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L Michaels

Publications and source records attributed to L Michaels.

At least 19 recordsLinked to original sources
PubMed2001

Prevalence of otosclerosis in an unselected series of temporal bones.

BACKGROUND: Histologic otosclerosis is a disease process without clinical symptoms or manifestations that can be discovered only by sectioning of the temporal bone at autopsy. Clinical otosclerosis is otosclerosis at a site where it causes conductive hearing loss by interfering with the motion of the stapes or of the round window membrane. Various authors have studied the prevalence of histologic otosclerosis on laboratory collections of temporal bones. Some 12% to 15% of temporal bones with histologic otosclerosis have demonstrated stapedial fixation. Using these figures for calculating the prevalence of clinical otosclerosis gives an extrapolated clinical prevalence of 0.99% to 1.2%. This does not correlate well with the clinical data on otosclerotic families, from which a clinical prevalence of 0.3% has been estimated. OBJECTIVE: To study the prevalence of histologic otosclerosis in an unselected series of temporal bones. STUDY DESIGN: During a 1-year period, 118 consecutive pairs of temporal bones of deceased patients at a tertiary care center were collected to determine the prevalence of otosclerosis. Although histology remains the gold standard for evaluation of otosclerosis, the gross observation of temporal bone slices combined with microradiography was used to screen for otosclerotic lesions more rapidly and with a lower cost/benefit ratio. The temporal bones, which were suspected of having otosclerosis with these techniques, were further analyzed by conventional histology. RESULTS: 2.5% of the 236 temporal bones (or 3.4% of patients) studied demonstrated histologic otosclerosis. CONCLUSIONS: Although the prevalence of 2.5% is much lower than previously published figures on histologic otosclerosis, the extrapolated data (extrapolated clinical prevalence = 0.30% to 0.38%) correlate well with clinical studies of otosclerotic families. The previous studies based on laboratory collections were likely biased by hearing loss or other otologic diseases.

Adolescent↗
PubMed2000

The development of the stria vascularis in the human foetus.

The development of the stria vascularis in the human cochlea was studied in step sections of 81 human foetal temporal bones. The stria vascularis primordium can be identified as a ridge of epithelial cells on the lateral wall of the cochlear duct. The first signs of differentiation appear at the 11th week, but it is not until the 17th-18th week that the typical trilaminar structure is observed. The appearance of similar cells with notched nuclei in both marginal and mesenchymal layers at this stage suggests the possibility that some of the intermediate cells may be of epithelial origin. By the 21st week, the overall appearance resembles that of the adult structure. This occurs 1 week after the opening of the tunnel of Corti, and possibly marks the onset of cochlear function.

Cochlear Duct↗
PubMed2000

Origin and spread of allergic fungal disease of the nose and paranasal sinuses.

Although expansion of bony walls occurs in allergic fungal disease of the nose and paranasal sinuses by increased mucus secretion and fungal growth, the latter is apparently confined to the lumen and does not invade the tissues. Nevertheless, spread of the disease process from paranasal sinuses to orbit, cheek and intracranial cavity is well described. An imaging and histopathological study was carried out in 16 cases to determine how the disease originates and spreads. The infection starts in the nasal cavity, the lumen of a sinus or in a seromucinous gland or duct. A thin vascular zone of intense allergic inflammation surrounds the infected mucin. Erosion of bone takes place focally, probably by substances produced by the inflammatory tissue, allowing intromission by the thin vascular layer together with its underlying fungus-containing mucus and so extension of the disease process through the eroded bone.

Adult↗
PubMed2000

The Ljubljana classification: a practical strategy for the diagnosis of laryngeal precancerous lesions.

There is no internationally accepted classification of epithelial hyperplastic laryngeal lesions (EHLL). The majority of current classifications follow criteria similar to those commonly used for cervical epithelial lesions. However, the different etiology of laryngeal cancer and its particular clinical and histologic features necessitate a grading system more appropriate to this region. The Ljubljana classification of EHLL was devised in 1971 to cater to this requirement. Detailed criteria for histologic grading in this classification were formulated by a working group on EHLL of the European Society of Pathology in 1999. The system recognizes four grades: simple and abnormal hyperplasia are benign categories; atypical hyperplasia ("risky" epithelium) is potentially malignant, and carcinoma in situ actually malignant. The main features by which the proposed grading system differs from other classifications are: 1. the distinction between benign and potentially malignant lesions; 2. the positive separation of carcinoma in situ from atypical hyperplasia; 3. the lack of prognostic significance for any surface keratin layer. The eventual outcome of EHLL patients so graded justifies the proposal for separating the lesions into a benign group, showing malignant transformation in only 0.9% of cases, from a potentially malignant group showing malignant transformation in 11% of cases. For diagnostically difficult cases, supplementary techniques such as those using morphometry, immunohistochemical and molecular biology are advised to improve the accuracy of diagnosis and predictions of their biological behavior.

