Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 7 of 7
-
ItemThe effect of inflammation on blood vessel area as a cause of variation in ganglion cell density measurements in the cat cochlea [Abstract]( 1992)The success of a cochlear implant depends on an adequate number of surviving spiral ganglion cells. Further loss of ganglion cells may arise from the biology of cochlear implantation itself. The quantitative analysis of ganglion cells is, therefore, an important consideration when assessing the biological safety of a cochlear implant.
-
ItemMultichannel cochlear implants in children: an overview of experimental and clinical results at the University of Melbourne [Opening Lecture]( 1992)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 The University of Melbourne in association with Cochlear Pty Ltd, electrically stimulates selective regions of the auditory nerve using an array of 22 platinum (Pt) electrodes located in the scala tympani. Its development followed basic experimental studies and the development and evaluation of a prototype device in the 1970's. Following safety studies and a successful clinical trial, the Melbourne/Cochlear multichannel implant was approved for use in adults by the United States Food and Drug Administration (FDA) in 1985. More than 3000 patients throughout the world have since been implanted with this device, many being able to understand a significant amount of unfamiliar, connected speech without lipreading Following miniaturization of the implant, it became suitable for use with children. In 1990, after additional biological safety and clinical investigations, the FDA approved the use of the Melbourne/Cochlear multichannel implant for profoundly deaf children above the age of two years. And in 1991, the device received the medical device implantation approval certificate from the Japanese Government. The present paper presents an overview of our recent biological safety studies and clinical experience in children, and discusses the likely future development of these devices.
-
ItemAn antibacterial seal and fixation device for cochlear implants in young children [Abstract]( 1992)Concerns associated with cochlear implantation in young children include intracochlear spread of infection along the electrode array during otitis media, and electrode extraction caused by skull growth post-implantation. New biomaterials were used to seal and secure the electrode at its entry point into the cochlea. Hydroxyapatite was deposited around the outside of an electrode cuff and it bonded well to the surrounding bone of the otic capsule. The electrode cuff accommodated variable insertion depths with the help of a new, silicone based hydroscopic polymer. Preliminary results, including experimental testing of the device in an animal model of pneumococcal otitis media, indicate protection of the implanted cochlea against the spread of infection. Electrode leadwire displacement is prevented by fixation of the array at its entry point This concept may play an important role in the development of a safe cochlear implant design for children under two years of age, who are expected to benefit most from early auditory rehabilitation.
-
ItemCochlear implantation in young children: studies on head growth, leadwire design and electrode fixation in the monkey model [Abstract]( 1992)For the safety of cochlear implantation in children under two, the implant assembly must not adversely effect the tissue of compromise head growth. Furthermore, growth changes and tissue responses should not impair functioning of the device. Dummy receiver-stimulators, interconnect plugs and leadwire-lengthening systems have been implanted for periods of 40 months in the young monkey to most effectively model the implantation of the young human child. The results show that implanting a receiver-stimulator package has no effect on skull growth or brain tissue under the package. The system for fixing the electrode at the fossa includes proved effective. There was marked osteoneogenesis in the mastoid cavity and this also resulted in fixation of the leadwire outside the cochlea. This study provides evidence for the safety of cochlear implantation in young children.
-
ItemCochlear implantation in young children: long-term effects of implantation on the skull and underlying central nervous system tissues in a primate model [Abstract]( 1992)Recent independent studies reporting results obtained by profoundly deaf children implanted with the Melbourne 22-channel cochlear implant have provided further impetus for assessing the feasibility of implanting children under two. Studies in appropriate animal models must first establish the safety of this procedure.
-
ItemCochlear implantation in young children: long-term effects of implantation on normal hair cells and spiral ganglion cells in the monkey model [Abstract]( 1992)Recent independent results obtained by profoundly deaf children implanted with the Melbourne 22-channel cochlear implant (1) have provided further impetus. for examining thefeasibility of implanting children under two and children with profound deafness. Safety st1,ldies, in appropriate animal models, must first establish the safety of this procedure.
-
Item