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Biomedical subjects

F R Galey

Publications and source records attributed to F R Galey.

At least 19 recordsLinked to original sources
PubMed1991

Cochlear implants: histopathologic findings related to performance in 16 human temporal bones.

This paper presents results of a histologic study of 16 temporal bones with cochlear implants from 13 subjects. Damage caused by electrode insertion in the basal turn of the cochlea was evaluated. Dendrite and spiral ganglion cell populations were compared to clinical performance scores to determine structures necessary for stimulation and the minimum number needed for electrical stimulation. Results show that damage from insertion of long electrodes was located mainly at the most anterior part of the basal turn; that despite total degeneration of dendrites in the area near the electrode, some spiral ganglion cells remained; and that spiral ganglion cells or possibly axons are the stimulated structures and that fewer of them than previously thought are necessary to achieve a hearing sensation from electrical stimulation.

Adult↗
PubMed1991

Cochlear implant histopathology.

Twenty-two temporal bones and one brain stem from 13 cochlear implant patients were examined histologically. Sixteen temporal bones had undergone one or more implant procedure. Results of analysis suggested that the ganglion cells were the responding elements to the implant and that useful auditory sensation could result from as few as 10 percent of the normal number of ganglion cells. All implanted bones exhibited varying amounts of fibrosis (some ossified) in the basal turn of the cochlea and beyond in some cases. Usually there was damage to the surviving elements of the organ of Corti and the dendrites throughout the extent of the electrode insertion. However, the ganglion cell population was not affected. Prolonged electrical stimulation (up to 14 years) did not affect ganglion cell survival in three cases, and had no effect on the cochlear nerves in two cases or on cochlear nuclei in one case.

Adult↗
PubMed1991

Inner ear morphologic changes resulting from cochlear implantation.

Insertion of electrodes into the cochlea can damage the spiral ligament, organ of Corti, osseous spiral lamina, and dendrites. The amount of damage depends on the method of insertion and the amount of surgical trauma. Damage is limited to the area immediately adjacent to the electrode. Damage in the cochlea and prolonged electrical stimulation do not affect ganglion cell population. The ganglion cell population responds directly to the electrical stimulus. Examination of three auditory nerves from three cases and the cochlear nuclei from one case also reveals no effect of prolonged electrical stimulation.

Cochlear Implants↗
PubMed1990

Lermoyez's syndrome: histopathologic report of a case.

This paper reports findings in a pair of temporal bones from a patient with clinical evidence of Lermoyez's syndrome, a rare variant of Meniere's disease. Endolymphatic hydrops is limited to the basal turn of the cochlea and saccule in Lermoyez's syndrome, but more generalized in Meniere's disease.

Cochlear Duct↗
PubMed1989

Electron microscopy of hyalin bodies in the human intraosseous endolymphatic sac.

Hyalin bodies are amorphous, eosinophilic masses protruding from the subepithelial connective tissue into the lumen of the intraosseous endolymphatic sac (ES). We studied hyalin bodies at the electron microscopic level. Celloidin- embedded temporal bone sections known to have hyalin bodies were re-embedded into plastic and cut into thin sections appropriate for electron microscopy. The results revealed that the hyalin bodies are composed predominantly of thick bundles of collagenous fibers arranged in various directions. Fibroblasts and disintegrated macrophages were occasionally observed among the collagen fibers. Concentric calcific structures found within the hyalin bodies were composed of multiple smaller, concentric, lamellar calcifications. The results of this study support the hypothesis that the hyalin bodies are a repository of membranous cellular debris phagocytized by the macrophages.

Calcinosis↗
PubMed1989

Computer-generated three-dimensional reconstruction of the cochlea.

Computer-generated three-dimensional reconstructions of the nerve fibers from the organ of Corti to the spiral ganglion were used to determine the optimum maximal length of the cochlear implant electrode. The spiral ganglion within the modiolus is much shorter than the organ of Corti. The spiral ganglion has 1 3/4 turns and reaches no higher than the middle of the second turn of the organ of Corti, which has 2 3/4 turns. The spiral ganglion is concentric and basal with respect to the organ of Corti. The spiral ganglion dendrites within the osseous spiral lamina of the basal turn project radially, nearly perpendicular to the central axis of the modiolus. Upon entering the modiolus, they turn basally at an angle of approximately 120 degrees. The projection of dendrites within the osseous spiral lamina became increasingly oblique as the ganglion extended apically. The organization of the cochlear nerve results from the spiraling of the ganglion. These findings are in agreement with previous reports. Implications of these findings and their possible relevance to the optimum length of the cochlear implant electrode are discussed with reference to cochlear damage resulting from longer electrodes.

