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Biomedical subjects

L Michaels

Publications and source records attributed to L Michaels.

At least 37 records · Page 2Linked to original sources
PubMed1990

Temporal bone pathology of adult-type osteopetrosis.

We present the pathologic features in the temporal bones of a 62-year-old woman with the adult benign form of osteopetrosis. Most of the bony tissue was expanded by dense lamellar bone, with, in some places, the presence of residual calcified cartilage. In the otic capsule, globuli interossei were greatly increased in number. The ossicles were enlarged with fixation of the stapes. Narrowing of mastoid air cells, the internal auditory meati, and eustachian tubes was present, the latter associated with chronic otitis media. The bone deposition in the ossicles contributed to the conductive hearing loss, which was a prominent feature in this patient's otologic findings. The narrowing of the internal auditory meati may similarly have contributed to a degree of sensorineural hearing loss.

Ear Ossicles↗
PubMed1990

Auditory epithelial migration on the human tympanic membrane: II. The existence of two discrete migratory pathways and their embryologic correlates.

The pathways of movement of dye-markings on the tympanic membranes of 30 ears of 15 volunteers were investigated by photography with a Hopkin's rod. Two discrete pathways were identified. Movement on the pars tensa was centrifugal in all directions from the edge of the handle of malleus surface. This supported our previous suggestion that pars tensa epithelial migration is based on growth of the meatal plate. Movement on the more central part of the handle surface itself, however, was always upwards to the pars flaccida epithelium and then, with all dye on the latter, in a posterosuperior direction only. The covering epithelium of the pars flaccida/handle of malleus arises from the fundus of the early embryonic external canal. To explore the possibility that its migration may also commence early, the fundus was examined histologically in 12 embryo ears. It was shaped like an inverted pear to conform to the primordial head of the malleus above and its handle below. There was distinct flattening of the whole fundal epithelium in contrast to the side wall of the external canal, lending support to the concept of a primordial flux of epithelium in the main fundus and its inferior extension. The meatal plate grew from the rim of the fundus producing the pars tensa and deep external canal epithelia. This process, however, was not associated with significant cytologic alterations or increased expression of the human proliferation antigen, Ki-67, at that rim. This suggests that the pars tensa epithelium grows and moves without the active involvement of the epithelium of the pars flaccida/handle of malleus.

Adult↗
PubMed1990

Pathology of the otic capsule.

The otic capsule is unique in retaining calcified cartilage, known as globuli interossei, throughout life and shows changes consequently, which are peculiar to it. In Paget's disease of bone, the otic capsule appears resistant to involvement and this occurs with extensive disease at a late stage. In contrast, otosclerosis is a new bone formation of unknown cause that is limited to the otic capsule. In osteogenesis imperfecta, the poor formation of collagen leads to abnormally thin bony trabeculae with a poorly formed otic capsule. In osteopetrosis, the otic capsule is greatly expanded by increased globuli interossei, as a result of defective osteoclast function. When fractured the middle layer of the otic capsule does not form callus, but heals by fibrosis.

Bone Diseases↗
PubMed1990

Histopathological changes in the temporal bone in Bell's palsy.

The changes in the facial nerve at autopsy are described in a case in which there had been an acute onset of lower motor neurone facial paralysis, with a clinical diagnosis of Bell's palsy, 11 days before death. There was congestion and infiltration of the nerve in the internal auditory meatus and proximal fallopian canal by lymphocytes. Features indicating compression of the nerve in the proximal part of the fallopian canal were seen in the presence of congestion and osteoclastic resorption of the bone surrounding the proximal fallopian canal. Demyelination was present in the tympanic part of the nerve. A bulge below Bill's bar was found on the normal as well as the pathological side and cannot be accepted as evidence of pathological change. It is suggested on the basis of the pathological findings that the symptoms of Bell's palsy may arise from compression of the facial nerve in the proximal part of the fallopian canal.

Aged↗
PubMed1990

Histopathology of vocal cord palsy from recurrent laryngeal nerve damage.

The detailed postmortem laryngeal findings of a man with an established vocal cord palsy from an inoperable bronchial carcinoma is presented. Fine dissection of the monoblock specimen from skull base to superior mediastinum allowed sampling of vagus, recurrent and superior laryngeal nerves at different levels for fiber counts in order to compare the affected left and unaffected right side. Horizontal slicing of the whole larynx showed that the main cause of lateral displacement of the paralyzed left cord was gross atrophy of the underlying intrinsic laryngeal muscles. Cricothyroid muscle and superior laryngeal nerves were unaffected. Lateral cord drift due to underlying muscle atrophy is a better explanation of paralyzed cord position in this case than the Wagner and Grossmann theory of cord palsy.

