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Biomedical subjects

F R Galey

Publications and source records attributed to F R Galey.

7 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↗