Cochlea↗
PubMed1987

Computer-aided three-dimensional reconstruction of the cochlear nerve root.

Computer-aided three-dimensional reconstruction techniques have been used for reconstruction of the cochlear nuclei and the cochlear nerve root. The cochlear nuclei, the nerve root, and the other adjacent structures were studied in serial frontal and horizontal sections. Boundaries of these structures were digitized into a computer and eight three-dimensional models were produced. Two solid models (reconstructions) showed the spatial surface topography, while the others revealed the appearance of the nerve root within the nuclei. The reconstructions also showed the position of the tenia of the tela choroidea on the surface of the nuclei and its relation to the root. This knowledge makes it possible to use the tenia as a landmark for determination of the root position within the nuclei. As the nerve enters the nucleus and forms the root, there is an appreciable reduction in its thickness. At the same time, the distance between the nuclei surface and the root, which has a cone shape, increases. The cone is curved along its longitudinal axis toward the inferior cerebellar peduncle. The top of the root borders the dorsal cochlear nucleus. This study stems from work in this institution on placement of the central electroauditory prosthesis on the cochlear nuclei surface. The results obtained further knowledge of the anatomy of the nuclei, specifically the areas used for the prosthesis implantation and the underlying tissue.

Brain Stem↗
PubMed1987

Experimental freeze-dried microarterial allografts in rabbits.

Arterial allografts, 3.5 cm in length, were freeze-dried and placed into the femoral arteries of 20 female rabbits (16 experimental subjects and four controls). Immediate patency was 100%. Subjects were surgically explored after two months of observation. Overall patency at this time was 31% (5/16). A patency rate of 50% (5/10) was achieved with size-matched femoral grafts. However, all of the smaller diameter brachial grafts were unsuccessful. Analysis by light microscopy as well as transmission and scanning electron microscopy demonstrated intimal hyperplasia, which was more prominent in nonpatent grafts. There was no evidence of a cellular immune response to the freeze-dried grafts by the host. The use of size-matched grafts and postoperative anticoagulants in future studies may improve patency rates and the potential clinical applicability of this promising microvascular technique.

Animals↗
PubMed1986

Microsurgical application of freeze-dried arterial allografts.

Arterial allografts of 1.0 mm diameter and 1.0 cm length were freeze-dried and placed into the femoral arteries of 15 Sprague-Dawley albino male rats in order to study patency and tissue reactions of the host. Patency in the first three postoperative days was determined by monitoring viability of the epigastric island flap. All grafts were patent during this early postoperative period. Fourteen of the subjects were surgically explored after 2 months of observation. At that time, 13 (93%) remained patent. Histopathological studies, and transmission and scanning electron microscopy were used to analyze the specimens. These data demonstrated that freeze-dried arteries are remodeled by the host, but do not induce a cellular immune reaction. Dependable freeze-dried microarterial allografts have potential future application in clinical microvascular surgery.

Animals↗
PubMed1986

Filamentous structures morphologically similar to viral nucleocapsids in otosclerotic lesions in two patients.

Two of four patients with active stapedial otospongiosis had abnormal filamentous structures in osteoblast-like cells. These structures were rare in these cells and did not occur in any other cells. The structures were 17 nm wide and clustered in a loose skein in dilated cisternae of the rough endoplasmic reticulum. They resembled the nucleocapsids of subacute sclerosing panenecephalitis, a variant of measles virus.

Capsid↗
PubMed1983

A mixed carcinoid tumour of the middle ear.

Carcinoid tumours belong to the rarest neoplasms of the middle ear. Murphy et al. (1980) described an interesting carcinoid tumour of the middle ear displaying adenomatous features. The histological similarity of carcinoid tumours to adenomatous tumours of the middle ear has also been noted by Fayemi and Toker (1975). We describe a similar case which caused certain diagnostic difficulties. Light microscopy on frozen sections favoured the diagnosis of a low-grade adenocarcinoma but electron microscopy has revealed the presence of many intracellular membrane-bound neurosecretory granules and the diagnosis was revised to that of a mixed carcinoid tumour.

Adult↗
PubMed1981

Human vestibular epithelia: prospects for future study.

