Graeme Clark Collection
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ItemHearing restoration with the multichannel auditory brainstem implant( 1997)Restoration of useful hearing is now possible in patients with bilateral acoustic neuromas by direct electrical stimulation of the cochlear nucleus. Our first experience with the Multichannel Auditory Brainstem Implant is reported. A forty four year old female with bilateral acoustic neuromas and a strong family history of Neurofibromatosis Type II presented with profound bilateral hearing impairment. Translabyrinthine removal of the right tumour was performed with placement of the Nucleus eight electrode Auditory Brainstem Implant. Intraoperative electrically evoked auditory brainstem response monitoring successfully confirmed placement over the cochlear nucleus. Postoperatively, auditory responses were obtained on stimulation of all electrodes with minimal non-auditory sensations. The patient now receives useful auditory sensations using the "SPEAK" speech processing strategy. Auditory brainstem Implantation should be considered for patients with Neurofibromatosis Type II in whom hearing preservation tumour removal is not possible.
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ItemObjective hearing level estimation in infants with severe to profound impairment: role of Steady State Evoked Potential threshold testing [Abstract]( 1998)Accurate determination of hearing levels in potential cochlear implant candidates is an important part of pre-operative investigation. This is particularly the case for children younger than two years of age in whom speech perception testing is not possible. We have found the Steady-State Evoked Potential (SSEP) technique to be a reliable and accurate objective measure of residual hearing. Threshold estimation using the click-evoked auditory brainstem response cannot quantify hearing loss in the severe to profound range because of the presentation level restriction (? 100 dBnHL) and the broadband stimulus. The SSEP technique employs modulated tones at levels as high as 120 dBHL and can be used to estimate the audiograms of subjects with little or no residual hearing and absent click-auditory brainstem responses. We have demonstrated a strong relationship between behavioural and SSEP thresholds and believe that the procedure provides an important safeguard in the paediatric selection process. The possible exception is in children with retrocochlear abnormalities such as �Auditory Neuropathy�. In these subjects we have found poorer correlation between SSEP and behavioural thresholds.
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ItemHearing restoration with the multichannel auditory brainstem implant [Abstract]( 1996)Restoration of useful hearing is new possible in patients with bilateral acoustic neuromas by direct electrical stimulation of the cochlear nucleus.