Graeme Clark Collection
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ItemIs deep insertion of the cochlea implant electrode array necessary and possible?( 1995)Hyaluronate (Healon TM) appears to be useful in achieving deeper electrode insertions than are generally achieved at present. However, biosafety studies are still being conducted. If found to be a safe technique, further work to explore different electrical stimulation strategies and speech processing schemes will also need to be undertaken. This work is ongoing.
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ItemClinical results with a multichannel pseudobipolar system( 1983)A receiver-stimulator and multiple-electrode array were implanted in the scala tympani of a 46-year-old totally deaf man on August 1, 1978. This patient had lost all hearing after a head injury 18 months prior to surgery. Pure-tone Bekesy and speech audiometry showed no hearing in either ear at the maximum output levels of the audiometer, and no vibrotactile responses were elicited. A second patient, a 63-year-old man, received an implant on July 17, 1979. This patient had a progressive sensorineural hearing loss extending over 30 years due to bomb blast and chronic infection. He had no help from a hearing aid for 13 years prior to surgery. Pure-tone Bekesy audiometry under headphones revealed no hearing in the left ear, and in the right he had thresholds of 125 dB SPL at 0.125 kHz; 115 dB at 0.25 kHz, and 117 dB at 0.5 kHz. There was no speech discrimination in either ear under headphones or in a monitored sound field. His right ear was fitted with a hearing aid (Calaid G12G) by the National Acoustics Laboratory, but at its maximum output level he received only a limited gain at 5.0 kHz and could not be aided. (From Introduction)
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ItemDesign and fabrication of the banded electrode array( 1983)A multiple-channel electrode array must meet certain design requirements; these are listed in TABLE 1. First, there should be no trauma associated with the surgical insertion, and if there is a need to replace the array, this procedure should also be atraumatic. Second, it should be biologically inert. This means that it should be biocompatible with the tissues. When placed in the cochlea, the array should also not predispose the patient to local infection, and this is particularly important in children, in whom recurrent middle ear infections could spread to the inner ear. There should also be no risk of carcinogenicity with long-term implantation. Third, the electrode array should be designed so that the stimulus current can be localized to discrete groups of nerve fibers, and it should also be possible to stimulate as many groups as possible from the total remaining nerve population. Fourth, with long-term stimulation, there should be no significant corrosion of the electrodes used, and the electrical stimulation should not lead to damage of the tissues in the cochlea, especially the residual nerve fibers. Fifth, the electrode array should be mechanically robust and stable. It should not be prone to break as a result of repeated stress by the acceleration of the head during everyday movements. The array should also be capable of being fixed in place so that it will not shift its position. Sixth, it is desirable that the means of fabrication of the multiple-channel array should be simple and inexpensive. (From Introduction)