Biomedical subjects

M Hawke

Publications and source records attributed to M Hawke.

At least 73 records · Page 4Linked to original sources

PubMed1990

The perilymphatic fistula: the end of an enigma?

While the existence of a perilymphatic fistula may be suggested on the basis of a patient's history and physical findings, at present the diagnosis can only be established by the identification of the actual fistula at the time of tympanotomy. In some cases, repeated reaccumulation of clear colorless fluid within the middle ear is interpreted as representing perilymph and has been considered to indicate the presence of a fistula that cannot be visualized. This subjective type of observation is made by the operating surgeon and is consequently subject to bias. At the present time there is no objective method, such as histopathology, to confirm the diagnosis of a perilymphatic fistula in this type of situation. As a result, there is some variation and controversy in the otology literature as to what surgical findings at tympanotomy should be considered as "proof" of a perilymphatic fistula. In this paper we will propose a new method for confirmation of the diagnosis of perilymphatic fistulas based on a unique biochemical property of perilymph.

Ear Diseases↗

PubMed1990

Steroid sulfatase activity in the skin of the external ear canal.

Steroid sulfatase is an enzyme which has an important role in the complex process of cell desquamation. The specific activity of this enzyme was found to be higher in the epithelium of the deep external auditory canal than in the epithelium of the superficial external canal. We speculate that this steroid sulfatase activity gradient is involved in the outward migration of the keratinocytes of the canal epithelium.

Analysis of Variance↗

PubMed1990

Outer ear canal shape and its relation to the effectiveness of sound attenuating earplugs.

This investigation was undertaken to explore the relationship between the level of sound attenuation achieved by the wearing of hearing protectors, and the shape of the external ear canal. Bilateral molds of the outer portion of the external ear canal were made in 93 males and females with normal hearing, who had participated in a previous study on the effect of gender on sound attenuation, measured for a variety of insert type devices. The ear canal molds were analyzed in terms of tortuosity, caliber, and degree of funneling. The results showed that individuals with straight canals achieved significantly higher attenuation scores than those with twisted canals. With regard to caliber, the more important of the two parameters reviewed was the cross-sectional area of the canal measured at the cartilaginous-bony junction (IA). The relationship between IA and attenuation depended on both gender and the type of earplug tested. Funneling, measured by the ratio of concheomeatal and cartilaginous-bony cross-sectional areas, had the opposite effect of that for IA. These findings underscore the need for more controlled prescription and fitting procedures for the insert type of hearing protectors commonly used in the industrial setting.

Ear Canal↗

PubMed1989

Histopathologic consequences of surgical approaches to the singular nerve.

Selective sectioning of the singular nerve has proven successful in the relief of incapacitating benign positional vertigo (BPV), presumably on the histopathologic basis of posterior ampullary cupulolithiasis. Although the surgical techniques of transmeatal and the recently introduced retrosigmoid IAC approach have been well described, little has been written about the singular nerve's anatomical relationships determined histologically for each surgical approach. The anatomical relationships of the singular nerve in both the transmeatal and retrosigmoid IAC approaches are discussed. Histologic evidence presented suggests that other mechanisms may also be ultimately responsible for improvement in the symptoms of BPV following transmeatal surgery. Moreover, the high incidence of injury to the endolymphatic duct during retrosigmoid surgery raises questions about the exact role of the endolymphatic duct and sac in inner ear homeostasis.

Ear, Inner↗

PubMed1989

The mechanism of ceruminolysis.

In a previous study comparing the efficacy of a selection of commonly used ceruminolytics, the authors noted that aqueous-based preparations, and in particular solutions of sodium bicarbonate, were more effective in disintegrating cerumen than most organic-based preparations. In that study, the authors also observed that not only had the wax truly disintegrated following exposure to the aqueous-based preparations, but also that a marked degree of swelling of the wax spheres had occurred with these preparations. In this paper the mechanism of ceruminolysis was investigated by means of a number of commonly available histological techniques. Our findings show that desquamated sheets of corneocytes are the major constituent of cerumen plugs and provide the structural framework of the wax bolus. Ceruminolytics work by hydrating the keratin cells of these sheets of desquamated stratum corneum and subsequently inducing keratolysis, with disintegration of the wax.

Antipyrine↗

PubMed1989

The glomus tympanicum: a middle ear chemoreceptor?