Carcinoma in Situ↗
PubMed2000

Congenital malformations of the ear and cochlear implantation in children: review and temporal bone report of common cavity.

The objective of this review is to analyze aspects of congenital malformation of the ear in relation to cochlear implantation in children. Having briefly described the in utero development of the ear and the classification of types of external, middle and inner ear malformation, five practical aspects of these malformations are discussed. It seems likely that the combination of bilateral profound sensorineural deafness with bilateral microtia severe enough to make a surgical approach to the cochlea difficult will be extremely uncommon. No such cases have been reported, although Klippel-Feil deformity seems the syndrome most likely to produce this set of circumstances. Abnormalities in the intratympanic course of the facial nerve have been associated with cochlear malformation, emphasizing the benefit of intra-operative facial nerve monitoring, and a technique suggested for safely avoiding an abnormally placed nerve. Fistulae of cerebrospinal fluid (CSF) and perilymph can complicate surgery and are relatively common in common cavity and Mondini malformations. Strategies for facilitating surgery in the presence of 'gushers', for measuring the pressure of a gusher and for placement of the cochlear implant electrode array are reviewed, with reports of fluctuating levels of electric current when implants lie in dysplastic cochleas. The relationship of implant performance to VIIIth nerve tissue in malformed cochleas is discussed, with a description of the histological findings in a common cavity cochlea. Techniques for identifying the absence of the cochlear nerve are reviewed. Stimulation of the facial nerve by cochlear implants has been described in cases of congenital malformation of the labyrinth but is relatively uncommon. Case reports of the benefit received by implanted children with congenital cochlear malformation have appeared since 1988. Most cases reported have not yet been followed for long enough to establish a clear picture of the outcome following cochlear implantation in such children; no centre has yet built up a large series of cases, but there have been two multicentre postal surveys. It seems likely that in cochlear malformation the range of potential outcomes in terms of hearing threshold and the development of speech perception and production will be similar to the range found in implanted children without cochlear dysplasia. However there is, as yet, no clear picture of the mean level of performance within this range.

Adolescent↗
PubMed1999

Family with low-grade neuroendocrine carcinoma of salivary glands, severe sensorineural hearing loss, and enamel hypoplasia.

Four sibs in a family on the Isle of Man, two brothers and two sisters ranging in age from 33 to 45 years, presented with low-grade malignant tumors of the submandibular gland in three cases and of the nasal cavities and maxillary sinuses in one. The neoplasms were all of the same histological type, apparently hitherto undescribed, showing well-differentiated neoplastic ducts, surrounded by neoplastic myoepithelial cells, together with sheets of epithelial cells expressing neuroendocrine markers by immunohistochemistry. Cervical neck node metastases have developed in all four cases. In the sib with a primary sinonasal neoplasm, widespread bloodstream metastases also became manifest and a single such metastasis in his brother. All four sibs have severe enamel hypoplasia and the same lesion is present in 5 of their 11 children. In the two male patients, severe sensorineural hearing loss has developed in adult life, unilateral in the left ear in one brother, bilateral in the other. In the brother with bilateral sensorineural hearing loss, magnetic resonance imaging revealed a vestibular schwannoma on the left side, which is currently under treatment. The inherited hearing loss is thought to be unilateral in this case also.

Adolescent↗
PubMed1999

Histopathological findings suggest the diagnosis in an atypical case of Pendred syndrome.

Radiological malformation of the labyrinth, specifically dilatation of the vestibular aqueduct, has been clearly established as a feature in the majority of patients with Pendred syndrome. Mutations of the Pendred syndrome (PDN) gene have been identified in this autosomal recessive form of deafness. There is no direct correlation between the nature of the underlying mutation and the clinical features of deafness, thyroid dysfunction and cochlear malformation. We report a family, the proband of which was thought to deafness secondary to congenital hypothyroidism. At autopsy, histopathological examination of this patient revealed a dilated vestibular aqueduct. Subsequent work on the family has confirmed the diagnosis of Pendred syndrome in the proband and her affected sister.