Aged↗
PubMed1990

Scanning electron microscopy of tympanic membrane epithelium during in vitro migration.

The en masse locomotion in tissue culture of stratified squamous epithelium of the tympanic membrane and cholesteatoma is a unique feature of these epithelia. A scanning electron microscopy study of cultures was carried out to seek features of surface architecture that might throw light on this special activity. Differences from cultures of non-migratory stratified squamous epithelium include the following: numerous lamellae emanating from the top surface of cells at the leading edge, a ridge of spent leading edge cells behind that edge, a cap of keratin behind the latter and large balloon-like swelling of cells is prevalent in the trailing edge. It is suggested that differentiation of migrating stratified squamous epithelium in tissue culture is towards specialized cells active in migration as shown by the leading and trailing edge cells, as well as towards keratinization as shown by the keratin cap.

Adult↗
PubMed1989

Development of the stratified squamous epithelium of the human tympanic membrane and external canal: the origin of auditory epithelial migration.

The development of the stratified squamous epithelium of the tympanic membrane and external canal was studied in 167 embryonic, fetal, and postnatal human ears. It originates as a tube derived from the epithelium of the fundus of the primary external canal (zone 1). The tube is composed of a thin, flat epithelium on the medial side (zone 2), continuous with a thicker one (zone 3) on the lateral side; zone 3 thereafter merges with the external epithelium of the primary external canal (zone 4). Proliferative activity, as indicated by a thickened epithelium, with rete ridges in later fetal life, is present mainly in zones 1 and 3. Cornification at 18 weeks gestation is followed by clearing of keratinous debris to the exterior. Subsequently the canal widens, zone 1 now covering the pars flaccida region, a tongue-shaped area passing inferiorly from it and a part of the postero-superior deep canal adjacent to it; zone 2 covers the pars tensa and zone 3 most of the deep external canal. On the basis of the original embryonic growth, migratory epithelial movement throughout life is postulated to be generated in zone 1 by mitotic interposition and then to pass to zone 2. It then moves en masse through to zone 3, where unilateral progression by mitotic means takes the epithelium up to the cartilaginous canal. Such a pathway is approximately that seen in the marked, living eardrum and canal.

Cell Movement↗
PubMed1989

Aspergillosis of the nose and paranasal sinuses.

Fulminant aspergillosis was diagnosed on nasal biopsy in a 49 year old man who had features of an aspergilloma. Further postmortem examination of this area was performed and the results were contrasted with the histological features of other Aspergillus infections. The nasal biopsy specimen and postmortem examination showed infiltrating Aspergillus hyphae with tissue necrosis and little inflammatory response. The hyphae were easily seen with routine stains. This contrasts with the findings in invasive aspergillosis where there is fibrosis and a granulomatous response to the Aspergillus hyphae. The hyphae are seen in giant cells using fungal stains. In the saprophytic infections aspergilloma and allergic Aspergillus sinusitis there is no tissue invasion or destruction. Aspergillus infections of the nose and paranasal sinuses often require biopsy for accurate diagnosis. As treatment varies pathologists need to be able to distinguish the different patterns of infection.

Aspergillosis↗
PubMed1989

Laryngeal papillomatosis: correlation between severity of disease and presence of HPV 6 and 11 detected by in situ DNA hybridisation.

A technique using a biotin-streptavidin polyalkaline phosphatase complex was applied to routinely fixed and processed biopsy specimens of laryngeal papillomata from 45 patients taken over the past 20 years to detect human papilloma virus (HPV) types 6 and 11. Two thirds of both adult and juvenile onset cases were positive for HPV 6 or HPV 11 or both. Five specimens of normal vocal cord epithelium were negative for HPV 6 and 11. The detailed clinical history, endoscopic findings, success of treatment and eventual prognosis were compared with the HPV state of biopsy material for each patient. Patients with multiple confluent lesions when first seen, whose histology showed florid koilocytosis and who had strongly positive reactivity for HPV 6 or 11 present in the surface epithelial cell nuclei, had a poor prognosis requiring multiple endoscopies to control their disease.

Adolescent↗
PubMed1989

Biology of cholesteatoma.

