Graeme Clark Collection

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Author: Shepherd, Robert × End date: 1992 × Start date: 1992 × Type: Conference Item × Subject: cochlear implant × Subject: otolaryngology ×

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    Investigation of curved intracochlear electrode arrays [Abstract]
    Xu, Shi-Ang ; Xu, J. ; Seldon, H Lee. ; Shepherd, R. K. ; Clark, G. M. ( 1992)
    It has been demonstrated that the Melbourne/Cochlear multi-channel cochlear implant is safe and effective for use in profoundly-totally deaf patients. Recent studies have highlighted the importance of deaf insertion and placing the electrodes closer to the spiral ganglion neurons. In order to improve the electrode insertion depth and proximity to the modiolus, we have investigated curved electrode arrays. Prototypes of such arrays and their accessory inserter have been made. Trial insertions were performed on skeletonized cochleae of human temporal bones. The preliminary results showed that, when compared with conventional straight electrode arrays, the curved arrays could be inserted deeper and located closer to the modiolus. These findings indicate that the curved --.~ electrodes currently under investigation should result in a reduction in stimulus threshold and improve pitch perception and may also result in the use of more channels of stimulation.
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    Electrical stimulation of the auditory nerve in deaf kittens: effects on the spiral ganglion [Abstract]
    Shepherd, R. K. ; Matsushima, J ; Clark, Graeme M. ( 1992)
    Cochlear pathology following the administration of ototoxic drugs results in a widespread and rapid loss of sensory hair cells followed by a gradual degeneration of auditory nerve fibres and their cell bodies, the spiral ganglion. Recently, two studies have described increased spiral ganglion cell survival in the cochleas of deafened animals following chronic electrical stimulation of the auditory nerve (Hartshorn et al., 1991; Leake et al., ]991). If electrical stimulation is shown to have a trophic effect on degenerating auditory nerve fibres, these findings will significantly influence the preoperative management of cochlear implant patients. The aim of the present study was to corroborate these earlier reports and to evaluate the general tissue response of deafened cochleae in young animals following chronic electrical stimulation.
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    Multichannel cochlear implants in children: an overview of experimental and clinical results at the University of Melbourne [Opening Lecture]
    Shepherd, R. K. ; Dowell, R. C. ; Xu, S-A. ; McDermott, H. J. ; McKay, C. M. ; Clark, Graeme M. ( 1992)
    During the last decade there has been great progress in the clinical management of profound, postlinguistically deafened adults through the use of multichannel cochlear implants. The device developed by The University of Melbourne in association with Cochlear Pty Ltd, electrically stimulates selective regions of the auditory nerve using an array of 22 platinum (Pt) electrodes located in the scala tympani. Its development followed basic experimental studies and the development and evaluation of a prototype device in the 1970's. Following safety studies and a successful clinical trial, the Melbourne/Cochlear multichannel implant was approved for use in adults by the United States Food and Drug Administration (FDA) in 1985. More than 3000 patients throughout the world have since been implanted with this device, many being able to understand a significant amount of unfamiliar, connected speech without lipreading Following miniaturization of the implant, it became suitable for use with children. In 1990, after additional biological safety and clinical investigations, the FDA approved the use of the Melbourne/Cochlear multichannel implant for profoundly deaf children above the age of two years. And in 1991, the device received the medical device implantation approval certificate from the Japanese Government. The present paper presents an overview of our recent biological safety studies and clinical experience in children, and discusses the likely future development of these devices.
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    Cochlear implantation in young children: long-term effects of implantation on normal hair cells and spiral ganglion cells in the monkey model [Abstract]
    Burton, Martin J. ; Shepherd, R. K. ; Xu, S-A. ; Clark, Graeme M. ( 1992)
    Recent independent results obtained by profoundly deaf children implanted with the Melbourne 22-channel cochlear implant (1) have provided further impetus. for examining thefeasibility of implanting children under two and children with profound deafness. Safety st1,ldies, in appropriate animal models, must first establish the safety of this procedure.