Adolescent↗
PubMed1999

Criteria for grading in the Ljubljana classification of epithelial hyperplastic laryngeal lesions. A study by members of the Working Group on Epithelial Hyperplastic Laryngeal Lesions of the European Society of Pathology.

AIMS: To validate histological criteria for the grading of epithelial hyperplastic laryngeal lesions (EHHL) (dysplastic laryngeal lesions), we used a system that had been devised and tested in Ljubljana, Slovenia over many years and was felt to be more appropriate to laryngeal pathology than is the commonly-used model of intraepithelial neoplasia in the cervix. METHODS AND RESULTS: Vocal cord biopsies of 45 patients with a broad spectrum of EHLL were reviewed. Detailed histological criteria were formulated for each of the four grades of EHLL in the Ljubljana classification, comprising simple hyperplasia (benign spinous layer augmentation), abnormal hyperplasia (benign basal and parabasal layer augmentation), atypical hyperplasia (risky for malignancy) and carcinoma in situ (actually malignant, but without invasion). CONCLUSIONS: Using these criteria a high degree of concordance of histological diagnoses of grading levels for the Ljubljana classification was achieved between the pathologists of the Working Group. The system was found to be more precise for routine diagnostic work than the others in vogue. The different grades of the Ljubljana classification correspond to significantly different levels yielded in each grade by the semiobjective methods of quantitative morphometry and immunohistochemistry.

Epithelium↗
PubMed1999

Authors' reply

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Journal Article↗
PubMed1999

[Epidermoid formation in the pathogenesis of congenital cholesteatoma--a current review].

BACKGROUND: Many theories have been suggested regarding the origin, pathogenesis, diagnosis, and incidence of congenital cholesteatoma. REVIEW OF LITERATURE: An overview on the current literature on congenital cholesteatoma of the middle ear is presented. It comprises the possible etiology and pathogenesis of congenital cholesteatoma. Among other theories, germ scattering, metaplasia, ingrowth of meatal epidermis, and reflux of amniotic fluid have been proposed. Special emphasis is put on the epidermoid formation theory, which has been described by Michaels and others. CONCLUSIONS: It is widely accepted that congenital cholesteatomas may originate from the postpartum persistence of epidermoid formations. Nevertheless, a clear transition from epidermoid formation to congenital cholesteatoma has yet to be confirmed.

Cholesteatoma, Middle Ear↗
PubMed1998

The epidermoid formation and its affinity to congenital cholesteatoma.

The epidermoid formation was reinvestigated in stained step sections of foetal and neonatal temporal bones to assess its relationship to congenital cholesteatoma. Epidermoid formations were found in 88 of 211 temporal bones (42%) at from 12 weeks gestation to 6 months post-partum. The site was usually near the roof of the anterolateral epitympanum at an average of 389 microns anterior to the anterior edge of the tympanic membrane. Seven epidermoid formations however, were sited on the medial anterosuperior tympanic membrane surface. The mean surface diameter of epidermoid formations was 242 microns. Some were greater than 1500 microns, which approaches the size of small congenital cholesteatomas. They are often in proximity to a developmental epithelial fold which could close off to produce a cyst. These features support the concept that the epidermoid formation is a precursor of the small anterosuperior congenital cholesteatoma.

Cholesteatoma↗
PubMed1998

Development and evaluation of a chromatographic procedure for partial purification of substance P with quantitation by an enzyme immunoassay.

We have developed a simple chromatographic procedure for the partial purification of substance P (SP) from acidified plasma and serum samples. We have evaluated a sensitive antigen competition enzyme immunoassay (EIA) for the quantitation of SP. The chromatographic procedure has recovery efficiencies ranging from 94.8 to 125%. The immunoreactivity of unknown amounts of purified SP subjected to the preparative procedure yielded a coefficient of variance of 9.4%. The EIA yielded reproducible standard curves having an interassay (n = 8) correlation coefficient of 0.984. The evaluation of normal adult control serum yielded a mean value of 51 pg/ml (range, 35 to 61 pg/ml). The evaluation of 3.33 x concentrates of serum-derived partially purified SP provided uncorrected SP values of 117 to 201 pg/ml, which fell within the midpoint of the three-decalog standard curve. These studies indicate that both the preparative and quantitative procedures are required for the detection of SP in plasma or serum samples collected from patients with several clinical disorders.