Acquired cholesteatoma is a disease of the posterior superior part of the middle ear cleft that may arise from the external epithelium of the tympanic membrane. Three distinct epithelial zones of differing thicknesses characterize the development of this latter epithelium, and the thickness differences and their distribution in the eardrum and deep external canal, which delineate the zones, are found at all stages of life, including the mature ear. It is postulated that epithelial migratory activity follows the pathways of early development, the flow occurring through the three zones. The detailed validity of this model was confirmed by otoscopic photography of dye movements on the tympanic membrane. Cholesteatoma may develop from the earliest and most active of these zones situated on the pars flaccida. The pathologic anatomy of cholesteatoma suggests vigorous growth. Retraction pockets provide a source for bands of squamous epithelium growing into the middle ear. Cholesteatoma and tympanic membrane epithelium move en masse in tissue culture, a property not shown by any other stratified squamous epithelium.

Cholesteatoma↗
PubMed1989

Congenital cholesteatomas of the middle ear in children: origin and management.

Cholesteatomas (epidermoids) of the middle ear appearing medial to a normal tympanic membrane are identified in increasing numbers of young children. The evidence that these lesions are congenital in origin includes the young mean age of presentation, the normal appearance of the middle ear mucosa in almost all cases of small lesions, normal mastoid pneumatization documented by computerized tomography, the relatively large number of children with associated minor or major congenital malformations, and the consistent 3:1 ratio of males to females with the disorder in all of the large series reviewed. A direct relationship between congenital cholesteatomas (epidermoids) of the middle ear and the epidermoid formation is supported by the position of the epidermoid formation at a histologic transition zone in the anterior superior lateral quadrant of the tympanic cavity, which is also the site of greatest occurrence of congenital cholesteatomas. The epidermoid formation may not always involute and as it expands it would be expected to become visible medial to the tympanic membrane in the anterior superior quadrant. It seems evident that as the congenital cholesteatoma expands it can block the eustachian tube; during a bout of otitis media the tympanic membrane could perforate and the cholesteatoma could become secondarily infected. The congenital cholesteatoma in this situation would be difficult or impossible to distinguish from the more common acquired type.

Child, Preschool↗
PubMed1989

Osteoma of the incus.

Osteomas of the temporal bone are rare. Osteomas of the middle ear have been reported but none involving an ossicle. We describe a case of a 28-year-old man who had a conductive hearing loss caused by an osteoma of the incus.

Adult↗
PubMed1988

Origin of congenital cholesteatoma from a normally occurring epidermoid rest in the developing middle ear.

The sites of involvement of congenital cholesteatoma, a lesion which has recently become more frequently recognized, are reviewed from literature sources. There is a propensity for its occurrence, especially when small, in the anterior superior part of the middle ear. The same situation is the precise location of an epidermoid cell rest, the epidermoid formation (EF). This is seen in most fetal ears at the junction of the Eustachian tube with the middle ear near the anterior limb of the tympanic ring, until 33 weeks gestation, when it disappears. Its origin is traced to early fetal life from the ectoderm of the first branchial groove. In embryonic and early in fetal life it seems to act as an organizer in the development of the tympanic membrane and middle ear. It is likely that congenital cholesteatoma is derived from the EF by its continued growth instead of regression. Congenital cholesteatomas show a thinner and flatter matrix than acquired cholesteatomas, probably because the former are most frequently 'closed' and therefore subject to pressure effects from the keratin within the cyst. 'Open' forms also occur in smaller numbers. It is possible that a screening program for congenital cholesteatoma in infants might reduce the incidence of the severe, extended form of the disease.

Cholesteatoma↗
PubMed1988

Evolution of the epidermoid formation and its role in the development of the middle ear and tympanic membrane during the first trimester.

In a study of 20 ears from embryos and early fetuses, 16 contained structures recognizable as precursors of the epidermoid formation (EF). The earliest were small, but later they took the form of a long epithelial bud which emanated from the tip of the tubotympanic recess or Eustachian tube. At a later stage still the EF protruded into the lumen of the Eustachian tube. The early formation of the tympanic membrane, the middle ear cavity and the osseous tympanic ring all take place in the vicinity of the EF precursor. It is possible that the EF precursor may act as an organizer, playing a prominent part in the migration of the first pharyngeal pouch towards the first branchial groove and the development of the middle ear and tympanic membrane.

Ear, Middle↗