Graeme Clark Collection

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    Multicenter evaluations of speech perception in adults and children with the nucleus (cochlear) 22-channel cochlear implant
    Clark, Graeme M. ; Dowell, Richard C. ; Cowan, Robert S. ; Pyman, Brian C. ; Webb, Robert L. (Kugler, 1996)
    The Nucleus 22-channel cochlear implant has been implanted in over 10,500 patients in 79 countries. and used for more than 25 languages. It arose as a result of our early physiological, behavioral and biological research on experimental animals. The historical development of the Nucleus device has been outlined in detail by Clark. Our ongoing research has led to improvements in the way speech is processed with the 22-channel device that are now resulting in improved speech perception for profoundly totally deaf people that is, on average, better than the speech perception obtained by many deaf people with hearing aids. The multiple-channel cochlear implant was first approved by the US Food and Drug Administration (FDA) for use in postlinguistically deaf adults in 1985. It was subsequently approved for use in children in 1990. The proportion of children (18 years of age and under) to have now received it is approximately 439C (4,500 out of 10.500). In evaluating improvements in speech processing it is important to design well-controlled studies, and a number of important ones which have previously been published are summarized in this paper. In addition, speech perception results for all the Nucleus speech processing strategies have been obtained four to six months postoperatively from unselected patients presenting to the Cochlear Implant Clinic at the Royal Victorian Eye & Ear Hospital (RVEEH), Melbourne, and are presented in this paper. As results can vary greatly with different durations of experience it is essential to make comparisons at the same time postoperatively. These clinical data are the most complete to date for comparing the Nucleus speech processing strategies.
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    Selection of patients for multiple-channel cochlear implantation
    Brown, A. M. ; Dowell, R. C. ; Clark, Graeme M. ; Martin, L. F. A. ; Pyman, B. C. (Raven Press, 1985)
    Only profoundly, bilaterally deaf adults are considered for evaluation. It is necessary to determine that the patient's communication ability cannot be improved to any significant degree with conventional hearing aids currently available. Initial assessment consists of audiometry, hearing aid evaluation(s), otological and medical examination, and for patients with no recent experience with hearing aids, a hearing aid trial. Polytome x-rays of temporal bones is carried out to ensure that cochlea structures are not grossly abnormal. Electrical stimulation of the promontory is used to confirm the presence of residual auditory nerve fibers. Where there is an audiometric difference between ears, the poorer ear is chosen for implantation provided there are no other contraindications. Intensive counselling is carried out to enable patients to make a fully informed decision about implantation. Patients undergo a battery of speech discrimination and lipreading tests with their hearing aid after their hearing aid trial. This is to provide a baseline for comparison with postoperative results and to assess the benefit obtained from the hearing aid. Any significant improvement in test results when using a hearing aid over lipreading alone would be a contraindication for implantation. Medical assessment is carried out as for any major surgery, including pathology, respiratory function tests and cardiovascular assessment. Particular emphasis is placed on infection prevention immediately preoperatively and during surgery.