Adult↗
PubMed1997

Argyrophilic nucleolar organizer regions in auditory meatal skin and middle ear cholesteatoma.

Comparative silver-staining of argyrophilic nuclear organizer regions (AgNORs) was performed to study the proliferative activity of auditory meatal skin and middle ear cholesteatoma. AgNOR expression patterns were counted by standardized methods in two centres, Bochum and London, and mean numbers of dots per nucleus were calculated. Specimens of normal auditory meatal skin showed 1.54 dots/nucleus (n = 12) in the Bochum study, whereas cholesteatoma had 3.71 dots/nucleus (n = 21). In the London study normal meatal skin showed two dots/nucleus (n = 4), whereas acquired cholesteatoma (n = 8) gave a mean of 4.90 dots/nucleus and congenital cholesteatoma a mean of 4.70 dots/nucleus (n = 2). Our findings confirm the hyperproliferative state of middle ear cholesteatoma, suggest that the congenital variety of cholesteatoma may have a similar activity and indicate that AgNOR staining is a useful technique for assessing cellular proliferation in cholesteatoma and objectifying and quantifying its aggressive behaviour.

Cell Division↗
PubMed1997

The Kambic-Gale method of assessment of epithelial hyperplastic lesions of the larynx in comparison with the dysplasia grade method.

Sections of vocal cord biopsies from 47 cases in whom had been previously assessed by a dysplasia grading system at from I to III, were reclassified according to the Ljubljana system. The majority of the Grade I lesions were reclassified as "non-risky", but a small number were put into the risky or even carcinoma in situ groups. While most of the Grade III cases were reclassified as "risky" there were a few who were assigned to a non-risky category. It is suggested that with the Ljubljana histological grading system a more clear-cut separation of cases with risk of developing vocal cord malignancy from those with no such risk, is possible. Attention is drawn to a lesion denoted as "large cell hyperplasia", which is not covered in the grading or Ljubljana categorization of vocal cord lesions. The malpighian cells in this lesion are enlarged to over 30 microm in diameter, and show prominent nucleoli: apoptotic cells are prominent. Evidence is presented that this may be a categorical risk for the development of malignant changes.

Apoptosis↗
PubMed1996

The ear in the acquired immunodeficiency syndrome: II. Clinical and audiologic investigation.

Patients with acquired immunodeficiency syndrome (AIDS) were investigated to determine the sites, nature, and severity of any otologic abnormalities. Tinnitus, "muffled" or "echoing" hearing, and vertigo were frequent complaints. Eight percent of the 155 patients studied showed evidence of chronic otitis media, usually with effusion. Mostly mild, but occasionally severe sensorineural hearing loss was found in many, affecting more severely the higher and lower frequencies than the middle range. Almost all patients showed diminished otoacoustic emissions, suggesting cochlear dysfunction resulting from infection or ototoxicity as the basis for the hearing loss. Impairment of the otoacoustic emissions by a subclinical otitis media with effusion cannot, however, be excluded. On the basis of this study it is suggested that the provision of otologic care to patients with AIDS may enhance their quality of life and, by the early detection and treatment of severe otitis media, may even prolong life.

Acoustic Impedance Tests↗
PubMed1996

Benign mucosal tumors of the nose and paranasal sinuses.

The histogenesis of benign mucosal tumors of the nose and paranasal sinuses is reviewed in this report. In contradistinction to the view favored in the literature, these comprise three distinct entities. Everted and cylindric cell papillomas are true papillomas, lined by stratified squamous and microcyst-laden, columnar, and oncocytic epithelium, respectively. Inverted papillomas are polyps with marked, patchy squamous metaplasia in ductal and surface epithelium and numerous microcysts containing macrophages in those epithelia. Low-grade squamous carcinoma of the nose and paranasal sinuses may be difficult to distinguish from inverted papilloma. There are no intermediate forms from any one of the three types of benign mucosal tumors of the nose and paranasal sinuses to another. The site of origin of everted papilloma is from the nasal septum or nasal vestibular epithelium. Inverted and cylindric cell papillomas arise on the other hand from the lateral wall of the nose, ethmoid, or maxillary sinuses. Inverted papillomas alone among the three have a strong tendency to recur, and some cases are associated with carcinoma, although the development of malignancy is unusual.

Biopsy↗