Graeme Clark Collection

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http://hdl.handle.net/11343/375

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Author: Shepherd, Robert × End date: 1999 × Start date: 1990 × Type: Journal Article × Subject: cochlear implants × Subject: deafness ×

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    Acute effects of high-rate stimulation on auditory nerve function in guinea pigs
    Tykocinski, M. ; Shepherd, R. K. ; Clark, Graeme M. ( 1995)
    Cochlear implants have been shown to successfully provide profoundly deaf patients with auditory cues for speech discrimination. Furthermore, a number of safety studies using the Melbourne/Cochlear electrode array indicated that chronic electrical stimulation using charge-balanced biphasic current pulses and stimulus rates between 100 and 500 pulses per second (pps) do not result in additional spiral ganglion loss or general cochlear pathology.1-3 However, safe maximum levels for stimulus parameters (stimulus rate, charge per phase, charge density) have not yet been adequately defined.
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    Partial hearing loss in the macaque following the co-administration of kanamycin and ethacrynic acid
    Shepherd, R. K. ; Xu, S. A. ; Clark, Graeme M. ( 1994)
    Co-administration of kanamycin (KA) with the loop diuretic ethacrynic acid (EA) rapidly produces a profound hearing loss in the cat while maintaining normal renal function [Xu et al., Hear. Res. 70, 205-215 (1993)]. In the present paper we have applied this deafening procedure to the old world monkey Macaca fascicularis (macaque). Following the co-administration of KA and EA, the hearing loss in the macaque developed far slower than we observed in the cat. Moreover, unlike the cat, there was evidence of a partial recovery in the animal’s hearing, resulting in a bilaterally symmetrical high frequency hearing loss. The extent of this hearing loss was dependent on the dose of the EA administered. Finally, the most unexpected result of the present study was the degree of acute nephrotoxicity experienced by these animals following the drug administration. The sensitivity of this species to renal failure restricted the dose of EA that could be safely administered. In conclusion, the co-administration of KA and EA cannot reliably produce a profound hearing loss in the macaque. While it can produce a dose dependent high frequency hearing loss the animal will also experience acute renal failure that requires careful management.