Negative pressure in the middle ear has been identified as an important factor in the pathogenesis of middle ear disease. Unfortunately, to date, the physiological mechanisms that control middle ear pressure are poorly understood. Recent interest has focused on the possible role of carotid body-like tissue in the middle ear (the glomus tympanicum) as a chemoreceptor for changes in the gas composition of the middle ear. From the few anatomical studies of normal glomus tissue in the temporal bone it would seem that glomus bodies may not be consistently present in the middle ear. In this study, glomus bodies were sought in histological preparations of the promontory mucosa and tympanic plexus. It was found that the glomus tympanicum is only occasionally present in the middle ear mucosa, and thus a chemoreceptor role specific to the middle ear is unlikely.

Chemoreceptor Cells↗

PubMed1989

The efficacy of ceruminolytics: everything old is new again.

Impacted cerumen frequently poses a problem to both patients and physicians. Over the years, many topical ceruminolytics have been advocated, many of which are currently used with no scientific proof of their effectiveness. The effects of a variety of ceruminolytics were tested in vitro on standard spheres of normal human cerumen. The only truly effective ceruminolytics had an aqueous base, and the most effective ceruminolytic was a 10% solution of sodium bicarbonate. In contrast, those ceruminolytics which had an organic base, including most of the commonly available commercial preparations, had little ceruminolytic effect. When we consider that Joseph Toynbee recommended the use of sodium bicarbonate ear drops as a ceruminolytic in 1860, then surely, when looking for the ideal ceruminolytic, "everything old is new again".

Bicarbonates↗

PubMed1989

Neurothekeoma (peripheral nerve sheath myxoma) of the external auditory canal.

A patient who presented with an isolated soft-tissue tumor in the lateral portion of the external auditory canal, which after removal was diagnosed histopathologically as a peripheral nerve sheath neurothekeoma, is presented. Peripheral nerve sheath myxomas (neurothekeomas or perineural myxomas) have been reported to occur on the central area of the face, arms and shoulders. This is the first case in which a tumor of this type has been reported to develop in the external auditory canal. The distinguishing histopathological characteristics and the differential diagnosis of this tumor are discussed.

Ear Canal↗

PubMed1989

Cavernous hemangioma of the incus (an incidental finding).

The incidental discovery of a cavernous hemangioma in an apparently normal incus found during pathological examination is reported. The incus had been removed during the course of a total osseous labyrinthectomy for delayed endolymphatic hydrops (DEH), and this unexpected finding noted. Although rare, hemangiomatous involvement of the temporal bone does occur and its manifestations are discussed. To date there have been no other reports of a hemangioma involving the incus solely.

Adult↗

PubMed1989

Computed tomographic analysis of the intratemporal facial nerve and facial nerve neuromas.

High-resolution computed tomography (HRCT) has replaced multidirectional tomography in the detailed analysis of the temporal bone because of its excellent resolution of fine bony detail. Small soft-tissue masses not discernible on plain tomograms are easily seen using HRCT. Unsuspected early disease which has not caused recognizable bone erosion in also demonstrable by HRCT. Last but not least, the amount of radiation received by a patient as a result of HRCT is considerably less. We illustrate the normal course of the facial nerve through the temporal bone, its anatomical relationship to various adjacent structures, and the numerous branches given off during its course through the temporal bone. The clinical features of facial nerve neuromas (schwannomas) depend on their location and include facial nerve weakness or paralysis, otalgia or facial pain, hearing loss or imbalance, and loss of taste sensation. HRCT allows the identification of a soft-tissue mass along the course of the facial nerve, with its bony canal usually enlarged by the mass. Pressure erosion of the underlying bone is often noted and erosion of the ossicles may be demonstrated in the case of middle ear involvement. The importance of both clinical and radiological correlation cannot be overemphasized in the discovery of these tumors.

Adult↗

PubMed1988

Severe sensorineural hearing loss caused by lightning. A temporal bone case report.

To our knowledge, this article represents the second temporal bone case report in the literature of profound bilateral sensorineural deafness resulting from a lightning strike to the neck. Initial survival permitted antemortem audiologic testing, the results of which suggested severe cochlear abnormalities. Both temporal bones showed widespread inner-ear changes with absent organs of Corti, rupture and collapse of Reissner's membrane, strial degeneration, and a decreased spiral ganglion cell population. The occurrence of inner-ear trauma with an intact tympanic membrane and normal middle-ear structures suggests that a mechanism other than blast injury was responsible for the pathologic changes in this case.

Adult↗

PubMed1988

Anatomy of the external ear canal: a new technique for making impressions.

