Graeme Clark Collection
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ItemWhere to now? - Impact of New Technologies on use of cochlear implants( 2000)The history of cochlear implant use by adults and children with profound hearing loss although relatively short (20 some years), has been characterised by continual technological innovations which have enhanced the performance, packaging, and clinical use of these devices. In particular, the development of the Nucleus multiple channel cochlear implant has included a series of speech processing hardware and speech processing strategy, implemented by Cochlear Limited, and based on research findings that have resulted in an increase in mean speech perception benefits for adults and children.
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ItemSafety studies for a prototype Nucleus 22 channel implant at high stimulation rates [Abstract]( 1995)The safe stimulation of neural tissue requires that the stimulation does not produce any toxic electrochemical by-products and that the nerves are not damaged by the very act of responding to the stimulation. The Nucleus stimulator has been proven safe in several chronic animal studies using pulse rates of up to 500 pps and stimulus levels that produced sensations of moderate loudness, and subsequently in clinical use by more that 10,000 patients. Additional safety studies are necessary before considering the use of the Nucleus stimulator at higher rates. This paper describes in vitro investigations using such high rates while animal studies are currently under way to examine the effects of chronic, high rate stimulation.
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ItemRadiological evaluation of multiple-channel intracochlear implant insertion depth [Abstract]( 1993)Post-operative plain film x-rays are necessary in all multiple-channel cochlear implant patients to confirm intracochlear position of active electrodes, detect possible electrode kinking and provide a reference if post-operative slippage occurs. In addition precise documentation of multiple-channel intracochlear electrode insertion depths is necessary for comparison of speech recognition results between patients and may be of use for future speech processing strategies. In the present study a method has been devised using a modified Stenver's view to more accurately document insertion depths of the electrode array and location of individual electrodes on 50 multiple-channel cochlear implant patients. Surgical estimates of insertion depth are shown to have great variability in regard to distance along the basilar membrane when compared with x-ray documentation. The technique shows promise to facilitate mapping of binaural implant patients, young children, difficult adult cases, and possible new speech processing strategies as well as research activities requiring localization of individual electrodes.
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ItemClinical comparison of open-set speech perception with MSP and WSPIII speech processors and preliminary results for the new SPEAK processor [Abstracts]( 1993)There are several studies which compare the WSP III (FOIF11F2) and MSP (Multipeak) speech processors for the Nucleus multiple-channel cochlear implant in small, controlled groups of patients. In the present study we were interested in the benefits of open set speech perception provided by the MSP over the prior WSP III speech processor in a large, unselected clinical population.
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ItemChronic electrical stimulation of the auditory nerve in cats( 1982)One requirement for the success of a cochlear hearing prosthesis is that long-term electrical stimulation must not have adverse effects on the residual spiral ganglion cell population. Electrochemically 'safe' stimulation regimes have been defined for the cortex (Brummer &Turner, 1977). However, few investigators have examined the effects of long-term intracochlear electrical stimulation. Walsh et al (1980), stimulating with current densities greater than the 'safe' limits defined by Brummer &Turner (1977), for periods of up to 800 hours at current levels of 4.0-8.0 mA, recorded slight local neural degeneration adjacent to the electrodes.