Graeme Clark Collection
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ItemPneumococcal meningitis post-cochlear implantation: preventative measures.(Wiley, 2010-11)OBJECTIVE: Both clinical data and laboratory studies demonstrated the risk of pneumococcal meningitis post-cochlear implantation. This review examines strategies to prevent post-implant meningitis. DATA SOURCES: Medline/PubMed database; English articles after 1980. Search terms: cochlear implants, pneumococcus meningitis, streptococcus pneumonia, immunization, prevention. REVIEW METHODS: Narrative review. All articles relating to post-implant meningitis without any restriction in study designs were assessed and information extracted. RESULTS: The presence of inner ear trauma as a result of surgical technique or cochlear implant electrode array design was associated with a higher risk of post-implant meningitis. Laboratory data demonstrated the effectiveness of pneumococcal vaccination in preventing meningitis induced via the hematogenous route of infection. Fibrous sealing around the electrode array at the cochleostomy site, and the use of antibiotic-coated electrode array reduced the risk of meningitis induced via an otogenic route. CONCLUSION: The recent scientific data support the U.S. Food and Drug Administration recommendation of pneumococcal vaccination for the prevention of meningitis in implant recipients. Nontraumatic cochlear implant design, surgical technique, and an adequate fibrous seal around the cochleostomy site further reduce the risk of meningitis.
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ItemPneumococcal meningitis post-cochlear implantation: potential routes of infection and pathophysiology.(Wiley, 2010-11)OBJECTIVE: This review describes the current concept of pneumococcal meningitis in cochlear implant recipients based on recent laboratory studies. It examines possible routes of Streptococcus pneumoniae infection to the meninges in cochlear implant recipients. It also provides insights into fundamental questions concerning the pathophysiology of pneumococcal meningitis in implant recipients. DATA SOURCES: Medline/PubMed database; English articles after 1960. Search terms: cochlear implants, meningitis, pneumococcus, streptococcus pneumonia. REVIEW METHODS: Narrative review. All articles relating to post-implant meningitis without any restriction in study designs were assessed and information extracted. RESULTS: The incidence of pneumococcal meningitis in cochlear implant recipients is greater than that of an age-matched cohort in the general population. Based on the current clinical literature, it is difficult to determine whether cochlear implantation per se increases the risk of meningitis in subjects with no existing risk factors for acquiring the disease. As this question cannot be answered in humans, the study of implant-related infection must involve the use of laboratory animals in order for the research findings to be applicable to a clinical situation. The laboratory research demonstrated the routes of infection and the effects of the cochlear implant in lowering the threshold for pneumococcal meningitis. CONCLUSION: The laboratory data complement the existing clinical data on the risk of pneumococcal meningitis post-cochlear implantation.
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ItemCriteria of suitability for cochlear implantation [Abstract]( [1990])In order to be considered for a cochlear implant, the person should have a profound bilateral hearing 1088, with little or no benefit from hearing aids. People with minimal open-set speech discrimination can be considered, with phoneme scores of up to 20% in the better ear, provided the ear to be implanted does not obtain significant open-set speech discrimination. Where there is any degree of benefit from hearing aids, even as an aid to lipreading, the poorer hearing ear is preferred for implantation. A team approach is necessary to detect and correct medical, learning and psychosocial problems. The CT scan has been designed to measure the patency of the cochlear spiral and detect any lesions of the internal auditory meatus, air cell system or emissary veins which could make for surgical difficulty. The electrical stimulation of the remaining auditory neurones by a needle on the promontory aims to confirm the responsiveness of the auditory nerve and should be performed on all candidates 12 years and older. There is a battery of assessments available but if the pulse cannot be detected before it reaches a current level producing pain the ear should not be implanted. The threshold and minimal gap detection tests have no prognostic value but the patient's observations about the percept produced by pulses of 50, 100 and 200pps are useful. There is a relationship between the ability to detect change in pulse rate and the postoperative CID sentence score. This may be used to choose a preferred ear and to give a guide to the possibility of a high or a low speech perception score. We believe the tests are an important part in gaining realistic expectations especially when the patient can listen to speech through a FO extraction speech processor attached to the needle.
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ItemInitial speech perception results with the new multipeak speech processor for the 22-electrode cochlear prosthesis [Abstract]( [1990])A new speech processor has been developed for the 22-electrode cochlear prosthesis by Cochlear Pty Ltd working in conjunction with the Department of Otolaryngology at the University of Melbourne. The new device, known as the MSP, combines smaller, more efficient hardware with a new speech coding scheme in an attempt to provide better speech perception in everyday environments for implant users. The MSP operates with the current implant device so there is no need for existing implantees to have revision surgery to make use of the new development. The multipeak speech coding scheme, which has been implemented in the MSP, provides information from three high frequency spectral bands, in addition to the parameters of voice pitch, amplitude and first and second formants which have been provided in the existing FOFIF2 coding scheme for the last four years. Initial speech perception results with research subjects have shown significant improvements in performance for the MSP over the older system (WSP III). The most encouraging result is that open-set speech perception in the presence of competing noise has improved substantially. For example, mean scores for BKB sentences in a 10 dB signal-to-noise ratio were 64% for the MSP and 31% for the WSP III. Further investigations have shown that both the hardware improvements and the new multipeak speech coding scheme have contributed significantly to the overall improvement in performance. Studies are continuing to analyse further the potential of the new system.
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ItemMultiple-channel cochlear implants for children [Abstract]( [1991])The children's program at The University of Melbourne Cochlear Implant Clinic involves a team of ENT surgeons, audiologists, speech pathologists and a teacher of the deaf. After a child is considered suitable for implantation, he/she enters a preoperative program for a minimum of three months. During this time, there is counselling of parents, liaison with teachers, weekly training in speech production, language and speech perception and baseline assessments in these three areas. The child continues to receive weekly training and regular assessments in the postoperative period. Twenty children have been implanted in Melbourne with the 22-electrode cochlear implant to date. Formal results have been collected over time for nine of these children. Five children (aged 6.0 to 14.8 years at implantation) have known open-set speech recognition through hearing. Four of these five children were implanted before adolescence and the fifth, who had a deteriorating loss, was implanted during adolescence. The remaining children who did not demonstrate open-set recognition, were implanted during adolescence after a long duration of profound deafness. Postoperative performance on closed-set speech perception tests was better that preoperative performance for the group of five children with open-set recognition. There were also improvements in speech and language assessments.