Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 3 of 3
-
ItemMultichannel cochlear implants in children: an overview of experimental and clinical results [Abstract]( 1991)During the last decade there has been great progress in the clinical management of profound, postlinguistically deafened adults through the use of multichannel cochlear implants. The device developed by Cochlear Pty. Ltd. in association with the University of Melbourne, electrically stimulates selective regions of the residual auditory nerve using an array of 22 Pt electrodes located within the scala tympani. A speech processing strategy has been developed to provide patients with both voice pitch, and first and second formant information. Following experimental safety studies and successful clinical trials, this device was approved for use in adults by the United States FDA in 1985. In 1990, following further miniaturization of the implant, the FDA approved the device for use in profoundly deafened children above the age of two years. The present paper presents an overview of our recent biological safety studies and clinical experience with cochlear implants in children, and discusses the likely future development of these devices. Our biological safety studies were designed to evaluate the safety and design requirements of cochlear implantation in children, and more recently has focussed on issues for implantation in very young children (< 2 years old). These studies included the measurement of growth in the human temporal bone and the development of lead wires that can accommodate such growth, the development of an electrode fixation technique close to the cochlea, the effect of cochlear implantation on skull growth, the effect of long-term electrical stimulation on the maturing auditory system and the stimulating electrodes, and the effect of middle ear infection on cochlear implantation. Our clinical experience is based on twenty-five children that have now been implanted in our clinic. They include (i) postlinguistically deafened children; (ii) congenitally or early-deafened young children; and (iii) congenitally or early deafened adolescents. Clinical testing has shown improvements in speech perception, speech production and language in all three groups. Postlinguistically deafened children show similar speech perception results to postlinguistically deafened adults. For the congenitally deaf, younger children tend to show better results than the adolescents. Significantly, these clinical results are consistent with results from 142 children obtained from clinics throughout the world. These experimental and clinical results support the use of cochlear implants in young children. Further clinical improvements can be expected in the future with advances in both hardware and speech processing strategies.
-
ItemClinical results for children using the 22-channel cochlear prosthesis [Abstract]( 1991)Twenty five profoundly/totally hearing-impaired children aged between 2 and 18 years have been implanted with the 22-channel cochlear prosthesis (Cochlear Pty. Ltd.) at The University of Melbourne over the last five years. Speech perception, speech production and language development have been monitored for these children both pre- and postoperatively. Results have shown improvements for all children in speech perception, postoperatively. The younger children (< 12 years) and those with an acquired (postlinguistic) profound hearing loss, have demonstrated some open-set speech recognition without visual clues. In general, older children with a prelinguistic profound hearing loss have not attained this level of performance. Improvements in speech production and language have also been demonstrated and tend to occur faster in younger children. Importantly, a number of congenitally deaf young children have shown significant improvements in speech perception, production and language. Important factors in the success of cochlear implants in children appear to be: educational environment - it is vital to have a strong auditory component (i.e. non-signing); careful attention to correct programming and maintenance of the prosthesis; support of family and other professionals.
-
ItemMultichannel cochlear implantation in Usher's Syndrome(Kelleher & Associates, 1990)Four patients with Usher's syndrome have been implanted with the multichannel cochlear prosthesis developed by the University of Melbourne and Cochlear Pty. Ltd. All four patients have made good progress with the implant and use the device during most waking hours. One subject, an adult who developed speech and language before developing profound deafness, has learned to use the cochlear implant for auditory alone communication. Her results on speech perception testing compare favourably with other implanted adults. The other subjects were adolescents or young adults when implanted and had congenital profound or total hearing losses. These subjects retained adequate vision for lipreading but had lost hearing before the development of speech and language. Results for these subjects have indicated that the cochlear implant significantly aids lipreading and improves the detection and recognition of environmental sounds. However, they have not, as yet, been able to use the device for communication in the auditory alone condition. The ability to use the device in this condition would become important should vision deteriorate further. These preliminary results suggest that for patients with Usher's syndrome where deafness is progressive and speech and language have developed normally, the multichannel cochlear implant can provide an alternative auditory communication system when vision is no longer functional. When Usher's syndrome has caused a congenital profound deafness, it maybe necessary for the cochlear implant to be integrated into the child's normal speech and language development from an early age to obtain optimal results.