The lateral ampullae of thirteen patients, removed during translabyrinthine surgery for various disorders, have been examined with light and electron microscopy. Correlation of results of vestibular function tests with changes of histology and ultrastructure have been attempted. Light and electron microscopy revealed the same features that other investigators have reported as pathologic changes in the sensory epithelium and associated subepithelial structures. The occurrence of these features did not correlate with the vestibular function tests, indicating that these features, in our tissue samples, were handling and preparation artifacts. Two observations made in a specimen from a patient with Meniere's disease were difficult to ascribe to handling or preparation artifact. One was the presence of densely stained granular inclusions in the basal portion of the sensory epithelium. The location and contents of these inclusions as seen in the electron microscopy indicated they were hypertrophied degenerating nerve terminals. Similar inclusions were also seen in the axoplasm of myelinated nerve fibers in the sensory subepithelial connective tissue. The other observation believed to be relevant to the symptoms of Meniere's disease, was the presence of widened tight junctions between adjoining sensory and supporting epithelial cells. The attempt at correlation of histologic and ultrastructural changes of ampullae with vestibular function has made possible some differentiation between pathology and artifact. The significance of the ultrastructural observations is discussed.

Adult↗
PubMed1980

Initiation and stages of mineralization in tympanosclerosis.

The ultrastructure of tympanosclerotic tissue is described with particular reference to the structure of matrix vesicles and calcospherules, often of intricate structure, and to their role in the induction of calcification. The vesicles formed by degenerating cells within the collagenous matrix or epithelium of the tympanosclerotic tissues are the primary site of calcification. The released spherules appear scattered throughout the collagenous layers, and form the organic basis of calcospherules. Through fusion larger aggregates are formed which lead to the development of macroscopically recognizable calcified plaques in the middle ear cleft. The entire process is triggered off by the inflammatory processes of otitis media. Compared with other processes of excessive fibrogenesis and calcification, tympanosclerosis fits well into the overall scheme of induced calcification in both normal and pathological conditions which is similar in all mineralizing tissues composed of collagen and protoglycons. The cause of the prolific fibrogenesis and mineralization has remained doubtful. Clearly inflammatory and degenerative processes in otitis media may trigger off the release of a factor (or factors), and of matrix vesicles acting as fibrogenetic stimulants and primary sites of calcification. Katchburian's working hypothesis of mineralization (Katchburian, 1973) has universal appeal and can be confirmed on the basis of our observations on tympanosclerosis. Tympanosclerosis may be added to the 'crystal deposition diseases' of McCarthy.

Calcinosis↗
PubMed1980

Scanning and transmission electron microscopy of the rugose portion of the human endolymphatic sac--a preliminary report.

The rugose portion of two human endolymphatic sacs--one from a Meniere's disease patient, the other from a patient who underwent removal of an eighth nerve tumor and had no other evidence of inner ear disease--has been examined by scanning and transmission electron microscopy. The only morphological finding that distinguished the normal from the Meniere's disease specimen was more folds in the epithelium of the normal sac. Two types of cells have been distinguished in the two sacs through both scanning and transmission electron microscopy: cuboidal-to-columnar cells with a convex luminal surface and microvilli, and squamous cells with a flat luminal surface and microvilli. Qualitative differentiation of the two specimens according to frequency of cellular type or difference in cellular or microvillar morphology was not possible. Observations of this study on the epithelial morphology of the rugose portion did not correspond with descriptions of the epithelial morphology in animals. It is, therefore, tentatively concluded that the morphology of the rugose portion of the human endolymphatic sac is different from that of animals. This study suggests that scanning electron microscopy can be used to determine the number and location of cell types and/or the quantity of microvilli in the rugose portion of the endolymphatic sac. Comparison of measurements of normal endolymphatic sacs and those from Meniere's disease patients may demonstrate significant differences.

Ear, Inner↗
PubMed1980

Scanning electron microscopy of the human endolymphatic sac: a preliminary report.

Scanning electron microscopy has been used to examine and compare one normal endolymphatic sac with one endolymphatic sac from a patient with Meniere's disease. The surgical procedure for obtaining these specimens and their preparation for scanning electron microscopy are described. The luminal surface of the rugose portion of both specimens was lined with two populations of epithelial cells: one with a dome-shaped apical surface, the other with a flattened polygonal surface. The surface of dome-shaped cells in both specimens was covered with microvilli. Neither specimen had observable loss of epithelial integrity or fibrosis.

Ear, Inner↗