The study of the topographical and three dimensional anatomy of the human external auditory canal and tympanic membrane has been simplified by applying a dental impression technique to the cadaver ear. A light silicone resin was catalyzed and syringed into the anterior recess and then into the entire external canal. Analysis of these impressions showed them to compare well with earlier morphological techniques, and to provide a durable and reliable replica of the surface of the tympanic membrane, the interior of the external auditory canal, and the lateral surface of the pinna. The resulting impressions displayed the anatomical features of the external auditory canal in a unique three-dimensional fashion which was also suitable for measurement of the anatomical features of the canal.

Dental Impression Technique↗

PubMed1988

Epidermal cyst attached to the chorda tympani nerve.

The incidental post-mortem finding of a small epidermal cyst in the middle ear of a 78-year-old female is presented. The epidermal cyst was attached to the chorda tympani nerve adjacent to the body of the incus, but was not associated with bony erosion or any other suggestion of enlargement or invasive growth. The pathological relationship of this lesion to previously reported "congenital cholesteatomas" of the middle ear is discussed.

Aged↗

PubMed1988

Intradermal nevus of the ear canal.

While intradermal nevi are common benign pigmented skin tumors, their occurrence within the external auditory canal is uncommon. The clinical and pathologic features of an intradermal nevus arising within the external auditory canal are presented, and the literature reviewed.

Adult↗

PubMed1988

Corneocyte architecture in the human external auditory canal.

Using skin dissected from the external auditory canals of fresh cadaveric temporal bones, the structure of the stratum corneum was investigated by the techniques of alkaline expansion of cryostat sections, silver staining of epidermal sheets, and scanning electron microscopy. Ordered epidermal column formation was observed in the stratum corneum from skin obtained from both the bony and cartilaginous portions of the canal. Occasionally, in areas of skin where the stratum corneum was considerably thickened, this vertical organization was lost, and the corneocytes randomly arranged. This orderly cellular architectural arrangement is a feature of the non-migratory skin of lower mammals, and has also been reported to occur in some areas of human skin. The functional relevance of this finding in the skin of the external canal is that the whole of the stratum corneum must migrate as one in order to preserve a regular vertical structure, suggesting that epidermal migration occurs in the deeper layers of the meatal epidermis.

Aged↗

PubMed1988

Benign osteitis of the external auditory meatus.

Benign osteitis of the external auditory canal is a distinct clinical entity characterized by localized ulceration in the skin of the floor of the bony external auditory meatus with underlying osteitis and sequestration of the underlying tympanic bone. Consideration of clinical and pathological data suggests that continued self-inflicted minor trauma is an etiological factor in at least some cases. The purpose of this paper is to review benign osteitis of the external auditory canal, presenting further clinical documentation and to offer etiological suggestions based upon clinical, pathological and experimental observations. The benign nature of this condition is emphasized.

Aged↗

PubMed1988

Computer-generated three-dimensional reconstruction of the singular nerve.

Advances in computer technology have made it possible for detailed and accurate three-dimensional images of complex anatomical structures to be reconstructed from serial histologic sections. This technique is useful in visualizing the morphologic nature and relationships between many intratemporal structures. In this paper, the three-dimensional anatomy of the singular nerve was examined by means of a three-dimensional computer reconstruction. Future applications for this technique are discussed.

Computer Graphics↗

PubMed1988

Stratum corneum morphology in the human tympanic membrane and external auditory meatus.

This report documents the spatial architecture of corneocytes in the human tympanic membrane and external auditory meatus. Using specimens of tympanic membrane and meatal skin dissected from fresh cadaveric temporal bones, the structure of the stratum corneum was investigated by the techniques of scanning electron microscopy and silver staining of epidermal sheets. An ordered vertical architecture was demonstrated in the skin obtained from both bony and cartilaginous portions of the auditory meatus, whereas the corneocytes of the tympanic membrane were randomly distributed. This orderly cellular configuration is a feature of the non-migratory skin of lower mammals, and some areas of human skin, but has not been previously reported to occur in the human external auditory meatus. The implication of these findings in terms of lateral epithelial migration is that in the external auditory meatus in order to maintain a vertically aligned structure the stratum corneum must move as one layer, being passively transported above the deeper epidermal layers in which migration occurs. In the tympanic membrane, however, net epithelial dispersion occurs by random insertion of new cells into a pavement-like layer of corneocytes.

Aged↗