studies in which middle ear ventilation was not provided. These results indicate that negative middle ear pressure is not a necessary factor for cholesteatoma development following application of chemical irritants in experimental animals.

Animals↗